Important Questions for Class 8 Science - Reproduction in Animals

Q1: What are the two modes of reproduction in animals, and how do they differ from each other?
Ans: The two modes of reproduction in animals are sexual reproduction and asexual reproduction. Sexual reproduction involves the fusion of male and female gametes, while asexual reproduction only involves a single parent.

Q2: Explain the male reproductive organs in humans, and what is their role in reproduction?
Ans: Male reproductive organs in humans include testes, sperm ducts, and the penis. Testes produce sperm, which are male gametes. The sperm's role is to fertilize the female egg during sexual reproduction.

Q3: Describe the female reproductive organs in humans and their functions.
Ans: Female reproductive organs in humans consist of ovaries, oviducts (fallopian tubes), and the uterus. Ovaries produce eggs (ova). The oviducts transport the egg to the uterus, where fertilization can occur. The uterus is where the embryo develops during pregnancy.

Q4: What is fertilization, and how does it occur in humans?
Ans: Fertilization is the fusion of a sperm cell from a male with an egg cell from a female. In humans, fertilization takes place in the oviduct when a sperm cell meets an egg cell.

Q5: Explain the difference between internal and external fertilization with examples.
Ans: Internal fertilization occurs inside the female's body, as in humans and some other animals like dogs and cows. External fertilization occurs outside the female's body, often in water, as in frogs and fish.

Q6: What is the significance of producing a large number of eggs and sperm in animals that undergo external fertilization?
Ans: Producing a large number of eggs and sperm increases the chances of successful fertilization because many eggs and sperm may not survive due to exposure to external factors like water movement or predation.

Q7: How does the zygote develop into an embryo in animals?
Ans: The zygote undergoes repeated cell divisions to form a ball of cells, which eventually differentiate into different tissues and organs. This developing structure is called an embryo.

Q8: What is metamorphosis, and provide an example of an animal that undergoes metamorphosis.
Ans: Metamorphosis is a process in which an animal undergoes drastic changes in its body structure during its life cycle. Frogs are an example; they start as eggs, then become tadpoles (larvae), and finally develop into adult frogs.

Q9: Differentiate between viviparous and oviparous animals, and provide examples of each.
Ans: Viviparous animals give birth to live young ones, while oviparous animals lay eggs. Examples of viviparous animals include humans and dogs, while examples of oviparous animals include birds and reptiles.

Q10: How does asexual reproduction differ from sexual reproduction, and what are the methods of asexual reproduction mentioned in the chapter?
Ans: Asexual reproduction involves a single parent and does not involve the fusion of gametes. Methods of asexual reproduction mentioned in the chapter include budding (as seen in hydra) and binary fission (as seen in amoeba).

Q11: Explain the process of budding in hydra and its significance.
Ans: Budding in hydra involves the development of new individuals as outgrowths from a single parent. This allows hydra to reproduce asexually and increase its population rapidly.

Q12: Describe the process of binary fission in amoeba and its significance.
Ans: Binary fission in amoeba begins with the division of the nucleus, followed by the division of the body into two, resulting in two new amoebae. This method allows amoeba to reproduce asexually and increase its numbers.

Q13: Why is it important for animals to reproduce, and what role does reproduction play in the continuation of a species?
Ans: Reproduction is crucial for the continuation of a species as it ensures the production of new individuals that carry the genetic information of the species. Without reproduction, a species would become extinct.

Q14: How do the reproductive organs in male and female animals contribute to sexual reproduction?
Ans: Male reproductive organs produce gametes (sperm), while female reproductive organs produce gametes (eggs) and provide a suitable environment for fertilization and embryo development.

Q15: Can you provide examples of animals that reproduce asexually other than those mentioned in the chapter, and explain the method they use for asexual reproduction?
Ans: Students may research and provide examples of other animals that reproduce asexually, such as starfish (regeneration) or planarians (fission). They should explain the specific methods these animals use for asexual reproduction.