AP 8th Class Biology 4th Lesson Questions and Answers Reproduction in Animals

AP State Board new syllabus 8th Class Biology Guide 4th Lesson Reproduction in Animals Textbook Exercise Questions and Answers.

AP 8th Class Biology 4th Lesson Questions and Answers Reproduction in Animals

8th Class Biology 4th Lesson Reproduction in Animals Questions and Answers (Exercise)

Question 1.
Explain the importance of reproduction in organisms.
Answer:

• Reproduction is essential for the continuation of a species.
• It ensures the continuation of similar kinds of individuals, generation after generation.

Question 2.
Describe the process of fertilisation in human beings.
Answer:

• Internal fertilisation takes place in human beings.
• The first step in the process of reproduction is fusion of a sperm and an ovum.
• When millions of sperms come in contact with the egg, such fusion of egg and sperm is called fertilisation.
• During the fertilisation the nuclei of the sperm and the egg fuse to form a single nucleus. .
• This results in the formation of a fertilised egg or zygote.

Question 3.
Choose the most appropriate answer.
a) Internal fertilisation occurs
i) in female body
ii) outside female body
iii) in male body
iv) outside male body
Answer:
(i) in female body

b) A tadpole develops into an adult frog by the process of
i) fertilisation
ii) metamorphosis
iii) embedding
iv) budding
Answer:
(ii) metamorphosis.

c) The number of nuclei present in a zygote is
i) none
ii) one
iii) two
iv) four
Answer:
(ii) one

Question 4.
Indicate whether the following statements are True (T) or False (F).
a) Oviparous animals give birth to young ones.
Answer: False

b) Each sperm is a single cell.
Answer:  True

c) External fertilisation takes place in frog.
Answer:  True

d) A new human individual develops from a cell called gamete.
Answer:  False

e) Egg laid after fertilisation is made up of a single cell.
Answer:  True

f) Amoeba reproduces by budding.
Answer:  False

g) Fertilisation is necessary even in asexual reproduction.
Answer:  False

h) Binary fission is a method of asexual reproduction.
Answer:  True

i) A zygote is formed as a result of fertilisation.
Answer: True

j) An embryo is made up of a single cell.
Answer: False

Question 5.
Give two differences between a zygote and a foetus.
Answer:

Zygote		Foetus
1.	It is unicellular	1.	It is multicellular
2.	It is formed by the fusion of male andfemale gamefes	2.	It is formed by the repeated divisions of zygote
3.	Body parts are not developed	3.	Developed body parts are seen.

Question 6.
Define asexual reproduction. Describe two methods of asexual reproduction in animals.
Answer:
The type of reproduction in which only a single parent is involved is called asexual reproduction.
By budding :

• Hydra reproduces through buds, so this method is called budding.
• In budding, a small bulge forms at the base of the parent Hydra. This bulge is called bud.
• The bud slowly grows in size and produces it’s tentacles.
• A small construction develops between parent Hydra and bud.
• The bud pinches off from the parent and lives independently.

By binary fission :

• Amoeba reproduces through a method called binary fission.
• Amoeba begins the process of reproduction by the division of it’s nucleus into nuclei.
• This is followed by division of it’s body into two, each part receiving a nucleus.
• Finally, two amoeba are formed from one parent amoeba.
  This type of asexual reproduction in which an animal reproduces by dividing into two individuals is called ‘binary fission’.

Question 7.
In which female reproductive organ does the embryo get embedded ?
Answer:
Uterus is the female reproductive organ in which embryo gets embedded.

Question 8.
What is metamorphosis ? Give examples.
Answer:

• The transformation of larva into an adult through drastic changes is called metamorphosis.
• Metamorphosis can be observed in animals like frog, butterfly, silkworm etc.

Question 9.
Differentiate between internal fertilisation and external fertilisation.
Answer:

	Internal fertilisation		External fertilisation
1.	Fertilisation takes place inside the female body.	1.	Fertilisation takes place outside the female body.
2.	Generally, it occurs in terrestrial animals.	2.	Generally it occurs in aquatic animals
3.	Male discharges the sperms inside the body of female.	3.	Both the male and female release their gametes in water.
4.	Development of embryo occurs inside the female body.	4.	Development of embryo occurs outside the female body.
5.	Survival chances of embryo is high.	5.	Survival chances of embryo is less due to predators and extreme weather conditions.
6.	Examples are Man, Cat, Cow etc.	6.	Examples are Fish and Frog

Question 10.
Complete the crossword puzzle using the hints given below.

Across
1. The process of 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 in vitro fertilisation.
4. These animals lay eggs.
Answer:

Complete the table — write the young ones.

S.No	Animal	Young one
1.	Human	Baby
2.	Cat
3.	Dog
4.	Butterfly
5.	Hen	Chick
6.	Cow
7.	Frog

Answer:

S.No	Animal	Young one
1.	Human	Baby
2.	Cat	Kitten
3.	Dog	Puppy
4.	Butterfly	Caterpillar
5.	Hen	Chick
6.	Cow	Calf
7.	Frog	Tadpole

Question 11.
Whit purpose does the tail in a sperm serve?
Answer:
Tail is useful in motility of the sperm cell. As sperms have to be motile and reach the non-motile fentale gamete in the oviduct. Then only fertilisation takes place in oviduct.

Question 12.
Why do fish and frogs lay eggs in hundreds whereas a hen lays only one egg at a time?
Answer:

• This is because the sperms and eggs which are released into the water, get exposed to,exterial factors like high temperature, water currents etc. Not only that, some of the predators in the pond feed on these eggs and sperms.
• All these factors prevent the sperms from reaching the eggs.
• So, it is necessary to produce large number of eggs and sperms to ensure fertilisation of atleast a few of them.
• In hen, internal fertilisation takes place. There is safety for the fertilised egg as mother hen broods and hatching of eggs takes place.
• The process of fertilization that occurs outside of an organism is called External Fertibization. E.g. Frog, Fish, Star fish etc.

Question 13.
How could a single cell become such a big individual?
Answer:
As a result of fertilisation zygote is formed. This zygote urder goes repeated cell divisions to give rise to complete individual. So, a single cell becomes an individual by the process of cell division.

Extended Learning – Activities And Projects

Question 1.
Visit a poultry farm. Talk to the manager of the farm and try to find out the answers to the following.
a) What are layers and broilers in a poultry farm?
b) Do hens lay unfertilised eggs ?
c) How can you obtain fertilised and unfertilised eggs ?
d) Are the eggs that we get in the stores fertilised or unfertilised?
e) Can you consume fertilised eggs ?
f) Is there any difference in the nutritional value of fertilised and unfertilised eggs?
Answer:
a) Egg laying hens are called layers. Broilers are the hens which are grown to get meat.
b) Hens lay fertilised eggs. But in poultry farms, by giving hormonal injections they obtain unfertilised eggs. This results in induced ovulation.
c) Fertilised eggs are obtained after internal fertilisation in hens.
d) Unfertilised eggs are obtained by induced ovulation in layers in poultry farms.
d) We can notice fertilised as well as unfertilised eggs in the stores.
e) Yes, we can consume fertilised egg too.
f) Yes, fertilised egg have more nutritional value.

Question 2.
Observe live hydra yourself and learn how they reproduce by doing the following activity.
Answer:
During the summer months collect water weeds from ponds or ditches along with the pond water and put them in a glass jar. After a day or so you may see several hydra clinging to the sides of the jar. Hydra is transparent, jelly-like and with tentacles. It clings to the jar with the base of its body. If the jar is shaken, the hydra will contract instantly into a small blob, at the same time drawing its tentacles in.
Now take out few hydras from the jar and put them on a watch glass. Using a hand lens or a binocular or dissection microscope, observe the changes that are taking place in their body. Note down your observations.
Answer:

• Hydra has cylindrical, transparent, jelly like body with tentacles.
• It attaches to the substratum with the help of it’s base.
• In Hydra locomotion takes place through it’s tentacles. They also help in capturing food particles.
• Hydra reproduces by forming projections from it’s body. They are called buds:

Question 3.
The eggs we get from the market are generally the unfertilised ones. In case you wish to observe a developing chick embryo, get a fertilised egg from the poultry or hatchery which has been incubated for 36 hours or more. You may then be able to see a white disc-like structure on the yolk. This is the developing embryo. Sometimes if the heart and blood vessels have developed you may even see a red spot.
Answer:
Student Activity.

Question 4.
Talk to a doctor. Find out how twinning occurs. Look for any twins in your neighbourhood, or among your friends. Find out if the twins are identical or nonidenfical. Also find out why identical twins are always of the same sex ? If you know of any story about twins, write it in your own words.
Answer:
Twinning happens in two ways.

• Two ova are released during ovulation and fuse with two sperms and fertilised to form two zygotes. They gradually develop in the uterus and form two unidentical twins.
• Single fertilised ovum undergoes fission giving rise to two foetus. This results in two identical twins. Identical twins always have same sex.

8th Class Biology 4th Lesson Questions and Answers (Lab Activities)

Activity – 1.

How do you observe the colour and size of the frog’s eggs in pond?
Answer:

• Visit a pond during rainy or spring season.
• Observe the floating eggs in the water.

Observation : Clusters of dull white coloured eggs of frogs can be observed on the surface of the water. These eggs are held together by a layer of jelly which protects them.

Activity – 2

Write the procedure to observe the eggs of frog, lizard, butterfly or moth, hen and crow or any other bird.
Answer:

• Visit a garden near your school.
• Search for the eggs of frogs, butterfly, lizard and crow.
• You can visit a shop where hen’s eggs are sold.
• Note down the differences among them.

Make drawings of these eggs in your note book.
Answer:

Activity -3

How do you observe budding in hydra ?
Answer:

• We can observe the permanent slides of Hydra under microscope to know how budding takes place.
• We can observe a bulb like projection from the parent body and count them.
• Observe the size of different projections in different slides.

Observations:

• In each hydra, there may be one or more bulges.
• These bulges are the developing new individuals and they are called buds.

Conclusion : Hydra develops buds from it’s body and they develop tentacles and detach from parent hydra. They live independently. This type of asexual reproduction is called “budding”.