1. What are oviparous animals? Explain with examples.
Answer:
Oviparous animals are species that lay eggs, with embryos developing outside the mother’s body. These animals typically protect their eggs through shells or other protective structures. Examples include:
- Birds: Hens and ducks lay hard-shelled eggs.
- Reptiles: Turtles and crocodiles lay leathery eggs.
- Amphibians: Frogs and toads lay jelly-coated eggs in water.
2. What are viviparous animals? How do they differ from oviparous animals?
Answer:
Viviparous animals give birth to live offspring, with the embryo developing inside the mother and receiving nourishment through a placenta or other structures.
Differences:
- Nourishment: Viviparous embryos are nourished internally; oviparous embryos rely on yolk.
- Protection: Viviparous animals provide more protection during development.
Examples: Humans, dogs, and whales.
3. Describe the advantages of oviparous reproduction.
Answer:
Advantages include:
- High offspring production: Large numbers of eggs can be laid at once.
- Reduced maternal investment: Less energy is spent on gestation.
- Environmental adaptation: Eggs can be laid in safe, suitable environments.
4. Discuss the advantages of viviparous reproduction.
Answer:
Advantages include:
- Protection of embryos: Developing young are safer inside the mother’s body.
- Parental investment: Ensures higher survival rates of offspring.
- Adaptation to environments: Suitable for habitats with high predation risks.
5. What is ovoviviparity? How is it different from oviparity and viviparity?
Answer:
Ovoviviparity refers to animals that retain eggs inside the mother until they hatch, giving birth to live young without a placenta.
- Oviparity: Eggs develop outside the body.
- Viviparity: Embryos are nourished via a placenta.
Example: Sharks and some snakes.
6. Explain how reproductive strategies are influenced by environmental factors.
Answer:
- Predation pressure: Viviparous animals protect embryos inside the body, while oviparous animals lay eggs in hidden or safe locations.
- Availability of resources: Viviparous reproduction requires more energy and is common in stable environments.
- Temperature: Many oviparous animals rely on external heat for egg incubation.
7. Compare external and internal fertilization in animals.
Answer:
- External Fertilization: Eggs and sperm are released into the environment (e.g., frogs). Common in oviparous species.
- Internal Fertilization: Fertilization occurs inside the body (e.g., mammals). Common in viviparous species.
8. What are the limitations of oviparous reproduction?
Answer:
- Egg vulnerability: Eggs are exposed to predators and environmental conditions.
- Dependence on yolk: Limited nourishment restricts the size and development of embryos.
- Environmental reliance: Eggs require suitable temperatures and conditions to develop.
9. Discuss the role of parental care in reproductive strategies.
Answer:
- Oviparous species: Parental care is minimal; parents often protect or hide eggs.
- Viviparous species: Parents invest heavily in offspring, ensuring higher survival rates.
10. What is the evolutionary significance of viviparity?
Answer:
Viviparity evolved as an adaptation to protect offspring in environments with high predation or harsh climates. It ensures better survival through internal nourishment and development.
11. Why do most birds exhibit oviparity?
Answer:
Birds exhibit oviparity due to:
- Flight adaptation: Laying eggs reduces the weight burden for flight.
- Nest-building: Eggs are safely incubated in nests.
12. How do reptiles exhibit diversity in reproductive strategies?
Answer:
Reptiles show oviparity, viviparity, and ovoviviparity. Examples:
- Oviparous: Turtles lay eggs on land.
- Viviparous: Boa constrictors give live birth.
- Ovoviviparous: Some lizards retain eggs internally.
13. What adaptations do oviparous animals have for egg protection?
Answer:
- Hard shells: Birds’ eggs have calcified shells to prevent damage.
- Camouflage: Eggs blend with the environment to avoid predators.
- Gelatinous coating: Amphibians lay jelly-like eggs to retain moisture.
14. Describe the role of the placenta in viviparous animals.
Answer:
The placenta facilitates:
- Nourishment: Transfers nutrients from mother to embryo.
- Gas exchange: Supplies oxygen and removes waste.
- Protection: Shields the embryo from infections and external shocks.
15. What are the reproductive strategies of monotremes?
Answer:
Monotremes like the platypus and echidna are oviparous mammals. They lay eggs but exhibit mammalian traits like producing milk to nourish their young.
16. Why do amphibians mostly exhibit oviparity?
Answer:
Amphibians rely on water for reproduction. Oviparity allows them to lay eggs in aquatic environments, which support external fertilization and larval development.
17. Explain the reproductive strategy of marsupials.
Answer:
Marsupials are viviparous but give birth to underdeveloped young. The young continue to develop externally in a pouch (e.g., kangaroos).
18. How do aquatic oviparous animals protect their eggs?
Answer:
- Egg clusters: Fish and amphibians lay eggs in groups for protection.
- Hidden locations: Eggs are laid in secluded spots to avoid predators.
- Chemical defenses: Some species coat eggs with substances to deter predators.
19. What are the challenges faced by viviparous animals during gestation?
Answer:
- High energy demands: Mothers require more food to nourish embryos.
- Physical strain: Carrying offspring limits mobility.
- Longer gestation: Prolonged development increases vulnerability to predators.
20. Summarize the reproductive strategies of mammals.
Answer:
Mammals primarily exhibit viviparity, with a few exceptions like monotremes. Most nourish their young through a placenta and invest heavily in parental care to ensure the survival of fewer, well-developed offspring.
