Saturday, October 12, 2013

CBSE Class 8 - Science - Ch-09-Reproduction in Animals(Notes and Question Answer)

Q.Draw label diagram of male and female reproductive organs in humans.
Q. What are different kinds of fertilization?
Answer: Fertilization which takes place inside the female body is called internal fertilization. Internal fertilization occurs in many animals including humans, cows, dogs and hens.
The fusion of a male and a female gamete takes place outside the body of the female is called external fertilization. It is very common in aquatic animals such as fish, starfish, etc.

Q. Differentiate between Viviparous and Oviparous Animals?
Answer: The animals which give birth to young ones are called viviparous animals. eg. cat ,dog, lion etc. Those animals which lay eggs are called oviparous animals.e.g. insect , fish ,frog, and reptile.

Q. What is metamorphosis?

Answer: Metamorphosis is the process of the transformation of larva into an adult through drastic change. For example pupa into adult butterfly.
Metamorphosis does not occur in viviparous animals because the young one resembles the adult at the time of birth.

Q. What do you mean by brooding?

Answer: In the hen, new individual hens [chick] develop from hen’s egg in about 3 weeks. Hen provides sufficient warmth to the egg to develop by sitting over it. This is called brooding.

Q. How does an embryo obtain nutrition for grow and develop its body parts?

Answer:  an embryo obtains nutrition for grow and develop its body parts from mother’s blood through placenta. The embryo attached to the wall of uterus by placenta.

Q. What is test-tube baby?

Answer: Oviducts of some women are blocked due to which these women are not be able to bear babies. In these type of cases IVF or in vitro fertilization is done in which freshly released egg and sperms are kept them together for a few hours.
Zygote is allowed to develop for about a week and then it placed in the mother’s uterus and the baby is born and this technique is called as test-tube babies.

Q. What is implantation?
Answer: The close attachment of the embryo with the walls of uterus is called implantation.

Q. What is placenta?
Answer:  A special tissue between the uterus wall and the embryo (foetus) that fulfils the nutritional, respiratory and excretory needs of the foetus from mother's body is called placenta.

Q. What is the function of amniotic fluid ?

Answer: The function of amniotic fluid is to protect the foetus against temperature changes and mechanical shocks.

Q. What is gestation?

Answer:  The development of the foetus inside the uterus till birth is called gestation.

Q. What is parturition?

Answer:  The birth of a fully developed foetus after the completion of gestation period is called parturition.

Q.  What are the differences between development of young ones in frogs and in humans?

Development in frogs
Development in humans
It takes place outside the body of the female.
It takes place inside the body of the female.
Stages in the development are egg, larva and adult.
Stages in the development are foetus, young one and adult.
The young one is different from the adult.
The young one is similar to the adult.

Q. Why does a child show some characteristics of the father and some of the mother? 

Answer: The process of fertilization is the meeting of an egg cell from the mother and a sperm cell from the father. So, the new individual inherits some characteristics from the mother and some from the father.

Q. Why do fish and frogs lay eggs in hundreds whereas a hen lays only one egg at a time?

Answer: 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 Unlike hen’s egg, frog’s egg is not covered by a shell and it is comparatively very delicate. A layer of jelly holds the eggs together and provides protection to the eggs

Q. Fill in the blanks:

(a) Male and female have different reproductive part testes and Ovaries respectively.

(b) Each parent produce special sex cell called gamete.

(c) The gamete produced by male and female is sperm and egg (Ovum) respectively.

(d) In most aquatic animal, external fertilization takes place.

(e) On reaching the uterus, the embryo attached to the wall of uterus by placenta. This is called implantation.

(f) In human fertilization of sperm and ovum takes place in the interior part of Oviduct

(g) The process of transformation of larva or tadpole into an adult through drastic changes is called metamorphosis.

(h) A hermaphrodite is a person who possesses the sexual organs of both male and female.

Q. Name the following:

(a) The organ which produces sperm

(b) The organ which produces egg

(c) The place where embryo develops in human female

(d) The organ in reproductive system which receives the sperm

(e) A muscular tissue which delivers the sperm into vagina of female

(f) Name the method of asexual reproduction in which individuals develops from the bud.

(g) Name the process of reproduction in Amoeba.
(a) Testes      (b) Ovaries    (c) Uterus       (d) Vagina        (e) Penis         (f) Budding      (g) Binary fission
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8th Chapter: Reaching the Age of Adolescence
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VIII  Reproduction in Animals    
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J Sunil said...

Chapter 9- Reproduction in Animals

Q1. Name the following
1. Two modes by which animals reproduce.
2. The production of an exact copy of a cell or any other living part.
3. The process that ensures the continuity of similar kinds of indiviuals.
4. The fertilised egg is also known as.
5. The type of fission in Amoeba.
6. Two animals which show metamorphosis.
7. Babies born through the technique of invitro fertilisation.
8. Two animals showing external fertilisation.
9. Two animals showing internal fertilisation.
10. Name the scientist who cloned an animal for the first time sucessfully.

J Sunil said...

Science (from Latin scientia, meaning “knowledge”) is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe.In an older and closely related meaning, “science” also refers to a body of knowledge itself, of the type that can be rationally explained and reliably applied

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