📘 Unit V – Expected Questions & Answers
2 Marks Questions
1. Define migration in birds.
Migration is the regular, seasonal movement of birds from one region to another for feeding or breeding, usually influenced by climate and food availability.
2. Name any two poisonous snakes of India.
Indian cobra (Naja naja), Common krait (Bungarus caeruleus).
3. What are air sacs in birds?
Thin-walled extensions of lungs that store air and allow double respiration, ensuring continuous oxygen supply during flight.
4. Give two examples of parental care in Amphibia.
Alytes (midwife toad) carries eggs on back. Rhacophorus builds foam nests.
5 Marks Questions
1. Explain adaptations in birds for flight.
- Streamlined body to reduce air resistance.
- Forelimbs modified into wings with feathers for lift.
- Lightweight pneumatic bones and a large keeled sternum for muscle attachment.
- Powerful flight muscles (pectoralis major, supracoracoideus).
- Lungs with air sacs for continuous oxygen supply.
These adaptations together make sustained flight possible.
2. Write a note on parental care in Amphibia.
- Guarding eggs (frog Rana).
- Foam nests (tree frog Rhacophorus).
- Carrying eggs on body (Alytes – on back, Darwin’s frog – in vocal sacs).
- Brood pouches (Nototrema).
- Viviparity in caecilians.
These methods enhance survival of young in risky environments.
3. List the poisonous snakes of India with their venom type.
- Cobra (Naja naja) – neurotoxic.
- Krait (Bungarus caeruleus) – neurotoxic.
- Russell’s viper (Daboia russelii) – hemotoxic.
- Saw-scaled viper (Echis carinatus) – hemotoxic.
These four are commonly called “Big Four” snakes of India.
12 Marks Question
Adaptations in Birds for Flight (~380 words)
Introduction:
Birds (Class Aves) are the only living vertebrates capable of true flight (except for bats among mammals). Their bodies show a unique combination of structural, physiological, and behavioral adaptations that allow them to fly efficiently.
1. Morphological adaptations
- Streamlined body reduces air resistance.
- Feathers: Flight feathers (remiges, rectrices) provide lift and thrust; contour feathers streamline the body.
- Forelimbs modified into wings: main organs of flight.
- Beak without teeth: reduces weight.
2. Skeletal adaptations
- Lightweight pneumatic bones reduce weight without losing strength.
- Fused bones (e.g., carpometacarpus, tibiotarsus) provide rigidity.
- Keeled sternum provides large surface area for muscle attachment.
- Furcula (wishbone) acts as a spring during wing beats.
3. Muscular adaptations
- Powerful pectoral muscles: Pectoralis major (downstroke), supracoracoideus (upstroke).
- Reduced hindlimb muscles close to center of gravity, reducing drag.
4. Respiratory adaptations
- Nine air sacs connected to lungs ensure unidirectional airflow.
- High oxygen uptake supports high metabolic rate during flight.
5. Circulatory and excretory adaptations
- Four-chambered heart ensures efficient double circulation.
- High metabolic rate maintains energy for wing movements.
- Excretion of uric acid reduces weight (no bladder).
6. Nervous and sensory adaptations
- Well-developed cerebellum coordinates flight and balance.
- Excellent vision with binocular and color capability.
Conclusion:
Birds’ success in flight results from structural lightness, muscular power, efficient respiration, and acute senses. These adaptations enhance not only flight but also survival, feeding, and migration.
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