Class 8 Science Chapter 9 Reproduction in Animals PDF

# Reproduction in Organisms ## Multiple Choice Questions 1. Although 2 cells called gametes fuse, the product formed is a single cell called zygote. Justify. 2. Stages in the life cycle of silkworm are given below. Write them in sequential order. - pupa - silkworm - egg - silkmoth...

# Reproduction in Organisms ## Multiple Choice Questions 1. Although 2 cells called gametes fuse, the product formed is a single cell called zygote. Justify. 2. Stages in the life cycle of silkworm are given below. Write them in sequential order. - pupa - silkworm - egg - silkmoth 3. What is the importance of reproduction? 4. In markets, eggs of birds are available but never eggs of dogs. Why? 5. The eggs of frogs do not have shells for protection, yet they are safe in water. How? ## Short Answer Type Questions 1. Fill up the blanks with the terms given below: - body - asexual - binary - single - nucleus Amoeba is a _single_ celled organism. It reproduces by _asexual_ reproduction. The process of reproduction begins by the division of its _nucleus_ into two. This is followed by the division of its _body_ into two. This type of reproduction is called _binary_ fission. 2. The term metamorphosis is not used while describing human development. Why? 3. Mother gives birth to a baby but the baby has characters of both parents. How is this possible? 4. How is reproduction in hydra different from that in amoeba? 5. State whether the following statements are True or False. If false, correct the statement: - (a) External fertilization can occur both in water and on land. **True** - (b) The eggs of fish are covered by hard shells for protection. **False**, The eggs of fish are not covered by hard shells for protection, they are covered by a jelly like substance. - (c) Human egg has a head, middle piece and tail. **False**, Human eggs have no head, middle piece or tail. - (d) In adult human females, a single mature egg is released into an oviduct every month. **True** 6. Why do only male gametes have a tail? ## Long Answer Type Questions 1. How can we say that fish exhibits external fertilization? - Fish exhibit external fertilization because they release their eggs and sperms into the water - Fertilization happens outside the body of the fish, in the water. 2. - After observing Fig. 9.3 answer the following. - Read the following statements and label them in the figure: - (i) The part which produces female gametes. **Ovary** - (ii) The part where development of the baby takes place. **Uterus** - (iii) The part through which the developing embryo passes to reach the uterus. **Oviduct** - Explain the future development of the embryo that would take place after it gets embedded in the uterus. - Once the embryo gets embedded in the uterus, it starts growing into a fetus. - The fetus will develop over a period of nine months, and will be ready for birth. - Hens and frogs are both oviparous exhibiting different types of fertilization. Explain. - In *Hens*, fertilization is internal. The male hen, called a rooster, mates with the female hen and the fertilization happens inside the female hen. The fertilized egg is laid and then the baby chick develops inside the egg outside the mother's body. - In *Frogs*, fertilization is external. In frogs the male and female frogs release their eggs and sperms outside their body, in the water. The fertilization happens outside their body in the water. - Both hen and frog are oviparous because they lay eggs, but they have very different types of fertilization. - Observe the following figures. - (a) The image depicts a human body - (b) The image depicts an egg being fertilized by sperm - (c) The image depicts the stages in the development of a baby - (d) The image depicts the stages in the development of a human baby. - (i) Identify the stages a to d in Fig. 9.4 during development of human baby. - a: Zygote - b: Morula - c: Blastocyst - d: Embryo - (ii) Arrange the stages in correct sequence of development. - The order of the development is: Zygote, Morula, Blastocyst, embryo - (iii) Explain the development that takes place in any one stage. - *Zygote* is the first stage of development: After the sperm fertilizes the egg, the zygote is formed. - *Morula* is the second stage of development: The zygote starts to divide into multiple cells, forming a solid ball of cells, called a Morula. - *Blastocyst* is the third stage of development: The Morula undergoes further division, resulting in a hollow ball of cells called blastocyst.