Topic: Sensory Organs; Subtopic: Insect Vision
Keyword Definitions:
Ommatidia: Individual photoreceptive units in a compound eye of insects.
Cockroach: Insect with compound eyes composed of multiple ommatidia.
Mosaic vision: Visual perception where multiple small images are combined to form a whole.
Sensitivity: Ability to detect low-intensity light or movement.
Resolution: Ability to distinguish fine details of an image.
Assertion-Reason: A type of MCQ where a statement is given along with a reason.
Compound eye: Eye type made of many ommatidia, typical in insects.
Perception: The ability to interpret sensory information.
Photoreceptor: Specialized cell sensitive to light stimulus.
Vision: The sense that allows an organism to perceive light and images.
Explanation: Detailed reasoning of why an answer is correct.
Lead Question - 2022 (Abroad)
Given below are two statements: One is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): With the help of several ommatidia, a cockroach can perceive several images of an object, i.e., mosaic vision.
Reason (R): Mosaic vision gives more sensitivity but less resolution.
In the light of the above statements, choose the most appropriate answer from the options given below:
(A) is correct but (R) is not correct
(A) is not correct but (R) is correct
Both (A) and (R) are correct and (R) is the correct explanation of (A)
Both (A) and (R) are correct but (R) is not the correct explanation of (A)
Explanation: The cockroach’s compound eyes contain numerous ommatidia, allowing it to perceive multiple small images of a single object, forming a mosaic vision. This structure provides high sensitivity to movement and light changes but limits resolution, meaning fine details cannot be clearly distinguished. Therefore, both the assertion and reason are correct, and the reason correctly explains the assertion. Correct answer: 3
1. SINGLE CORRECT ANSWER MCQ
What is the main advantage of mosaic vision in insects like cockroach?
High resolution
Greater sensitivity to light and motion
Color perception
Depth perception
Explanation: Mosaic vision allows insects to detect small changes in light and movement effectively, aiding survival. However, resolution is limited and fine details cannot be distinguished. Color perception and depth perception are secondary or limited in cockroach. Correct answer: 2
2. SINGLE CORRECT ANSWER MCQ
Which eye structure is characteristic of insects like cockroach?
Camera-type eye
Simple eye
Compound eye
Lensless eye
Explanation: Insects such as cockroaches possess compound eyes consisting of numerous ommatidia, each functioning as a small photoreceptive unit, forming mosaic vision. Camera-type eyes are typical in vertebrates. Correct answer: 3
3. SINGLE CORRECT ANSWER MCQ
Which statement about ommatidia is correct?
Each ommatidium can form a complete high-resolution image
Ommatidia collectively create a mosaic image
Ommatidia are found only in vertebrates
Ommatidia are color-blind structures only
Explanation: Ommatidia individually detect light and produce small images. Collectively, they create a mosaic image providing sensitivity to movement but low resolution. They are characteristic of insects, not vertebrates. Color perception is limited. Correct answer: 2
4. SINGLE CORRECT ANSWER MCQ
Low resolution in mosaic vision means:
Insects can see fine details clearly
Insects cannot distinguish small details
Insects are color-blind
Insects cannot detect movement
Explanation: Low resolution limits the ability to see fine details. Mosaic vision emphasizes sensitivity over clarity, enabling detection of motion and light variations, but insects cannot resolve small objects clearly. Correct answer: 2
5. SINGLE CORRECT ANSWER MCQ
Mosaic vision primarily enhances:
Color discrimination
Motion detection
Depth perception
Visual acuity
Explanation: Mosaic vision allows insects to rapidly detect movement in their environment, providing survival advantage. Color discrimination, depth perception, and high visual acuity are limited in cockroach eyes. Correct answer: 2
6. SINGLE CORRECT ANSWER MCQ
Which is true about cockroach compound eyes?
They provide single focused image like human eye
They contain multiple ommatidia forming mosaic vision
They cannot detect light intensity
They are absent in adult cockroaches
Explanation: Cockroach compound eyes are composed of many ommatidia, each detecting a part of the visual field. Combined, they form mosaic vision. They detect light intensity and motion. Single-focused image and absence in adults are incorrect. Correct answer: 2
7. ASSERTION-REASON MCQ
Assertion (A): Mosaic vision is suitable for detecting predators quickly.
Reason (R): Mosaic vision prioritizes sensitivity to motion over image resolution.
Both A and R are true and R explains A
Both A and R are true but R does not explain A
A is true but R is false
A is false but R is true
Explanation: Mosaic vision allows rapid detection of movement, which is crucial for predator avoidance. Sensitivity to motion comes at the cost of resolution. Therefore, both assertion and reason are correct and reason explains assertion. Correct answer: 1
8. MATCHING TYPE MCQ
Match visual term with characteristic:
Column A:
Ommatidia
Mosaic vision
Resolution
Sensitivity
Column B:
Individual photoreceptive units
Multiple small images forming a whole
Ability to distinguish fine details
Ability to detect low-intensity light
Explanation: Each ommatidium is a single photoreceptor unit; combined ommatidia form mosaic vision; resolution is the ability to see fine details; sensitivity allows detection of low light intensity. Correct matching: 1-1, 2-2, 3-3, 4-4
9. FILL IN THE BLANKS / COMPLETION MCQ
Insect compound eyes with multiple ommatidia create _______ vision.
Camera-type
Mosaic
Binocular
Monocular
Explanation: Compound eyes with multiple ommatidia allow insects to perceive a mosaic image, combining numerous small images to detect movement efficiently. Camera-type or monocular eyes are not characteristic of insects like cockroach. Correct answer: 2
10. CHOOSE THE CORRECT STATEMENTS MCQ
Statement I: Mosaic vision has high sensitivity but low resolution.
Statement II: Ommatidia act as individual light detectors.
Only Statement I is correct
Only Statement II is correct
Both Statements I and II are correct
Both Statements I and II are incorrect
Explanation: Mosaic vision combines images from multiple ommatidia, enhancing sensitivity but reducing resolution. Each ommatidium functions as a separate photoreceptor detecting light. Therefore, both statements are correct. Correct answer: 3
Topic: Cockroach Anatomy
Subtopic: Body Segmentation and Appendages
Keyword Definitions:
Tegmina: The leathery, thickened forewings of cockroach that cover and protect the hindwings when not in flight.
Mesothorax: The middle segment of thorax from which the forewings (tegmina) and second pair of legs arise.
Metathorax: The posterior thoracic segment bearing the hindwings and third pair of legs.
Prothorax: The anterior thoracic segment that bears the first pair of legs but no wings.
Exoskeleton: The hard chitinous outer covering that protects the cockroach’s body and provides attachment for muscles.
Lead Question – 2022
Tegmina in cockroach arises from:
(1) Mesothorax
(2) Metathorax
(3) Prothorax and Mesothorax
(4) Prothorax
Explanation: The forewings of cockroach, known as tegmina, are leathery and non-functional in flight. They arise from the mesothorax and cover the membranous hindwings of the metathorax. Thus, the correct answer is (1) Mesothorax.
1. The hindwings of cockroach arise from:
(1) Metathorax
(2) Mesothorax
(3) Prothorax
(4) Head region
Explanation: The membranous hindwings that help in flight arise from the metathoracic segment of the thorax. The correct answer is (1) Metathorax.
2. The number of legs present in a cockroach are:
(1) Two pairs
(2) Three pairs
(3) Four pairs
(4) One pair
Explanation: A cockroach has three pairs of jointed legs attached to each thoracic segment — one pair each on prothorax, mesothorax, and metathorax. The correct answer is (2) Three pairs.
3. In cockroach, which of the following is the first thoracic segment?
(1) Metathorax
(2) Mesothorax
(3) Prothorax
(4) Abdomen
Explanation: The thorax of cockroach is divided into three parts: prothorax, mesothorax, and metathorax. The first of these is the prothorax. The correct answer is (3) Prothorax.
4. The function of tegmina in cockroach is to:
(1) Help in flight
(2) Protect hindwings
(3) Store food
(4) Aid in reproduction
Explanation: Tegmina are leathery protective forewings that shield the delicate hindwings when the cockroach is at rest. The correct answer is (2) Protect hindwings.
5. Which structure helps in respiration in cockroach?
(1) Trachea
(2) Lungs
(3) Skin
(4) Gills
Explanation: Cockroach breathes through a tracheal system consisting of spiracles and branching tubes that deliver oxygen directly to tissues. The correct answer is (1) Trachea.
6. Which part of the cockroach body bears the wings?
(1) Head
(2) Thorax
(3) Abdomen
(4) Cephalothorax
Explanation: Both pairs of wings in cockroach arise from the thoracic region — the first pair from mesothorax and the second from metathorax. The correct answer is (2) Thorax.
7. Assertion (A): Tegmina are protective forewings of cockroach.
Reason (R): Tegmina are membranous and aid in active flight.
(1) Both A and R are true and R is correct explanation
(2) Both A and R are true but R is not correct explanation
(3) A is true but R is false
(4) Both A and R are false
Explanation: Tegmina are thick, leathery, and protective, not membranous or used for flight. Therefore, A is true but R is false. Correct answer is (3).
8. Match the following:
A. Prothorax — (i) First pair of legs
B. Mesothorax — (ii) Tegmina
C. Metathorax — (iii) Hindwings
Options:
(1) A-(ii), B-(iii), C-(i)
(2) A-(i), B-(ii), C-(iii)
(3) A-(iii), B-(i), C-(ii)
(4) A-(ii), B-(i), C-(iii)
Explanation: The prothorax bears the first pair of legs, mesothorax gives rise to tegmina and the second pair of legs, and metathorax bears hindwings. The correct answer is (2).
9. Fill in the blank:
The forewings of cockroach are called ______.
(1) Elytra
(2) Tegmina
(3) Halteres
(4) Alae
Explanation: The leathery forewings that cover and protect the hindwings in cockroach are called tegmina. The correct answer is (2) Tegmina.
10. Choose the correct statements:
(1) Tegmina help in flight
(2) Hindwings are used for protection
(3) Tegmina are protective forewings
(4) Prothorax bears tegmina
Explanation: Tegmina are thickened forewings that cover and protect the membranous hindwings. They are not used for flying. The correct answer is (3) Tegmina are protective forewings.
Hypopharynx: Tongue-like structure present within the mouth cavity of cockroach.
Sterna: Ventral plates of abdominal segments in insects.
Genital pouch: Reproductive chamber formed by fusion of sterna in female cockroach.
Anal cerci: Paired sensory appendages found on 10th abdominal segment.
Gastric caeca: Digestive glandular structures found at junction of foregut and midgut, not hindgut.
Midgut: Part of alimentary canal responsible for digestion and absorption.
Hindgut: Posterior part of digestive tract concerned with water absorption.
Exoskeleton: Hard protective chitinous covering of cockroach body.
Segment: Repeated body division in arthropods for structural organization.
Ovipositor: Egg-laying structure present in female cockroach.
Respiration: Occurs through spiracles and tracheal tubes in cockroach.
Lead Question - 2021
Which of the following characteristics is incorrect with respect to cockroach?
Options:
(1) Hypopharynx lies within the cavity enclosed by the mouth parts.
(2) In females, 7th-9th sterna together form a genital pouch
(3) 10th abdominal segment in both sexes, bears a pair of anal cerci
(4) A ring of gastric caeca is present at the junction of midgut and hind gut
Explanation: In cockroach, gastric caeca are present at the junction of foregut and midgut, not midgut and hindgut. Thus, statement 4 is incorrect. Other features are correct: hypopharynx location, genital pouch in females, and anal cerci in both sexes. Answer: Option 4.
1. Single Correct Answer MCQ: Which structure helps in sensory function in cockroach abdomen?
Options:
A. Ovipositor
B. Anal cerci
C. Hypopharynx
D. Gastric caeca
Explanation: Anal cerci are paired sensory appendages present on the 10th abdominal segment of cockroach. They help detect vibrations and protect against predators. Answer: Anal cerci.
2. Single Correct Answer MCQ: Where exactly are gastric caeca found in cockroach?
Options:
A. Foregut and midgut junction
B. Midgut and hindgut junction
C. Hindgut and anus junction
D. Crop and oesophagus junction
Explanation: The gastric caeca are eight in number, arranged as a ring at the junction of foregut and midgut. They secrete digestive enzymes aiding food digestion. Answer: Foregut and midgut junction.
3. Single Correct Answer MCQ: In female cockroach, the genital pouch is formed by fusion of:
Options:
A. 6th-8th sterna
B. 7th-9th sterna
C. 8th-10th sterna
D. 5th-7th sterna
Explanation: In female cockroach, the genital pouch is formed by fusion of the 7th, 8th, and 9th sterna, enclosing reproductive structures. Answer: 7th-9th sterna.
4. Single Correct Answer MCQ: Hypopharynx in cockroach acts as:
Options:
A. Egg-laying structure
B. Tongue-like organ
C. Digestive gland
D. Sensory appendage
Explanation: The hypopharynx is a tongue-like organ present inside the cavity of mouthparts in cockroach. It aids in manipulating food during feeding. Answer: Tongue-like organ.
5. Single Correct Answer MCQ: Which system in cockroach lacks red blood cells and hemoglobin?
Options:
A. Nervous system
B. Digestive system
C. Respiratory system
D. Circulatory system
Explanation: Cockroach has an open circulatory system with hemolymph lacking hemoglobin and red blood cells. Gas transport occurs through the tracheal system. Answer: Circulatory system.
6. Single Correct Answer MCQ: Which of the following is absent in cockroach?
Options:
A. Malpighian tubules
B. Lungs
C. Tracheae
D. Compound eyes
Explanation: Cockroach respires through tracheae and spiracles, not lungs. Malpighian tubules excrete wastes, and compound eyes aid in vision. Answer: Lungs.
7. Assertion-Reason MCQ:
Assertion (A): Cockroach has an open type circulatory system.
Reason (R): Hemolymph flows freely in body cavity without blood vessels.
Options:
A. Both A and R true, R correct explanation
B. Both A and R true, R not correct explanation
C. A true, R false
D. A false, R true
Explanation: Cockroach has an open circulatory system where hemolymph directly bathes tissues without closed vessels. Thus, assertion and reason are both correct, with reason explaining assertion. Answer: Option A.
8. Matching Type MCQ:
List I: a. Malpighian tubules b. Anal cerci c. Hypopharynx d. Gastric caeca
List II: i. Sensory appendage ii. Excretion iii. Food manipulation iv. Digestion
Options:
A. a-ii, b-i, c-iii, d-iv
B. a-i, b-ii, c-iv, d-iii
C. a-iv, b-iii, c-ii, d-i
D. a-iii, b-iv, c-i, d-ii
Explanation: Malpighian tubules handle excretion, anal cerci are sensory, hypopharynx manipulates food, and gastric caeca aid in digestion. Answer: a-ii, b-i, c-iii, d-iv.
9. Fill in the Blanks MCQ: The chitinous covering forming the exoskeleton of cockroach is composed of ______.
Options:
A. Cellulose
B. Chitin
C. Keratin
D. Collagen
Explanation: The cockroach exoskeleton is composed of chitin, a polysaccharide providing rigidity and protection. It also serves as attachment for muscles. Answer: Chitin.
10. Choose the correct statements MCQ:
Options:
A. Cockroach has compound eyes
B. Cockroach has closed circulation
C. Cockroach respires through lungs
D. Cockroach has Malpighian tubules for excretion
Select:
1. A and D
2. A and B
3. B and C
4. A and C
Explanation: Cockroach has compound eyes and Malpighian tubules for excretion. It does not have lungs or closed circulation. Correct statements are A and D. Answer: Option 1.
Subtopic: Digestive and Respiratory Systems
Keyword Definitions:
Proventriculus (Gizzard): Muscular part of foregut used for grinding food particles.
Hepatic caeca: Blind tubules at junction of foregut and midgut that secrete digestive enzymes.
Spiracles: Openings on the body segments of cockroach for gaseous exchange, ten pairs are present.
Anal cerci: Paired sensory structures located on the 10th abdominal segment.
Alary muscles: Fan-shaped muscles associated with circulation in cockroach.
Lead Question - 2020 (COVID Reexam)
Match the following columns with reference to cockroach and select the correct option :
Column - I Column - II
(a) Grinding of the food particles (i) Hepatic caeca
(b) Secrete gastric juice (ii) 10th segment
(c) 10 pairs (iii) Proventriculus
(d) Anal cerci (iv) Spiracles
(v) Alary muscles
1. (a)-(iii), (b)-(i), (c)-(iv), (d)-(ii)
2. (a)-(iv), (b)-(iii), (c)-(v), (d)-(ii)
3. (a)-(i), (b)-(iv), (c)-(iii), (d)-(ii)
4. (a)-(ii), (b)-(iii), (c)-(i), (d)-(iv)
Explanation: In cockroach, grinding of food occurs in proventriculus, secretion of gastric enzymes occurs in hepatic caeca, ten pairs of spiracles aid respiration, and anal cerci are present on the 10th segment as sensory appendages. Thus, the correct matching is (a)-(iii), (b)-(i), (c)-(iv), (d)-(ii). The correct answer is option 1.
1. The haemolymph in cockroach is
(1) Red and respiratory
(2) Colourless and non-respiratory
(3) Yellow and respiratory
(4) Blue and respiratory
Explanation: Cockroach haemolymph is colourless and lacks respiratory pigments like haemoglobin or haemocyanin. It plays a role in transport of nutrients and excretion, but respiration is carried out through tracheal tubes connected to spiracles. Hence, the correct answer is option 2.
2. Which structure regulates air passage in cockroach tracheal system?
(1) Tracheae
(2) Spiracles
(3) Air sacs
(4) Malpighian tubules
Explanation: Spiracles are paired openings on the thoracic and abdominal segments of cockroach. They are provided with valves to regulate entry and exit of air. Tracheae are branching tubes but spiracles are regulators. The correct answer is option 2.
3. In cockroach, Malpighian tubules are primarily concerned with
(1) Respiration
(2) Circulation
(3) Excretion
(4) Reproduction
Explanation: Malpighian tubules are fine, blind-ended tubules at the junction of midgut and hindgut. They absorb nitrogenous wastes like uric acid from haemolymph and discharge them into the gut for elimination. Thus, their main role is excretion. Correct answer is option 3.
4. Which organ in cockroach produces sound for warning signals?
(1) Antennae
(2) Anal cerci
(3) Stridulatory organ
(4) Wings
Explanation: Anal cerci in cockroach are paired appendages with sensory function. They can detect air movements and vibrations, alerting the insect to danger. Stridulatory organs produce sound in some insects like crickets but not in cockroaches. Thus, correct answer is option 2.
5. Which type of circulatory system is found in cockroach?
(1) Closed
(2) Open
(3) Double
(4) Lymphatic
Explanation: Cockroach has an open circulatory system. Haemolymph directly bathes tissues and organs in body cavities. It is pumped by a tubular heart but lacks closed vessels like arteries or veins. This is characteristic of arthropods. Hence, the correct answer is option 2.
6. In cockroach, how many chambers are present in heart?
(1) 6
(2) 8
(3) 12
(4) 13
Explanation: The heart of cockroach is a long, muscular, tube-like structure with 13 chambers arranged segmentally. It pumps haemolymph into the sinuses of the haemocoel. This is a feature of its open circulatory system. Correct answer is option 4.
7. Assertion (A): Cockroach has an open circulatory system.
Reason (R): Haemolymph flows in closed vessels like arteries and veins.
(1) Both A and R are true, R explains A
(2) Both A and R are true, R does not explain A
(3) A is true, R is false
(4) A is false, R is true
Explanation: Cockroach has an open circulatory system where haemolymph directly bathes organs in haemocoel. It does not flow in closed vessels, unlike vertebrates. Thus, assertion is true but reason is false. The correct answer is option 3.
8. Match the following:
Column I – Column II
A. Haemolymph – 1. Colourless
B. Heart chambers – 2. 13
C. Spiracles – 3. Ten pairs
D. Anal cerci – 4. Tenth segment
(1) A-1, B-2, C-3, D-4
(2) A-2, B-3, C-1, D-4
(3) A-3, B-1, C-2, D-4
(4) A-4, B-1, C-3, D-2
Explanation: Haemolymph in cockroach is colourless, the heart has 13 chambers, spiracles are 10 pairs, and anal cerci are located on the tenth segment. Correct matching is A-1, B-2, C-3, D-4. Hence, the correct answer is option 1.
9. Fill in the blank:
The fan-shaped muscles associated with cockroach heart are called _______.
(1) Anal cerci
(2) Hepatic caeca
(3) Alary muscles
(4) Tracheae
Explanation: Alary muscles are fan-shaped muscles attached to the tubular heart of cockroach. They help in the movement of haemolymph in the open circulatory system. Other options are unrelated to circulation. Hence, the correct answer is option 3.
10. Choose the correct statements:
(i) Cockroach has an open circulatory system.
(ii) Haemolymph is respiratory in function.
(iii) Heart has 13 chambers.
(iv) Spiracles are present in 10 pairs.
(1) (i), (iii), (iv) only
(2) (ii), (iii) only
(3) (i), (ii), (iii) only
(4) (i), (ii), (iii), (iv)
Explanation: Cockroach has an open circulatory system, haemolymph is non-respiratory, heart has 13 chambers, and spiracles occur in 10 pairs. Thus, correct statements are (i), (iii), and (iv). The correct answer is option 1.
Topic: Cockroach Anatomy
Subtopic: Digestive System
Keyword Definitions:
Foregut: Anterior part of cockroach digestive system including mouth, pharynx, oesophagus, crop, and gizzard.
Pharynx: Muscular tube connecting mouth and oesophagus.
Oesophagus: Narrow passage carrying food from pharynx to crop.
Crop: Saclike organ used for temporary storage of food.
Gizzard: Muscular organ lined with chitinous plates for grinding food.
Lead Question - 2020 (COVID Reexam)
In cockroach, identify the parts of the foregut in correct sequence:-
1. Mouth → Oesophagus → Pharynx → Crop → Gizzard
2. Mouth → Crop → Pharynx → Oesophagus → Gizzard
3. Mouth → Gizzard → Crop → Pharynx → Oesophagus
4. Mouth → Pharynx → Oesophagus → Crop → Gizzard
Explanation: The cockroach foregut begins with the mouth, followed by pharynx, oesophagus, crop, and ends with gizzard. The crop stores food, and the gizzard grinds it with chitinous plates. This correct sequence ensures proper storage and mechanical digestion before enzymatic breakdown. The right answer is option 4.
1. Which mouthpart in cockroach helps in cutting food?
(1) Labrum
(2) Mandibles
(3) Maxillae
(4) Labium
Explanation: Cockroach has biting and chewing type mouthparts. Mandibles are paired, strong, and used for cutting and crushing food before swallowing. Other mouthparts like labrum, labium, and maxillae help in holding and manipulating food. Thus, the correct answer is option 2.
2. The hepatic caeca in cockroach open into
(1) Oesophagus
(2) Crop
(3) Midgut
(4) Hindgut
Explanation: Hepatic caeca are finger-like blind tubules present at the junction of foregut and midgut. They secrete digestive enzymes into the midgut, aiding chemical digestion. They never open into oesophagus or crop. The correct answer is option 3.
3. Which structure in cockroach secretes digestive enzymes?
(1) Salivary glands
(2) Crop
(3) Gizzard
(4) Malpighian tubules
Explanation: Salivary glands in cockroach secrete saliva containing digestive enzymes that begin the breakdown of food. Crop is for storage, gizzard for grinding, and Malpighian tubules for excretion. Hence, the correct answer is option 1.
4. Which part of cockroach acts as grinding organ?
(1) Crop
(2) Gizzard
(3) Pharynx
(4) Oesophagus
Explanation: The gizzard of cockroach is a muscular grinding organ. Its thick chitinous plates and internal cuticular teeth help in grinding and crushing stored food. The crop is only for storage and pharynx and oesophagus are passage organs. The correct answer is option 2.
5. Which tissue lines the cockroach foregut?
(1) Endodermal
(2) Ectodermal
(3) Mesodermal
(4) Connective
Explanation: The foregut and hindgut of cockroach are ectodermal in origin and lined by cuticle. Only the midgut is endodermal and responsible for secretion and absorption. Thus, the correct answer is option 2.
6. Which part of cockroach digestive system stores food?
(1) Crop
(2) Gizzard
(3) Malpighian tubules
(4) Rectum
Explanation: The crop in cockroach is a thin-walled sac located after the oesophagus. It acts as a temporary food storage organ before food passes into the gizzard for grinding. Rectum reabsorbs water and Malpighian tubules are excretory. Hence, the correct answer is option 1.
7. Assertion (A): Gizzard in cockroach has chitinous plates.
Reason (R): It helps in grinding stored food.
(1) Both A and R are true, R explains A
(2) Both A and R are true, R does not explain A
(3) A is true, R is false
(4) A is false, R is true
Explanation: The gizzard is equipped with thick chitinous plates that act as teeth, grinding food into fine particles. This proves both assertion and reason true, and the reason correctly explains the assertion. Thus, the correct answer is option 1.
8. Match the following:
Column I – Column II
A. Crop – 1. Food grinding
B. Gizzard – 2. Food storage
C. Midgut – 3. Digestion
D. Rectum – 4. Water absorption
(1) A-2, B-1, C-3, D-4
(2) A-1, B-2, C-3, D-4
(3) A-3, B-4, C-2, D-1
(4) A-2, B-3, C-1, D-4
Explanation: Crop is for food storage, gizzard for grinding, midgut for enzymatic digestion, and rectum for water absorption and waste compaction. Correct matching is A-2, B-1, C-3, D-4. Hence, the correct answer is option 1.
9. Fill in the blank:
The _______ in cockroach secretes digestive enzymes into the midgut.
(1) Salivary gland
(2) Malpighian tubules
(3) Hepatic caeca
(4) Crop
Explanation: The hepatic caeca are glandular pouches that open into the midgut and secrete digestive enzymes aiding chemical digestion. Salivary glands secrete saliva, crop stores food, and Malpighian tubules are excretory organs. Thus, the correct answer is option 3.
10. Choose the correct statements:
(i) Crop stores food in cockroach.
(ii) Gizzard has chitinous plates.
(iii) Oesophagus is a grinding organ.
(iv) Midgut secretes digestive enzymes.
(1) (i), (ii), (iv) only
(2) (i), (iii) only
(3) (ii), (iii), (iv) only
(4) (i), (ii), (iii), (iv)
Explanation: Crop stores food, gizzard has chitinous plates for grinding, and midgut secretes digestive enzymes. Oesophagus is only a conducting tube, not a grinding organ. Therefore, correct statements are (i), (ii), and (iv). The correct answer is option 1.
Subtopic: Nervous System
Supra-oesophageal ganglia: A major brain-like ganglion in the head controlling sensory and motor functions.
Ventral nerve cord: A chain of ganglia along the underside of the body transmitting nerve impulses.
Segmental ganglia: Ganglia present in each body segment aiding local control of movement.
Cockroach nervous system: Consists of brain and ventral nerve cord with segmental ganglia; decentralized control allows survival without head briefly.
Reflex action: Automatic response generated by segmental ganglia without involving brain.
Decapitation survival: Ability of cockroach to live short time without head due to decentralized nervous system.
Neurotransmission: Transmission of impulses between neurons through chemical messengers.
Motor neuron: Nerve cell transmitting impulses to muscles for movement.
Sensory neuron: Nerve cell transmitting impulses from receptors to CNS.
Autonomic functions: Involuntary functions like breathing, circulation, controlled by ganglia.
Segmental control: Localized control of body segments independent of brain.
Lead Question (2020): If the head of cockroach is removed, it may live for few days because :
The head holds a small proportion of a nervous system while the rest is situated along the ventral part of its body
The head holds a 1/3rd of a nervous system while the rest is situated along the dorsal part of its body
The supra-oesophageal ganglia of the cockroach are situated in ventral part of abdomen
The cockroach does not have nervous system
Explanation: The correct answer is 1. Cockroach survives briefly after decapitation because most of its nervous system, including segmental ganglia, is located along the ventral nerve cord, allowing basic reflexes and movement even without the head. The head only contains a small proportion of the nervous system.
Guessed MCQs:
Question 1: Which part of cockroach's nervous system allows independent reflex action in each body segment?
A. Supra-oesophageal ganglia
B. Sub-oesophageal ganglia
C. Segmental ganglia
D. Ventral nerve cord
Explanation: The correct answer is C. Segmental ganglia present in each segment allow reflex movements independently of the brain, enabling the cockroach to show locomotion and reflex actions even after decapitation. These ganglia coordinate local sensory inputs and motor outputs effectively.
Question 2: Which ganglion in cockroach primarily controls sensory processing and motor coordination of the head?
A. Sub-oesophageal ganglion
B. Supra-oesophageal ganglion
C. Segmental ganglia
D. Thoracic ganglion
Explanation: The correct answer is B. Supra-oesophageal ganglion acts as the brain of the cockroach, controlling sensory input and motor coordination from antennae, eyes, and mouthparts. It is small compared to the ventral nerve cord, allowing survival of the cockroach without head for a short period.
Question 3: Which statement best describes cockroach survival after decapitation?
A. Cockroach cannot move at all
B. Reflexes persist due to ventral nerve cord
C. Cockroach dies immediately
D. Headless cockroach cannot breathe
Explanation: The correct answer is B. Reflex actions continue because the ventral nerve cord with segmental ganglia regulates local movements and responses. The head controls higher coordination but is not essential for immediate survival or basic motor activities.
Question 4: Cockroach’s ventral nerve cord is located along:
A. Dorsal side
B. Ventral side
C. Lateral side
D. Head only
Explanation: The correct answer is B. The ventral nerve cord runs along the underside (ventral side) of the cockroach’s body. It contains segmental ganglia which control local movements and reflexes, allowing the cockroach to survive briefly after decapitation.
Question 5: Which neurons transmit impulses from cockroach receptors to the ganglia?
A. Motor neurons
B. Sensory neurons
C. Interneurons
D. Sympathetic neurons
Explanation: The correct answer is B. Sensory neurons carry impulses from receptors to ganglia or brain, allowing the cockroach to sense stimuli. Segmental ganglia process these inputs locally for reflex actions, supporting survival without the head.
Question 6: Which function is least affected in a headless cockroach?
A. Coordinated walking
B. Feeding
C. Reflex movements
D. Sensory processing by antennae
Explanation: The correct answer is C. Reflex movements remain largely intact because segmental ganglia in ventral nerve cord handle local motor control, whereas feeding, sensory perception by antennae, and complex coordination require the head and brain.
Question 7: Assertion-Reason:
Assertion (A): Cockroach can survive a few days without head.
Reason (R): Ventral nerve cord and segmental ganglia control reflex actions.
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. Cockroach survives briefly without head because reflex actions are mediated by ventral nerve cord and segmental ganglia. Decentralized nervous system enables movement and basic responses even in absence of brain, making the reason a correct explanation.
Question 8: Matching Type: Match cockroach nervous components with their function:
i. Supra-oesophageal ganglia - A. Local reflex control
ii. Segmental ganglia - B. Brain-like coordination
iii. Ventral nerve cord - C. Connects ganglia
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. Supra-oesophageal ganglia act as brain, segmental ganglia control local reflexes, and ventral nerve cord connects all ganglia, enabling survival and movement even after decapitation, demonstrating decentralized control of cockroach nervous system.
Question 9: Fill in the Blanks: The cockroach can survive headless for few days due to ________ located in the ventral nerve cord.
A. Supra-oesophageal ganglia
B. Segmental ganglia
C. Brain cells
D. Thoracic ganglia
Explanation: The correct answer is B. Segmental ganglia in the ventral nerve cord control reflex actions in each body segment, allowing the cockroach to move and respond to stimuli without the head. This decentralized nervous system supports short-term survival.
Question 10: Choose the correct statements:
i. Cockroach has a decentralized nervous system
ii. Decapitation kills the cockroach instantly
iii. Segmental ganglia control reflex actions
iv. Supra-oesophageal ganglia are the major brain
A. i, iii, iv
B. ii, iii
C. i, ii
D. i, ii, iv
Explanation: The correct answer is A. Cockroach possesses a decentralized nervous system with supra-oesophageal ganglia as brain and segmental ganglia controlling reflex actions. This allows brief survival after decapitation and basic movement, reflecting efficient division of neural control.
Subtopic: Nervous System of Cockroach
Supra-oesophageal ganglia: Brain-like structure in cockroach controlling sensory input and motor functions, located above the oesophagus.
Ventral nerve cord: Main nerve cord running along the belly side of cockroach, coordinating movement and reflexes.
Segmental ganglia: Cluster of nerve cells in each body segment controlling local muscles and organs.
Cockroach: Common insect with a decentralized nervous system allowing survival even after decapitation for a short period.
Nervous system: Network of neurons and ganglia coordinating sensory perception and motor activity in animals.
Decapitation survival: Ability of cockroach to live briefly without head due to decentralized nervous system.
Reflex action: Automatic response controlled by ganglia without brain involvement.
Invertebrate: Animals without backbone, often with simpler or decentralized nervous systems.
Oesophagus: Tube connecting mouth to gut in cockroach, passing under the brain (supra-oesophageal ganglia).
Motor coordination: Control of movement by nerve impulses in body segments.
Autonomous functions: Life-sustaining actions managed by ganglia independent of brain.
Lead Question (2020): If the head of cockroach is removed, it may live for few days because:
Options:
1. The head holds a small proportion of a nervous system while the rest is situated along the ventral part of its body
2. The head holds a 1/3rd of a nervous system while the rest is situated along the dorsal part of its body
3. The supra-oesophageal ganglia of the cockroach are situated in ventral part of abdomen
4. The cockroach does not have nervous system
Explanation: Correct answer is 1. Cockroach has a decentralized nervous system with major ventral nerve cord and segmental ganglia controlling vital functions. The head contains only a small proportion of neurons in supra-oesophageal ganglia, so even after decapitation, the cockroach can survive for days performing basic movements and reflexes.
1. Single Correct Answer MCQ:
Which part of cockroach nervous system controls local segmental movements?
Options:
a. Supra-oesophageal ganglia
b. Segmental ganglia
c. Ventral nerve cord
d. Dorsal nerve cord
Explanation: Correct answer is b. Segmental ganglia in each body segment control local movements and reflexes, allowing cockroach to coordinate leg and body actions independently of the brain.
2. Single Correct Answer MCQ:
The ventral nerve cord in cockroach is located on:
Options:
a. Dorsal side
b. Ventral side
c. Lateral side
d. Inside head only
Explanation: Correct answer is b. The ventral nerve cord runs along the belly (ventral) side of the cockroach, connecting segmental ganglia and coordinating movement, which allows survival even after decapitation.
3. Single Correct Answer MCQ:
Which structure functions as the brain in cockroach?
Options:
a. Sub-oesophageal ganglia
b. Segmental ganglia
c. Supra-oesophageal ganglia
d. Ventral nerve cord
Explanation: Correct answer is c. The supra-oesophageal ganglia, located in the head above the oesophagus, acts as the brain of cockroach, processing sensory input and sending commands, but survival is possible even if it is removed due to other ganglia.
4. Single Correct Answer MCQ:
Which function in cockroach is maintained after decapitation?
Options:
a. Feeding
b. Reflex movements
c. Reproduction
d. Vision
Explanation: Correct answer is b. Reflex movements are controlled by ventral nerve cord and segmental ganglia, independent of head. This allows basic locomotion and survival for several days post decapitation.
5. Single Correct Answer MCQ:
Which ganglia in cockroach lies below the oesophagus?
Options:
a. Supra-oesophageal
b. Sub-oesophageal
c. Segmental
d. Thoracic only
Explanation: Correct answer is b. The sub-oesophageal ganglia are situated below the oesophagus and control mouthparts, legs, and other movements. They function autonomously in absence of the brain.
6. Single Correct Answer MCQ:
Which statement about cockroach nervous system is true?
Options:
a. Entirely centralized in head
b. Decentralized with segmental ganglia
c. Only dorsal nerve cord present
d. Lacks ventral nerve cord
Explanation: Correct answer is b. Cockroach has a decentralized nervous system, including supra-oesophageal ganglia, ventral nerve cord, and segmental ganglia, allowing partial survival even after head removal.
7. Assertion-Reason MCQ:
Assertion (A): Cockroach can survive for days without its head.
Reason (R): Segmental ganglia control vital functions independently.
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. Segmental ganglia coordinate vital functions and reflexes independently of the brain. This decentralization allows cockroach to survive several days post decapitation.
8. Matching Type MCQ:
Match cockroach structures with their functions:
(a) Supra-oesophageal ganglia - (i) Reflex movement
(b) Sub-oesophageal ganglia - (ii) Control mouthparts & legs
(c) Segmental ganglia - (iii) Process sensory input
Options:
1. a-iii, b-ii, c-i
2. a-i, b-iii, c-ii
3. a-ii, b-i, c-iii
4. a-iii, b-i, c-ii
Explanation: Correct answer is 1. Supra-oesophageal ganglia process sensory input, sub-oesophageal ganglia control mouthparts and legs, while segmental ganglia manage reflex movements in individual segments.
9. Fill in the Blanks MCQ:
The _______ runs along the ventral side of cockroach body.
Options:
a. Dorsal nerve cord
b. Ventral nerve cord
c. Supra-oesophageal ganglia
d. Sub-oesophageal ganglia
Topic: Cockroach Anatomy
Subtopic: Digestive System
Alimentary Canal: Continuous muscular tube in animals for digestion and absorption of food.
Pharynx: Muscular region connecting mouth to oesophagus, aiding food swallowing.
Oesophagus: Narrow tube transporting food from pharynx to crop or stomach.
Crop: Storage organ that temporarily holds food before digestion.
Gizzard: Muscular organ that grinds food mechanically.
Ileum: Midgut region where enzymatic digestion and nutrient absorption occurs.
Colon: Hindgut region absorbing water and forming feces.
Rectum: Terminal part of alimentary canal storing feces before excretion.
Digestive Enzymes: Biological catalysts that break down complex food into simpler forms.
Hindgut: Posterior part of alimentary canal including colon and rectum.
Foregut: Anterior part of alimentary canal including mouth, pharynx, oesophagus, crop, and gizzard.
Lead Question (2019): Select the correct sequence of organs in the alimentary canal of cockroach starting from mouth:
Options:
1. Pharynx Oesophagus Crop Gizzard Ileum Colon Rectum
2. Pharynx Oesophagus Gizzard Crop Ileum Colon Rectum
3. Pharynx Oesophagus Gizzard Ileum Crop Colon Rectum
4. Pharynx Oesophagus Ileum Crop Gizzard Colon Rectum
Explanation: Correct answer is 1. In cockroach, food passes sequentially through pharynx, oesophagus, crop (temporary storage), gizzard (grinding), ileum (digestion and absorption), colon (water absorption), and rectum (feces storage). This organized sequence ensures proper digestion, nutrient absorption, and waste excretion in insects.
1. Single Correct Answer MCQ:
Which organ in cockroach stores food temporarily?
Options:
a. Gizzard
b. Crop
c. Ileum
d. Rectum
Explanation: Correct answer is b. The crop is a thin-walled storage organ that temporarily holds ingested food before mechanical digestion in gizzard. Ileum digests nutrients, gizzard grinds food, and rectum stores feces. Crop ensures continuous food processing without immediate passage to the midgut.
2. Single Correct Answer MCQ:
Which organ grinds food mechanically in cockroach?
Options:
a. Ileum
b. Crop
c. Gizzard
d. Colon
Explanation: Correct answer is c. Gizzard is a thick, muscular organ with chitinous teeth that grinds food mechanically. Crop stores food, ileum digests nutrients enzymatically, and colon absorbs water. Mechanical grinding in gizzard ensures food particles are small enough for efficient enzymatic digestion in the midgut.
3. Single Correct Answer MCQ:
Where does enzymatic digestion and nutrient absorption mainly occur?
Options:
a. Gizzard
b. Ileum
c. Crop
d. Rectum
Explanation: Correct answer is b. The ileum, part of the midgut, is the site of enzymatic digestion and nutrient absorption. Gizzard mechanically grinds food, crop stores it, and rectum stores feces. Efficient absorption in ileum ensures that energy and nutrients are extracted before waste elimination.
4. Single Correct Answer MCQ:
Which organ absorbs water and forms feces?
Options:
a. Ileum
b. Rectum
c. Colon
d. Crop
Explanation: Correct answer is c. The colon absorbs water from undigested food and forms feces. Rectum stores the fecal matter temporarily before excretion. Crop and ileum function in storage and digestion. Water absorption in colon helps maintain osmotic balance and solidifies feces.
5. Single Correct Answer MCQ:
Pharynx connects mouth to:
Options:
a. Crop
b. Gizzard
c. Oesophagus
d. Ileum
Explanation: Correct answer is c. The pharynx is a muscular region connecting mouth to oesophagus, allowing passage of food. Crop stores, gizzard grinds, and ileum digests food. Pharynx movement ensures controlled swallowing and prevents backflow, initiating coordinated alimentary canal function.
6. Single Correct Answer MCQ:
Which part is the terminal organ of cockroach digestive system?
Options:
a. Colon
b. Rectum
c. Ileum
d. Crop
Explanation: Correct answer is b. Rectum is the terminal part, storing feces temporarily before excretion. Colon absorbs water, ileum digests, and crop stores food. Rectum ensures controlled elimination and contributes to osmotic regulation in the insect body.
7. Assertion-Reason MCQ:
Assertion (A): Gizzard is essential for mechanical digestion.
Reason (R): Crop grinds food using chitinous teeth.
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 c. Gizzard mechanically grinds food, making A true. R is false because crop stores food and does not grind it. Mechanical grinding in gizzard ensures smaller particles for efficient enzymatic digestion in the ileum, aiding nutrient absorption.
8. Matching Type MCQ:
Match organs with their functions:
Column-I Column-II
(a) Crop (i) Grinding food
(b) Gizzard (ii) Temporary storage
(c) Ileum (iii) Nutrient absorption
(d) Colon (iv) Water absorption
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-i, d-ii
4. a-iv, b-iii, c-ii, d-i
Explanation: Correct answer is 1. Crop stores food temporarily, gizzard grinds it, ileum digests and absorbs nutrients, and colon absorbs water. This mapping illustrates functional specialization of alimentary canal organs in cockroach, facilitating efficient digestion and excretion.
9. Fill in the Blanks / Completion MCQ:
The ________ absorbs water from undigested food in cockroach.
Options:
a. Ileum
b. Colon
c. Crop
d. Gizzard
Explanation: Correct answer is b. Colon, part of hindgut, absorbs water from undigested food, converting it into semi-solid feces. Ileum digests nutrients, crop stores food, and gizzard grinds mechanically. Water absorption is crucial for maintaining osmotic balance and proper excretion.
10. Choose the correct statements MCQ:
Select correct statements:
i. Gizzard grinds food
ii. Crop stores food
iii. Rectum absorbs nutrients
iv. Colon absorbs water
Options:
a. i, ii, iv
b. ii and iii
c. i and iii
d. i, ii, iii, iv
Explanation: Correct answer is a. Gizzard grinds food mechanically, crop stores it, and colon absorbs water. Rectum stores feces but does not absorb nutrients. Statements i, ii, and iv correctly describe functions of cockroach alimentary canal organs, ensuring proper digestion and excretion.
Subtopic: Sexual Dimorphism in Cockroaches
Keyword Definitions:
• Cockroach: Insect belonging to order Blattodea.
• Anal cerci: Paired appendages at the end of abdomen used for sensory function.
• Sternum: Ventral part of an abdominal segment.
• Caudal styles: Paired tail-like structures on some insects.
• Tegmina: Thickened forewings in insects.
• Sexual dimorphism: Differences in morphology between male and female individuals of a species.
• 9th abdominal segment: Posterior segment of insect abdomen, used for sex identification.
Lead Question - 2018
Which of the following feature is used to identify a male cockroach from a female cockroach :
(A) Presence of anal cerci
(B) Presence of a boat shaped sternum on the 9th abdominal segment
(C) Forewings with darker tegmina
(D) Presence of caudal styles
Explanation:
Answer is (B). Male cockroaches are identified by the boat-shaped sternum on the 9th abdominal segment, while females lack this feature. Anal cerci and caudal styles are present in both sexes, and forewing coloration may vary but is not a reliable sex determinant. This morphological difference aids in sex identification.
Guessed Questions for NEET UG:
1) Single Correct: Which appendages are used by cockroaches for sensing vibrations?
(A) Antennae
(B) Anal cerci
(C) Caudal styles
(D) Tegmina
Explanation:
Answer is (B). Anal cerci are paired sensory appendages at the end of the abdomen, detecting vibrations and helping in escape responses in both male and female cockroaches.
2) Single Correct: The hardened forewings of cockroaches are called:
(A) Tegmina
(B) Elytra
(C) Halteres
(D) Cerci
Explanation:
Answer is (A). Cockroach forewings are thickened into tegmina, protecting hindwings and abdomen while aiding in gliding during flight.
3) Single Correct: Which structure is sexually dimorphic in cockroaches?
(A) Anal cerci
(B) 9th abdominal sternum
(C) Tegmina
(D) Caudal styles
Explanation:
Answer is (B). The 9th abdominal sternum is boat-shaped in males but not in females, making it a reliable indicator of sex differences.
4) Assertion-Reason:
Assertion: Male cockroaches have a boat-shaped 9th abdominal sternum.
Reason: Females have wider and flatter sternum in the same segment.
(A) Both true, Reason correct
(B) Both true, Reason incorrect
(C) Assertion true, Reason false
(D) Both false
Explanation:
Answer is (A). Males have a boat-shaped 9th abdominal sternum for identification; females have a flatter sternum, making the assertion and reason both true and logically connected.
5) Single Correct: Caudal styles in cockroaches are:
(A) Present only in males
(B) Present only in females
(C) Present in both sexes
(D) Absent in all
Explanation:
Answer is (C). Caudal styles are small tail-like projections present in both sexes of cockroaches and are not useful for sex differentiation.
6) Single Correct: Which wing type protects the abdomen in cockroaches?
(A) Halteres
(B) Tegmina
(C) Membranous hindwings
(D) Elytra
Explanation:
Answer is (B). Tegmina are thickened forewings that protect the abdomen and hindwings, providing mechanical defense and facilitating controlled flight.
7) Matching Type:
Column I | Column II
a. Male cockroach | i. Boat-shaped 9th sternum
b. Female cockroach | ii. Flat 9th sternum
c. Anal cerci | iii. Sensory appendages
d. Tegmina | iv. Protective forewings
(A) a-i, b-ii, c-iii, d-iv
(B) a-ii, b-i, c-iii, d-iv
(C) a-i, b-ii, c-iv, d-iii
(D) a-iv, b-iii, c-i, d-ii
Explanation:
Answer is (A). Male 9th sternum is boat-shaped, female sternum is flat; anal cerci function as sensory appendages, and tegmina are protective forewings.
8) Fill in the Blank:
The ______ abdominal sternum helps distinguish male cockroaches from females.
(A) 8th
(B) 9th
(C) 10th
(D) 7th
Explanation:
Answer is (B). The 9th abdominal sternum is boat-shaped in males, serving as a key morphological feature to differentiate sexes.
9) Choose the correct statements:
(i) Anal cerci are present in both male and female cockroaches.
(ii) Tegmina color is reliable for sex identification.
(iii) Male 9th sternum is boat-shaped.
(A) i and iii only
(B) i and ii only
(C) ii and iii only
(D) i, ii, iii
Explanation:
Answer is (A). Anal cerci are present in both sexes, and the male 9th sternum is boat-shaped. Tegmina color varies and is not a reliable sex characteristic.
10) Clinical-type: A researcher wants to sex cockroaches quickly. Which structure should be examined first?
(A) Anal cerci
(B) Tegmina
(C) 9th abdominal sternum
(D) Caudal styles
Explanation:
Answer is (C). The 9th abdominal sternum is sexually dimorphic; males have a boat-shaped sternum, making it the most reliable and rapid way to determine sex in cockroaches.
Subtopic: Cockroach Reproductive System
Keyword Definitions:
- Vas deferens: Tube transporting sperm from testes to seminal vesicles.
- Seminal vesicles: Storage organ for mature sperm in male cockroaches.
- Mushroom glands: Accessory reproductive glands in male cockroaches producing seminal fluid.
- Testes: Organs producing sperms and male sex hormones.
- Spermatophore: Capsule containing sperm delivered to female during mating.
- Male reproductive system: Organs responsible for production, storage, and delivery of sperm.
- Cockroach: Hemimetabolous insect, model organism for studying insect physiology.
Lead Question - 2016 (Phase 2)
In male cockroaches, sperms are stored in which part of the reproductive system:
(1) Vas deferens
(2) Seminal vesicles
(3) Mushroom glands
(4) Testes
Answer & Explanation:
Correct answer: Seminal vesicles. In male cockroaches, testes produce sperms which are transported via vas deferens and stored in seminal vesicles before ejaculation. Mushroom glands secrete seminal fluid but do not store sperms. This storage ensures sperm availability during mating and increases reproductive success.
1. Which gland produces seminal fluid in male cockroaches?
(1) Seminal vesicles
(2) Mushroom glands
(3) Testes
(4) Vas deferens
Answer & Explanation:
Correct answer: Mushroom glands. Mushroom glands are accessory reproductive glands that secrete seminal fluid to nourish sperm and aid in its transfer during copulation. They do not store sperms.
2. Assertion (A): Vas deferens transports sperm.
Reason (R): Vas deferens stores sperm in male cockroaches.
(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, R is false
(4) A is false, R is true
Answer & Explanation:
Correct answer: (3) A is true, R is false. Vas deferens functions as a transport tube carrying sperm from testes to seminal vesicles. It does not store sperm; storage occurs in seminal vesicles for controlled release during mating.
3. Match the structure with its function:
A. Testes - (i) Produce sperm
B. Seminal vesicles - (ii) Store sperm
C. Mushroom glands - (iii) Produce seminal fluid
D. Vas deferens - (iv) Transport sperm
(1) A-i, B-ii, C-iii, D-iv
(2) A-ii, B-i, C-iv, D-iii
(3) A-iii, B-iv, C-ii, D-i
(4) A-iv, B-iii, C-i, D-ii
Answer & Explanation:
Correct answer: (1) A-i, B-ii, C-iii, D-iv. Testes produce sperms, seminal vesicles store them, mushroom glands secrete seminal fluid, and vas deferens transports sperms to seminal vesicles and later to female during mating.
4. Fill in the blank:
In male cockroaches, sperms mature and are stored in ________.
(1) Testes
(2) Seminal vesicles
(3) Vas deferens
(4) Mushroom glands
Answer & Explanation:
Correct answer: Seminal vesicles. Sperms produced in testes are transported via vas deferens and stored in seminal vesicles until mating. This allows regulated release of sperm during copulation, ensuring successful fertilization.
5. Clinical-type Question:
Why is seminal vesicle storage important in insect reproduction?
(1) Prevents sperm production
(2) Ensures availability of sperm during mating
(3) Secretes hormones
(4) Produces eggs
Answer & Explanation:
Correct answer: Ensures availability of sperm during mating. Seminal vesicles act as a reservoir for sperm, allowing male cockroaches to deliver sufficient sperms to females during copulation, which is critical for reproductive success and species continuation.
6. Which part of male cockroach produces sperm?
(1) Testes
(2) Seminal vesicles
(3) Mushroom glands
(4) Vas deferens
Answer & Explanation:
Correct answer: Testes. Testes are the primary reproductive organs in male cockroaches, responsible for spermatogenesis. Sperm then move to seminal vesicles for storage before mating.
7. Which structure aids in sperm transfer but does not store it?
(1) Seminal vesicles
(2) Vas deferens
(3) Testes
(4) Mushroom glands
Answer & Explanation:
Correct answer: Vas deferens. Vas deferens transports sperms from testes to seminal vesicles. While essential for sperm delivery, it does not act as a storage organ.
8. Choose the correct statements:
(a) Testes produce sperm
(b) Seminal vesicles store sperm
(c) Mushroom glands transport sperm
(d) Vas deferens stores sperm
Answer & Explanation:
Correct answer: a, b. Testes produce sperms, seminal vesicles store them. Mushroom glands secrete seminal fluid, and vas deferens functions as a transport tube, not a storage site.
9. Which structure secretes seminal fluid in male cockroaches?
(1) Testes
(2) Mushroom glands
(3) Seminal vesicles
(4) Vas deferens
Answer & Explanation:
Correct answer: Mushroom glands. Mushroom glands are accessory reproductive organs producing seminal fluid that nourishes sperms and facilitates their transfer to females.
10. Why is understanding insect reproductive anatomy clinically important?
(1) For managing human reproduction
(2) Helps control pest populations
(3) Determines plant pollination
(4) Predicts weather patterns
Answer & Explanation:
Correct answer: Helps control pest populations. Knowledge of reproductive organs, sperm storage, and mating strategies allows development of targeted biological or chemical controls to manage pest species like cockroaches effectively.
Keywords:
Periplaneta americana: Common American cockroach, used as model in entomology and physiology studies.
Schizocoelom: Body cavity formed by splitting of mesodermal masses; characteristic of protostomes.
Indeterminate cleavage: Cleavage pattern where each cell can develop into a complete organism; typical of deuterostomes.
Radial cleavage: Cleavage planes are parallel or perpendicular to the polar axis; seen in deuterostomes.
Exoskeleton: External skeleton composed of chitin (N-acetylglucosamine polymer) providing protection and support.
Metamerism: Body segmentation into repeated units, common in annelids and arthropods.
Protostome development: Mouth develops from blastopore; spiral and determinate cleavage typically observed.
Embryonic development: Stages from zygote to fully formed organism, including cleavage, gastrulation, and organogenesis.
Chitin: Nitrogen-containing polysaccharide forming exoskeleton of arthropods.
Arthropod body plan: Segmented body, jointed appendages, exoskeleton, and open circulatory system.
Comparative embryology: Study of embryonic development patterns among species to infer evolutionary relationships.
Chapter: Animal Morphology & Development
Topic: Insect Anatomy & Embryology
Subtopic: Periplaneta americana Features
Lead Question - 2016 (Phase 1): Which of the following features is not present in Periplaneta americana?
(1) Schizocoelom as body cavity
(2) Indeterminate and radial cleavage during embryonic development
(3) Exoskeleton composed of N-acetylglucosamine
(4) Metamerically segmented body
Answer: 2
Explanation: Periplaneta americana, a protostome arthropod, exhibits determinate and spiral cleavage, not indeterminate and radial cleavage. It has a schizocoelom, a chitinous exoskeleton, and a metamerically segmented body, making option 2 the feature not present in this species.
1. Single Correct Answer MCQ: The body cavity of Periplaneta americana is:
(A) Pseudocoelom
(B) Schizocoelom
(C) Coelom absent
(D) Blastocoel only
Answer: B
Explanation: Periplaneta americana is a protostome with schizocoelom, formed by splitting mesodermal tissue, providing space for organ development and circulation in arthropods.
2. Single Correct Answer MCQ: The exoskeleton of Periplaneta americana is primarily composed of:
(A) Cellulose
(B) N-acetylglucosamine (chitin)
(C) Collagen
(D) Calcium carbonate
Answer: B
Explanation: The exoskeleton of P. americana is made of chitin, a polymer of N-acetylglucosamine, providing rigidity, protection, and sites for muscle attachment in arthropods.
3. Single Correct Answer MCQ: Which cleavage pattern is observed in P. americana?
(A) Indeterminate and radial
(B) Spiral and determinate
(C) Radial and determinate
(D) Holoblastic and radial
Answer: B
Explanation: Being a protostome, P. americana exhibits spiral and determinate cleavage, meaning each blastomere’s fate is fixed early, unlike deuterostomes with radial and indeterminate cleavage.
4. Single Correct Answer MCQ: Body segmentation in Periplaneta americana is called:
(A) Metamerism
(B) Tagmatization
(C) Pseudometamerism
(D) Non-segmented
Answer: A
Explanation: P. americana shows metameric segmentation, where repeated body units contain similar structures. This is a fundamental arthropod characteristic contributing to mobility and flexibility.
5. Single Correct Answer MCQ: The cleavage in P. americana is considered:
(A) Holoblastic
(B) Meroblastic
(C) Discoidal
(D) Superficial
Answer: D
Explanation: Due to the yolk-rich eggs, P. americana exhibits superficial cleavage where nuclear division occurs without complete cytokinesis, typical of many insect embryos.
6. Single Correct Answer MCQ: The role of chitin in P. americana is:
(A) Digestive enzyme
(B) Skeletal support and protection
(C) Reproductive function
(D) Nervous conduction
Answer: B
Explanation: Chitin in the exoskeleton provides mechanical protection and structural support for muscles, crucial for movement and survival in arthropods.
7. Assertion-Reason MCQ:
Assertion (A): P. americana has a metamerically segmented body.
Reason (R): Metamerism allows flexibility and specialization of body regions.
(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
Answer: A
Explanation: The metamerically segmented body of P. americana allows for specialization of body regions and flexibility, enhancing locomotion and adaptability.
8. Matching Type MCQ: Match feature with characteristic in P. americana:
1. Exoskeleton A. Chitin-based
2. Cleavage B. Spiral, determinate
3. Body segmentation C. Metameric
(A) 1-A, 2-B, 3-C
(B) 1-B, 2-A, 3-C
(C) 1-C, 2-B, 3-A
(D) 1-A, 2-C, 3-B
Answer: A
Explanation: Exoskeleton is chitin-based, cleavage is spiral and determinate, and body is metamerically segmented, reflecting typical arthropod morphology.
9. Fill in the Blanks: P. americana exhibits _______ cleavage and a _______ exoskeleton.
(A) Spiral, chitinous
(B) Radial, calcareous
(C) Indeterminate, proteinaceous
(D) Radial, chitinous
Answer: A
Explanation: Spiral cleavage occurs in protostomes like P. americana, and the exoskeleton is made of chitin (N-acetylglucosamine polymer), providing mechanical support.
10. Passage-based MCQ:
Passage: A cockroach embryo develops through superficial cleavage, forming a segmented body with appendages. The exoskeleton contains chitin. Cleavage is spiral and determinate. One proposed feature, indeterminate cleavage, is absent.
Question: Which feature is not found in Periplaneta americana?
(A) Spiral cleavage
(B) Chitinous exoskeleton
(C) Indeterminate cleavage
(D) Metameric segmentation
Answer: C
Explanation: P. americana, a protostome, does not show indeterminate cleavage. It exhibits spiral, determinate cleavage, has a chitinous exoskeleton, and a segmented body, making indeterminate cleavage the absent feature.
NEET UG MCQs (Lead Q + 10 Guessed)
Keyword Definitions
Chitinous exoskeleton — a protective external covering made mainly of chitin that provides support and protection.
Metameric segmentation — body organized as a series of repeated segments (metameres) often visible externally or internally.
Parapodia — paired lateral appendages (often fleshy) found in annelids used for locomotion and respiration.
Jointed appendages — limbs with articulations (joints) common to arthropods for movement and manipulation.
Tagmata — fused groups of segments (e.g., head, thorax, abdomen) forming functional units in arthropods.
Hemocoel — primary body cavity of arthropods containing haemolymph, part of an open circulatory system.
Ecdysis — moulting process by which an organism sheds its old exoskeleton to grow a new one.
Chapter: Animal Kingdom (NCERT Class XI) — Sub-topic: Phylum Arthropoda — General Characters
Lead Question — 2016 (Phase 1)
Which of the following features is not present in the Phylum-Arthropoda?
(1) Chitinous exoskeleton
(2) Metameric segmentation
(3) Parapodia
(4) Jointed appendages
A. 1 only
B. 2 only
C. 3 only
D. 4 only
Answer: C. 3 only (Parapodia)
Explanation: Arthropods possess a chitinous exoskeleton, metameric segmentation (often modified into tagmata) and jointed appendages. Parapodia are lateral fleshy appendages characteristic of polychaete annelids, not arthropods. Thus option (3) parapodia is absent in Arthropoda. This distinction is important for phylum-level identification and taxonomy (≥50 words).
Guess Q1.
In arthropods, the body cavity that contains haemolymph and functions as the primary circulatory space is called —
A. Coelom
B. Pseudocoelom
C. Hemocoel
D. Blastocoel
Answer: C. Hemocoel
Explanation: Arthropods possess a reduced true coelom and a prominent hemocoel formed by the body cavity where haemolymph circulates in an open circulatory system. The hemocoel bathes tissues directly, aided by ostiate hearts and vessels, distinguishing arthropod circulation from closed systems. Hemocoel is the correct term and function for arthropods (≥50 words).
Guess Q2.
Which of the following processes allows arthropods to grow despite having a rigid chitinous exoskeleton?
A. Regeneration
B. Ecdysis (moulting)
C. Binary fission
D. Budding
Answer: B. Ecdysis (moulting)
Explanation: Arthropods periodically shed their old chitinous exoskeleton in a process called ecdysis or moulting. After shedding, a new, initially soft exoskeleton expands and hardens, permitting increase in body size. This cyclic moulting is hormonally regulated (e.g., ecdysteroids) and essential for arthropod development and growth (≥50 words).
Guess Q3.
Tagmosis in arthropods refers to the —
A. Formation of jointed legs
B. Fusion of segments into functional units
C. Development of parapodia
D. Loss of segmentation
Answer: B. Fusion of segments into functional units
Explanation: Tagmosis is the evolutionary process where serially repeated segments (metameres) become fused to form tagmata—specialized region(s) such as head, thorax and abdomen—each adapted for particular functions. This structural organization increases efficiency and specialization in arthropods and is a hallmark of their body plan (≥50 words).
Guess Q4.
Which structure in arthropods primarily performs gas exchange in many terrestrial insects?
A. Gills
B. Book lungs
C. Tracheal system with spiracles
D. Pulmonary cavity
Answer: C. Tracheal system with spiracles
Explanation: Terrestrial insects use a tracheal system — a network of air-filled tubes that open to the outside via spiracles — for direct oxygen delivery to tissues. Unlike gills or book lungs, the tracheal system supplies oxygen without blood transport, supporting high metabolic activity in insects. Spiracles regulate gas exchange and water loss (≥50 words).
Guess Q5.
Which of the following arthropod groups possesses book lungs?
A. Insects (Insecta)
B. Crustacea
C. Chelicerata (e.g., spiders)
D. Myriapoda
Answer: C. Chelicerata (e.g., spiders)
Explanation: Many chelicerates (notably spiders) possess book lungs — layered respiratory structures consisting of flattened lamellae that facilitate gas exchange. Crustaceans typically have gills and insects have tracheae; myriapods use tracheae as well. Book lungs are characteristic of certain terrestrial chelicerates and adapt them to air-breathing (≥50 words).
Guess Q6.
Which one of the following pairs is correctly matched for arthropod excretory organ and group?
A. Malpighian tubules — Crustacea
B. Coxal glands — Insects
C. Green glands (antennal glands) — Crustacea
D. Flame cells — Chelicerata
Answer: C. Green glands (antennal glands) — Crustacea
Explanation: Crustaceans commonly possess green glands (antennal glands) near the base of antennae for excretion and osmoregulation. Insects use Malpighian tubules, some arachnids use coxal or book gland structures, and flame cells are characteristic of some flatworms, not arthropods. Hence the correct match is green glands with Crustacea (≥50 words).
Guess Q7. (Assertion-Reason)
Assertion (A): Arthropods possess a segmented body plan that is externally visible.
Reason (R): In arthropods, segmentation always remains homonomous (all segments identical).
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 of A.
C. A is true but R is false.
D. A is false but R is true.
Answer: C. A is true but R is false.
Explanation: The assertion is correct — arthropods have a segmented (metameric) body plan often visible externally. However, segmentation in arthropods is typically heteronomous, with segments modified into different forms (tagmata) for specialized functions. Thus R is false; segments are not always identical, making option C correct (≥50 words).
Guess Q8. (Matching)
Match Column I (Structure) with Column II (Function / Group)
Column I
A. Mandible
B. Uropods
C. Book lungs
D. Malpighian tubules
Column II
1. Respiration — book lungs
2. Mastication of food (biting/chewing)
3. Tail appendages used in swimming and stabilization
4. Excretion in insects
A. A-2, B-3, C-1, D-4
B. A-4, B-2, C-3, D-1
C. A-2, B-1, C-3, D-4
D. A-3, B-2, C-1, D-4
Answer: A. A-2, B-3, C-1, D-4
Explanation: Mandibles (A) are paired mouthparts for chewing (2). Uropods (B) are posterior appendages in many crustaceans assisting swimming/stability (3). Book lungs (C) provide respiration in certain arachnids (1). Malpighian tubules (D) function in excretion/osmoregulation in insects (4). Therefore A matches the correct set (≥50 words).
Guess Q9. (Fill in the blanks)
Complete the sentence: In crustaceans, the primary limbs modified for locomotion and manipulation are called ________, and these animals typically use ________ for excretion.
A. Antennae; Malpighian tubules
B. Chelipeds and pereopods; Green glands (antennal glands)
C. Mandibles; Nephridia
D. Maxillipeds; Flame cells
Answer: B. Chelipeds and pereopods; Green glands (antennal glands)
Explanation: Crustaceans often possess specialized appendages — chelipeds (claw-bearing) and pereopods (walking legs) — for locomotion and handling. Their excretory organs are green glands (also called antennal glands) located near the base of antennae. This pairing is characteristic of many decapod crustaceans (≥50 words).
Guess Q10. (Passage-based)
Passage: "An arthropod specimen shows a segmented body divided into head and thorax fused as cephalothorax, a pair of chelate first pair of appendages, and multiple pairs of biramous limbs. The exoskeleton is calcified and it shows well-developed gills."
Based on the passage, which group does the specimen most likely belong to?
A. Insecta
B. Chelicerata (e.g., spiders, scorpions)
C. Crustacea (e.g., crabs, lobsters)
D. Myriapoda (e.g., centipedes)
Answer: C. Crustacea (e.g., crabs, lobsters)
Explanation: The passage describes a cephalothorax, chelate appendages, biramous limbs and gills — classic features of many crustaceans like crabs and lobsters. Calcified exoskeleton and biramous limbs are typical of decapod crustaceans. Insects lack biramous limbs and gills; chelicerates have uniramous appendages. Hence Crustacea fits best (≥50 words).
Guess Q11.
Which sensory structure in arthropods is primarily responsible for detecting chemical stimuli (smell/taste)?
A. Compound eyes
B. Statocyst
C. Antennae (or antenna-like sensilla)
D. Tympanum
Answer: C. Antennae (or antenna-like sensilla)
Explanation: Antennae (or sensilla on antennae) are primary chemosensory organs in many arthropods, detecting pheromones, food odors and environmental chemicals. Compound eyes detect visual cues; statocysts aid balance; tympanum (in some insects) senses sound. Antennae are thus key chemical sensors enabling foraging, mating and navigation (≥50 words).
Keyword Definitions:
Viroids: Small infectious pathogens consisting of a short strand of circular RNA without a protein coat.
Protein Coat: Protective outer layer of viruses, absent in viroids.
RNA: Ribonucleic acid, genetic material in viroids and some viruses.
Molecular Weight: Mass of a molecule, indicating size; viroid RNA is low molecular weight.
Infections: Viroids cause plant diseases by interfering with normal cell function.
Viruses: Infectious agents with nucleic acid and protein coat, larger than viroids.
Circular RNA: Structure of viroid RNA, single stranded and covalently closed.
Plant Pathogens: Organisms causing diseases in plants, including viroids and viruses.
Genomic Material: Genetic substance in pathogens, either DNA or RNA.
Answer: C) They are smaller than viruses and cause plant diseases
Viroids are naked RNA molecules smaller than viruses and primarily infect plants, causing diseases by interfering with cell metabolism.