Lakhmir Singh & Manjit Kaur: Reproduction In Animals- 2 | Lakhmir Singh & Manjit Kaur Solutions: Class 8 Science PDF Download

Q.31. Name the parent sheep of which Dolly was a clone.

Dolly was a healthy clone of the Finn Dorsett sheep.

Q.32. What name is given to the following ?
An animal which is an exact copy of its parents.

An animal which is an exact copy of its parents is called clone.

Q.33. What are the two general methods of reproduction in organisms?

There are two methods of reproduction:

• Sexual reproduction
• Asexual Reproduction

Q.34. State whether the following statements are True of False :
(a) Each sperm is a single cell.
(b) A new human individual develops from a cell called gametes.
(c) Egg laid after fertilization is made up of a single cell.
(d) A zygote is formed as a result of fertilization.
(e) External fertilization takes place in frog.
(f) An embryo is made up of a single cell.
(g) Oviparous animals give birth to young ones.
(h) Internal fertilization takes place in hens.
(i) The hens give birth to chicks like human beings give birth to babies.
(j) Amoeba reproduces by budding.
(k) Binary fission is a method of asexual reproduction.
(l) Fertilisation is necessary even in asexual reproduction.
(m) Cloning is a sexual reproduction method in mammals.

(a) True, sperm is a single cell with all the usual cell components.
(b) False, A new human individual develops from a cell called zygote.
(c) True, egg laid after fertilization is made up of a single cell.
(d) True, Fertilization results in the formation of zygote which begins to develop into an Embryo.
(e) True, External fertilization takes place in frog and fish.
(f) False, embryo is a developing structure which is made up of group of cells.
(g) False, those animals which lay eggs are called oviparous animals.
(h) True, Internal fertilization takes place in hens, humans and cow.
(i) False, Hens are oviparous animals which lay eggs.
(j) False, Amoeba reproduce by binary fission.
(k) True, Binary fission is a method of asexual reproduction.
(l) False, fertilization is not necessary in asexual reproduction.
(m) False, Cloning is the production of an exact copy of a cell, any other living part, or a complete organism.

Q.35. Fill in the following blanks with suitable words:
(a) The process of ______ ensure continuity of life on earth.
(b) The cells involved in sexual reproduction are called ______
(c) Fusion of gametes gives rise to a single cell called _______
(d) The process of fusion of gametes is called ______
(e) The other name of egg cell is ______
(f) A sperm is much ______ than an egg cell.
(g) In humans, one nature egg (or ovum) is released into oviduct every ______ by one of the ovaries.
(h) The egg laying animals are called ______ animals.
(i) The cow is a ______ animal whereas ostrich is an _______ animal.
(j) The change of caterpillar into an adult silk moth is called______
(k) The larva of frog is called ______
(l) The two common methods of asexual reproduction in animals are ______ and______
(m) Dolly , the sheep, was produced by the technique called ______

(a) reproduction

(b) gametes

(c) zygote

(d) fertilization

(e) ovum

(f) smaller

(g) month

(h) oviparous

(i) viviparous; oviparous

(j) metamorphosis

(k) tadpole

(l) binary fission; budding

(m) cloning

Q.36.
(A) What is the basic difference between asexual and sexual reproduction?

Difference between asexual and sexual reproduction:

(B) Which of the following organisms reproduces by sexual and which by asexual method?
Amoeba, Cats Humans, Hydra, Birds

Sexual method: Cats, humans, birds
Asexual method: Amoeba and Hydra

Q.37. What is meant by the terms ‘internal fertilization and ‘external fertilisation’? Explain with example.

Internal fertilization: Fertilization which takes place inside the female body is called internal fertilization. Internal fertilization occurs in many animals including humans, cows, dogs and hens.
External fertilization: This type of fertilization in which 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.38. Draw a labeled diagram of the human female reproductive system.
(a) Where in the human body does an egg (or ovum) get fertilized
(b) Where does a fertilized egg (or zygote) develop into a baby in the human body?

The diagram of the human female reproductive system is shown below:

(a) In the human body, an egg (or ovum) gets fertilized in the fallopian tubes.

(b) The fertilized egg (or zygote) develops into a baby in the uterus of the human body.

Q.39. What types of fertilization takes place in the following?
(a) Cow
(b) Frog
(c) Humans
(d) Fish
(e) Hen

Internal fertilization – (a) Cows (c) Humans (e) Hen
External fertilization – (b) Frog (d) Fish

Q.40. Why do female frogs (or female fish) lay hundreds of eggs?

The female frogs (or female fish) lay hundreds of eggs because there are fewer chances of surviving in that environment, so from 100 even if 5-10 survive, their species will survive.

Q.41. What is meant by an ‘embryo’ ? Can we identify the body features in an embryo ?

The zygote divides repeatedly to give rise to a ball of cells. The cells then begin to form groups that develop into different tissues and organs of the body. This developing structure is termed an embryo.
The stage of the embryo in which all the body parts can be identified is called a foetus.

Q.42. Give two differences between a zygote and a foetus.

Zygote is made up of a single cell while foetus is made up of many cells.

Zygote is formed by the fertilization of sperm and ovum, foetus is formed by the repeated divisions of the zygote.

Q.43. Describe the various steps involved in the sexual reproduction in animals.

Following steps are involved in the process of sexual reproduction in an animal:

• In the animal, male parent produces male gametes called sperms. Millions of sperms are produced by testes.
• The female parent produces female gamete called ova (eggs). Like a sperm, an egg is also a single cell.
• The next step is fertilization. In this step, sperm enters the ovum and fuses with it to form a new cell called zygote. The zygote is the beginning of a new individual.
• In this step, zygote begins to develop into an embryo. The zygote divides repeatedly to form a large number of cells and ultimately the zygote grows and develops to form a baby.

Q.44. Draw a labeled diagram of the human male reproductive system.

Q.45. Define foetus. After how many weeks of development, a human embryo is said to become a foetus ?

The stage of the embryo in which all the body parts can be identified is called a foetus. A human embryo becomes a foetus after about 8 weeks of pregnancy.

Q.46. What is metamorphosis ? Give two examples of metamorphosis.

The transformation of the larva into an adult through drastic changes is called metamorphosis. Metamorphosis occurs in frog and silk moth.

Q.47. What is the difference between viviparous animals and oviparous animals ?

Difference between viviparous animals and oviparous animals:

Q.48. Which of the following are oviparous animals and which are viviparous animals ?
Frog, Human being, Sparrow, Lizard, Cow, Dog, hen, Fish, Butterfly, Cat.

Oviparous animals – Frog, sparrow, lizard, hen, fish, butterfly
Viviparous animals – Human being, dog, cat.

Q.49. Give five example each of animals which develop :
(a) inside the mother.
(b) inside eggs which the mother lays.

(a) The animals which give birth to young one are called viviparous animals. In such animals, the baby develops inside the body of the mother.
Examples of Viviparous animals – Human beings, cat, dog, cow, tiger.
(b) The animals that reproduce by laying eggs are called oviparous animals. In such animals, the baby develops inside eggs that the mother lays.

Examples of Oviparous animals – Frog, sparrow, lizard, hen, fish, butterfly.

Q.50. Explain how, chicks are born. How much time does the embryo present in hen’s egg take to develop into a chick (when provided sufficient warmth) ?

In hens, internal fertilization take place but they do not give birth to chicks like human beings. After fertilization, the zygote divides repeatedly to form embryo which travels down the oviduct. As it travels down, many protective layer are formed around it.
The outermost protective layer is hard shell which we can see in a hen’s egg. After the hard shell is formed around the developing embryo, the hen finally lays the egg. The hen, then sits on the egg to provide sufficient warmth to the eggs for the development of the embryo into the chicks. The embryo takes about 3 weeks to develop into a complete chick.

Q.51. In which of the following animals the embryo develop fully inside the mother’s body and in which they develop fully in the eggs laid by mother ?
Cow, Ostrich, Frog, Lizard, Deer, Cat, Snake, Tiger, Dog, Hen

(a) Viviparous animals – Cow, deer, cat, tiger, dog.

(b) Oviparous animals – Ostrich, frog, lizard, snake, hen.

Q.52. Name two animals which undergo metamorphosis and two which do not.

Frog and silk moth undergo metamorphosis whereas cow and hen do not undergo metamorphosis.

Q.53. Which of the following animals undergo metamorphosis and which do not ?
Cow, Butterfly, Silk moth, Humans, Frog, Housefly, Sparrow, Hen, Mosquito, Money

Butterfly, silk moth, frog, housefly and mosquito undergo metamorphosis while cow, human, hen and monkey do not undergo metamorphosis.

Q.54.
(A) What are gametes?

The cells involved in sexual reproduction are called gametes.

(B) In which sort of reproduction are gametes fuse ?

Fertilization is the step of reproduction in which fusion of gametes take place.

(C) What is formed when two gametes involved ?

Zygote is formed when two gametes are fused together.

(D) What is this act of fusion called ?

The fusion of a sperm with an ovum to form a zygote during sexual reproduction is called fertilization.

Q.55. Match the terms given in column A with those given column B :
Column A
(i) Sperm
(ii) Ovary
(iii) Oviduct
(iv) Tests
Column B
(a) Female organ
(b) Egg tube
(c) Male organ
(d) Male gamete

(i) (d);
(ii) (a);
(iii) (b);
(iv) (c)

Q.56. Differentiate between internal fertilization and external fertilization. What type of fertilization takes place in
(a) frog, and
(b) fox ?

Differences between internal fertilization and external fertilization:

Q.57. What is meant by ‘cloning’? State whether gametes are involved in cloning or not. Name two animals which have been produced by cloning.

Cloning is the production of an exact copy of a cell, any other living part, or a complete organism. Yes, gametes are involved in cloning. Dolly and noah are two cloned animals.

Q.58. What is meant by ‘reproduction’ ? why is it essential ?

Reproduction is one of the important characteristics of living things. The ability of organism to produce young ones of its own kind is called reproduction. It is essential for the continuation of a species.

Q.59. Define asexual reproduction. Name two methods of asexual reproduction in animals. Name two animals which reproduce by these asexual reproduction methods.

The type of reproduction in which only a single parent is involved is called asexual reproduction. Binary fission and budding are two methods of asexual reproduction in animals. Amoeba reproduce by binary fission and Hydra reproduce by budding.

Q.60. What is a clone ? Name one famous clone.

The organisms which are produced asexually are genetically identical to the parent and are called clones.
Dolly was born on 5th July 1996 and was the first mammal to be cloned.