Anatomy of Flowring Plants

Topic: Permanent Tissues; Subtopic: Collenchyma

Keyword Definitions:

• Collenchyma: A living mechanical tissue that provides flexibility and support to growing plant parts.

• Parenchyma: A simple permanent tissue responsible for storage and photosynthesis.

• Sclerenchyma: Dead supportive tissue with lignified thick walls providing strength to mature parts.

• Epidermis: The outermost protective layer of cells in plants.

• Cellulose: A carbohydrate forming the main component of plant cell walls.

Lead Question - 2022 (Abroad)
Which of the following is not a character of collenchyma tissue?
1. They provide mechanical support to the growing part of the plant
2. They occur in layers below epidermis in dicotyledonous plants
3. They consist of cells with thick corners due to cellulose deposition
4. They are usually dead and without protoplasts
Explanation: Collenchyma cells are living and have a protoplast, unlike sclerenchyma which are dead. They possess unevenly thickened cellulose walls and occur beneath the epidermis in dicot stems to provide mechanical support. Hence, the statement “They are usually dead and without protoplasts” is incorrect. Therefore, the correct answer is option 4.

1. Collenchyma differs from sclerenchyma in being:
1. Living and flexible
2. Dead and rigid
3. Dead but elastic
4. Living and lignified
Explanation: Collenchyma is a living tissue with cellulose-thickened corners that provides flexibility and mechanical strength to young plant parts. Sclerenchyma is dead and lignified. Hence, collenchyma is living and flexible. Therefore, the correct answer is option 1.

2. Which of the following plant organs commonly contains collenchyma?
1. Mature roots
2. Petioles and leaf midribs
3. Secondary xylem
4. Pith of stem
Explanation: Collenchyma occurs in the petioles and leaf midribs of dicots where flexibility and strength are required. It is rarely found in roots or secondary xylem. The pith mainly consists of parenchyma. Hence, the correct answer is option 2.

3. Collenchyma thickening is mainly due to deposition of:
1. Lignin
2. Cutin
3. Cellulose and pectin
4. Suberin
Explanation: The thickening of collenchyma cell walls occurs due to deposition of cellulose, hemicellulose, and pectin in the corners, making them flexible yet strong. Lignin deposition is characteristic of sclerenchyma. Hence, the correct answer is option 3.

4. In dicot stems, collenchyma is located:
1. Just below the epidermis
2. In the central pith region
3. Around vascular bundles
4. Within xylem elements
Explanation: In dicot stems, collenchyma forms a continuous or discontinuous layer just below the epidermis (hypodermis). It provides mechanical support and flexibility to growing parts. Therefore, the correct answer is option 1.

5. The mechanical tissue that remains alive at maturity is:
1. Sclerenchyma
2. Collenchyma
3. Xylem fibers
4. Tracheids
Explanation: Among the mechanical tissues, only collenchyma remains alive at maturity and provides flexibility to young stems and leaves. Sclerenchyma, xylem fibers, and tracheids are dead at maturity. Hence, the correct answer is option 2.

6. Collenchyma is absent in:
1. Dicot stem
2. Monocot stem
3. Dicot petiole
4. Leaf midrib
Explanation: Collenchyma is typically absent in monocot stems, where mechanical support is provided by sclerenchyma fibers and vascular bundles. Dicot stems and petioles commonly possess collenchyma beneath the epidermis. Hence, the correct answer is option 2.

7. Assertion (A): Collenchyma provides flexibility to plants.
Reason (R): Collenchyma cells have lignified secondary walls.
1. Both A and R are true, and R is the correct explanation of A
2. Both A and R are true, but R is not the correct explanation of A
3. A is true but R is false
4. A is false but R is true
Explanation: Collenchyma provides flexibility because its cell walls are thickened by cellulose and pectin, not lignin. Lignin causes rigidity and is found in sclerenchyma. Hence, A is true but R is false. The correct answer is option 3.

8. Match the following:
A. Collenchyma — (i) Lignified thick walls
B. Parenchyma — (ii) Storage tissue
C. Sclerenchyma — (iii) Flexible support
1. A-(iii), B-(ii), C-(i)
2. A-(ii), B-(i), C-(iii)
3. A-(i), B-(iii), C-(ii)
4. A-(ii), B-(iii), C-(i)
Explanation: Collenchyma provides flexible support, parenchyma serves as storage tissue, and sclerenchyma has lignified walls giving rigidity. Hence, the correct matching is A-(iii), B-(ii), C-(i). The correct answer is option 1.

9. Fill in the blank:
_________ is a living mechanical tissue found beneath the epidermis of dicot stems.
1. Sclerenchyma
2. Collenchyma
3. Parenchyma
4. Chlorenchyma
Explanation: Collenchyma is a living mechanical tissue present beneath the epidermis in dicot stems. It supports growing parts and allows bending without breaking. Sclerenchyma is dead, while parenchyma and chlorenchyma are mainly storage and photosynthetic tissues. Hence, the correct answer is option 2.

10. Choose the correct statements:
1. Collenchyma is dead at maturity.
2. Collenchyma provides flexibility to plant organs.
3. Collenchyma cells have uniformly thickened walls.
4. Collenchyma is present in monocot roots.
Explanation: Collenchyma is a living, flexible mechanical tissue with unevenly thickened walls providing support to young plant organs. It is found mainly in dicot stems and petioles. Hence, only statement 2 is correct. Therefore, the correct answer is option 2.

Topic: Secondary Growth; Subtopic: Cork Cambium (Phellogen) Activity

• Cork Cambium: A lateral meristem in plants producing cork (phellem) externally and sometimes phelloderm internally.

• Phelloderm: Living parenchymatous tissue produced internally by cork cambium.

• Phellem (Cork): Dead protective tissue produced externally by cork cambium, often impregnated with suberin.

• Suberin: Waxy substance making cell walls impermeable to water and gases.

• Lateral Meristem: Meristematic tissue that increases girth of stem and root.

• Periderm: Protective tissue replacing epidermis in secondary growth, composed of cork, cork cambium, and phelloderm.

• Secondary Growth: Increase in thickness of plant organs by activity of lateral meristems.

• Tannins: Phenolic compounds deposited in cork cells making them resistant to decay.

• Resins: Viscous substances in plants aiding in protection of tissues.

• Protective Tissue: Tissue preventing water loss, mechanical injury, and pathogen attack.

• Meristematic Activity: Active cell division in meristem producing new cells for growth.

Lead Question - 2022 (Abroad)

Select the correct statements related to the activity of cork cambium

1. The outer cells differentiate into phelloderm

2. The cork differentiated from cork cambium, is impervious to water due to deposition of tannins and resins

3. Cuts the cells only on the outer side

4. Cuts the cells on inner as well as outer side

Explanation: Cork cambium (phellogen) is a lateral meristem producing cork (phellem) externally and sometimes phelloderm internally. Cork cells are dead and impregnated with suberin, tannins, and resins making them impermeable. The cambium cuts cells both inward and outward to form protective periderm. Correct statements: 1, 2, 4. Answer: 1, 2, 4

Q1: Cork cambium is classified as:

1. Apical meristem

2. Lateral meristem

3. Intercalary meristem

4. Primary meristem

Explanation: Cork cambium is a lateral meristem involved in secondary growth, increasing the girth of stem and root. Apical meristems are for length, intercalary meristems are at nodes, and primary meristems give rise to primary tissues. Answer: Lateral meristem. Answer: 2

Q2: Phelloderm is formed by:

1. External cells of cork cambium

2. Internal cells of cork cambium

3. Cork cells

4. Parenchyma of cortex

Explanation: Cork cambium produces phelloderm internally (towards cortex) and cork externally (towards outside). Phelloderm is living parenchymatous tissue. External cells differentiate into cork, not phelloderm. Answer: Internal cells of cork cambium. Answer: 2

Q3: Cork cells become impervious to water due to:

1. Suberin deposition

2. Lignin deposition

3. Cellulose thickening

4. Cutin deposition

Explanation: Cork cells produced by phellogen die and develop walls impregnated with suberin, tannins, and resins, making them impermeable to water and gases. Lignin or cellulose alone do not provide complete impermeability. Answer: Suberin deposition. Answer: 1

Q4: Periderm is composed of:

1. Cork only

2. Cork and cork cambium only

3. Cork, cork cambium, and phelloderm

4. Phelloderm only

Explanation: Periderm is a protective tissue formed during secondary growth. It consists of three layers: cork (phellem) externally, cork cambium (phellogen), and phelloderm internally. This replaces the epidermis and protects the stem and root. Answer: Cork, cork cambium, and phelloderm. Answer: 3

Q5: Tannins in cork cells serve to:

1. Provide color

2. Prevent microbial attack

3. Increase cell division

4. Stimulate photosynthesis

Explanation: Tannins are phenolic compounds deposited in cork cells, making them resistant to decay and microbial attack. They are not involved in cell division, photosynthesis, or merely providing color. Answer: Prevent microbial attack. Answer: 2

Q6: Cork cambium cuts cells in which directions?

1. Outward only

2. Inward only

3. Both inward and outward

4. None of the above

Explanation: Cork cambium (phellogen) produces cork externally and phelloderm internally, thus cutting cells in both directions to form protective periderm. Cutting in only one direction is incorrect. Answer: Both inward and outward. Answer: 3

Q7: Assertion (A): Cork cells are dead and impermeable.
Reason (R): Cork cambium produces suberized cells externally.

1. A is correct but R is not correct

2. A is not correct but R is correct

3. Both A and R are correct and R explains A

4. Both A and R are correct but R does not explain A

Explanation: Cork cambium produces cork cells externally, which become dead and impregnated with suberin, tannins, and resins, making them impermeable. Both assertion and reason are correct, and reason explains why cork cells are dead and water-proof. Answer: Both A and R are correct and R explains A. Answer: 3

Q8: Match cork cambium products with their direction:

1. Cork    A. Outward
2. Phelloderm    B. Inward

1. 1-A, 2-B

2. 1-B, 2-A

3. 1-A, 2-A

4. 1-B, 2-B

Explanation: Cork (phellem) is produced externally by cork cambium (outward), while phelloderm is produced internally (inward). This directional growth forms protective periderm. Answer: 1-A, 2-B. Answer: 1

Q9: Protective tissue formed during secondary growth replacing epidermis is called ______.

1. Cork

2. Phelloderm

3. Periderm

4. Cortex

Explanation: Periderm replaces epidermis during secondary growth and consists of cork externally, cork cambium, and phelloderm internally. Cork alone is part of periderm; phelloderm is internal, cortex is primary tissue. Answer: Periderm. Answer: 3

Q10: Choose correct statements about cork cambium:

1. It is a lateral meristem

2. It produces cork externally

3. It produces phelloderm internally

4. Cork cells are living and permeable

Explanation: Cork cambium is a lateral meristem producing cork externally and phelloderm internally. Cork cells are dead and impermeable. Therefore, statements 1, 2, and 3 are correct. Statement 4 is incorrect. Answer: 1, 2, 3

Topic: Secondary Growth
Subtopic: Xylem and Annual Rings

Keyword Definitions:
• Springwood/Earlywood: Part of annual ring formed in early growing season, light-colored and less dense.
• Autumnwood/Latewood: Part of annual ring formed later in the season, darker and denser.
• Cambium: Lateral meristem responsible for secondary growth producing xylem and phloem.
• Xylem: Vascular tissue conducting water and minerals from roots to aerial parts.
• Annual Rings: Concentric rings in wood representing one year’s growth.
• Density: Mass per unit volume of wood.
• Vessel Elements: Long tubular cells in xylem for water conduction.
• Secondary Growth: Increase in girth due to cambium activity.
• Concentric Rings: Rings of alternating springwood and autumnwood.
• Light Colour: Characteristic of earlywood due to thin-walled xylem elements.

Lead Question (2022):
The anatomy of springwood shows some peculiar features. Identify the correct set of statements about springwood.
(a) It is also called as the earlywood
(b) In spring season cambium produces xylem elements with narrow vessels
(c) It is lighter in colour
(d) The springwood along with autumnwood shows alternate concentric rings forming annual rings
(e) It has lower density
Choose the correct answer from the options given below:
1. (a), (c), (d) and (e) Only
2. (a), (b) and (d) Only
3. (c), (d) and (e) Only
4. (a), (b), (d) and (e) Only

Explanation: The correct answer is 1. Springwood or earlywood has light-colored, thin-walled xylem elements with lower density. Cambium produces wider vessels, not narrow ones. Along with autumnwood, it forms annual rings, marking seasonal growth. These characteristics allow efficient water conduction during early growth in spring, distinguishing it from latewood.

Guessed MCQs:

1. Which wood is formed early in the growing season?
Options:
(a) Springwood
(b) Autumnwood
(c) Heartwood
(d) Sapwood
Explanation: The correct answer is (a) Springwood. Springwood, also called earlywood, forms during early growth in spring. It has thin-walled, light-colored xylem elements with lower density, enabling efficient water transport. Autumnwood forms later with thick-walled, dense xylem, contributing to annual ring formation.

2. Autumnwood is characterized by:
Options:
(a) Light-colored, thin-walled cells
(b) Darker, thick-walled cells
(c) Lower density
(d) Absence of annual rings
Explanation: The correct answer is (b) Darker, thick-walled cells. Autumnwood develops later in the growing season and is denser than springwood. It, along with springwood, forms annual rings. Its thick-walled structure helps mechanical support and water conduction regulation during dry seasons.

3. Assertion-Reason MCQ:
Assertion (A): Springwood has wider vessels for water conduction.
Reason (R): Early season growth requires efficient water transport.
Options:
(a) Both A and R are true, R explains A
(b) Both A and R are true, R does not explain A
(c) A is true, R is false
(d) A is false, R is true
Explanation: The correct answer is (a). Springwood vessels are wider and thin-walled, allowing maximum water conduction during early growth when demand is high. This structural adaptation supports rapid growth in spring, explaining the relationship between vessel width and functional requirement.

4. Matching Type MCQ:
Match the type of wood with its features:
List - I List - II
(a) Springwood (i) Dense, thick-walled cells
(b) Autumnwood (ii) Light-colored, thin-walled cells
Options:
1. a-i, b-ii
2. a-ii, b-i
3. a-i, b-i
4. a-ii, b-ii
Explanation: The correct answer is 2. Springwood is light-colored, thin-walled, and less dense. Autumnwood is darker, thick-walled, and denser. Together, they form annual rings. This differentiation is key in dendrochronology for studying plant growth patterns and environmental conditions.

5. What is the main function of springwood?
Options:
(a) Mechanical support
(b) Water conduction
(c) Photosynthesis
(d) Storage
Explanation: The correct answer is (b) Water conduction. Springwood’s thin-walled xylem cells and wide vessels allow efficient water transport during early growth in spring. Mechanical support is primarily contributed by denser autumnwood, while photosynthesis and storage are performed by leaves and parenchyma, respectively.

6. Which statement about annual rings is correct?
Options:
(a) Formed only by autumnwood
(b) Formed by alternating springwood and autumnwood
(c) Formed only by springwood
(d) Not visible in woody plants
Explanation: The correct answer is (b). Annual rings are concentric rings in wood formed by alternation of light-colored springwood and dense autumnwood. They indicate seasonal growth, help in age estimation of trees, and reflect environmental conditions during the year.

7. Fill in the Blanks:
The __________ formed in spring is light-colored and less dense.
Options:
(a) Autumnwood
(b) Heartwood
(c) Springwood
(d) Sapwood
Explanation: The correct answer is (c) Springwood. Formed during early growth in spring, it has thin-walled xylem elements and lower density, facilitating water transport. Its light color distinguishes it from autumnwood, which develops later with thick-walled, dense cells, contributing to structural support.

8. Single Correct Answer:
Which feature is NOT characteristic of springwood?
Options:
(a) Light color
(b) Thin-walled vessels
(c) High density
(d) Forms part of annual ring
Explanation: The correct answer is (c) High density. Springwood has low density due to thin-walled xylem cells. It is light-colored, forms part of annual rings along with autumnwood, and facilitates water conduction during early growth, contrasting with dense autumnwood formed later.

9. Which statement correctly describes earlywood and latewood?
Options:
(a) Earlywood dense, latewood light
(b) Both have same density
(c) Earlywood light, latewood dense
(d) Neither forms annual rings
Explanation: The correct answer is (c) Earlywood light, latewood dense. Earlywood forms in spring, with thin-walled, light-colored cells for water transport. Latewood forms later with thick-walled, dense cells providing mechanical support. Together, they create visible annual rings in woody plants.

10. Choose the correct statements:
(i) Springwood is less dense
(ii) Autumnwood is darker
(iii) Springwood forms part of annual rings
(iv) Autumnwood has thin-walled cells
Options:
(a) i, ii, iii
(b) i, iii, iv
(c) ii, iv
(d) i, ii, iv
Explanation: The correct answer is (a) i, ii, iii. Springwood is lighter and less dense, autumnwood is darker and dense. Together they form annual rings. Autumnwood has thick-walled, dense cells, not thin-walled. These features help in water conduction and mechanical support throughout the growing season.

Topic: Vascular Tissue System
Subtopic: Vascular Bundles

Keyword Definitions:

• Xylem: Vascular tissue that conducts water and minerals from roots to shoots and leaves.

• Phloem: Vascular tissue that transports organic nutrients, mainly sucrose, from leaves to other parts of the plant.

• Vascular Bundle: A strand of xylem and phloem tissue in stems, roots, or leaves.

• Cambium: A lateral meristem responsible for secondary growth in plants.

• Endarch: Protoxylem located towards the center of the stem.

• Conjoint Bundle: Xylem and phloem present together in a single bundle.

• Open Bundle: Vascular bundle with cambium present, allowing secondary growth.

• Closed Bundle: Vascular bundle without cambium, no secondary growth possible.

• Alternate Arrangement: Xylem and phloem arranged alternately along radii in root.

Lead Question (2022)
Read the following statements about the vascular bundles:
(a) In roots, xylem and phloem in a vascular bundle are arranged in an alternate manner along the different radii
(b) Conjoint closed vascular bundles do not possess cambium
(c) In open vascular bundles, cambium is present in between xylem and phloem
(d) The vascular bundles of dicotyledonous stem possess endarch protoxylem
(e) In monocotyledonous root, usually there are more than six xylem bundles present
Options:
(1) (b), (c), (d) and (e) only
(2) (a), (b), (c) and (d) only
(3) (a), (c), (d) and (e) only
(4) (a), (b) and (d) only

Explanation:
In vascular bundles, roots show alternate arrangement of xylem and phloem. Open bundles have cambium, closed bundles lack cambium. Dicot stems show endarch protoxylem, while monocot roots usually have fewer than six xylem bundles. Hence, statements (b), (c), (d), and (e) correctly describe vascular bundle characteristics. Correct answer is (1).

1. Which type of vascular bundle is present in monocot stem?
(1) Conjoint open
(2) Conjoint closed
(3) Radial
(4) Bicollateral

Explanation:
Monocot stems possess conjoint closed vascular bundles, meaning xylem and phloem are together without cambium, so secondary growth does not occur. Hence, the correct answer is (2).

2. In dicot root, the arrangement of vascular bundle is:
(1) Radial
(2) Conjoint open
(3) Conjoint closed
(4) Collateral closed

Explanation:
Dicot roots have radial vascular bundles, where xylem and phloem alternate along different radii. Cambium is absent in primary root bundles. Hence, the correct answer is (1).

3. The cambium is present in:
(1) Open vascular bundles
(2) Closed vascular bundles
(3) Monocot stem bundles
(4) All of the above

Explanation:
Cambium is a lateral meristem present in open vascular bundles, located between xylem and phloem, allowing secondary growth. Closed bundles lack cambium. Hence, the correct answer is (1).

4. In dicot stem, protoxylem is:
(1) Exarch
(2) Endarch
(3) Mesarch
(4) None of these

Explanation:
Dicot stem vascular bundles are endarch, meaning protoxylem is located towards the center while metaxylem is towards periphery. This is typical of dicot stems. Hence, the correct answer is (2).

5. In monocot root, the number of xylem bundles is usually:
(1) More than six
(2) Exactly four
(3) Less than six
(4) Variable but always even

Explanation:
Monocot roots generally contain fewer than six xylem bundles arranged radially. This contrasts with dicot roots, which usually have more. Hence, the correct answer is (3).

6. The vascular bundles of dicot stem are:
(1) Conjoint open
(2) Conjoint closed
(3) Radial
(4) Collateral closed

Explanation:
Dicot stems have conjoint open vascular bundles with cambium present, allowing secondary growth. Xylem is inner, phloem is outer. Hence, the correct answer is (1).

7. Assertion-Reason MCQ:
Assertion (A): Closed vascular bundles do not allow secondary growth.
Reason (R): They lack cambium between xylem and phloem.
(1) Both A and R are correct and R explains A
(2) Both A and R are correct but R does not explain A
(3) A is correct but R is false
(4) Both A and R are false

Explanation:
Closed vascular bundles lack cambium, so secondary growth is not possible. This directly explains why secondary growth does not occur. Hence, both A and R are correct, and R explains A. Correct answer is (1).

8. Matching Type:
Match the plant part with vascular bundle type:
A. Dicot stem — 1. Conjoint open
B. Monocot stem — 2. Conjoint closed
C. Dicot root — 3. Radial
D. Monocot root — 4. Radial
Options:
(1) A–1, B–2, C–3, D–4
(2) A–2, B–1, C–3, D–4
(3) A–1, B–2, C–4, D–3
(4) A–2, B–1, C–4, D–3

Explanation:
Dicot stems have conjoint open bundles, monocot stems have conjoint closed bundles. Dicot roots show radial arrangement, monocot roots also radial but usually simpler. Hence, the correct match is (1).

9. Fill in the Blanks:
The cambium is present in ______ vascular bundles, enabling secondary growth.
(1) Closed
(2) Open
(3) Radial
(4) Monocot stem bundles

Explanation:
Open vascular bundles possess cambium between xylem and phloem, allowing secondary growth. Closed bundles and monocot stems lack cambium. Hence, the correct answer is (2).

10. Choose the Correct Statements:
(a) Radial vascular bundles are present in roots.
(b) Endarch protoxylem is found in dicot stems.
(c) Closed bundles contain cambium.
(d) Open bundles allow secondary growth.
Options:
(1) (a), (b), (d) only
(2) (a), (c), (d) only
(3) All statements
(4) (b) and (c) only

Explanation:
Radial bundles are seen in roots, dicot stems have endarch protoxylem, and open bundles allow secondary growth. Closed bundles do not contain cambium. Hence, statements (a), (b), and (d) are correct. Correct answer is (1).

Topic: Secondary Growth

Subtopic: Heartwood and Sapwood Formation

Keyword Definitions:

• Secondary Xylem: The wood formed during secondary growth by the vascular cambium, consisting of tracheids, vessels, and fibers.

• Heartwood: The darker, non-functional inner wood formed by deposition of tannins, gums, and resins, providing strength and resistance to decay.

• Sapwood: The lighter, outer functional xylem that conducts water and minerals.

• Tannins and Resins: Secondary metabolites that make wood resistant to microbial and insect attack.

Lead Question (2022):

In old trees the greater part of secondary xylem is dark brown and resistant to insect attack due to:

(a) Secretion of secondary metabolites and their deposition in the lumen of vessels.
(b) Deposition of organic compounds like tannins and resins in the central layers of stem.
(c) Deposition of suberin and aromatic substances in the outer layer of stem.
(d) Deposition of tannins, gum, resin and aromatic substances in the peripheral layers of stem.
(e) Presence of parenchyma cells, functionally active xylem elements and essential oils.
(1) (c) and (d) Only
(2) (d) and (e) Only
(3) (b) and (d) Only
(4) (a) and (b) Only

Explanation (Answer: 4)
Old trees develop dark-colored heartwood due to the deposition of secondary metabolites like tannins, gums, and resins within xylem vessels. This process makes the wood hard, durable, and resistant to insect and fungal attacks, marking it distinct from sapwood, which remains physiologically active.

1. Heartwood differs from sapwood in being:

(1) Dark and non-functional
(2) Light and functional
(3) Living and soft
(4) Containing active vessels

Explanation (Answer: 1)
Heartwood is dark, non-functional, and contains deposits like gums, tannins, and resins. These make it resistant to microbial and insect damage, unlike sapwood, which is lighter and conducts water and minerals.

2. The lighter outer region of secondary xylem is called:

(1) Heartwood
(2) Sapwood
(3) Periderm
(4) Secondary phloem

Explanation (Answer: 2)
Sapwood is the lighter-colored outer xylem that remains functional in water and mineral transport. It eventually becomes heartwood as secondary growth continues and deposition of substances occurs.

3. Which of the following substances are commonly deposited in heartwood?

(1) Tannins, gums, and resins
(2) Starch and proteins
(3) Lipids and chlorophyll
(4) Pectins and cellulose

Explanation (Answer: 1)
Heartwood develops its characteristic color and durability from tannins, gums, and resins deposited in the xylem lumen, reducing permeability and preventing decay or insect infestation.

4. In secondary growth, vascular cambium produces:

(1) Secondary xylem and phloem
(2) Primary xylem and phloem
(3) Cork and cortex
(4) Pericycle and endodermis

Explanation (Answer: 1)
The vascular cambium forms secondary xylem (wood) toward the inside and secondary phloem toward the outside, leading to an increase in the girth of the stem during secondary growth.

5. The main function of heartwood is to:

(1) Conduct water
(2) Provide mechanical strength
(3) Transport minerals
(4) Store food

Explanation (Answer: 2)
Heartwood is non-conducting but provides strength and rigidity to the plant. Its cells are dead and filled with deposits that make the wood resistant to decay and pressure.

6. Which of the following correctly differentiates sapwood and heartwood?

(1) Sapwood - lighter, Heartwood - darker
(2) Sapwood - darker, Heartwood - lighter
(3) Both are dark
(4) Both are light

Explanation (Answer: 1)
Sapwood appears lighter as it contains living tissues and conducts water. Heartwood is darker due to the accumulation of secondary metabolites and loss of function.

7. Assertion-Reason Type:

Assertion (A): Heartwood provides mechanical strength to the stem.
Reason (R): It conducts water and minerals efficiently.
(1) Both A and R are true, and R is the correct explanation of A.
(2) Both A and R are true, but R is not the correct explanation of A.
(3) A is true, R is false.
(4) A is false, R is true.

Explanation (Answer: 3)
Heartwood provides mechanical strength but does not conduct water or minerals, as it consists of dead, lignified cells filled with deposits. Thus, the reason is false.

8. Matching Type:

Match the following:
A. Heartwood — (i) Conducts water
B. Sapwood — (ii) Functional xylem
C. Cambium — (iii) Produces secondary xylem
(1) A–i, B–ii, C–iii
(2) A–ii, B–i, C–iii
(3) A–iii, B–i, C–ii
(4) A–ii, B–iii, C–i

Explanation (Answer: 1)
Heartwood provides strength but does not conduct water, sapwood is functional xylem conducting water, and cambium produces secondary xylem during growth.

9. Fill in the Blanks:

Heartwood is formed due to the deposition of ________ like tannins, resins, and gums in the xylem vessels.

(1) Secondary metabolites
(2) Primary metabolites
(3) Minerals
(4) Pigments

Explanation (Answer: 1)
Heartwood forms as secondary metabolites such as tannins, resins, and gums accumulate within xylem vessels, making it darker, durable, and resistant to decay.

10. Choose the Correct Statements:

(1) Heartwood is non-functional but strong.
(2) Sapwood conducts water and minerals.
(3) Heartwood is dark due to secondary metabolites.
(4) All of the above.

Explanation (Answer: 4)
All statements are correct. Heartwood is dark, strong, and non-conducting, whereas sapwood remains functional in water transport. The deposition of secondary metabolites adds color and durability to the heartwood.

Subtopic: Vascular and Epidermal Cells

• Dicot Leaves: Leaves with two cotyledons in seed, usually reticulate venation and distinct mesophyll layers.

• Vascular Bundles: Arrangements of xylem and phloem in leaf or stem, may have conjunctive tissue.

• Medullary Rays: Parenchymatous cells between vascular bundles aiding in radial transport.

• Spongy Parenchyma: Loosely arranged cells in leaf mesophyll for gaseous exchange.

• Subsidiary Cells: Specialized cells surrounding guard cells in stomata.

• Epidermis: Outer protective layer of cells in leaves and stems.

• Conjunctive Tissue: Tissue connecting xylem and phloem within a bundle.

• Interfascicular Cambium: Cambium located between vascular bundles in stems.

• Lens-shaped Opening: Small ruptures in bark or epidermis for gas exchange.

• Colorless Epidermal Cells: Cells in grass leaves lacking chloroplasts, often forming subsidiary cells.

• Leaf Anatomy: Structural arrangement of tissues within a leaf including epidermis, mesophyll, and vascular tissues.

Lead Question - 2021

Select the correct pair.

1. In dicot leaves, vascular bundles are surrounded by large thick-walled cells.
Options:
A. Collenchyma
B. Conjunctive tissue
C. Spongy parenchyma
D. Epidermis

Explanation: The large thick-walled cells surrounding vascular bundles in dicot leaves provide mechanical support and are called conjunctive tissue. These cells lie between xylem and phloem within the bundle, ensuring proper connection and stability, maintaining leaf structural integrity. Answer: Conjunctive tissue.

2. Cells of medullary rays form part of cambial ring.
Options:
A. Vascular cambium
B. Interfascicular cambium
C. Conjunctive tissue
D. Spongy parenchyma

Explanation: Medullary ray cells lying between vascular bundles contribute to the interfascicular cambium, which forms part of the continuous cambial ring in dicot stems. This facilitates radial transport and secondary growth. Answer: Interfascicular cambium.

3. Loose parenchyma cells rupturing the epidermis and forming a lens-shaped opening in bark.
Options:
A. Spongy parenchyma
B. Collenchyma
C. Cork cells
D. Subsidiary cells

Explanation: Certain spongy parenchyma cells become loose, rupture the epidermis, and form lens-shaped openings called lenticels, aiding in gaseous exchange through bark. Answer: Spongy parenchyma.

4. Large colorless empty cells in the epidermis of grass leaves.
Options:
A. Subsidiary cells
B. Guard cells
C. Mesophyll cells
D. Collenchyma

Explanation: Grass leaves have subsidiary cells surrounding guard cells, which are large, colorless, and empty. They provide structural support to stomata and assist in opening and closing. Answer: Subsidiary cells.

5. Which tissue connects xylem and phloem in a vascular bundle?
Options:
A. Collenchyma
B. Conjunctive tissue
C. Sclerenchyma
D. Epidermis

Explanation: The tissue that connects xylem and phloem within a vascular bundle is called conjunctive tissue. It provides mechanical support and ensures proper functioning of the vascular system. Answer: Conjunctive tissue.

6. Medullary rays primarily aid in:
Options:
A. Radial transport
B. Photosynthesis
C. Mechanical support
D. Transpiration

Explanation: Medullary rays consist of parenchyma cells that facilitate radial transport of water, nutrients, and metabolites across vascular bundles in stems. They are crucial for secondary growth and maintaining stem function. Answer: Radial transport.

7. Assertion-Reason:
Assertion (A): Subsidiary cells in grasses are large and colorless.
Reason (R): They surround guard cells and assist in stomatal opening.
Options:
A. Both A and R are true, R is correct explanation of A
B. Both A and R are true, R is not correct explanation
C. A is true, R is false
D. A is false, R is true

Explanation: Grass leaves have subsidiary cells that are large, colorless, and surround guard cells. They help in opening and closing stomata efficiently, supporting the assertion. Answer: Both A and R are true, R is correct explanation of A.

8. Match the following:
Column I: 1. Conjunctive tissue 2. Interfascicular cambium 3. Spongy parenchyma 4. Subsidiary cells
Column II: A. Radial transport B. Surrounding xylem-phloem C. Lens-shaped openings D. Guard cell support
Options:
A. 1-B, 2-A, 3-C, 4-D
B. 1-B, 2-A, 3-D, 4-C
C. 1-A, 2-B, 3-C, 4-D
D. 1-D, 2-B, 3-A, 4-C

Explanation: Correct matching: Conjunctive tissue surrounds xylem-phloem (B), Interfascicular cambium aids radial transport (A), Spongy parenchyma forms lens-shaped openings (C), and Subsidiary cells support guard cells (D). Answer: 1-B, 2-A, 3-C, 4-D.

9. Fill in the blank: Large thick-walled cells between xylem and phloem in dicot leaves are called __________.
Options:
A. Collenchyma
B. Conjunctive tissue
C. Sclerenchyma
D. Parenchyma

Explanation: The large thick-walled cells between xylem and phloem in dicot leaves are conjunctive tissue, providing mechanical support and linking xylem and phloem within vascular bundles. They are crucial for maintaining structural integrity of leaves. Answer: Conjunctive tissue.

10. Choose the correct statements:
1. Medullary rays form part of cambial ring.
2. Subsidiary cells support stomatal function.
3. Spongy parenchyma ruptures epidermis forming lenticels.
Options:
A. 1 and 2 only
B. 2 and 3 only
C. 1 and 3 only
D. 1, 2 and 3

Explanation: All statements are correct. Medullary rays contribute to cambial ring, subsidiary cells support stomata, and spongy parenchyma forms lens-shaped openings in bark. These are key features of leaf and stem anatomy. Answer: 1, 2 and 3.

Topic: Tissues
Subtopic: Types of Plant Tissues

Keyword Definitions:

• Meristematic cells: Cells with active division capacity responsible for plant growth.

• Simple tissue: Tissue composed of similar cells performing the same function.

• Sclereids: Dead cells with highly thickened walls providing mechanical support.

• Vascular tissue: Tissue responsible for conduction of water, minerals, and nutrients.

• Parenchyma: A simple tissue with thin-walled living cells, often involved in storage and photosynthesis.

• Collenchyma: Simple living tissue providing flexible support to plant organs.

• Xylem: Complex vascular tissue conducting water and minerals from roots to shoots.

• Phloem: Complex vascular tissue conducting food from leaves to other plant parts.

Lead Question - 2021

Match List - I with List - II.
List - I List - II
(a) Cells with active cell division capacity    (i) Vascular tissue
(b) Tissue having all cells similar in tissue structure and function    (ii) Meristematic
(c) Tissue having different types of cells    (iii) Sclereids
(d) Dead cells with highly thickened walls and narrow lumen    (iv) Simple tissue
Select the correct answer from the options given below:
(a) (b) (c) (d)
(1) (iv) (iii) (ii) (i)
(2) (i) (ii) (iii) (iv)
(3) (iii) (ii) (iv) (i)
(4) (ii) (iv) (i) (iii)

Explanation: Correct answer is (4) (ii) (iv) (i) (iii). Meristematic cells (a) have active division capacity. Simple tissue (b) has similar cells. Vascular tissue (c) contains different cell types for transport. Sclereids (d) are dead cells with thickened walls providing mechanical support, demonstrating plant tissue diversity.

Guessed Questions:

1) Single Correct Answer: Which tissue is responsible for water conduction?
(1) Parenchyma
(2) Xylem
(3) Collenchyma
(4) Sclerenchyma

Explanation: Correct answer is (2) Xylem. Xylem is a vascular tissue composed of tracheids and vessels, responsible for conducting water and minerals from roots to aerial parts of the plant.

2) Single Correct Answer: Which tissue consists of living thin-walled cells for storage?
(1) Parenchyma
(2) Collenchyma
(3) Xylem
(4) Sclerenchyma

Explanation: Correct answer is (1) Parenchyma. Parenchyma cells are living, thin-walled, and function mainly in storage, photosynthesis, and tissue repair.

3) Single Correct Answer: Tissue providing flexible support in stems and petioles is:
(1) Collenchyma
(2) Sclerenchyma
(3) Parenchyma
(4) Xylem

Explanation: Correct answer is (1) Collenchyma. Collenchyma cells are living with unevenly thickened walls, providing flexible support to growing organs without restricting elongation.

4) Single Correct Answer: Meristematic tissue is primarily:
(1) Permanent
(2) Dead
(3) Actively dividing
(4) Conductive

Explanation: Correct answer is (3) Actively dividing. Meristematic tissues contain undifferentiated cells capable of continuous division, responsible for growth in length and girth of plants.

5) Single Correct Answer: Sclerenchyma cells are:
(1) Alive and thin-walled
(2) Dead with thickened walls
(3) Conductive
(4) Photosynthetic

Explanation: Correct answer is (2) Dead with thickened walls. Sclerenchyma cells like sclereids provide mechanical strength and are typically dead at maturity with lignified walls.

6) Assertion-Reason:
A: Collenchyma provides flexible support.
R: Collenchyma cells have unevenly thickened walls.
Options:
(1) Both A and R true, R explains A
(2) Both A and R true, R does not explain A
(3) A true, R false
(4) A false, R true

Explanation: Correct answer is (1). Collenchyma's unevenly thickened walls provide structural flexibility, allowing stems and leaves to resist bending without breaking.

7) Matching Type: Match tissue type with characteristic:
List–I List–II
(a) Parenchyma    (i) Dead and thick-walled
(b) Collenchyma    (ii) Storage and photosynthesis
(c) Sclerenchyma    (iii) Flexible support
(d) Xylem    (iv) Water conduction

Explanation: Correct answer: (a) ii, (b) iii, (c) i, (d) iv. Parenchyma stores food, Collenchyma provides flexible support, Sclerenchyma is dead and strengthens, Xylem conducts water.

8) Single Correct Answer: Simple tissue includes:
(1) Xylem
(2) Phloem
(3) Collenchyma
(4) Sclerenchyma

Explanation: Correct answer is (3) Collenchyma. Simple tissues are composed of similar cells, including parenchyma, collenchyma, and some sclerenchyma types, performing uniform functions.

9) Fill in the blank: Vascular tissues consist of ______ types of cells.
(1) Similar
(2) Different
(3) Dead only
(4) Living only

Explanation: Correct answer is (2) Different. Vascular tissues (xylem and phloem) contain various cell types performing conduction, support, and storage functions.

10) Choose the correct statements:
(a) Parenchyma cells are living
(b) Sclerenchyma provides mechanical support
(c) Collenchyma cells are dead
(d) Meristematic cells divide actively
Options:
(1) a, b, d
(2) a, c, d
(3) b, c
(4) All of the above

Explanation: Correct answer is (1). Parenchyma cells are living, Sclerenchyma provides mechanical support, and meristematic cells actively divide. Collenchyma cells are alive; therefore, statement c is incorrect.

Topic: Secondary Growth in Plants
Subtopic: Structure and Function of Periderm

Keyword Definitions:

• Lenticels: Small openings in bark that allow exchange of gases between internal tissues and the atmosphere.

• Cork Cambium (Phellogen): Lateral meristem that produces cork cells outward and phelloderm inward during secondary growth.

• Secondary Cortex: Tissue formed between cork cambium and phloem, often called phelloderm.

• Cork (Phellem): Protective tissue formed outward from cork cambium, often with suberin for waterproofing.

• Suberin: Waxy substance deposited in cork cell walls, making them impermeable to water and gases.

• Phelloderm: Inner layer of cork cambium producing parenchymatous cells forming part of secondary cortex.

• Secondary Growth: Increase in girth of plant stems and roots due to activity of lateral meristems.

• Periderm: Protective outer tissue replacing epidermis in older stems and roots, composed of cork, cork cambium, and phelloderm.

Lead Question - 2021

Match List - I with List - II.
List–I    List–II
(a) Lenticels (i) Phellogen
(b) Cork cambium    (ii) Suberin deposition
(c) Secondary cortex    (iii) Exchange of gases
(d) Cork    (iv) Phelloderm
Choose the correct answer from the options given below:
(a) (b) (c) (d)
(1) (iii) (i) (iv) (ii)
(2) (ii) (iii) (iv) (i)
(3) (iv) (ii) (i) (iii)
(4) (iv) (i) (iii) (ii)

Explanation: The correct answer is (1) (iii) (i) (iv) (ii). Lenticels facilitate exchange of gases (iii). Cork cambium or phellogen produces cork and phelloderm (i). Secondary cortex refers to phelloderm (iv). Cork cells are deposited with suberin to provide protection and waterproofing (ii). This sequence illustrates periderm organization in secondary growth.

Guessed Questions:

1) Single Correct Answer: Which tissue forms the outer protective layer in secondary growth?
(1) Secondary cortex
(2) Cork
(3) Xylem
(4) Phloem

Explanation: The correct answer is (2) Cork. Cork forms the outer protective layer in stems and roots during secondary growth. Its suberized cells prevent water loss, mechanical injury, and pathogen entry, replacing the epidermis in mature stems.

2) Single Correct Answer: Cork cambium is also known as:
(1) Phelloderm
(2) Phellem
(3) Phellogen
(4) Lenticels

Explanation: The correct answer is (3) Phellogen. Cork cambium, a lateral meristem, produces cork cells outward and phelloderm inward, forming the periderm. It plays a key role in secondary growth by replacing the epidermis and providing protective tissue.

3) Single Correct Answer: Lenticels primarily help in:
(1) Water transport
(2) Food storage
(3) Gas exchange
(4) Mechanical support

Explanation: The correct answer is (3) Gas exchange. Lenticels are spongy openings in the periderm that allow oxygen to enter and carbon dioxide to leave the inner tissues, ensuring respiration in stems and roots covered by cork.

4) Single Correct Answer: Suberin is deposited in:
(1) Xylem vessels
(2) Cork cell walls
(3) Phloem fibers
(4) Secondary cortex parenchyma

Explanation: The correct answer is (2) Cork cell walls. Suberin is a waxy substance deposited in cork to make the cells impermeable to water and gases, providing protection and minimizing water loss in stems and roots during secondary growth.

5) Single Correct Answer: Secondary cortex in plants refers to:
(1) Phelloderm
(2) Collenchyma
(3) Sclerenchyma
(4) Phloem fibers

Explanation: The correct answer is (1) Phelloderm. Secondary cortex consists of parenchymatous cells formed inwardly by cork cambium (phellogen). It lies between cork and phloem and forms part of the protective periderm system in secondary growth.

6) Single Correct Answer: Cork cambium produces phelloderm in which direction?
(1) Outward
(2) Inward
(3) Both directions
(4) Laterally

Explanation: The correct answer is (2) Inward. Cork cambium produces cork (phellem) outward and phelloderm inward. Phelloderm forms part of the secondary cortex, while cork provides external protection.

7) Matching Type: Match the tissue with its function.
List-I    List-II
(a) Cork    (i) Gas exchange
(b) Lenticels    (ii) Protection and waterproofing
(c) Phelloderm    (iii) Storage and support
(d) Cork cambium    (iv) Cell production

Explanation: Correct answer: (a) ii, (b) i, (c) iii, (d) iv. Cork provides protection (ii), lenticels enable gas exchange (i), phelloderm forms part of secondary cortex (iii), and cork cambium produces cells inward and outward (iv), illustrating periderm function.

8) Single Correct Answer: Which layer forms the periderm in older stems?
(1) Epidermis
(2) Cork, cork cambium, and phelloderm
(3) Secondary phloem
(4) Collenchyma

Explanation: The correct answer is (2) Cork, cork cambium, and phelloderm. These layers collectively replace epidermis in mature stems, forming the periderm, a protective tissue system essential for secondary growth.

9) Single Correct Answer: The term “phellem” refers to:
(1) Cork cambium
(2) Cork
(3) Secondary cortex
(4) Lenticels

Explanation: The correct answer is (2) Cork. Phellem or cork cells are produced outwardly by cork cambium, impregnated with suberin, and serve as a protective barrier against mechanical injury, pathogens, and water loss.

10) Choose the correct statements:
(a) Lenticels allow gas exchange.
(b) Cork is suberized and impermeable.
(c) Phelloderm is produced outward by cork cambium.
(d) Cork cambium is also called phellogen.
Options:
(1) a, b, d
(2) a, c, d
(3) b, c, d
(4) All are correct

Topic: Secondary Growth
Subtopic: Cork Cambium

Keyword Definitions:
• Cork Cambium: A lateral meristem that produces periderm tissues during secondary growth.
• Periderm: Protective tissue replacing epidermis in secondary growth, including phellogen, phellem, and phelloderm.
• Phellogen: Another name for cork cambium.
• Phellem: Cork cells produced outwardly by cork cambium.
• Phelloderm: Secondary cortex formed inwardly by cork cambium.
• Lenticels: Aerating pores formed in periderm for gas exchange.

Lead Question - 2020 (COVID Reexam)
Which of the following statements about cork cambium is incorrect?
1. It forms a secondary cortex on its outside
2. It forms a part of periderm
3. It is responsible for the formation of lenticels
4. It is a couple of layers thick
Explanation: The correct answer is (1). Cork cambium produces secondary cortex (phelloderm) towards the inside, not outside. It forms periderm and gives rise to lenticels. It is only a few layers thick. Hence, the incorrect statement is that it forms secondary cortex outside, making option (1) correct.

Question 1: Cork cambium is also called:
(1) Phellem
(2) Phellogen
(3) Phelloderm
(4) Lenticel
Explanation: The correct answer is (2). Cork cambium is scientifically termed phellogen. It is a secondary meristem forming periderm during secondary growth. Phellem refers to cork, phelloderm to secondary cortex, and lenticels are aerating structures. Thus, option (2) is the correct synonym for cork cambium in plants.

Question 2: Outward products of cork cambium are:
(1) Phelloderm
(2) Cork (Phellem)
(3) Xylem
(4) Phloem
Explanation: The correct answer is (2). Cork cambium produces phellem or cork cells towards the outside, which are dead, suberized, and protective. Inwardly, it produces phelloderm, a living tissue. Xylem and phloem arise from vascular cambium, not cork cambium. Hence, outward product is cork, confirming option (2).

Question 3: Inward product of cork cambium is:
(1) Phellem
(2) Phelloderm
(3) Secondary phloem
(4) Epidermis
Explanation: The correct answer is (2). Phelloderm or secondary cortex is produced inwardly by cork cambium. Phellem is produced outwardly. Secondary phloem is produced by vascular cambium, not cork cambium. Epidermis is the original outer protective tissue. Thus, inward product is phelloderm, validating option (2).

Question 4: Which of the following is not part of periderm?
(1) Phellogen
(2) Phellem
(3) Phelloderm
(4) Vascular cambium
Explanation: The correct answer is (4). Periderm consists of phellogen (cork cambium), phellem (cork), and phelloderm (secondary cortex). Vascular cambium is a separate lateral meristem involved in secondary xylem and phloem production. Therefore, vascular cambium is not a periderm component, making option (4) correct.

Question 5: Lenticels arise due to activity of:
(1) Vascular cambium
(2) Phellogen
(3) Apical meristem
(4) Intercalary meristem
Explanation: The correct answer is (2). Lenticels are spongy openings formed in periderm for gaseous exchange. They arise from phellogen or cork cambium. Vascular cambium produces vascular tissues, apical meristem produces primary tissues, and intercalary meristem elongates internodes. Thus, lenticels originate from phellogen activity, confirming option (2).

Question 6: Cork cells are impregnated with:
(1) Cutin
(2) Suberin
(3) Lignin
(4) Cellulose
Explanation: The correct answer is (2). Cork or phellem cells are dead and have walls impregnated with suberin, a hydrophobic material that prevents water loss and pathogen entry. Cutin is present in cuticle, lignin strengthens xylem, and cellulose forms primary wall. Therefore, option (2) is the accurate answer.

Question 7 (Assertion-Reason):
Assertion (A): Cork cambium contributes to secondary growth protection.
Reason (R): It forms vascular bundles.
(1) Both A and R true, R explains A
(2) Both A and R true, R does not explain A
(3) A true, R false
(4) A false, R true
Explanation: The correct answer is (3). Cork cambium protects plants during secondary growth by forming periderm. It does not form vascular bundles, which arise from vascular cambium. Hence, assertion is true but reason is false. This makes option (3) the correct choice for assertion-reason relationship here.

Question 8 (Matching Type):
Match the tissue with origin:
A. Cork – 1. Vascular cambium
B. Secondary cortex – 2. Phellogen
C. Secondary xylem – 3. Phellogen
D. Secondary phloem – 4. Vascular cambium
Options:
(1) A-2, B-3, C-1, D-4
(2) A-3, B-2, C-4, D-1
(3) A-2, B-2, C-1, D-4
(4) A-2, B-2, C-4, D-4
Explanation: The correct answer is (3). Cork (phellem) and secondary cortex (phelloderm) originate from phellogen. Secondary xylem and phloem arise from vascular cambium. This accurate mapping explains roles of different meristems, making option (3) correct in matching origin of these tissues in plant secondary growth.

Question 9 (Fill in the Blanks):
Cork cells are dead and their walls contain __________, making them impermeable to water.
(1) Lignin
(2) Cutin
(3) Suberin
(4) Pectin
Explanation: The correct answer is (3). Suberin is a waxy substance deposited in cork cell walls, making them waterproof and protective. Lignin is for strength, cutin forms cuticle, and pectin forms middle lamella. Thus, the blank is filled with suberin, confirming option (3) as accurate.

Question 10 (Choose Correct Statements):
Select the correct statements:
(i) Cork cambium is secondary meristem
(ii) Phellem is produced outward
(iii) Phelloderm is produced inward
(iv) Cork cells are living
Options:
(1) (i), (ii), (iii)
(2) (i), (iii), (iv)
(3) (ii), (iv)
(4) All of the above
Explanation: The correct answer is (1). Cork cambium is a secondary meristem. It produces cork outward and phelloderm inward. Cork cells are dead, not living. Thus, only statements (i), (ii), and (iii) are correct, confirming option (1) as the accurate choice here.

Topic: Leaf Anatomy
Subtopic: Special Epidermal Cells

Keyword Definitions:
• Adaxial Epidermis: Upper surface layer of a leaf.
• Bulliform Cells: Large, colorless cells along veins in grass leaves that help in leaf folding.
• Lenticels: Pores in bark for gas exchange.
• Guard Cells: Cells surrounding stomata controlling gas exchange.
• Bundle Sheath Cells: Cells surrounding vascular bundles, involved in photosynthesis.
• Grass Leaf: Monocot leaf with parallel venation and specialized epidermal cells.

Lead Question - 2020 (COVID Reexam)
Large, empty colorless cells of the adaxial epidermis along the veins of grass leaves are:
1. Lenticels
2. Guard cells
3. Bundle sheath cells
4. Bulliform cells
Explanation: The correct answer is (4). Bulliform cells are large, empty, and colorless cells found on the upper (adaxial) epidermis along the veins of grass leaves. They help in folding and unfolding the leaf during water stress, reducing water loss. Lenticels, guard cells, and bundle sheath cells have different functions, making option (4) correct.

Question 1: Function of bulliform cells in grass leaves?
(1) Gas exchange
(2) Leaf folding
(3) Photosynthesis
(4) Water absorption
Explanation: The correct answer is (2). Bulliform cells are large, colorless cells in the adaxial epidermis of grass leaves. They collapse when water is scarce, causing the leaf to fold and reduce transpiration. This adaptive feature conserves water. Guard cells, bundle sheath cells, and other cells have different functions, confirming option (2) is correct.

Question 2: Bundle sheath cells are located:
(1) Around veins
(2) Around stomata
(3) On leaf surface
(4) In root cortex
Explanation: The correct answer is (1). Bundle sheath cells surround vascular bundles in leaves and are important in photosynthesis, especially in C4 plants. They are not involved in gas exchange directly like guard cells. Therefore, option (1) correctly identifies their location and function in leaf anatomy.

Question 3: Guard cells function is:
(1) Water storage
(2) Leaf folding
(3) Controlling stomatal opening
(4) Photosynthesis
Explanation: The correct answer is (3). Guard cells surround stomata and regulate opening and closing to control gas exchange and transpiration. They differ from bulliform cells, which help in leaf folding. Bundle sheath cells perform photosynthesis, making option (3) the accurate answer for guard cell function.

Question 4: Lenticels are primarily for:
(1) Leaf folding
(2) Gas exchange in stems
(3) Water absorption
(4) Photosynthesis
Explanation: The correct answer is (2). Lenticels are small openings in bark that allow gas exchange between internal tissues and the atmosphere. They are not involved in leaf folding or photosynthesis. Bulliform cells perform folding in grass leaves. Therefore, option (2) is correct.

Question 5: Which cells are large and colorless in grass leaves?
(1) Guard cells
(2) Bulliform cells
(3) Bundle sheath cells
(4) Parenchyma cells
Explanation: The correct answer is (2). Bulliform cells are large, colorless, and present along veins on the adaxial epidermis of grass leaves. They facilitate leaf folding during water stress. Guard cells and bundle sheath cells have distinct shapes and functions. Hence, option (2) is accurate.

Question 6: Adaxial epidermis is located:
(1) Upper leaf surface
(2) Lower leaf surface
(3) Around veins
(4) In stem cortex
Explanation: The correct answer is (1). Adaxial epidermis refers to the upper surface of a leaf. Bulliform cells are present here in grass leaves to help fold the leaf. The abaxial epidermis is the lower surface. Therefore, option (1) correctly identifies the location of adaxial epidermis.

Question 7 (Assertion-Reason):
Assertion (A): Bulliform cells help reduce water loss.
Reason (R): They fold the leaf during water stress.
(1) Both A and R true, R explains A
(2) Both A and R true, R does not explain A
(3) A true, R false
(4) A false, R true
Explanation: The correct answer is (1). Bulliform cells collapse under water stress, causing leaf folding. This reduces surface area exposed and decreases transpiration, conserving water. Both assertion and reason are correct, and the reason directly explains the water-saving function of bulliform cells. Option (1) is accurate.

Question 8 (Matching Type):
Match the cell type with its function:
A. Bulliform cells – 1. Gas exchange
B. Guard cells – 2. Leaf folding
C. Bundle sheath cells – 3. Photosynthesis
Options:
(1) A-2, B-1, C-3
(2) A-1, B-2, C-3
(3) A-3, B-1, C-2
(4) A-2, B-3, C-1
Explanation: The correct answer is (1). Bulliform cells fold leaves under water stress, guard cells regulate stomatal gas exchange, and bundle sheath cells assist in photosynthesis. This accurate matching reflects the distinct functions of each cell type in leaf anatomy, confirming option (1) is correct.

Question 9 (Fill in the Blanks):
The __________ of grass leaves helps fold the leaf, while the __________ controls stomatal opening.
(1) Bulliform cells, guard cells
(2) Bundle sheath cells, bulliform cells
(3) Guard cells, bulliform cells
(4) Lenticels, bundle sheath cells
Explanation: The correct answer is (1). Bulliform cells are large adaxial cells that fold leaves during water stress. Guard cells regulate stomata opening and closing for gas exchange. Bundle sheath cells and lenticels do not perform these functions. Therefore, option (1) correctly fills the blanks for the specific cell roles.

Question 10 (Choose Correct Statements):
Select the correct statements:
(i) Bulliform cells are colorless
(ii) Guard cells are found along veins
(iii) Bundle sheath cells perform photosynthesis
(iv) Lenticels are in leaves
Options:
(1) (i) and (iii)
(2) (i) and (ii)
(3) (ii) and (iv)
(4) All of the above
Explanation: The correct answer is (1). Bulliform cells are colorless and aid in leaf folding. Bundle sheath cells perform photosynthesis in C4 plants. Guard cells are on leaf surfaces, not only along veins. Lenticels are in stems, not leaves. Therefore, only statements (i) and (iii) are correct, making option (1) accurate.

Topic: Wood Structure

Subtopic: Heartwood and Sapwood

• Sapwood: The outer, living xylem of a tree that conducts water and minerals from roots to leaves.

• Heartwood: Inner, non-living xylem providing mechanical strength; usually darker due to deposition of resins, tannins, and oils.

• Xylem: Vascular tissue responsible for transport of water and minerals in plants.

• Secondary xylem: Xylem formed from vascular cambium, increasing the girth of stems and roots.

• Tannins: Organic compounds that darken heartwood and protect it from decay and pathogens.

• Resins: Protective substances deposited in heartwood to prevent microbial attack.

• Mechanical support: Structural strength provided by tissues like heartwood to maintain tree rigidity.

• Conducting tissue: Plant tissue that transports water, minerals, and nutrients (xylem and phloem).

• Vascular cambium: Lateral meristem producing secondary xylem and phloem.

• Mineral transport: Movement of dissolved ions from soil to leaves via xylem.

• Water conduction: Process of transporting water from roots to aerial parts through xylem vessels.

Lead Question (2020): Identify the incorrect statement :

1. Sapwood is the innermost secondary xylem and is lighter in colour

2. Due to deposition of tannins, resins, oils etc, heartwood is dark in colour

3. Heartwood does not conduct water but gives mechanical support

4. Sapwood is involved in conduction of water and minerals from root to leaf

Explanation: The correct answer is 1. Sapwood is actually the outermost secondary xylem, not the innermost, and it is lighter in colour. It actively conducts water and minerals from roots to leaves, whereas heartwood is inner, non-conducting, and primarily provides mechanical strength to the stem.

Guessed MCQs:

1. Question 1: Which xylem tissue primarily conducts water and minerals?
   A. Heartwood
   B. Sapwood
   C. Pith
   D. Phloem
   Explanation: The correct answer is B. Sapwood is the functional outer xylem that actively transports water and minerals from roots to leaves. It is lighter in colour and living, whereas heartwood is inner, non-living, and mainly provides mechanical support without participating in water conduction.

2. Question 2: Why is heartwood darker than sapwood?
   A. It has more water
   B. Due to deposition of tannins, resins, and oils
   C. It conducts minerals
   D. It contains chlorophyll
   Explanation: The correct answer is B. Heartwood accumulates tannins, resins, and oils over time, which darken its colour. These substances also protect it from microbial decay and insects. Heartwood does not conduct water, distinguishing it from the lighter-coloured sapwood responsible for transport.

3. Question 3: Heartwood primarily provides:
   A. Water conduction
   B. Mineral transport
   C. Mechanical support
   D. Photosynthesis
   Explanation: The correct answer is C. Heartwood is non-living and forms the central portion of stems and roots. Its main function is to provide structural rigidity and mechanical strength, while sapwood continues to transport water and minerals. The deposited substances also make it decay-resistant.

4. Question 4: Which statement about sapwood is correct?
   A. It is inner xylem
   B. It is non-living
   C. It conducts water and minerals
   D. It provides only mechanical support
   Explanation: The correct answer is C. Sapwood is the outer, living portion of secondary xylem that actively conducts water and minerals from roots to leaves. It is lighter in colour compared to heartwood, which is inner, non-conducting, and primarily supports the plant mechanically.

5. Question 5: Tannins in heartwood serve to:
   A. Increase water conduction
   B. Protect against decay
   C. Facilitate photosynthesis
   D. Store starch
   Explanation: The correct answer is B. Tannins, along with resins and oils, accumulate in heartwood to prevent microbial attack and decay. They darken the wood and enhance durability. Heartwood does not transport water or minerals but provides mechanical strength and protection.

6. Question 6: Secondary xylem is produced by:
   A. Apical meristem
   B. Vascular cambium
   C. Cork cambium
   D. Pith
   Explanation: The correct answer is B. Vascular cambium, a lateral meristem, produces secondary xylem towards the inside and secondary phloem towards the outside. Secondary xylem forms sapwood and heartwood, increasing stem girth, with sapwood conducting water and heartwood providing mechanical support.

7. Question 7: Assertion-Reason:
   Assertion (A): Heartwood does not conduct water.
   Reason (R): Heartwood accumulates resins, tannins, and oils.
   A. Both A and R are true, R is correct explanation of A
   B. Both A and R are true, R is not correct explanation of A
   C. A is true, R is false
   D. A is false, R is true
   Explanation: The correct answer is A. Heartwood is non-living and does not conduct water. The deposition of resins, tannins, and oils in its structure contributes to decay resistance and mechanical strength, correctly explaining why it is non-conductive while providing support.

8. Question 8: Matching Type: Match xylem components with function:
   i. Sapwood - A. Mechanical support
   ii. Heartwood - B. Water conduction
   iii. Secondary xylem - C. Structural growth
   Choices:
   A. i-B, ii-A, iii-C
   B. i-A, ii-B, iii-C
   C. i-C, ii-B, iii-A
   D. i-B, ii-C, iii-A
   Explanation: The correct answer is A. Sapwood conducts water and minerals, heartwood provides mechanical support and is decay-resistant, and secondary xylem contributes to structural growth by increasing stem girth through vascular cambium activity.

9. Question 9: Fill in the Blanks: The outer, lighter xylem responsible for water conduction is called ________.
   A. Heartwood
   B. Sapwood
   C. Pith
   D. Phloem
   Explanation: The correct answer is B. Sapwood forms the outer, living xylem in stems and roots. It conducts water and dissolved minerals from roots to leaves. Heartwood is inner, non-conducting, darker, and provides mechanical strength without transporting water.

10. Question 10: Choose the correct statements:
    i. Sapwood conducts water and minerals
    ii. Heartwood is inner, non-living and dark
    iii. Heartwood contributes to mechanical support
    iv. Sapwood does not conduct water
    A. i, ii, iii
    B. ii, iii, iv
    C. i, iv
    D. i, ii, iv
    Explanation: The correct answer is A. Sapwood is active in water and mineral conduction. Heartwood is inner, non-living, darker, and provides mechanical support. These characteristics distinguish sapwood and heartwood functions in stems and roots of trees, supporting plant survival and structure.

Topic: Plant Tissue System
Subtopic: Stem and Root Structure

• Transverse Section: A cross-sectional cut of plant tissue perpendicular to the longitudinal axis to study internal anatomy.

• Vascular Bundle: A part of the transport system in plants consisting of xylem and phloem.

• Bundle Sheath: Layer of cells surrounding vascular bundles, providing support and protection.

• Parenchyma: Fundamental tissue composed of thin-walled cells, often for storage and photosynthesis.

• Conjoint Vascular Bundle: A vascular bundle in which xylem and phloem are together in the same bundle.

• Closed Bundle: Vascular bundle without cambium, unable to form secondary growth.

• Dicotyledonous Stem: Stem of dicot plants usually with vascular bundles in a ring and distinct cortex and pith.

• Monocotyledonous Stem: Stem of monocots, usually with scattered vascular bundles and no secondary growth.

• Phloem Parenchyma: Parenchymatous cells in phloem involved in storage and transport.

• Ground Tissue: Tissue other than epidermis and vascular tissues, consisting mainly of parenchyma.

• Scattered Bundles: Arrangement typical of monocot stems where vascular bundles are distributed throughout the ground tissue.

Lead Question (2020): The transverse section of a plant shows following anatomical features:
(a) Large number of scattered vascular bundles surrounded by bundle sheath
(b) Large conspicuous parenchymatous ground tissue
(c) Vascular bundles conjoint and closed
(d) Phloem parenchyma absent
Identify the category of plant and its part:
Options:
1. Dicotyledonous stem
2. Dicotyledonous root
3. Monocotyledonous stem
4. Monocotyledonous root

Explanation: Correct answer is 3. The anatomical features described are typical of a monocotyledonous stem: scattered conjoint and closed vascular bundles surrounded by bundle sheath, conspicuous parenchymatous ground tissue, and absence of phloem parenchyma. Dicots have vascular bundles in a ring and usually possess phloem parenchyma.

1. Single Correct Answer MCQ:
Which plant tissue is primarily responsible for storage and photosynthesis?
Options:
a. Collenchyma
b. Parenchyma
c. Sclerenchyma
d. Xylem

Explanation: Correct answer is b. Parenchyma cells are thin-walled, versatile cells responsible for storage, photosynthesis, and forming the bulk of ground tissue in stems and roots.

2. Single Correct Answer MCQ:
Which characteristic is typical of monocot stems?
Options:
a. Vascular bundles arranged in a ring
b. Presence of secondary growth
c. Scattered conjoint vascular bundles
d. Phloem parenchyma present

Explanation: Correct answer is c. Monocot stems have scattered vascular bundles that are conjoint and closed. They lack cambium, so secondary growth is absent, and phloem parenchyma is usually absent.

3. Single Correct Answer MCQ:
The bundle sheath in vascular bundles primarily functions to:
Options:
a. Store food
b. Support and protect vascular tissue
c. Conduct water
d. Photosynthesis only

Explanation: Correct answer is b. Bundle sheath cells surround vascular bundles, providing structural support and protection to the conducting tissues.

4. Single Correct Answer MCQ:
Which feature differentiates dicot and monocot stems?
Options:
a. Number of leaves
b. Arrangement of vascular bundles
c. Presence of flowers
d. Root type

Explanation: Correct answer is b. Dicot stems have vascular bundles arranged in a ring, while monocot stems have scattered vascular bundles, helping in identification under microscopic examination.

5. Single Correct Answer MCQ:
Closed vascular bundles are characteristic of:
Options:
a. Dicot stems
b. Monocot stems
c. Both dicot and monocot roots
d. All dicot plants

Explanation: Correct answer is b. Closed vascular bundles, which lack cambium, are typical of monocot stems and prevent secondary growth, unlike dicot stems which have open bundles.

6. Single Correct Answer MCQ:
The prominent ground tissue in monocot stem is mainly:
Options:
a. Collenchyma
b. Sclerenchyma
c. Parenchyma
d. Xylem

Explanation: Correct answer is c. The ground tissue in monocot stems is largely parenchymatous, providing bulk, storage, and mechanical support.

7. Assertion-Reason MCQ:
Assertion (A): Monocot stems lack secondary growth.
Reason (R): Vascular bundles in monocots are closed and lack cambium.
Options:
a. Both A and R are true, R explains A
b. Both A and R are true, R does not explain A
c. A is true, R is false
d. A is false, R is true

Explanation: Correct answer is a. The absence of cambium in closed vascular bundles prevents secondary growth in monocot stems.

8. Matching Type MCQ:
Match the following:
(a) Dicot stem - (i) Scattered vascular bundles
(b) Monocot stem - (ii) Vascular bundles in a ring
(c) Phloem parenchyma - (iii) Present in dicot stems
(d) Bundle sheath - (iv) Surrounds vascular bundles
Options:
1. a-ii, b-i, c-iii, d-iv
2. a-i, b-ii, c-iv, d-iii
3. a-iv, b-iii, c-ii, d-i
4. a-iii, b-iv, c-i, d-ii

Explanation: Correct answer is 1. Dicot stems have vascular bundles in a ring, monocot stems have scattered bundles, phloem parenchyma is present in dicot stems, and bundle sheath surrounds vascular bundles.

9. Fill in the Blanks MCQ:
In monocot stems, the vascular bundles are ________ and ________.
Options:
a. Open, scattered
b. Closed, scattered
c. Closed, in a ring
d. Open, in a ring

Explanation: Correct answer is b. Monocot stems have vascular bundles that are closed (without cambium) and scattered throughout the ground tissue.

10. Choose the correct statements MCQ:<

Topic: Secondary Growth
Subtopic: Annual Rings in Trees

• Annual Rings: Concentric rings in tree stems formed due to seasonal growth variations.

• Spring Wood / Early Wood: Light-colored, less dense xylem formed during rapid growth in spring.

• Autumn Wood / Late Wood: Dark-colored, dense xylem formed during slower growth in autumn.

• Cambium: Lateral meristem producing secondary xylem and phloem during secondary growth.

• Secondary Growth: Increase in girth of stems and roots due to cambial activity.

• Temperate Region: Regions with distinct seasonal changes, influencing tree growth.

• Light and Dark Bands: Visual representation of early and late wood in annual rings.

• Climatic Influence: Seasonal variations in temperature and rainfall affecting cambial activity.

• Tree Age: Annual rings indicate the age of the tree.

• Growth Rate: Variation in wood density reflects faster or slower cambial growth.

• Ring Prominence: Clear visibility of rings depending on species and climate.

Lead Question (2019): Which of the statements given below is not true about formation of Annual Rings in trees :

Options:
1. Annual ring is a combination of spring wood and autumn wood produced in a year
2. Differential activity of cambium causes light and dark bands of tissue - early and late wood respectively.
3. Activity of cambium depends upon variation in climate.
4. Annual rings are not prominent in trees of temperate region

Explanation: Correct answer is 4. Annual rings are highly prominent in trees of temperate regions due to distinct seasonal variations affecting cambial activity. Statements 1, 2, and 3 are correct as spring wood and autumn wood form annual rings, differential cambial activity creates light and dark bands, and climate influences growth rate.

1. Single Correct Answer MCQ:
Which type of wood is formed during rapid growth in spring?
Options:
a. Autumn wood
b. Heartwood
c. Spring wood
d. Sapwood

Explanation: Correct answer is c. Spring wood, or early wood, forms during rapid growth in spring and is light-colored and less dense. Autumn wood is dense and dark, heartwood is non-living central xylem, and sapwood is outer living xylem. Seasonal growth differences create visible annual rings in stems.

2. Single Correct Answer MCQ:
Dark-colored dense xylem formed in autumn is called:
Options:
a. Spring wood
b. Autumn wood
c. Sapwood
d. Cambium

Explanation: Correct answer is b. Autumn wood, or late wood, is dense and dark-colored due to slower growth in autumn. Spring wood is light and less dense, sapwood is outer living xylem, and cambium produces secondary xylem and phloem. The contrast between early and late wood forms annual rings.

3. Single Correct Answer MCQ:
Cambial activity is influenced by:
Options:
a. Temperature and rainfall
b. Soil texture only
c. Light intensity only
d. Wind direction

Explanation: Correct answer is a. Cambial activity varies with climate factors like temperature and rainfall, affecting secondary growth and annual ring formation. Soil texture, light intensity, and wind have minor roles. Seasonal climate changes determine width and density of early and late wood, producing annual rings.

4. Single Correct Answer MCQ:
Annual rings indicate:
Options:
a. Tree age
b. Photosynthetic rate
c. Leaf size
d. Root length

Explanation: Correct answer is a. Annual rings indicate tree age by counting concentric rings formed each year. Photosynthetic rate, leaf size, and root length are unrelated. Visible ring patterns result from seasonal growth variations, making rings reliable indicators of age and historical climatic conditions.

5. Single Correct Answer MCQ:
Differential activity of cambium results in:
Options:
a. Light and dark bands in xylem
b. Formation of leaves
c. Flowering
d. Root branching

Explanation: Correct answer is a. Differential cambial activity during early and late growth seasons produces light spring wood and dark autumn wood, forming annual rings. Leaf formation, flowering, and root branching are developmental processes not directly caused by cambial activity in secondary xylem.

6. Single Correct Answer MCQ:
In which region are annual rings most distinct?
Options:
a. Tropical region
b. Temperate region
c. Equatorial region
d. Desert region

Explanation: Correct answer is b. Temperate regions with distinct seasons show clear early and late wood, forming prominent annual rings. Tropical and equatorial regions with less seasonal variation produce indistinct rings. Deserts may show ring-like structures due to water availability, but temperate regions have the most reliable annual ring formation.

7. Assertion-Reason MCQ:
Assertion (A): Annual rings can be used to study past climatic conditions.
Reason (R): Cambial activity varies with seasonal climate changes.
Options:
a. Both A and R are true, R explains A
b. Both A and R are true, R does not explain A
c. A is true, R is false
d. A is false, R is true

Explanation: Correct answer is a. Annual rings reflect seasonal variations in cambial activity caused by temperature and rainfall changes. By analyzing ring width and density, scientists can infer historical climate conditions. This dendroclimatic method relies on the direct link between cambial activity and environmental factors.

8. Matching Type MCQ:
Match the type of wood with its characteristic:
Column-I Column-II
(a) Spring wood (i) Dense, slow-growing
(b) Autumn wood (ii) Light, fast-growing
(c) Heartwood (iii) Non-living central wood
(d) Sapwood (iv) Living outer xylem
Options:
1. a-ii, b-i, c-iii, d-iv
2. a-i, b-ii, c-iv, d-iii
3. a-iv, b-iii, c-ii, d-i
4. a-iii, b-iv, c-i, d-ii

Explanation: Correct answer is 1. Spring wood is light and fast-growing, autumn wood is dense, heartwood is non-living central wood, and sapwood is living outer xylem. This differentiation contributes to annual ring formation and reflects both growth season and wood functional status in tree stems.

9. Fill in the Blanks / Completion MCQ:
The width of annual rings depends upon ________ and rainfall.
Options:
a. Soil pH
b. Temperature
c. Wind speed
d. Leaf size

Explanation: Correct answer is b. Temperature and rainfall directly influence cambial activity, determining the width of annual rings. Warm and wet seasons produce wider rings, while cold or dry seasons produce narrow rings. Soil pH, wind speed, and leaf size have minor roles in ring formation.

10. Choose the correct statements MCQ:
Select correct statements:
i. Annual rings form due to seasonal cambial activity
ii. They indicate tree age
iii. Prominent in temperate trees
iv. Not prominent in temperate regions
Options:
a. i, ii, iii
b. ii and iv
c. i and iv
d. ii, iii, iv

Explanation: Correct answer is a. Annual rings result from seasonal variations in cambial activity, indicate tree age, and are prominent in temperate trees due to clear seasonal changes. Statement iv is incorrect as annual rings are highly visible in temperate regions, making options i, ii, and iii the correct choices.

Subtopic: Phloem Structure

Keyword Definitions:

• Phloem: Vascular tissue responsible for transport of organic nutrients, mainly sucrose, in plants.

• Gymnosperms: Seed-producing plants without flowers, e.g., pine, fir, which have different phloem structure from angiosperms.

• Sieve tubes: Long tube-like phloem cells in angiosperms that conduct food.

• Companion cells: Angiosperm phloem cells that support sieve tube elements.

• Albuminous cells: Nucleated cells in gymnosperm phloem associated with sieve cells, help in transport and support.

• Sieve cells: Phloem conducting cells in gymnosperms, elongated with sieve areas instead of sieve plates.

Lead Question (2019):

Phloem in gymnosperms lacks:
(1) Albuminous cells and sieve cells
(2) Sieve tubes only
(3) Companion cells only
(4) Both sieve tubes and companion cells

Explanation: Correct answer is (3). Gymnosperm phloem contains sieve cells and albuminous cells but lacks companion cells. Companion cells are specific to angiosperms, where they maintain and support sieve tube elements, whereas gymnosperms rely on albuminous cells to assist sieve cells in transport.

1) Single Correct Answer MCQ:
Which cell type is absent in gymnosperm phloem?
(1) Sieve cells
(2) Albuminous cells
(3) Companion cells
(4) Parenchyma

Explanation: Correct answer is (3). Gymnosperm phloem has sieve cells and albuminous cells but does not have companion cells, which are found only in angiosperm phloem to support sieve tube elements.

2) Single Correct Answer MCQ:
Albuminous cells in gymnosperms are analogous to:
(1) Sieve elements in angiosperms
(2) Companion cells in angiosperms
(3) Xylem vessels
(4) Parenchyma cells

Explanation: Correct answer is (2). Albuminous cells in gymnosperms function similarly to companion cells in angiosperms by supporting sieve cells, facilitating transport of organic substances and maintaining cell viability.

3) Single Correct Answer MCQ:
Sieve cells in gymnosperms differ from sieve tubes in that they:
(1) Are dead at maturity
(2) Lack sieve areas
(3) Lack companion cells
(4) Are short and wide

Explanation: Correct answer is (3). Sieve cells in gymnosperms are elongated conducting cells without companion cells. Transport is aided by albuminous cells. Sieve tubes of angiosperms are associated with companion cells.

4) Single Correct Answer MCQ:
Which is the main conducting cell in gymnosperm phloem?
(1) Sieve tube element
(2) Sieve cell
(3) Companion cell
(4) Tracheid

Explanation: Correct answer is (2). Sieve cells are the primary conducting cells in gymnosperm phloem, facilitating transport of food substances. They are assisted by albuminous cells rather than companion cells.

5) Single Correct Answer MCQ:
Companion cells are associated with:
(1) Gymnosperm sieve cells
(2) Angiosperm sieve tube elements
(3) Xylem vessels
(4) Albuminous cells

Explanation: Correct answer is (2). Companion cells are specialized angiosperm phloem cells that support sieve tube elements in transporting organic nutrients efficiently.

6) Single Correct Answer MCQ:
Which of the following is present in gymnosperm phloem?
(1) Companion cells
(2) Sieve tubes
(3) Albuminous cells
(4) Vessel elements

Explanation: Correct answer is (3). Gymnosperm phloem contains albuminous cells along with sieve cells. Sieve tubes and companion cells are absent, which distinguishes it from angiosperm phloem.

7) Assertion-Reason MCQ:
Assertion (A): Gymnosperm phloem lacks companion cells.
Reason (R): Gymnosperms have albuminous cells that perform the supportive role.
Options:
(1) A true, R true, R correct explanation
(2) A true, R true, R not correct explanation
(3) A true, R false
(4) A false, R true

Explanation: Correct answer is (1). Gymnosperm phloem does not have companion cells; instead, albuminous cells support sieve cells in transport, making the reason correct and explaining the assertion accurately.

8) Matching Type MCQ:
Match the following phloem elements with plant type:
(a) Companion cells - (i) Gymnosperms
(b) Albuminous cells - (ii) Angiosperms
(c) Sieve tubes - (iii) Angiosperms
(d) Sieve cells - (iv) Gymnosperms
Options:
(1) a-ii, b-i, c-iii, d-iv
(2) a-i, b-ii, c-iv, d-iii
(3) a-iii, b-iv, c-ii, d-i
(4) a-iv, b-iii, c-i, d-ii

Explanation: Correct answer is (1). Companion cells and sieve tubes are characteristic of angiosperms, whereas albuminous cells and sieve cells are found in gymnosperm phloem, reflecting structural differences in transport tissues.

9) Fill in the Blanks MCQ:
Gymnosperm phloem lacks ________, which is present in angiosperms.
(1) Sieve cells
(2) Albuminous cells
(3) Companion cells
(4) Parenchyma

Explanation: Correct answer is (3). Companion cells are absent in gymnosperms; instead, albuminous cells provide the necessary support to sieve cells for nutrient transport.

10) Choose the correct statements MCQ:
(1) Gymnosperm phloem has sieve cells
(2) Gymnosperm phloem has albuminous cells
(3) Gymnosperm phloem has companion cells
(4) Sieve tubes are absent in gymnosperms

Explanation: Correct answer is (1,

Subtopic: Leaf Adaptations to Drought

Keyword Definitions:

• Bulliform cells: Large, thin-walled epidermal cells present in grass leaves that help in folding and unfolding in response to water stress.

• Stomata: Pores on leaf surfaces that regulate gas exchange and water loss.

• Spongy mesophyll: Tissue in leaves with air spaces that facilitate gas diffusion.

• Flaccidity: Loss of turgor pressure, causing cells to collapse.

• Tyloses: Outgrowths of parenchyma cells into xylem vessels blocking water flow.

Lead Question (2019):

Grass leaves curl inwards during very dry weather. Select the most appropriate reason from the following:
(1) Closure of stomata
(2) Flaccidity of bulliform cells
(3) Shrinkage of air spaces in spongy mesophyll
(4) Tyloses in vessels

Explanation: Correct answer is (2). Bulliform cells lose turgor during drought, causing leaves to curl inward and reduce exposed surface area. This adaptation minimizes water loss through transpiration and helps the plant survive prolonged dry conditions. Stomatal closure occurs but does not directly cause leaf rolling, which is mediated by bulliform cells.

1) Single Correct Answer MCQ:
Which cells are primarily responsible for leaf rolling in grasses?
(1) Mesophyll cells
(2) Guard cells
(3) Bulliform cells
(4) Parenchyma cells

Explanation: Correct answer is (3). Bulliform cells control leaf folding and unfolding in response to water availability, helping grasses reduce water loss during drought by rolling leaves inward.

2) Single Correct Answer MCQ:
Leaf rolling in grasses is an adaptation to:
(1) Excess water
(2) High light intensity
(3) Drought
(4) Cold temperature

Explanation: Correct answer is (3). Leaf rolling reduces exposed surface area and water loss during drought, protecting the plant from dehydration and stress.

3) Single Correct Answer MCQ:
Which of the following occurs when bulliform cells become flaccid?
(1) Leaves expand
(2) Leaves curl inward
(3) Stomata open
(4) Air spaces increase

Explanation: Correct answer is (2). Flaccid bulliform cells cause the leaf blade to curl inward, an adaptive response to limit water loss in dry conditions.

4) Single Correct Answer MCQ:
Which tissue in leaves contains air spaces aiding gas diffusion?
(1) Bulliform cells
(2) Spongy mesophyll
(3) Palisade mesophyll
(4) Epidermis

Explanation: Correct answer is (2). Spongy mesophyll has intercellular air spaces for gas exchange but does not directly cause leaf rolling, which is mediated by bulliform cells.

5) Single Correct Answer MCQ:
Tyloses formation in xylem primarily functions to:
(1) Reduce water loss via leaf rolling
(2) Block vessels and prevent pathogen spread
(3) Aid photosynthesis
(4) Increase transpiration

Explanation: Correct answer is (2). Tyloses block xylem vessels to prevent pathogen entry or air embolism. They do not directly contribute to leaf curling during drought.

6) Single Correct Answer MCQ:
Closure of stomata during drought is primarily for:
(1) Leaf rolling
(2) Minimizing water loss
(3) Enhancing photosynthesis
(4) Increasing transpiration

Explanation: Correct answer is (2). Stomatal closure limits transpiration and conserves water during drought. Leaf rolling complements this mechanism but is mediated by bulliform cells.

7) Assertion-Reason MCQ:
Assertion (A): Grass leaves roll inward during drought.
Reason (R): Bulliform cells lose turgor pressure in dry conditions.
Options:
(1) A true, R true, R correct explanation
(2) A true, R true, R not correct explanation
(3) A true, R false
(4) A false, R true

Explanation: Correct answer is (1). Both assertion and reason are true. Loss of turgor in bulliform cells causes leaves to roll inward, reducing surface area and water loss, an adaptive drought response.

8) Matching Type MCQ:
Match the cell type with its function:
(a) Bulliform cells - (i) Leaf folding
(b) Guard cells - (ii) Stomatal opening
(c) Spongy mesophyll - (iii) Gas diffusion
Options:
(1) a-i, b-ii, c-iii
(2) a-ii, b-i, c-iii
(3) a-iii, b-i, c-ii
(4) a-i, b-iii, c-ii

Explanation: Correct answer is (1). Bulliform cells mediate leaf folding, guard cells regulate stomatal opening, and spongy mesophyll facilitates gas diffusion in leaves.

9) Fill in the Blanks MCQ:
Leaf rolling in grasses occurs due to ______ of bulliform cells during drought.
(1) Flaccidity
(2) Expansion
(3) Lignification
(4) Death

Explanation: Correct answer is (1). Bulliform cells become flaccid during water deficit, causing leaves to curl inward, an adaptive mechanism to minimize transpiration.

10) Choose the correct statements MCQ:
(1) Leaf rolling reduces water loss
(2) Bulliform cells mediate leaf curling
(3) Spongy mesophyll causes leaf rolling
(4) Tyloses aid in leaf folding
Options:
(1) 1 and 2
(2) 2 and 3
(3) 3 and 4
(4) All of the above

Explanation: Correct answer is (1). Leaf rolling reduces water loss and is controlled by bulliform cells. Spongy mesophyll and tyloses do not directly contribute to this adaptive response.

Topic: Stomata Types

Subtopic: Grass Leaf Stomata

Keyword Definitions:

• Stomata: Pores in the epidermis of leaves and stems for gas exchange.

• Grass leaf: Monocot leaf with parallel venation, often having specialized stomata.

• Dumb-bell shaped stomata: Stomata with elongated guard cells and central pore, typical of grasses.

• Barrel shaped stomata: Common in dicots, kidney-shaped guard cells.

• Gas exchange: Process of CO2 uptake and O2 release during photosynthesis.

• Guard cells: Cells surrounding stomatal pore controlling opening and closing.

Lead Question (2018):

Stomata in grass leaf are:

(A) Barrel shaped

(B) Dumb-bell shaped

(C) Rectangular

(D) Kidney shaped

Explanation:

The correct answer is (B) Dumb-bell shaped. Grass, being a monocot, has dumb-bell shaped stomata with narrow ends and central pore, which allow efficient opening and closing. Barrel or kidney-shaped stomata are typically found in dicots. This structure helps in water conservation and gas exchange in grasses.

1. The main function of stomata is:

(A) Photosynthesis

(B) Gas exchange

(C) Transport of water

(D) Nutrient absorption

Explanation:

The correct answer is (B) Gas exchange. Stomata allow CO2 uptake for photosynthesis and O2 release. While stomata influence transpiration and water balance, their primary function is gas exchange, not nutrient absorption or direct photosynthesis.

2. Guard cells of grass stomata contain:

(A) Chloroplasts

(B) No chloroplasts

(C) Only mitochondria

(D) Only vacuoles

Explanation:

The correct answer is (A) Chloroplasts. Guard cells in grass have chloroplasts that help in sensing light and producing ATP for stomatal opening. They are metabolically active and contribute to opening and closing mechanisms.

3. Monocot stomata differ from dicot stomata in being:

(A) Kidney-shaped

(B) Dumb-bell shaped

(C) Circular

(D) Irregular

Explanation:

The correct answer is (B) Dumb-bell shaped. Monocots like grasses have dumb-bell shaped stomata for efficient opening. Dicots usually have kidney or barrel-shaped stomata. This adaptation helps monocots conserve water and respond rapidly to environmental changes.

4. Stomatal opening is regulated by:

(A) Light and potassium ions

(B) CO2 only

(C) Temperature only

(D) Oxygen only

Explanation:

The correct answer is (A) Light and potassium ions. Light triggers photosynthesis in guard cells, leading to K+ ion accumulation, osmotic water influx, and stomatal opening. CO2, temperature, and humidity also influence stomata, but K+ ions and light are primary regulators.

5. In which plant type are dumb-bell shaped stomata common?

(A) Dicots

(B) Monocots

(C) Gymnosperms

(D) Ferns

Explanation:

The correct answer is (B) Monocots. Dumb-bell shaped stomata are characteristic of monocot leaves such as grasses, aiding in rapid opening and closing. Dicots and gymnosperms have kidney or barrel-shaped stomata.

6. Stomatal density is generally higher on:

(A) Upper epidermis

(B) Lower epidermis

(C) Both equally

(D) Stem only

Explanation:

The correct answer is (B) Lower epidermis. Most leaves have higher stomatal density on the lower epidermis to minimize water loss while allowing gas exchange. Upper epidermis may have fewer stomata or none.

7. Assertion-Reason Question:

Assertion (A): Grass stomata are dumb-bell shaped.

Reason (R): This shape allows efficient opening and closing.

(A) Both A and R true, R explains A

(B) Both A and R true, R does not explain A

(C) A true, R false

(D) A false, R true

Explanation:

Correct answer is (A). The dumb-bell shape of guard cells in grasses enables rapid and efficient opening and closing of stomata, conserving water while ensuring adequate gas exchange. Both assertion and reason are true, with the reason explaining the assertion.

8. Matching Type Question:

Match stomatal types with plant examples:

(i) Dumb-bell shaped – (a) Grass

(ii) Kidney-shaped – (b) Sunflower

(iii) Barrel-shaped – (c) Bean

(iv) Circular – (d) Some algae

(A) i-a, ii-b, iii-c, iv-d

(B) i-b, ii-a, iii-d, iv-c

(C) i-c, ii-d, iii-b, iv-a

(D) i-d, ii-c, iii-a, iv-b

Explanation:

Correct answer is (A). Dumb-bell shaped stomata occur in grasses, kidney-shaped in sunflower, barrel-shaped in beans, and circular in some algae. Matching highlights structural diversity in stomata across plant groups.

9. Fill in the Blanks:

Stomata in monocots like grass are ______ and help in ______.

(A) Barrel-shaped, photosynthesis

(B) Dumb-bell shaped, efficient gas exchange

(C) Kidney-shaped, water storage

(D) Rectangular, transpiration only

Explanation:

Correct answer is (B) Dumb-bell shaped, efficient gas exchange. Grass stomata are dumb-bell shaped, allowing rapid opening and closing for gas exchange and water conservation. Barrel-shaped and kidney-shaped stomata are common in dicots.

10. Choose the correct statements:

(A) Grass stomata are dumb-bell shaped

(B) Stomata allow gas exchange

(C) Guard cells contain chloroplasts

(D) Monocots have kidney-shaped stomata

Options:

(1) A, B, C

(2) A, C, D

(3) B, C, D

(4) A, B, D

Explanation:

Correct answer is (1) A, B, C. Grass stomata are dumb-bell shaped, facilitate gas exchange, and guard cells contain chloroplasts. Monocots do not have kidney-shaped stomata, which are typical of dicots.

Topic: Secondary Growth in Plants

Subtopic: Plants with Minimal or No Secondary Growth

Keyword Definitions:

• Secondary growth: Increase in girth of plant due to vascular cambium activity.

• Cycads: Gymnosperms with thick woody stems but slow secondary growth.

• Grasses: Monocots with primary growth only, no true secondary growth.

• Conifers: Gymnosperms with extensive secondary growth forming wood.

• Deciduous angiosperms: Flowering plants shedding leaves seasonally, often with secondary growth.

Lead Question - 2018

Plants having little or no secondary growth are:

(A) Cycads

(B) Grasses

(C) Conifers

(D) Deciduous angiosperms

Explanation:

Answer is (B). Grasses are monocots, which lack vascular cambium, so they do not exhibit significant secondary growth. Their stems increase in length (primary growth) but not in thickness, unlike dicots or conifers that have well-developed secondary growth through vascular cambium.

Guessed NEET UG MCQs:

1) Single Correct: Which of the following monocots has negligible secondary growth?

(A) Bamboo

(B) Mango

(C) Pinus

(D) Cycas

Explanation:

Answer is (A). Bamboo, a monocot, exhibits primary growth only and lacks a vascular cambium, so secondary thickening is minimal despite its tall stems.

2) Single Correct: Vascular cambium in plants contributes to:

(A) Leaf formation

(B) Stem thickening

(C) Flowering

(D) Root hair formation

Explanation:

Answer is (B). Vascular cambium produces secondary xylem and phloem, increasing stem and root girth, which is absent or minimal in grasses and most monocots.

3) Single Correct: Which plant shows extensive secondary growth?

(A) Grass

(B) Wheat

(C) Mango

(D) Rice

Explanation:

Answer is (C). Mango, a dicot, develops vascular cambium leading to secondary growth, unlike monocots like wheat or rice which have primary growth only.

4) Assertion-Reason:

Assertion: Grasses lack secondary growth.

Reason: Monocots do not form vascular cambium.

(A) Both true, Reason correct

(B) Both true, Reason incorrect

(C) Assertion true, Reason false

(D) Both false

Explanation:

Answer is (A). Monocots like grasses lack a vascular cambium, so they cannot produce secondary xylem or phloem, resulting in negligible secondary growth.

5) Single Correct: Cycads show:

(A) Extensive secondary growth

(B) No growth

(C) Minimal secondary growth

(D) Only reproductive growth

Explanation:

Answer is (C). Cycads are gymnosperms with woody stems; secondary growth exists but is slow and limited compared to conifers or deciduous trees.

6) Single Correct (Clinical-type): A patient reports using bamboo fibers for medical dressings. Bamboo stems are suitable because:

(A) Thick secondary xylem

(B) Minimal secondary growth

(C) High resin content

(D) Extensive lignification

Explanation:

Answer is (B). Bamboo, having little secondary growth, has flexible stems, making it ideal for lightweight, bendable medical fibers without rigid thickening.

7) Matching Type:

Column I (Plant) | Column II (Characteristic)

a. Rice | i. Secondary thickening present

b. Mango | ii. Primary growth only

c. Pinus | iii. Woody stem with secondary growth

d. Wheat | iv. Minimal secondary growth

(A) a-ii, b-i, c-iii, d-iv

(B) a-ii, b-i, c-iii, d-ii

(C) a-iv, b-i, c-iii, d-ii

(D) a-ii, b-iii, c-i, d-iv

Explanation:

Answer is (B). Rice and wheat are monocots (primary growth), mango shows secondary growth, Pinus has extensive secondary xylem development.

8) Fill in the Blank:

Monocots like grasses have ______ secondary growth.

(A) Extensive

(B) Minimal or absent

(C) Irregular

(D) Fast

Explanation:

Answer is (B). Monocots do not develop vascular cambium, so secondary growth is minimal or absent, unlike dicots which thicken stems through secondary xylem and phloem.

9) Choose the correct statements:

(i) Grasses lack vascular cambium.

(ii) Conifers have secondary growth.

(iii) Deciduous angiosperms show secondary thickening.

(A) i and ii only

(B) i and iii only

(C) ii and iii only

(D) i, ii, iii

Explanation:

Answer is (D). Grasses (monocots) lack vascular cambium; conifers and deciduous dicots develop secondary xylem and phloem, contributing to stem thickening.

10) Clinical-type: A horticulturist notes that bamboo stems cannot be used for timber beams because:

(A) They have slow secondary growth

(B) They are monocots with negligible secondary growth

(C) They contain minimal lignin

(D) They are carnivorous

Explanation:

Answer is (B). Bamboo, a monocot, lacks vascular cambium and substantial secondary growth, so its stems do not thicken enough to provide strong timber beams.

Topic: Secondary Growth in Dicot Stem

Subtopic: Role of Cambium in Xylem and Phloem Formation

Keyword Definitions:

• Secondary xylem: Woody tissue formed internally during secondary growth, responsible for water conduction.

• Secondary phloem: Tissue formed externally during secondary growth, responsible for transport of food.

• Axillary meristems: Meristematic tissues located in leaf axils, producing branches.

• Apical meristems: Growing tips of stems and roots responsible for primary growth.

• Phellogen: Cork cambium producing periderm in stems and roots.

• Vascular cambium: Lateral meristem producing secondary xylem and phloem in stems and roots.

Lead Question - 2018

Secondary xylem and phloem in dicot stem are produced by:

(A) Axillary meristems

(B) Apical meristems

(C) Phellogen

(D) Vascular cambium

Explanation:

Answer is (D). Vascular cambium is a lateral meristem that produces secondary xylem internally and secondary phloem externally in dicot stems, enabling an increase in girth during secondary growth.

Guessed NEET UG MCQs:

1) Single Correct: The tissue responsible for increasing stem thickness in dicots is:

(A) Apical meristem

(B) Axillary meristem

(C) Vascular cambium

(D) Phellogen

Explanation:

Answer is (C). Vascular cambium, a lateral meristem, produces secondary xylem and phloem, resulting in thickening of dicot stems during secondary growth.

2) Single Correct: Which meristem produces cork in dicot stems?

(A) Apical meristem

(B) Phellogen

(C) Vascular cambium

(D) Axillary meristem

Explanation:

Answer is (B). Phellogen, or cork cambium, produces cork cells externally, forming protective periderm in stems and roots.

3) Single Correct: Secondary xylem is located:

(A) Externally to vascular cambium

(B) Internally to vascular cambium

(C) In leaf axils

(D) At stem tip

Explanation:

Answer is (B). Secondary xylem forms internally to the vascular cambium and functions in water conduction and structural support.

4) Assertion-Reason:

Assertion: Vascular cambium is responsible for secondary growth.

Reason: Apical meristems produce secondary xylem and phloem.

(A) Both true, Reason correct

(B) Both true, Reason incorrect

(C) Assertion true, Reason false

(D) Both false

Explanation:

Answer is (C). Vascular cambium causes secondary growth by producing secondary xylem and phloem. Apical meristems are responsible for primary growth, not secondary growth.

5) Single Correct: Secondary phloem is located:

(A) Internal to vascular cambium

(B) External to vascular cambium

(C) In root tip

(D) In leaf midrib

Explanation:

Answer is (B). Secondary phloem is formed externally to the vascular cambium and conducts organic nutrients throughout the plant.

6) Single Correct (Clinical-type): A dicot tree with damaged vascular cambium would show:

(A) Stunted primary growth

(B) Reduced thickening of stem

(C) Excessive leaf formation

(D) Increased branch formation

Explanation:

Answer is (B). Damage to vascular cambium impairs production of secondary xylem and phloem, reducing stem thickening and weakening the plant.

7) Matching Type:

Column I (Function) | Column II (Tissue)

a. Produces secondary xylem | i. Apical meristem

b. Produces secondary phloem | ii. Vascular cambium

c. Produces cork | iii. Phellogen

d. Produces branches | iv. Axillary meristem

(A) a-ii, b-ii, c-iii, d-iv

(B) a-i, b-i, c-iii, d-ii

(C) a-ii, b-iii, c-i, d-iv

(D) a-iii, b-ii, c-i, d-iv

Explanation:

Answer is (A). Secondary xylem and phloem are produced by vascular cambium, cork by phellogen, and branches arise from axillary meristems.

8) Fill in the Blank:

The lateral meristem that contributes to stem thickening is ______.

(A) Apical meristem

(B) Vascular cambium

(C) Axillary meristem

(D) Phellogen

Explanation:

Answer is (B). Vascular cambium is a lateral meristem responsible for secondary xylem and phloem formation, increasing stem thickness.

9) Choose the correct statements:

(i) Vascular cambium produces both secondary xylem and phloem.

(ii) Apical meristem contributes to primary growth.

(iii) Phellogen produces protective cork cells.

(A) i and ii only

(B) i and iii only

(C) ii and iii only

(D) i, ii, iii

Explanation:

Answer is (D). All statements are correct: vascular cambium produces secondary xylem and phloem, apical meristem contributes to primary growth, and phellogen produces cork cells.

10) Clinical-type: If vascular cambium activity stops in a mature dicot stem:

(A) Leaves continue to expand normally

(B) Stem thickening ceases

(C) Flowers fail to form

(D) Root elongation increases

Explanation:

Answer is (B). Cessation of vascular cambium activity stops secondary xylem and phloem production, halting stem thickening and limiting structural support.

Topic: Secondary Growth

Subtopic: Heartwood and Sapwood

Keyword Definitions:

• Heartwood – Inner, non-living part of secondary xylem providing structural support.

• Sapwood – Outer, living xylem that conducts water and minerals.

• Lignified – Cell walls strengthened with lignin, making them rigid.

• Organic compounds – Substances like tannins, resins, and oils deposited in heartwood.

• Durable – Resistant to decay and pests.

• Secondary xylem – Woody tissue formed during secondary growth.

• Dead elements – Xylem cells that no longer have protoplasm.

• Water conduction – Transport of water through xylem.

• Mineral transport – Movement of dissolved minerals through xylem.

• Structural support – Function of heartwood in maintaining tree rigidity.

Lead Question – 2017:

Identify the wrong statement in context of heartwood:

(A) It comprises dead elements with highly lignified walls

(B) Organic compounds are deposited in it

(C) It is highly durable

(D) It conducts water and minerals efficiently

Explanation:

Heartwood consists of dead, lignified cells with deposited organic compounds, making it highly durable. It no longer participates in water and mineral conduction, which is the function of sapwood. Hence, the statement that heartwood conducts water and minerals efficiently is incorrect. (Answer: D)

1) Single Correct Answer MCQ:

Which part of the xylem primarily conducts water in mature trees?

(A) Heartwood

(B) Sapwood

(C) Pith

(D) Cork

Explanation:

Sapwood consists of living xylem elements responsible for water and mineral conduction in trees, whereas heartwood is non-conducting and provides structural support. (Answer: B)

2) Single Correct Answer MCQ:

Heartwood is characterized by:

(A) Living parenchyma cells

(B) Highly lignified dead elements

(C) Active water transport

(D) Lack of durability

Explanation:

Heartwood is composed of dead, highly lignified cells, resistant to decay, and rich in deposited organic compounds. It provides strength and durability but does not transport water. (Answer: B)

3) Single Correct Answer MCQ:

Which compounds increase the durability of heartwood?

(A) Sugars

(B) Resins and tannins

(C) Chlorophyll

(D) Proteins

Explanation:

Deposition of resins, tannins, and other organic compounds in heartwood increases resistance to pests and decay, making it highly durable compared to sapwood. (Answer: B)

4) Single Correct Answer MCQ:

Which statement is true about sapwood?

(A) It is dead and lignified

(B) It conducts water and minerals

(C) It is highly resistant to decay

(D) It stores tannins

Explanation:

Sapwood is the outer xylem of trees that is alive and actively conducts water and minerals from roots to leaves. Heartwood, not sapwood, is highly resistant to decay. (Answer: B)

5) Single Correct Answer MCQ:

Which of the following is primarily a structural function in trees?

(A) Sapwood

(B) Heartwood

(C) Phloem

(D) Cortex

Explanation:

Heartwood provides mechanical support and rigidity to trees, supporting the plant structure, while sapwood primarily transports water and minerals. (Answer: B)

6) Single Correct Answer MCQ:

Dead xylem elements are found in:

(A) Heartwood

(B) Sapwood

(C) Phloem

(D) Cambium

Explanation:

Heartwood consists of dead, lignified xylem elements, while sapwood contains living xylem conducting water. Phloem and cambium serve different functions. (Answer: A)

7) Assertion-Reason MCQ:

Assertion (A): Heartwood is highly durable.

Reason (R): It contains deposited resins and tannins.

(A) Both A and R true, R explains A

(B) Both A and R true, R does not explain A

(C) A true, R false

(D) A false, R true

Explanation:

Both assertion and reason are correct. Deposited resins and tannins enhance decay resistance, making heartwood highly durable. (Answer: A)

8) Matching Type MCQ:

Match characteristic with xylem type:

1. Heartwood – (i) Water conduction

2. Sapwood – (ii) Structural support

3. Dead elements – (iii) Present in heartwood

4. Organic compounds – (iv) Deposited in heartwood

Options:

(A) 1-ii, 2-i, 3-iii, 4-iv

(B) 1-i, 2-ii, 3-iv, 4-iii

(C) 1-iv, 2-iii, 3-ii, 4-i

(D) 1-iii, 2-iv, 3-i, 4-ii

Explanation:

Correct matching: Heartwood – structural support; Sapwood – water conduction; Dead elements – present in heartwood; Organic compounds – deposited in heartwood. (Answer: A)

9) Fill in the Blanks MCQ:

________ xylem is responsible for mechanical support and durability in trees.

(A) Sapwood

(B) Heartwood

(C) Phloem

(D) Cambium

Explanation:

Heartwood provides mechanical support, rigidity, and durability to trees due to dead lignified cells and deposited organic compounds, while sapwood conducts water. (Answer: B)

10) Choose the correct statements MCQ:

1. Heartwood is dead.

2. Heartwood deposits organic compounds like tannins.

3. Heartwood efficiently conducts water.

4. Heartwood is highly durable.

Options:

(A) 1, 2, 3

(B) 1, 2, 4

(C) 2, 3, 4

(D) 1, 3, 4

Explanation:

Statements 1, 2, and 4 are correct. Heartwood is dead, contains organic deposits, and is highly durable. It does not conduct water efficiently; sapwood performs that function. (Answer: B)

Topic: Tissue Systems

Subtopic: Simple and Complex Tissues

Keyword Definitions:

• Phloem – Complex tissue transporting organic nutrients, mainly sucrose, in plants; composed of living cells.

• Xylem parenchyma – Living cells in xylem that store food and help lateral conduction.

• Collenchyma – Living supportive tissue with thickened cell walls providing mechanical strength.

• Phellem – Also called cork; dead cells forming protective outer bark.

• Dead cells – Cells that have lost protoplasm, usually serving structural or protective roles.

• Clinical/agronomic relevance – Knowledge of dead vs living tissues aids in understanding plant physiology, wood formation, and crop improvement.

• Tissue differentiation – Distinguishing between living and dead cells is crucial for plant anatomy and horticultural studies.

Lead Question – 2017:

Which of the followings is made up of dead cells :

(A) Phloem

(B) Xylem parenchyma

(C) Collenchyma

(D) Phellem

Explanation:

Phellem, or cork, is composed of dead cells that form the protective outer layer of bark. Phloem, collenchyma, and xylem parenchyma are living tissues with active protoplasm. Phellem cells prevent water loss, protect against pathogens, and provide mechanical strength. (Answer: D)

1) Which tissue primarily provides mechanical support in young stems?

(A) Collenchyma

(B) Xylem

(C) Phellem

(D) Phloem

Explanation:

Collenchyma is a living supportive tissue with unevenly thickened walls. It provides flexible mechanical support to young stems and leaves, allowing growth and resistance to bending. Xylem and phellem provide different types of support or protection. (Answer: A)

2) Xylem tracheids and vessels are composed of:

(A) Living cells

(B) Dead cells

(C) Parenchymatous cells only

(D) Collenchymatous cells only

Explanation:

Xylem vessels and tracheids are dead cells at maturity. They form hollow tubes facilitating water and mineral transport. Unlike living parenchyma, their protoplasm degenerates to allow unimpeded conduction. This is crucial for understanding plant water transport physiology. (Answer: B)

3) Clinical/agronomic case: Cork harvested from trees is primarily composed of:

(A) Phloem fibers

(B) Collenchyma

(C) Phellem

(D) Xylem parenchyma

Explanation:

Phellem forms cork, a protective outer layer of bark composed of dead cells. Its impermeability to water and resistance to pathogens make it commercially valuable for cork products. Knowledge of tissue types is important in forestry and sustainable harvesting practices. (Answer: C)

4) Which of the following tissues is living and involved in nutrient transport?

(A) Phloem

(B) Xylem vessels

(C) Phellem

(D) Sclerenchyma fibers

Explanation:

Phloem is a living tissue that transports organic nutrients like sugars. Companion cells assist sieve elements in metabolic functions. Xylem vessels are dead, phellem is dead cork, and sclerenchyma fibers are dead supportive cells. This distinction is critical in plant physiology studies. (Answer: A)

5) Which tissue stores food in xylem?

(A) Xylem parenchyma

(B) Tracheids

(C) Vessels

(D) Sclerenchyma

Explanation:

Xylem parenchyma is living and stores starch, proteins, and other nutrients. Unlike tracheids or vessels, which are dead, parenchyma maintains metabolic activity and aids lateral transport. Understanding tissue function helps in wood anatomy and crop improvement. (Answer: A)

6) Which tissue provides outer protection against water loss?

(A) Phellem

(B) Collenchyma

(C) Phloem

(D) Xylem

Explanation:

Phellem forms the outer bark in plants and consists of dead, suberized cells. It prevents water loss, mechanical injury, and pathogen invasion. Collenchyma, phloem, and xylem serve support and transport functions, but phellem specifically provides protective advantages. (Answer: A)

7) Assertion-Reason type:

Assertion (A): Phellem is composed of dead cells.

Reason (R): Dead cells cannot divide but provide protection and structural support.

(A) Both A and R are true, and R is the correct explanation of A

(B) Both A and R are true, but R is not the correct explanation

(C) A is true, R is false

(D) A is false, R is true

Explanation:

Both assertion and reason are true, and R correctly explains A. Phellem cells are dead at maturity and provide waterproofing, mechanical strength, and protection. Their death allows suberization, making cork effective for external protection and industrial applications. (Answer: A)

8) Matching type:

Match tissue with characteristics:

(A) Phellem – (i) Dead, protective

(B) Collenchyma – (ii) Living, supportive

(C) Phloem – (iii) Living, transport

(D) Xylem parenchyma – (iv) Living, storage

Options:

(A) A-i, B-ii, C-iii, D-iv

(B) A-ii, B-iii, C-i, D-iv

(C) A-iii, B-iv, C-ii, D-i

(D) A-iv, B-i, C-ii, D-iii

Explanation:

Correct matches: Phellem – dead/protective, Collenchyma – living/supportive, Phloem – living/transport, Xylem parenchyma – living/storage. This classification aids understanding of tissue function, plant physiology, and practical applications in agriculture and forestry. (Answer: A)

9) Fill in the blanks:

Cork tissue made of dead cells is called ______.

(A) Phellem

(B) Collenchyma

(C) Phloem

(D) Xylem parenchyma

Explanation:

Phellem is cork tissue composed of dead, suberized cells. It provides protection, prevents water loss, and enhances mechanical strength. Recognizing dead versus living tissue is fundamental in plant anatomy and applied botany studies. (Answer: A)

10) Choose the correct statements:

1. Phloem is made of living cells.

2. Phellem is composed of dead cells.

3. Collenchyma is living supportive tissue.

4. Xylem parenchyma is dead.

(A) 1, 2, 3 only

(B) 2, 3, 4 only

(C) 1, 3, 4 only

(D) All are correct

Explanation:

Statements 1, 2, and 3 are correct; statement 4 is incorrect because xylem parenchyma is living. Distinguishing living and dead plant tissues is essential for understanding plant structure, physiology, and agricultural applications. (Answer: A)

Topic: Secondary Growth
Subtopic: Vascular Cambium

• Vascular Cambium: Lateral meristem in plants producing secondary xylem and phloem, contributing to stem thickening.

• Periderm: Protective tissue replacing epidermis during secondary growth.

• Phelloderm: Parenchymatous cells formed inwardly by cork cambium.

• Primary Phloem: Phloem formed during primary growth, outside the vascular cambium.

• Secondary Xylem: Wood produced inwardly by vascular cambium.

• Secondary Phloem: Phloem formed outwardly by vascular cambium.

• Meristem: Tissue in plants responsible for continuous growth.

• Clinical Relevance: Knowledge of vascular cambium informs botany, plant tissue culture, and wood-based medical studies.

• Lateral Meristem: Meristem responsible for increase in girth or thickness of plant organs.

• Secondary Growth: Growth in thickness due to activity of lateral meristems.

Lead Question - 2017: The vascular cambium normally gives rise to :

1. Periderm

2. Phelloderm

3. Primary phloem

4. Secondary xylem

Explanation: The correct answer is (4). Vascular cambium produces secondary xylem (wood) inwardly and secondary phloem outwardly. Clinically, understanding this helps in identifying plant structural features, wood quality, and tissue development, which are essential in botany and pharmacognosy.

Chapter: Plant Anatomy
Topic: Secondary Growth
Subtopic: Vascular Cambium

• Vascular Cambium: Lateral meristem producing secondary xylem and phloem.

• Secondary Xylem: Wood formed inwardly by vascular cambium.

• Secondary Phloem: Phloem formed outwardly by vascular cambium.

• Periderm: Protective tissue replacing epidermis in secondary growth.

• Phelloderm: Parenchyma formed inwardly by cork cambium.

• Primary Phloem: Phloem formed during primary growth.

• Meristem: Plant tissue responsible for continuous growth.

• Lateral Meristem: Meristem responsible for increase in girth of stems or roots.

• Secondary Growth: Increase in thickness due to lateral meristems.

• Clinical Relevance: Knowledge of vascular cambium aids understanding wood formation, tissue culture, and medicinal plant research.

1. Secondary phloem is formed by:

1. Cork cambium

2. Vascular cambium

3. Apical meristem

4. Primary xylem

Explanation: Correct answer is (2). Secondary phloem forms outwardly from vascular cambium, supporting transport of organic nutrients. Clinically, understanding secondary phloem helps in identifying plant growth patterns and sap flow relevant for medicinal plant studies.

2. Cork cambium produces:

1. Secondary xylem

2. Secondary phloem

3. Periderm

4. Primary xylem

Explanation: Correct answer is (3). Cork cambium generates periderm, providing protective outer covering during secondary growth. Clinically, periderm studies help in understanding bark formation and pharmacologically important plant tissues.

3. Primary phloem differs from secondary phloem in:

1. Origin from apical meristem

2. Transport function

3. Cell type

4. Both transport and structure

Explanation: Correct answer is (1). Primary phloem originates from apical meristem during primary growth, unlike secondary phloem from vascular cambium. Clinically, understanding this distinction aids in interpreting stem anatomy in medicinal plants.

4. Secondary xylem contributes to:

1. Transport of water and minerals

2. Protection

3. Leaf formation

4. Flower development

Explanation: Correct answer is (1). Secondary xylem transports water and minerals from roots to aerial parts. Clinically, knowledge of secondary xylem is important in dendrology and plant-based pharmaceutical studies.

5. Lateral meristems are responsible for:

1. Increase in length of stems

2. Increase in girth of stems and roots

3. Flowering

4. Leaf formation

Explanation: Correct answer is (2). Lateral meristems like vascular and cork cambium increase girth during secondary growth. Clinically, understanding lateral meristems informs wood anatomy and medicinal tissue studies.

6. Vascular cambium is located between:

1. Xylem and phloem

2. Phloem and periderm

3. Periderm and cortex

4. Cortex and pith

Explanation: Correct answer is (1). Vascular cambium lies between xylem and phloem, producing secondary tissues. Clinically, this helps in interpreting cross-sections of stems and roots in botanical research.

7. Assertion (A): Secondary xylem is more abundant than secondary phloem.
Reason (R): Vascular cambium produces more xylem inwardly than phloem outwardly.

1. A is true, R is true, R explains A

2. A is true, R is true, R does not explain A

3. A is true, R is false

4. A is false, R is true

Explanation: Correct answer is (1). Vascular cambium produces abundant secondary xylem inwardly and less phloem outwardly. Clinically, understanding this explains stem thickening and wood formation in plants used for medicinal purposes.

8. Match tissue with function:

1. Secondary xylem

2. Secondary phloem

3. Cork

4. Phelloderm

A. Transport of water and minerals
B. Transport of organic nutrients
C. Protective covering
D. Storage and support

Explanation: Correct matching: 1-A, 2-B, 3-C, 4-D. Each tissue has a distinct role during secondary growth. Clinically, knowledge of these tissues is crucial in plant anatomy, wood studies, and pharmacognosy.

9. Fill in the blank: Vascular cambium produces ______ inwardly and ______ outwardly.

1. Secondary phloem; secondary xylem

2. Primary xylem; primary phloem

3. Secondary xylem; secondary phloem

4. Periderm; phelloderm

Explanation: Correct answer is (3). Vascular cambium produces secondary xylem inwardly and secondary phloem outwardly. Clinically, this knowledge aids in understanding stem anatomy, tissue culture, and pharmacognostic applications of medicinal plants.

10. Choose the correct statements regarding vascular cambium:

1. It is a lateral meristem

2. Produces secondary xylem and phloem

3. Located between primary xylem and phloem

4. All of the above

Explanation: Correct answer is (4). Vascular cambium is a lateral meristem producing secondary xylem inwardly and phloem outwardly, located between primary xylem and phloem. Clinically, this understanding is important in botany, wood anatomy, and medicinal plant tissue research.

Topic: Xylem and Tyloses

Subtopic: Structure and Function of Tyloses

Keyword Definitions:

• Tyloses: Balloon-shaped outgrowths from xylem parenchyma cells into vessels.

• Xylem Vessels: Tubular structures conducting water and minerals in plants.

• Sapwood: The outer, living part of the wood in a tree.

• Lumen: The interior space of a vessel or cell.

• Xylem Parenchyma Cells: Living cells in xylem involved in storage and lateral transport.

Lead Question - 2016 (Phase 2):

The balloon-shaped structures called tyloses

(1) Are linked to the ascent of sap through xylem vessels

(2) Originate in the lumen of vessels

(3) Characterize the sapwood

(4) Are extensions of xylem parenchyma cells into vessels

Explanation: Tyloses are balloon-shaped outgrowths of xylem parenchyma cells that protrude into xylem vessels, blocking them to prevent the spread of pathogens and regulate water conduction. The correct answer is (4) Are extensions of xylem parenchyma cells into vessels, key in plant structural defense mechanisms.

1. Single Correct Answer MCQ:

What is the primary function of tyloses in xylem vessels?

(1) Facilitate water transport

(2) Block xylem vessels to prevent pathogen spread

(3) Store starch

(4) Support structural rigidity

Explanation: Tyloses primarily block xylem vessels to prevent the spread of pathogens and air embolisms. This blockage helps in maintaining plant health and regulating water transport. The correct answer is (2) Block xylem vessels to prevent pathogen spread, important for understanding plant defense anatomy.

2. Single Correct Answer MCQ:

Where do tyloses originate from?

(1) Xylem vessels

(2) Xylem parenchyma cells

(3) Phloem sieve tubes

(4) Epidermal cells

Explanation: Tyloses originate from xylem parenchyma cells that expand and protrude into the xylem vessels. This formation is crucial for blocking vessels under stress or infection. Thus, the correct answer is (2) Xylem parenchyma cells, a fundamental fact in plant physiology studies.

3. Single Correct Answer MCQ:

Tyloses are most commonly found in which part of the plant?

(1) Phloem

(2) Cortex

(3) Xylem vessels

(4) Epidermis

Explanation: Tyloses are balloon-shaped structures specifically formed within xylem vessels to block them. They are not found in phloem, cortex, or epidermis. The correct answer is (3) Xylem vessels, an essential concept in vascular plant anatomy for NEET UG.

4. Single Correct Answer MCQ:

Tyloses are important for:

(1) Enhancing water conduction

(2) Preventing spread of pathogens and air embolism

(3) Storing water

(4) Providing mechanical support

Explanation: The primary role of tyloses is to prevent the spread of pathogens and air embolisms in xylem vessels by blocking them. They do not enhance water conduction or store water. Thus, the correct answer is (2) Preventing spread of pathogens and air embolism.

5. Single Correct Answer MCQ (Clinical-type):

How does knowledge of tyloses benefit pharmacognosy?

(1) Identifies therapeutic compounds

(2) Helps in correct identification of woody plants

(3) Ensures safety in herbal drug sourcing

(4) Has no relevance

Explanation: Tyloses help in identifying wood species and differentiating healthy from infected wood, aiding in correct identification of medicinal plants during pharmacognosy studies. This prevents misidentification and ensures drug safety. The correct answer is (2) Helps in correct identification of woody plants.

6. Single Correct Answer MCQ:

Which condition stimulates tylose formation?

(1) Rapid growth

(2) Pathogen infection or aging

(3) High photosynthesis rate

(4) Low humidity

Explanation: Tylose formation is primarily stimulated by pathogen infection or the aging process in plants. They block vessels to isolate damaged or infected areas. Therefore, the correct answer is (2) Pathogen infection or aging, crucial for understanding plant defense mechanisms in NEET UG preparation.

7. Assertion-Reason MCQ:

Assertion (A): Tyloses help in preventing air embolism in xylem vessels.

Reason (R): Tyloses block the vessel lumen formed by xylem parenchyma cells.

(1) Both A and R are true and R is correct explanation of A

(2) Both A and R are true but R is not correct explanation of A

(3) A is true but R is false

(4) A is false but R is true

Explanation: Both the assertion and reason are correct and the reason correctly explains the assertion. Tyloses effectively block vessels to prevent air embolism, which can interrupt water transport. Thus, the correct answer is (1) Both A and R are true and R is correct explanation of A.

8. Matching Type MCQ:

Match the structure with its function:

A. Tyloses

B. Xylem Parenchyma

C. Xylem Vessels

D. Endodermis

1. Conducts water

2. Stores starch and forms tyloses

3. Acts as a selective barrier

4. Blocks vessels under stress

Options:

(1) A-4, B-2, C-1, D-3

(2) A-1, B-3, C-2, D-4

(3) A-2, B-1, C-3, D-4

(4) A-3, B-1, C-4, D-2

Explanation: The correct matching is A-4 (Tyloses block vessels under stress), B-2 (Xylem parenchyma stores starch and forms tyloses), C-1 (Xylem vessels conduct water), D-3 (Endodermis acts as a selective barrier). The correct answer is (1) A-4, B-2, C-1, D-3.

9. Fill in the Blanks MCQ:

Tyloses are formed by the protrusion of ______ cells into xylem vessels.

(1) Parenchyma

(2) Collenchyma

(3) Sclerenchyma

(4) Phloem

Explanation: Tyloses are balloon-like protrusions formed by xylem parenchyma cells into the lumen of xylem vessels. This process helps block the vessels to prevent pathogen spread and embolism. The correct answer is (1) Parenchyma, a key fact in plant anatomy for NEET UG.

10. Choose the Correct Statements MCQ:

Select correct statements regarding tyloses:

(1) They aid in water conduction

(2) They block xylem vessels

(3) Formed from parenchyma cells

(4) Found in healthy sapwood only

Options:

(1) 2 and 3 only

(2) 1 and 4 only

(3) 1, 2, and 3

(4) All statements are correct

Explanation: Statements 2 and 3 are correct: tyloses block xylem vessels and are formed from parenchyma cells. They do not aid in water conduction or appear only in healthy sapwood. Correct answer is (1) 2 and 3 only, crucial knowledge for NEET UG botany section.

Subtopic: Cortex in Plants

Keyword Definitions:

• Cortex: The region of a plant between the epidermis and the vascular tissues.

• Endodermis: Innermost layer of the cortex acting as a selective barrier for substances entering the vascular bundle.

• Vascular Bundle: A part of the transport system in vascular plants, consisting of xylem and phloem.

• Epidermis: Outermost layer of cells covering the plant body.

• Stele: The central part of the root or stem containing vascular tissue.

• Pericycle: Layer of cells just inside the endodermis, important for lateral root development.

• Pith: Central tissue in stems, primarily parenchymatous cells storing nutrients.

Lead Question - 2016 (Phase 2):

Cortex is the region found between

(1) Endodermis and vascular bundle

(2) Epidermis and stele

(3) Pericycle and endodermis

(4) Endodermis and pith

Explanation: Cortex is the region between the epidermis and stele, primarily composed of parenchyma cells. It plays a key role in storage, photosynthesis, and transport of nutrients. The correct answer is (2) Epidermis and stele, a fundamental concept in plant anatomy for NEET UG preparations.

1. Single Correct Answer MCQ:

What is the primary function of the cortex in roots?

(1) Photosynthesis

(2) Nutrient transport

(3) Storage of starch

(4) Water absorption

Explanation: The cortex in roots primarily stores starch, acting as a reserve energy source for plant growth and metabolism. Though involved in transport and support, starch storage is the main function. The correct answer is (3) Storage of starch, crucial for understanding plant structural functions in NEET UG syllabus.

2. Single Correct Answer MCQ:

Which tissue lies directly inside the cortex?

(1) Epidermis

(2) Pericycle

(3) Endodermis

(4) Phloem

Explanation: The endodermis is directly inside the cortex and acts as a selective barrier regulating the movement of water and minerals into the vascular bundle. It plays a crucial role in root function. Therefore, the correct answer is (3) Endodermis, key for understanding plant vascular anatomy.

3. Single Correct Answer MCQ:

In stems, the cortex is located between

(1) Epidermis and vascular bundle

(2) Epidermis and pith

(3) Endodermis and pericycle

(4) Xylem and phloem

Explanation: In stems, the cortex is the tissue between the epidermis and vascular bundles. It serves functions such as mechanical support, storage, and sometimes photosynthesis. Hence, the correct answer is (1) Epidermis and vascular bundle, essential in plant anatomical studies for NEET UG.

4. Single Correct Answer MCQ:

Which type of cells predominantly makes up the cortex?

(1) Collenchyma

(2) Parenchyma

(3) Sclerenchyma

(4) Xylem

Explanation: The cortex is primarily composed of parenchyma cells, which are loosely packed and help in storage, photosynthesis, and transport. Collenchyma and sclerenchyma are more for support, while xylem is a vascular tissue. The correct answer is (2) Parenchyma, crucial in plant histology.

5. Single Correct Answer MCQ (Clinical-type):

Why is knowledge of cortex structure important in clinical pharmacognosy?

(1) It helps in drug synthesis

(2) Cortex stores active medicinal compounds

(3) Cortex is rich in alkaloids only

(4) Cortex is non-functional in drug studies

Explanation: The plant cortex often stores active medicinal compounds such as alkaloids, tannins, and glycosides, which are crucial for drug development. Understanding its structure aids in accurate extraction of these bioactive components. Thus, the correct answer is (2) Cortex stores active medicinal compounds, important in pharmacognosy.

6. Single Correct Answer MCQ:

Which layer surrounds the stele in roots?

(1) Cortex

(2) Endodermis

(3) Pericycle

(4) Epidermis

Explanation: The cortex surrounds the stele and is involved in storage and transport of materials from the epidermis to the vascular tissue. The correct answer is (1) Cortex, a basic yet crucial fact for plant anatomy sections in NEET UG preparation.

7. Assertion-Reason MCQ:

Assertion (A): Cortex plays a significant role in storage of starch.

Reason (R): Cortex consists mainly of parenchyma cells which store starch.

(1) Both A and R are true and R is correct explanation of A

(2) Both A and R are true but R is not correct explanation of A

(3) A is true but R is false

(4) A is false but R is true

Explanation: The assertion and reason are both correct and the reason accurately explains the assertion. Parenchyma cells in the cortex store starch, which serves as an energy reserve. Therefore, the correct answer is (1) Both A and R are true and R is correct explanation of A.

8. Matching Type MCQ:

Match the plant part with its component:

A. Cortex

B. Epidermis

C. Stele

D. Pericycle

1. Outer protective layer

2. Central vascular tissue

3. Layer between epidermis and stele

4. Layer just inside endodermis

Options:

(1) A-3, B-1, C-2, D-4

(2) A-2, B-3, C-1, D-4

(3) A-1, B-3, C-4, D-2

(4) A-3, B-1, C-4, D-2

Explanation: The correct match is A-3 (Cortex-layer between epidermis and stele), B-1 (Epidermis-outer protective layer), C-2 (Stele-central vascular tissue), D-4 (Pericycle-layer just inside endodermis). Correct understanding of plant structural components is vital for NEET UG botany section. Correct answer is (1) A-3, B-1, C-2, D-4.

9. Fill in the Blanks MCQ:

The cortex primarily consists of ______ cells.

(1) Parenchyma

(2) Collenchyma

(3) Sclerenchyma

(4) Xylem

Explanation: The cortex is primarily composed of parenchyma cells that function in storage, photosynthesis, and nutrient transport. Parenchyma cells are loosely arranged, allowing easy exchange of materials. Therefore, the correct answer is (1) Parenchyma, fundamental knowledge for NEET UG plant anatomy.

10. Choose the Correct Statements MCQ:

Select the correct statements regarding the plant cortex:

(1) It stores starch

(2) It lies between the epidermis and vascular tissues

(3) It is composed only of sclerenchyma cells

(4) It plays no role in plant support

Options:

(1) 1 and 2 only

(2) 2 and 3 only

(3) 1, 2, and 4

(4) All statements are correct

Explanation: Statements 1 and 2 are correct: the cortex stores starch and lies between the epidermis and vascular tissues. Statement 3 is incorrect as the cortex mainly consists of parenchyma, not only sclerenchyma cells. The correct answer is (1) 1 and 2 only, essential for NEET UG botany syllabus.

Chapter: Plant Anatomy

Topic: Plant Tissues

Subtopic: Epidermal Cells and Stomatal Complex

Keyword Definitions:

• Guard Cells: Specialized epidermal cells that control stomatal opening and closing in plants.

• Subsidiary Cells: Specialized epidermal cells surrounding guard cells, aiding stomatal function.

• Bulliform Cells: Large epidermal cells that help in leaf folding and unfolding under water stress.

• Lenticels: Spongy openings in bark allowing gas exchange in woody plants.

• Stomata: Microscopic pores on leaf epidermis facilitating gas exchange and transpiration.

• Epidermal Cells: Outer layer cells of plants providing protection and regulating gas exchange.

2016 (Phase 1)

Lead Question: Specialised epidermal cells surrounding the guard cells are called:

• (1) Complementary cells

• (2) Subsidiary cells

• (3) Bulliform cells

• (4) Lenticels

Answer & Explanation: The correct answer is (2). Subsidiary cells are specialized epidermal cells adjacent to guard cells in the stomatal complex. They assist guard cells in regulating stomatal aperture by providing mechanical support and aiding ion exchange during opening and closing, thus playing a critical role in plant transpiration and gas exchange.

Single Correct Answer MCQ: The main function of bulliform cells in monocot leaves is to:

• (1) Assist in photosynthesis

• (2) Facilitate leaf folding to reduce water loss

• (3) Store starch

• (4) Transport nutrients

Answer & Explanation: The correct answer is (2). Bulliform cells are large, bubble-shaped cells on the upper epidermis of monocot leaves. They collapse under drought conditions, causing the leaf to fold, thereby reducing surface area and minimizing water loss through transpiration during dry conditions.

Assertion-Reason MCQ:

Assertion (A): Lenticels facilitate gas exchange in woody plants.

Reason (R): They are spongy tissue areas in the bark that allow passage of gases.

• (1) Both A and R are true, and R is correct explanation of A.

• (2) Both A and R are true, but R is not correct explanation of A.

• (3) A is true, but R is false.

• (4) A is false, but R is true.

Answer & Explanation: The correct answer is (1). Lenticels are specialized structures in bark composed of loosely packed cells with intercellular spaces. They facilitate the exchange of gases (O₂ and CO₂) between internal tissues and the atmosphere, critical for respiration in woody plants.

Matching Type MCQ: Match the term to its role:

A. Guard Cells            1. Gas exchange control

B. Subsidiary Cells        2. Support guard cells

C. Lenticels               3. Gas exchange in woody plants

D. Bulliform Cells         4. Leaf folding during water stress

• (1) A-1, B-2, C-3, D-4

• (2) A-2, B-1, C-4, D-3

• (3) A-1, B-3, C-2, D-4

• (4) A-3, B-4, C-1, D-2

Answer & Explanation: The correct answer is (1). Guard cells regulate stomatal opening and closing for gas exchange; subsidiary cells provide mechanical and physiological support; lenticels allow gas exchange in woody plants; bulliform cells help leaves fold under water stress.

Fill in the Blanks / Completion MCQ: The specialised epidermal cells adjacent to guard cells are called ________.

• (1) Bulliform cells

• (2) Subsidiary cells

• (3) Complementary cells

• (4) Lenticels

Answer & Explanation: The correct answer is (2). Subsidiary cells are epidermal cells closely associated with guard cells that assist in regulating the movement of stomata by aiding ion transport and providing mechanical support, thus facilitating efficient gas exchange.

Choose the correct statements MCQ:

• 1. Subsidiary cells help in stomatal movement.

• 2. Lenticels are present in leaves.

• 3. Bulliform cells are prominent in monocots.

• 4. Guard cells regulate transpiration.

• (1) 1, 3, and 4 only

• (2) 1 and 2 only

• (3) 2 and 3 only

• (4) 1, 2, and 4 only

Answer & Explanation: The correct answer is (1). Subsidiary cells assist guard cells in stomatal function; bulliform cells are significant in monocot leaves for water stress response; guard cells regulate transpiration. Lenticels are present in stems and bark, not in leaves, hence statement 2 is incorrect.