Topic outline

    • Reproduction in Animals

      Q37. Why do fish and frogs lay eggs in hundreds?

      Ans. Though these animals lay hundreds of eggs and release millions of sperms, all the eggs do not get fertilized and develop into new individuals. This is because the eggs and sperms get exposed to water movement, wind and rainfall. Also, there are other animals in the pond which may feed on eggs. Thus, production of large number of eggs and sperms is necessary to ensure fertilization of at least a few of them.


      Q38. Explain how chicks are born.

      Ans. Internal fertilization takes place in hens also. Soon after fertilization, the zygote divides repeatedly and travels down the oviduct. As it travels down, many protective layers are formed around it. The hard shell that we see in a hen’s egg is one such protective layer. After the hard shell is formed around the developing embryo, the hen finally lays the egg. The embryo takes about 3 weeks to develop into a chick.

      Q39. Define asexual reproduction. Describe two methods of asexual reproduction in animals.

      Ans. The type of reproduction in which only a single parent is involved is called asexual reproduction. The two methods of asexual reproduction in animals are:

      Budding – In this type of asexual reproduction, a small part of the body of parent organism grows as a ‘bud’ which then detaches and becomes a new organism. Example- hydra

      Binary fission - In this type of asexual reproduction, the parent organism splits (or divides) to form two new organisms. Example - Amoeba reproduces by binary fission by dividing itself into two parts.


      Q40. Differentiate between Viviparous and Oviparous Animals.

      Ans. Difference between Viviparous and Oviparous Animals

      Viviparous Animals

      Oviparous Animals

      1. The animals which give birth to young ones are called viviparous animals.

      1. Those animals which lay eggs are called oviparous animals.

      2. Examples of viviparous animals are cow, dog, cat, lion, tiger, horse, rabbit etc.

      2. Examples of oviparous animals are butterfly, frog, fish, crow, sparrow, snake, lizard, ostrich etc.

      Q41. What is the basic difference between asexual and sexual reproduction?

      Ans. Difference between asexual and sexual reproduction

      Asexual reproduction

      Sexual reproduction

      1. The type of reproduction in which only a single parent is involved is called asexual reproduction.

      1. Reproduction resulting from the fusion of male and female gametes is called sexual reproduction.

      2. No formation or fusion of gametes occurs.

      2. Gametes are always formed, and fusion also occurs.

      3. No fertilization takes place.

      3. Fertilization takes place.


      Q42. Differentiate between internal fertilization and external fertilization.

      Ans. Difference between internal fertilization and external fertilization

      Internal fertilization

      External fertilization

      1. Fertilization which takes place inside the female body is called internal fertilization.

      1. Fertilization that takes place outside the female body is called external fertilization.

      2. This is observed in human beings and other animals such as hens, cows and dogs.

      2. This is observed in frogs, fish, starfish, etc.

      Q43. What is metamorphosis? Give examples.

      Ans. The transformation of the larva into adult through drastic changes is called metamorphosis. Commonly known examples of metamorphosis include the process undergone by most insects, and the transformation of tadpoles into frogs. The diagram below shows the stages of this change, wherein the small fish-like tadpoles transform into what seems a completely different animal:

      Image from NCERT


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