NOTES PREPARED BY
ASHAQ HUSSAIN BHAT
TEACHER SCHOOL
EDUCATION DEPARTMENT
JAMMU AND KASHMIR
'REPRODUCTION IN ANIMALS'
KEYWORDS
TEXT BOOK EXERCISES
Q.1. Explain the importance of reproduction.
Ans. Reproduction is very important as it ensures the continuation of similar kinds of individuals, generation after generation.
Q.2. Describe the process of fertilization in human beings.
Q.3. Choose the most appropriate answer :
(ii) outside female body.
(iv) outside male body.
(iii) in male body.
Ans. Internal fertilization occurs in female body.
(b) A tadpole develops into an adult by the process of:
(i) fertilization.
(ii) metamorphosis.
(iii) embedding.
(iv) budding.
Ans. A tadpole develops into an adult by the process of metamorphosis.
(c) The number of nuclei is present in zygote is :
(i) None (ii) One (iii) two (iv) four
Ans. Only one nuclei is present in zygote.
Q.4. Indicate whether the following sentences as True (T) or False (F):
(1)Oviparous animals give birth to young ones.
(ii) Each sperm is a single cell.
(iii) External fertilization occurs in frog.
(iv) First cell of a new human individual is called a gamete,
(v) Egg laid after fertilization is made up of a single cell.
(vi) Amoeba reproduces by budding.
(vii) Fertilization is necessary even in asexual reproduction.
(viii) Binary fission is a method of asexual reproduction.
(ix) A zygote is formed as a result of fertilization.
(x) An embryo is made up of a single cell.
Ans.
(i) - False;
(ii) - True;
(iii) - True;
(iv) - False;
(v) - False;
(vi) -False;
(vii) False;
(viii) - True;
(ix) - True;
(x) - False.
Q .5 .Give two differences between a zygote and a foetus.
Ans.
Zygote :
(1) The fusion of sperm and egg is called a zygote.
(i) It is single celled structure.
Foetus
(i) The stage of embryo, in which cell body parts are identifiable is called foetus.
(ii) It is a multicellular structure
Q.6. Define asexual reproduction. Describe the two methods of asexual reproduction in animals.
Ans. The type of reproduction, in which only single parent is involved is called asexual reproduction. Asexual reproduction takes places by different methods.
(i) Budding: This process takes place in hydra and bacterial. A part of organisms starts bulging out. Slowly, it grows and develops into a separate individual.
(ii) Binary Fission : This type of reproduction takes place in amoeba. The nucleus of amoeba gets divided into two followed by division of their bodies, each part getting one nucleus. Each part developed into separate amoeba. This type of reproduction is common in unicellular organisms.
Q.7. In which female reproductive organ does embedding of the embryo take place ?
Ans. The embryo gets embedded in the wall of the uterus.
Q.8. What is metamorphosis? Name some animals that undergo metamorphosis.
Ans. Metamorphosis is a biological process, by which an animal, physically, develops after birth or hatching, involving a conspicuous and relatively, abrupt change in the animal's body structure through cell growth and differentiation. Examples: Frogs, caterpillar, silkworm, etc. undergo metamorphosis, which is usually accompanied by a change of habitat or behaviour
Q.9. Differentiate between internal fertilization and external fertilization.
Ans.
Internal fertilization
(1) The fusion of gametes occurs inside the body.
(Ovum).
(ii) Only the male discharge their gametes into genital tract of female.
(iii) Development may occur inside the body.
(iv) Example: Human, Cattle, Shark, Birds.
External fertilization
(1)The fusion of male gamete (sperm) and female gamete
(ii)Both individuals discharge gametes outside the body.
(iii)Development occurs outside the body.
(iv) Example: Frog.
Q.10. Complete the cross-word puzzle using the hints given below
Across:
1. The process of the fusion of the gametes.
6. The type of fertilisation in hen.
7. The term used for bulges observed on the sides of the body of hydra.
8.Eggs are produced here.
Down:
2. Sperms are produced in these male reproductive organs.
3. Another term for the fertilised egg.
4. These animals lay eggs.
5.A type of fission in amoeba.
Ans
1.........Fertilization,
2.........Testes
3........Zygote
4..... Oviparious
5........Binary
6........Internal
7........Buds
8........Ovary
ADDITIONAL SHORT ANSWER TYPE QUESTIONS
Q.1. What is the purpose of tail in sperms?
Ans. The sperms swim in the oviduct with the help of their tails reach the eggs.
Q.2. Why animals, which undergo external fertilization, such as, fish and frogs lay eggs in hundreds, whereas a hen lays only one egg at a time?
Ans. 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. These factors prevent the sperms from reaching the eggs. Thus, production of large number of eggs and sperms is necessary to ensure fertilization of at least a few of them.
Q.3. How a single cell could become such a big individual?
Ans. Fertilization results in the formation of zygote. Which begins to develop into an embryo.
Q.4. What are gametes? What is the difference between unisexual and hermaphrodite ?
Ans. Gametes: Gametes are the reproductive cells, which are produced by the sex organs of the body. There are two types of gametes male and female. Due to the union of gametes, fertilisation takes place.
Unisexual organism: Unisexual organism are those which have only one kind of sex organs either male or female.
Hermaphrodite: Hermaphrodite are those organisms, which have both kinds of sex organs.
Q.5. What is hermaphrodite ? Give two examples.
Ans. The organisms, which can produce, both, the male and female gamete are called hermaphrodites or bisexual. Example :
(i)Earthworm (ii) Hydra.
Q.6. Differentiate the following:
(a) Sperm and Ovum
(b) Zygotes, Embryo and Foetus.
(c) Vas deferens and Fallopian tube
Ans.
(a) Differentiate between Sperm and Ovum
Sperm
(i) The sperm is produces in males.
(ii) Sperm has tail, and it can actively move.
(iii) It is smaller in size.
Ovum
(i) The ovum is produce by females.
(ii) Ovum is oval in shape, cant move it's own.
(iii) It is bigger in size due to presence of yolk.
(b) Difference between Zygotes, Embryo and Foetus
Zygote
1. A zygote is formed by the fusion of male and female gametes (sperm and egg)
2. A zygote is the beginning of the formation of a baby.
3.A zygote is a single cell. It is smaller than a full stop (.)
Embryo
1. An embryo is formed 1.A foetus is formed by the by the repeated cell division of a zygote. growth and development of an embryo.
2. An embryo is an baby in the uterus in the early stages of development (up to 8 weeks)
3. An embryo is multicellular. The body features of growing baby in the embryo are not much developed.
Foetus
1.A foetus is formed by the growth And development of An embryo
2. A foetus is an unborn in the uterus in the later stages of development (after 8 weeks till birth).
3. A foetus is also multicellular. The body features of developing baby (like hands, legs, head, eyes and ears, etc.) can be identified.
(c) Difference between Vas deferens and Fallopian tube
Vas deferens
(i) Vas deferens is a part of male reproductive system.
(ii) It serves to conduct the sperm from the testis to the urethra.
Fallopian tube
(1) Fallopian tube is a part of female reproductive system.
(ii)It serves to conduct the ovum from the ovary to the uterus.
Q.7. What do you understand by test tube baby?
Ans. Some women are unable to bear babies because sperms cannot reach the egg for fertilisation. In such cases, doctors collect, freshly, released egg and sperm and keep them together for few hours for IVF (In Vitro Fertilisation), which is called fertilisation outside the body.
In case, fertilisation occurs, the zygote is allowed to develop for week and then it is placed in the mother's uterus. Complete development takes place in the uterus and the baby is born, like; any other baby. Babies, born through this technique are called Test Tube Baby.
Q.8. How does a zygote develop into a foetus ?
Ans. A zygote undergoes repeated cell division to increase in size. Slowly it becomes a ball of cells and different tissues are formed. Group of tissues get arranged to form the body parts. At this stage, the developing zygote is called an embryo. The embryo attaches to the uterus. It again grows in size and the parts of the structure, like; limbs, nose, eyes, etc. become distinct. At this stage, it is called foetus. When foetus is, fully, developed, it is given birth of the young one takes a long period of about ten months.
ADDITIONAL LONG ANSWER TYPE QUESTIONS
Q.9. What do you mean by reproduction? Explain various modes of reproduction.
Or
Differentiate between Sexual and Asexual Reproduction.
Ans. The process of producing young ones of the same species. It is important process. It helps in the continuation of species on the earth.
Modes of Reproduction: There are following modes of reproduction:
(i) Sexual reproduction
( ii) Asexual reproduction
(i) Sexual reproduction: The process of reproduction in which two parents (male and female) are involved, is called sexual reproduction. In this process, male produces male gametes and female produces female gametes. Both, the gametes are fused to form zygote. The zygote developed into baby. Example: cow, cat, dog and human beings.
(ii) Asexual reproduction: The mode of reproduction, in which only one parent involves to produce new young ones. Budding, fragmentation spore formation and binary fission are the methods of asexual reproduction, like; hydra, amoeba and bacteria etc.
Q.10.Draw and describe the male reproductive organs in humans.
Ans. The male reproductive organs include a pair of testes singular, testis), two sperm ducts and a penis. The testes produce the male gametes called sperms. Millions of sperms are produced by the testes. Though sperms are very small in size, each has a head, a middle piece and a tail. Indeed, each sperm is a single cell with all the usual cell components.
Q.11. Draw and explain the female reproductive organs is human.
Ans. Female Reproductive Organs: The female reproductive organs are a pair of ovaries, oviducts (fallopian tubes) and the uterus. Ovary produces female gametes called ova (eggs). In human beings, a single matured egg is released into the oviduct by one of the ovaries every month. Uterus is the part, where development of the baby takes place. Like, sperms, an egg is also a single cell.
Q.12. What is the Cloning ? Explain the formation of clone dolly.
Ans. Cloning is the production of an exact copy of a cell, a part or complete body. Dolly was the first clone born on 5th of July, 1996 and was the first mammal to be cloned. It is cloned by Ian Wilmot and his colleagues. During the process of cloning dolly, a cell was collected from the mammary gland of female Finn Dorsett sheep. Simultaneously, an egg was obtained from s Scottish blackface eve. The nucleus was removed from the egg and then the nucleus of mammary gland cell from the Finn Dorsett sheep was inserted into egg of Scottish blackface ewe. Development of this egg followed normally and finally Dolly was born. It was found to be absolutely identical to the Finn Dorsett sheep and produced several off springs of her own through normal sexual means. Dolly died on 14th of February, 2003 died to a certain lung disease.
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