Subtopic: Types of Roots
Prop roots: Adventitious roots that arise from the base of stem to provide extra support.
Lateral roots: Roots that develop from the primary root to increase absorption surface.
Fibrous roots: Thin, branched roots arising from the stem or base, forming a dense network.
Primary root: Main root developing from radicle during germination.
Adventitious roots: Roots that arise from organs other than radicle, like stem or leaf.
Radicle: Embryonic root from seed germination, develops into primary root.
Support roots: Roots that stabilize plant, often prop roots in tall or weak-stemmed plants.
Root system: Entire network of roots in a plant, including primary, lateral, and adventitious roots.
Monocot root system: Fibrous roots predominating without a prominent primary root.
Dicot root system: Taproot system with a prominent primary root and lateral branches.
Root morphology: Study of shape, type, and arrangement of roots in plants.
Lead Question (2020): The roots that originate from the base of the stem are:
Options:
1. Prop roots
2. Lateral roots
3. Fibrous roots
4. Primary roots
Explanation: Correct answer is 1. Prop roots are adventitious roots that emerge from the stem base and provide mechanical support to the plant. Unlike lateral or primary roots, these roots originate from stem tissue and help stabilize tall or weak-stemmed plants, commonly observed in species like maize and banyan.
1. Single Correct Answer MCQ:
Which root type arises directly from the radicle?
Options:
a. Prop roots
b. Lateral roots
c. Fibrous roots
d. Adventitious roots
Explanation: Correct answer is b. Lateral roots develop from the primary root, which originates from the radicle, increasing root surface area for absorption. Prop roots and adventitious roots arise from stem or leaf, not directly from radicle.
2. Single Correct Answer MCQ:
Fibrous roots are characteristic of:
Options:
a. Monocots
b. Dicots
c. Gymnosperms
d. Bryophytes
Explanation: Correct answer is a. Monocots typically have a fibrous root system where adventitious roots arise from stem base or nodes, forming a dense mat without a prominent primary root, aiding in soil stabilization and water absorption.
3. Single Correct Answer MCQ:
Which root provides mechanical support to tall plants?
Options:
a. Lateral roots
b. Prop roots
c. Fibrous roots
d. Primary roots
Explanation: Correct answer is b. Prop roots grow from the stem base and anchor the plant to the soil, providing stability and support to tall plants like maize and banyan, preventing them from toppling due to wind or weight.
4. Single Correct Answer MCQ:
Primary root is formed from:
Options:
a. Stem base
b. Radicle
c. Leaf
d. Node
Explanation: Correct answer is b. The primary root develops from the radicle of the embryo during germination. It forms the main taproot in dicots, while monocots may replace it with a fibrous root system.
5. Single Correct Answer MCQ:
Adventitious roots arise from:
Options:
a. Radicle
b. Stem or leaf
c. Lateral roots
d. Tap root
Explanation: Correct answer is b. Adventitious roots develop from organs other than the radicle, typically from stem nodes or leaves, performing functions such as support, vegetative propagation, or absorption.
6. Single Correct Answer MCQ:
Which root system has no prominent primary root?
Options:
a. Taproot system
b. Fibrous root system
c. Prop root system
d. Lateral root system
Explanation: Correct answer is b. Fibrous root systems, typical of monocots, consist of adventitious roots arising from the stem or base and lack a dominant primary root, forming a dense network that efficiently absorbs water and nutrients.
7. Assertion-Reason MCQ:
Assertion (A): Prop roots are adventitious in origin.
Reason (R): They arise from the base of stem to support the plant.
Options:
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. Prop roots are adventitious, arising from stem base, and their function is mechanical support. Both the assertion and reason are true, and the reason explains the assertion.
8. Matching Type MCQ:
Match root type with its characteristic:
(a) Prop roots - (i) Adventitious, support
(b) Lateral roots - (ii) Branches of primary root
(c) Fibrous roots - (iii) Thin, branched network
(d) Primary root - (iv) First root from radicle
Options:
1. a-i, b-ii, c-iii, d-iv
2. a-ii, b-iii, c-i, d-iv
3. a-iii, b-iv, c-i, d-ii
4. a-iv, b-i, c-ii, d-iii
Explanation: Correct answer is 1. Prop roots provide support, lateral roots branch from primary root, fibrous roots form thin branched networks, and primary root arises from the radicle during germination.
9. Fill in the Blanks MCQ:
Roots arising from stem base for mechanical support are called ______.
Options:
a. Lateral roots
b. Prop roots
c. Fibrous roots
d. Primary roots
Explanation: Correct answer is b. Prop roots emerge from the stem base and provide stability to plants like maize and banyan, functioning as mechanical support and anchorage.
10. Choose the correct statements MCQ:
Select all correct statements:
i. Fibrous roots have no prominent primary root
ii. Prop roots are adventitious and provide support
iii. Lateral roots originate from stem base
iv. Primary root develops from radicle
Options:
1. i, ii, iv
2. ii, iii
3. i, iii, iv
4. All of the above
Explanation: Correct answer is 1. Statements i, ii, and iv are correct.
Subtopic: Root Modifications for Storage
Keyword Definitions:
• Sweet potato: Edible tuberous root storing carbohydrates.
• Tap root: Primary root that grows downward and may become fleshy for storage.
• Adventitious root: Roots arising from non-root tissue like stem or leaves.
• Rhizome: Underground horizontal stem for vegetative propagation.
• Stem: Main axis of plant above ground supporting leaves and flowers.
Lead Question - 2018
Sweet potato is a modified:
(A) Rhizome
(B) Stem
(C) Tap root
(D) Adventitious root
Explanation:
Answer is (C). Sweet potato is a modified tap root. It becomes fleshy and stores starch, functioning as a storage organ. It is not a stem, rhizome, or adventitious root. Tap roots swell due to accumulation of food materials, aiding in vegetative propagation and survival during adverse conditions.
Guessed NEET UG MCQs:
1) Single Correct: Which of the following is a stem modification for storage?
(A) Potato tuber
(B) Sweet potato
(C) Carrot
(D) Radish
Explanation:
Answer is (A). Potato tubers are modified stems that store starch. Sweet potato is a modified tap root. Carrot and radish are modified tap roots, not stems.
2) Single Correct: Which structure stores food in carrot?
(A) Stem
(B) Adventitious root
(C) Tap root
(D) Rhizome
Explanation:
Answer is (C). Carrot is a tap root modified to store food as carbohydrates. Its main root swells to form an edible storage organ.
3) Single Correct: A rhizome differs from a tuber in that it:
(A) Grows horizontally underground
(B) Stores water
(C) Is a tap root
(D) Produces leaves above ground only
Explanation:
Answer is (A). Rhizomes are horizontal underground stems that grow laterally and help in vegetative propagation. Tubers can be stem (potato) or root (sweet potato).
4) Assertion-Reason:
Assertion: Sweet potato is a modified tap root.
Reason: Tap roots swell due to accumulation of food materials.
(A) Both true, Reason correct
(B) Both true, Reason incorrect
(C) Assertion true, Reason false
(D) Both false
Explanation:
Answer is (A). Sweet potato swells as a tap root by accumulating carbohydrates. This adaptation allows the plant to store energy and survive periods of dormancy or adverse conditions.
5) Single Correct (Clinical-type): Which modification is seen in banyan roots?
(A) Tap root
(B) Pneumatophore
(C) Adventitious root
(D) Rhizome
Explanation:
Answer is (C). Banyan trees develop adventitious roots from branches that reach the soil, supporting heavy branches. Unlike sweet potato, these roots are for support, not storage.
6) Single Correct: Which of the following is a stem modification for vegetative propagation?
(A) Sweet potato
(B) Ginger
(C) Carrot
(D) Radish
Explanation:
Answer is (B). Ginger is a rhizome, a modified underground stem for vegetative propagation. Sweet potato and carrot are roots, while radish is a tap root.
7) Matching Type:
Column I (Plant) | Column II (Modification)
a. Sweet potato | i. Stem tuber
b. Ginger | ii. Rhizome
c. Carrot | iii. Tap root
d. Potato | iv. Stem tuber
(A) a-iii, b-ii, c-iii, d-iv
(B) a-ii, b-i, c-iii, d-iv
(C) a-iii, b-iv, c-ii, d-i
(D) a-iii, b-ii, c-iv, d-i
Explanation:
Answer is (A). Sweet potato and carrot are modified tap roots, ginger is a rhizome, and potato is a stem tuber for food storage.
8) Fill in the Blank:
________ is a modified root storing carbohydrates.
(A) Sweet potato
(B) Potato
(C) Ginger
(D) Onion
Explanation:
Answer is (A). Sweet potato is a tap root modified for storage, accumulating carbohydrates for energy reserve and vegetative propagation.
9) Choose the correct statements:
(i) Sweet potato is a modified tap root
(ii) Potato is a modified stem
(iii) Ginger is a modified root
(A) i and ii only
(B) i and iii only
(C) ii and iii only
(D) i, ii, iii
Explanation:
Answer is (A). Sweet potato is a tap root, potato is a stem tuber, and ginger is a rhizome (stem), not a root.
10) Clinical-type: In plants with edible storage roots like sweet potato, deficiency of which mineral may affect root swelling?
(A) Nitrogen
(B) Phosphorus
(C) Potassium
(D) Iron
Explanation:
Answer is (C). Potassium is essential for carbohydrate translocation and accumulation in storage roots. Its deficiency may reduce swelling and yield in sweet potato.
Topic: Adaptations to Aquatic and Saline Environments
Subtopic: Specialized Roots – Pneumatophores
Keyword Definitions:
• Pneumatophores: Specialized aerial roots growing upwards from submerged roots to facilitate gaseous exchange.
• Submerged hydrophytes: Plants entirely underwater, e.g., Hydrilla.
• Halophytes: Salt-tolerant plants growing in saline soils, e.g., Avicennia.
• Carnivorous plants: Plants deriving nutrients by trapping insects, e.g., Dionaea.
• Free-floating hydrophytes: Aquatic plants floating on water surface, e.g., Eichhornia.
Lead Question - 2018
Pneumatophores occur in:
(A) Submerged hydrophytes
(B) Halophytes
(C) Carnivorous plants
(D) Free-floating hydrophytes
Explanation:
Answer is (B). Halophytes like Avicennia develop pneumatophores to facilitate oxygen intake in waterlogged, anaerobic soils. These upward-growing roots allow gaseous exchange, supporting respiration in saline swampy conditions, an essential adaptation for survival in tidal or marshy environments.
Guessed NEET UG MCQs:
1) Single Correct: Pneumatophores are primarily found in:
(A) Submerged hydrophytes
(B) Mangrove plants
(C) Free-floating hydrophytes
(D) Terrestrial desert plants
Explanation:
Answer is (B). Mangrove halophytes develop pneumatophores for oxygen absorption in waterlogged, anoxic soils, ensuring root respiration and plant survival.
2) Single Correct: The main function of pneumatophores is:
(A) Water absorption
(B) Food storage
(C) Gaseous exchange
(D) Support in strong winds
Explanation:
Answer is (C). Pneumatophores are aerial roots that allow gas exchange between the submerged root system and the atmosphere, ensuring adequate oxygen supply for respiration.
3) Single Correct: Which plant has pneumatophores?
(A) Hydrilla
(B) Avicennia
(C) Utricularia
(D) Eichhornia
Explanation:
Answer is (B). Avicennia, a mangrove halophyte, produces pneumatophores to facilitate oxygen intake in anoxic, waterlogged soils for root respiration.
4) Assertion-Reason:
Assertion: Pneumatophores grow upwards from underground roots.
Reason: They help in gaseous exchange in waterlogged soils.
(A) Both true, Reason correct
(B) Both true, Reason incorrect
(C) Assertion true, Reason false
(D) Both false
Explanation:
Answer is (A). Pneumatophores grow vertically from buried roots, allowing oxygen exchange in waterlogged and anoxic soils, which is vital for root respiration.
5) Single Correct: Pneumatophores are absent in:
(A) Submerged hydrophytes
(B) Halophytes
(C) Mangroves
(D) Plants in tidal swamps
Explanation:
Answer is (A). Fully submerged hydrophytes do not develop pneumatophores because they have other adaptations like thin cuticles and aerenchyma for underwater gaseous exchange.
6) Single Correct (Clinical-type): A mangrove plant in oxygen-poor soil lacks pneumatophores. Likely outcome:
(A) Enhanced growth
(B) Reduced root respiration
(C) Increased seed production
(D) No effect
Explanation:
Answer is (B). Absence of pneumatophores in anoxic, waterlogged soils restricts oxygen intake, impairing root respiration and limiting plant growth and survival.
7) Matching Type:
Column I (Plant) | Column II (Adaptation)
a. Avicennia | i. Carnivory
b. Hydrilla | ii. Pneumatophores
c. Utricularia | iii. Floating leaves
d. Eichhornia | iv. Submerged habit
(A) a-ii, b-iv, c-i, d-iii
(B) a-i, b-ii, c-iii, d-iv
(C) a-ii, b-iii, c-iv, d-i
(D) a-iv, b-ii, c-i, d-iii
Explanation:
Answer is (A). Avicennia develops pneumatophores, Hydrilla is fully submerged, Utricularia is carnivorous, and Eichhornia has floating leaves.
8) Fill in the Blank:
Pneumatophores help halophytes survive in ______ soils.
(A) Sandy
(B) Waterlogged
(C) Arid
(D) Loamy
Explanation:
Answer is (B). Pneumatophores allow halophytes to absorb oxygen efficiently in waterlogged, anoxic soils, ensuring root respiration and survival.
9) Choose the correct statements:
(i) Pneumatophores grow upward from underground roots.
(ii) They are common in submerged hydrophytes.
(iii) They facilitate oxygen intake.
(A) i and ii only
(B) i and iii only
(C) ii and iii only
(D) i, ii, iii
Explanation:
Answer is (B). Pneumatophores grow upwards from buried roots and enable oxygen intake. They are absent in fully submerged hydrophytes.
10) Clinical-type: A mangrove planted in dry soil shows reduced pneumatophore development. Likely consequence:
(A) Root suffocation
(B) Excessive growth
(C) No change
(D) Increased flowering
Explanation:
Answer is (C). Pneumatophores are adaptations to waterlogged, oxygen-poor soils; in dry soils, oxygen is abundant, so their development is reduced without negative impact.
Topic: Root Structure
Subtopic: Zones of Root Growth and Root Hair Formation
Keyword Definitions:
• Root hairs – Tubular extensions of epidermal cells that increase surface area for absorption.
• Meristematic region – Zone of active cell division at the root tip.
• Elongation zone – Region where newly formed cells increase in length.
• Maturation zone – Region where cells differentiate and root hairs develop.
• Root cap – Protective structure covering the root tip, facilitating growth through soil.
• Absorption – Process of water and mineral uptake by roots.
• Clinical/agronomic relevance – Root hair development affects nutrient absorption, soil fertility management, and crop yield optimization.
Lead Question – 2017:
Root hairs develop from the region of :
(A) Meristematic activity
(B) Maturation
(C) Elongation
(D) Root cap
Explanation:
Root hairs develop in the maturation zone of roots where cells differentiate. They increase surface area for water and mineral absorption. The meristematic region divides cells, the elongation zone increases cell length, and the root cap protects the tip. Root hairs are essential for efficient nutrient uptake. (Answer: B)
1) Which root zone is responsible for active cell division?
(A) Meristematic region
(B) Maturation zone
(C) Elongation zone
(D) Root hairs
Explanation:
The meristematic region at the root tip contains actively dividing cells. These new cells contribute to root growth. Elongation and maturation zones follow division, and root hairs arise in the maturation zone. Meristematic activity is vital for primary root elongation. (Answer: A)
2) The elongation zone in roots functions to:
(A) Absorb water
(B) Increase cell length
(C) Produce root hairs
(D) Protect root tip
Explanation:
In the elongation zone, cells increase in length, pushing the root tip deeper into the soil. This is distinct from the maturation zone where root hairs form. Proper elongation ensures root penetration and access to water and nutrients. (Answer: B)
3) Clinical/agronomic case: Root hair density affects:
(A) Photosynthesis
(B) Water and nutrient uptake
(C) Leaf transpiration
(D) Flower formation
Explanation:
Root hair density directly affects water and mineral absorption from soil, influencing overall plant health, nutrient status, and crop yield. Roots without hairs have limited absorption capacity. Agronomic practices often aim to optimize root hair development through soil management and fertilization. (Answer: B)
4) Root cap primarily functions to:
(A) Absorb nutrients
(B) Protect the growing root tip
(C) Produce root hairs
(D) Elongate cells
Explanation:
The root cap covers the tip of roots, protecting the meristematic region as roots penetrate soil. It also secretes mucilage to facilitate movement. Absorption and root hair development occur in other zones. Root cap is crucial for root survival and growth direction. (Answer: B)
5) Which tissue in the root forms the actual root hairs?
(A) Epidermis
(B) Cortex
(C) Endodermis
(D) Xylem
Explanation:
Root hairs are tubular outgrowths of epidermal cells in the maturation zone. They increase the surface area for absorption of water and minerals. Cortex and endodermis function in storage and selective transport, while xylem conducts water. Epidermis specialization is key for root hair formation. (Answer: A)
6) Zone where cells differentiate into xylem, phloem, and epidermal tissues:
(A) Meristematic
(B) Elongation
(C) Maturation
(D) Root cap
Explanation:
The maturation zone is where cells differentiate into xylem, phloem, cortex, and epidermal tissues, including root hairs. Differentiation is essential for functional roots capable of water conduction, nutrient transport, and absorption. (Answer: C)
7) Assertion-Reason type:
Assertion (A): Root hairs develop in the maturation zone.
Reason (R): Cells in the maturation zone undergo differentiation and elongation.
(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. Cells in the maturation zone differentiate to form specialized structures like root hairs. These hairs increase absorptive surface, crucial for water and mineral uptake, while elongation occurs primarily in the elongation zone. (Answer: A)
8) Matching type:
Match root zones with functions:
(A) Meristematic – (i) Cell division
(B) Elongation – (ii) Cell length increase
(C) Maturation – (iii) Root hair formation
(D) Root cap – (iv) Protection
Options:
(A) A-i, B-ii, C-iii, D-iv
(B) A-ii, B-iii, C-i, D-iv
(C) A-iii, B-i, C-ii, D-iv
(D) A-i, B-iv, C-ii, D-iii
Explanation:
Correct matches: Meristematic – cell division, Elongation – cell length increase, Maturation – root hair formation, Root cap – protection. Understanding root zones is crucial for botany, agronomy, and clinical studies related to nutrient absorption. (Answer: A)
9) Fill in the blanks:
Tubular extensions of epidermal cells in roots are called ______.
(A) Root hairs
(B) Root cap
(C) Lateral roots
(D) Xylem vessels
Explanation:
Root hairs are tubular outgrowths of epidermal cells in the maturation zone. They increase surface area for water and mineral absorption, enhancing plant nutrition and growth. Root hairs are vital for soil nutrient uptake and crop productivity. (Answer: A)
10) Choose the correct statements:
1. Root hairs form in the maturation zone.
2. Meristematic zone is for cell division.
3. Elongation zone increases cell length.
4. Root cap produces root hairs.
(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 root hairs develop in the maturation zone, not root cap. Knowledge of root zones and functions is fundamental for plant physiology and agronomy. (Answer: A)