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These NCERT Solutions for Class 8 Science Chapter 9 Reproduction in Animals Questions and Answers are prepared by our highly skilled subject experts to help students while preparing for their exams.

Reproduction in Animals NCERT Solutions for Class 8 Science Chapter 9

Class 8 Science Chapter 9 Reproduction in Animals Textbook Exercise Questions and Answers

Page 110-111

Question 1.
Explain the importance of reproduction in organisms.
Answer:
Reproduction is very important for the organisms. The organisms reproduce to generate young ones like them. It helps to maintain their existence generation after generation. If reproduction does not take place, no living being will survive on the earth. Had the process of reproduction not been there, all the plants and animals would have become extinct. Secondly, special characters of an organism are carried over to its next generation through reproduction only.

Question 2.
Describe the process of fertilisation in human beings.
Answer:
The mode of reproduction in human beings is sexual reproduction. Ovaries in females produce ova while the testes in males produce sperms. Millions of sperms are ejected inside the female reproductive tract where one of them fuses with the ovum and forms zygote. This process is known as internal fertilisation. The zygote, then, begins to develop into an embryo which attaches to the female uterus wall.

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. ( )
b. Each sperm is a single cell. ( )
c. External fertilisation takes place in frog. ( )
d. A new human individual develops from a cell called gamete. ( )
e. Egg laid after fertilisation is made up of a single cell. ( )
f. Amoeba reproduces by budding. ( )
g. Fertilisation is necessary even in asexual reproduction. ( )
h. Binary fission is a method of asexual reproduction. ( )
i. A zygote is formed as a result of fertilisation. ( )
j. An embryo is made up of a single cell. ( )
Answer:
a. False
b. True
c. True
d. False
e. False
f. False
g. False
h. True
i. True
j. False

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

Question 6.
Define asexual reproduction. Describe two methods of asexual reproduction in animals.
Answer:
When a single parent is involved in reproduction and gametes are not formed, it is called asexual reproduction. Two methods of asexual reproduction are as follows:

i. Budding: Budding involves the formation of a new individual from the bulges or outgrowths, known as buds, formed on the parent body. This method of reproduction is common in Hydra. In Hydra, the cells divide rapidly at a specific site and develops into an outgrowth, called the bud. These buds, while being attached to the parent plant, develop into smaller individuals. When these individuals become mature enough, they detach from the parent’s body and become independent individuals.

ii. Binary Fission: It is a type of asexual reproduction in which a single cell divides into two halves. Organisms that reproduce through binary fission are bacteria and Amoeba. In Ainoeba, the division of cells can take place in any plane. It involves the division of its nucleus into two nuclei, which is followed by the division of the cytoplasm into two halves. Each half of the body receives a nucleus.

Question 7.
In which female reproductive organ does the embryo get embedded?
Answer:
The embryo gets embedded in the wall of the uterus. The embryo, while it is still attached to the uterus, gradually develops the various body parts such as hands, legs, head, eyes, etc. The embryo at this stage is called a foetus.

Question 8.
What is metamorphosis? Give examples.
Answer:
In case of indirect development, the transformation of the young ones into an adult through drastic changes is called metamorphosis. Larva of butterfly undergoes metamorphosis to become a butterfly. A tadpole undergoes metamorphosis to become a frog.

The tadpole that emerges from the egg contains gills, a tail and a small circular mouth. It can swim freely in water. The tadpole grows and undergoes abrupt changes in its structure and develops into a mature frog. A tadpole’s metamorphosis begins with the development of limbs, lung development and finally the absorption of the tail by the body.

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

Question 10.
Complete the crossword 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 in-vitro fertilisation.
4. These animals lay eggs.
5. A type of fission in

Answer:
1. Fertilisation
2. Testes
3. IVF
4. Oviparous
5. Binary
6. Internal
7. Buds
8. Ovary

NCERT 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?
Hint:
a. Layers are chickens raised for eggs and broilers are chickens raised for meat.
b. Yes, hens lay both the fertilised egg (if mating has occurred) and the unfertilised egg (according to light patterns if no mating has occurred).
c. Fertilised eggs are obtained by allowing hens to mate with roosters. Unfertilised eggs are obtained by exposing hens to suitable light patterns.
d. They are mostly unfertilised eggs.
e. Yes, fertilised eggs can be consumed.
f. No, there is no difference in the nutritional value of fertilised and unfertilised egg.

Question 2.
Observe live Hydra yourself and learn how they reproduce by doing the following activity:
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.
Hint:
Do it yourself.

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.
Hint:
Do it yourself.

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 non-identical. 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.
Hint:
Twins are identical when they are formed due to a random splitting in the developing embryo which then develops into two different individuals. Since they are formed from the same zygote, their sex is always the same. However, non-identical twins are formed by the fertilisation of two different egg cells.

Activity 1

Objective: To observe and study the eggs of frog.
Procedure: Visit some ponds or slow-flowing streams during spring or rainy season and observe the colour and size of frog’s eggs floating on the water.
Observation: Amphibian eggs do not have a hard protective shell like the eggs of birds or reptiles. Frogs and toads lay eggs in jelly-like masses, and unless the eggs are covered with water, they will dry up and die.

Most amphibian eggs become much bigger after they are laid because the eggs absorb water and swell up to several times their original volume. The colour of the eggs is dull white and size ranges from less than a centimetre to a few centimetres.

Asexual Reproduction: The type of reproduction in which only a single parent is involved is called asexual reproduction. It can be of the following major types:
i. Budding: This method is seen in multicellular organisms which are highly simple in structure. A small bud develops on the body. The bud grows and starts resembling its parent cell. After sufficient growth, the bud gets detached from the parent’s body to begin life as a new individual. Examples: Hydra and sponges reproduce by budding.

Activity 2

Objective: To study budding in Hydra with the help of permanent slide.
Materials Required: Permanent slide of Hydra and a compound microscope.
Procedure:

• Get permanent slides of Hydra, observe them using a hand lens or a microscope.
• First observe the slide under low power and then under high power.
• Note the features and draw rough sketches.

Observations:

• Hydra uses regenerative cells for reproduction in the process of budding.
• In Hydra, a bud develops as an outgrowth due to repeated cell division at one specific site.
• These buds develop into tiny individuals and when fully mature, they detach from the parent body and become new independent individuals.

Conclusion: Budding is an asexual mode of reproduction as it involves only a single parent.

ii. Binary Fission: This method is seen in unicellular organisms, e.g., Amoeba. Binary fission begins with nuclear division where the parent nucleus divides into two nuclei. This is followed by cytoplasmic division, with each part getting one nucleus. In this way, the cell of Amoeba divides into two daughter cells. Each daughter cell becomes a new individual.

Cloning: The offspring which is morphologically as well as genetically identical to its parent is called a clone. The process of producing clones is called cloning. In the process of cloning of Dolly, a cell was collected from the mammary gland of female Finn Dorsett sheep. Simultaneously an egg was obtained from a Scottish blackface ewe. The nucleus was removed from the egg cell and mammary gland cell’s nucleus was inserted in it. Development of egg followed normally and finally Dolly was born on 5lh July, 1996 in Scotland and was the first mammal to be cloned. It was found to be absolutely identical to the Finn Dorsett sheep, from which the nucleus was taken.

Class 8 Science Chapter 9 Reproduction in Animals Additional Important Questions and Answers

Very Short Answer Type Questions

Question 1.
What is sexual reproduction?
Answer:
When two parents are involved in the process of reproduction and gamete formation takes place, it is called sexual reproduction.

Question 2.
What is asexual reproduction?
Answer:
When a single parent is involved in reproduction and gamete formation does not take place, it is called asexual reproduction.

Question 3.
What is conception?
Answer:
Implantation of embryo in the wall of the uterus is called conception.

Question 4.
Give some examples of oviparous animals.
Answer:
Hen, lizards, all birds, etc.

Question 5.
Give some examples of viviparous animals.
Answer:
Cow, dog, cat and human beings.

Question 6.
Give the stages of development of a silk worm.
Answer:
Egg → Larva → Pupa → Adult

Question 7.
Name the male and female gametes.
Answer:
Mate gamete: Sperm Female gamete: Ovum

Question 8.
Name the reproductive organs of male and female.
Answer:
Male reproductive organs: Testes sperm ducts, penis.
Female reproductive organs: Ovaries, oviduct, uterus.

Question 9.
Name the male sex hormone.
Answer:
Testosterone.

Question 10.
Give the other name of oviduct.
Answer:
Fallopian tube.

Question 11.
What do you understand by the term ‘gestation’?
Answer:
It is the period between fertilisation and child birth, in which a foetus develops.

Question 12.
Name the female sex hormone.
Answer:
Estrogen.

Question 13.
Write the full form of IVF.
Answer:
In-vitro fertilisation.

Question 14.
Where does the development of embryo take place in the body of a female?
Answer:
The development of embryo takes place in the uterus of the female body.

Question 15.
What is foetus?
Answer:
A well developed embryo with distinct and identifiable body parts is called foetus.

Question 16.
Name the various methods of asexual reproduction in animals.
Answer:
Budding, fission, regeneration and fragmentation.

Question 17.
What type of reproduction takes place in Amoeba?
Answer:
Asexual reproduction (binary fission).

Short Answer Type Questions

Question 1.
What is the difference between sexual and asexual reproduction?
Answer:

Question 2.
Briefly explain in-vitro fertilisation.
Answer:
Any biological process carried out in laboratory is called ‘in-vitro’ process. Thus, fertilisation carried out in laboratory is called in-vitro fertilisation. Many women may fail to conceive due to certain problems. In-vitro fertilisation helps such women to bear a child. In this technique, a freshly released sperm (from the father) and an ovum (from the mother) are collected and allowed to fuse under artificial conditions. After in-vitro fertilisation, zygote is allowed to develop into a mass of cells and is then transferred into the uterus for subsequent development.

Question 3.
Explain the steps of development of embryo.
Answer:
Conception and child birth: It takes place in the female reproductive system through the following steps:

• A single egg comes out of the ovary every month and reaches the fallopian tube.
• Sperms reach the fallopian tube where a sperm fertilises the egg. This results in the formation of zygote.
• Zygote undergoes several rounds of cell division to become a ball of cells.
• The cells begin to form groups that develop into different tissues and organs of the body. This structure is called embryo.
• This embryo moves down and gets implanted in the wall of the uterus. This process is called conception. Conception marks the beginning of pregnancy.
• Embryo develops further inside the uterus to form various body parts such as hands, head, eyes, etc. This stage of embryo is called foetus.
• When the development of the embryo is complete, the mother gives birth to the baby.

Question 4.
Describe the male reproductive organs.
Answer:
The male reproductive organs are a pair of testes, sperm ducts and a penis. Testes produce male gametes called sperms. The two sperm ducts open into the top of urethra. Urethra carries both the sperms and the urine. The urethra is a narrow tube and runs through the penis to the outside.

Question 5.
Differentiate between budding and binary fission.
Answer:

Question 6.
Describe the female reproductive organs.
Answer:
Female reproductive organs include a pair of ovaries, oviduct and the uterus. In human beings, a single matured egg is released into the oviduct by one of the ovaries every month. Fallopian tube carries the egg from ovaries to the uterus. Uterus is the part where development of the baby takes place.

Question 7.
Define sperm. Describe its structure.
Answer:
The testes secrete millions of sperm cells together. A sperm comprises a single cell and has a specific structure with three main parts as given below:
a. Head: It consists of the nucleus which contains the DNA information of the cell.
b. Middle Piece: It is packed with cell organelle called mitochondria. The mitochondria are responsible for producing energy in the cell. Sperm uses this energy to move.
c. Tail: It allows the sperm cell to travel at a fast pace.

Question 8.
Define ovum. Describe its structure.
Answer:
Ovum or egg is the female gamete which produces zygote after fertilisation with the male gamete. An ovum is single-celled and spherical in shape. If consists of a prominent nucleus and a dense cytoplasm which is full of nutrition.

Question 9.
What are test-tube babies?
Answer:
In some women, the oviducts are blocked and hence the eggs are unable to reach the uterus. This means that these women are not able to bear babies because of blocked oviducts. However, due to the process of in-vitro fertilisation or IVF, the freshly released eggs of females and the male sperms can be fertilised externally. The zygote thus formed is allowed to develop for a week outside the female body in safe conditions and is then placed in the mother’s uterus. In this way, these women can bear babies. The babies that are born with the IVF process are called test-tube babies.

Question 10.
Why are gametes produced in large numbers in organisms that exhibit external fertilisation?
Answer:
Organisms that take part in external fertilisation produce a large number of gametes because:
a. in external fertilisation, there is a great chance that the sperms and the eggs released by the organisms can be affected by the environmental factors, like desiccation, predators, etc. So, to compensate for the high mortality rate of the gametes, the organism produces a large number of gametes.

b. producing a large number of gametes increases the chances for at least some eggs and sperms to fuse in the environment ensuring that at least a stable number of offspring are produced.

Question 11.
How are chicks born? Explain their developmental process.
Answer:
After fertilisation the zygote divides repeatedly and travels down the oviduct. As it travels down, many protective layers are formed around it. The hard shell on the hen’s egg is one such protective layer. The hen finally lays the egg. The embryo takes about three weeks to develop into a chick. After the chick is completely developed, it bursts open the egg shell and hatches out.

Question 12.
How are general growth and sexual maturation different from each other?
Answer:
General growth refers to different types of developmental process in the body like increase in height, weight gain, changes in shape and size of the body but sexual maturation is specific to change reflected at puberty like cracking of voice, new hair patterns, development of breast in female, etc.

Question 13.
Explain the life cycle of silkworm in brief.
Answer:
The adult lays eggs on mulberry leaves. The caterpillar hatches out from the egg and feeds actively. If then converts itself into pupa. The pupa stage is inactive. This pupa finally metamorphosis into the adult silk moth. Hence, following stages can be summed up in the life cycle of a silkmoth:
Egg → Larva or Caterpillar → Pupa → Adult

Question 14.
Explain the process of fertilisation in frogs.
Answer:
Frogs undergo external fertilisation. During rainy season, they move to ponds and slow flowing streams. The female lays hundreds of eggs which are not covered by a shell and are very delicate. A layer of jelly holds the eggs together and provides protection. The male deposits sperms over these eggs. The sperms swim randomly in water and fuse with the eggs resulting in fertilisation.

Question 15.
Birth of a new born baby in a family is rejoicing and celebrating. Unfortunately, about 3% of the new born suffer from one of the other birth defects.
a. What are the factors that cause such defects?
b. List the different techniques being used towards parental diagnosis of such anomalies.
c. How are these techniques useful in counselling for such cases?
Answer:
a. Anomalies are due to a number of genetic and environmental factors.
b. A number of techniques are available nowadays for detecting such disorders. These include blood test of the mother and ultrasound, etc.
c. Based on these reports, expert advice is sought for continuation of pregnancy through suitable medical treatment or for termination of pregnancy.

Long Answer Type Questions

Question 1.
What is reproduction? Describe the various modes of reproduction.
Answer:
Reproduction is the process by which living organisms produce more living organisms of their own kind. It helps in the continuation of a species on the earth.

Modes of Reproduction: There are two main modes of reproduction in living organisms:
a. Asexual reproduction: The mode of reproduction in which a single organism is able to produce one or more organisms of its kind by itself is called asexual reproduction. Asexual reproduction does not require the involvement of both the male and the female. The organisms like Amoeba, yeast, Hydra, etc., reproduce by this mode of reproduction.

b. Sexual reproduction: In sexual mode of reproduction, both the parents (male and female) are needed to produce individuals of the same kind. Fish, frog, higher animals such as cow, dog, horse and human beings reproduce by the mode of sexual reproduction.

Question 2.
Describe the formation of egg shell in hens.
Answer:
Internal fertilisation takes place in hens. After fertilisation, the zygote divides continuously and moves to the oviduct. As it travels down, many protective layers are formed around it. The hard shell in a hen’s egg is one such protective layer. After the hard shell is formed, the hen finally lays the egg. The embryo takes about 3 weeks to develop into a chick.

The hen sits on the eggs to provide sufficient warmth. After the chick is completely developed, it bursts open the egg shell.

Question 3.
Define cloning. Describe the formation of Dolly.
Answer:
Cloning is the process of production of an exact copy of a cell, any other living part, or a complete organism. Cloning process of an animal was successfully performed for the first time by Ian Wilmut and his colleagues at the Roslin Institute in Edinburgh, Scotland. They successfully cloned a sheep named Dolly.

During the process of cloning a sheep named Dolly, a cell was collected from the mammary gland of a female Finn Dorsett sheep. Simultaneously, an egg was collected from a Scottish blackface ewe. The nucleus was removed from the egg. After that, the nucleus of the mammary gland cell from the Finn Dorsett sheep was inserted into the egg of the Scottish blackface ewe whose nucleus had been removed. Then this egg was implanted into the Scottish blackface ewe. Development of this egg followed normally and then finally Dolly was born. It was found to be absolutely identical to the Finn Dorsett sheep, from which the nucleus was taken.

Picture-Based Questions

Question 1.
Draw a labelled diagram to show the male reproductive system in human beings.
Answer:

Question 2.
Draw a labelled diagram to show the female reproductive system in human beings.
Answer:

Question 3.
Observe the given figure and answer the questions that follow.

a. Name the components labelled A and B.
b. Identify the process.
c. What happens during the process and what is formed?
Answer:
a. A-sperms, B-ovum (egg).
b. The process is fertilisation.
c. During the process, the sperm nucleus fuses with the egg nucleus; as a result of which, a zygote is formed.

Question 4.
Identify the following diagram and answer the questions:

a. Where does the embryo develop in human body?
b. How many days does an embryo take to develop into a fully mature foetus.
Answer:
The diagram shows the development of foetus inside the uterus.
a. The embryo develops inside the uterus of the human female body.
b. The embryo takes about 270 to 280 days to develop into a fully mature foetus.

Question 5.
a. Draw the diagram of a human sperm and label its head, middle piece and tail.
b. What is the function of its tail?
Answer:
a.

b. The tail of the sperm helps it in swimming in the liquid medium.

NCERT Solutions for Class 7 English

The Cop and the Anthem NCERT Solutions for Class 7 English An Alien Hand Chapter 4

The Cop and the Anthem NCERT Text Book Questions and Answers

The Cop and the Anthem Exercises Question and Answer

Answer the following questions.

Question 1.
What are some of the signs of approaching winter referred to in the text?
Answer:
Some of the signs of the approaching winter include birds beginning to fly south; people buying and checking out new warm coats; leaves falling from the trees. Besides this, when one sees Soapy move restlessly on his seat in the park, one knows that winter is near.

Question 2.
Write ‘True’or ‘False ’against each of the following.

• Soapy did not want to go to prison. False
• Soapy had been to prison several times. True
• It was not possible for Soapy to survive in the city through the winter. False
• Soapy hated to answer questions of a personal nature. True

Question 3.
What was Soapy s first plan? Why did it not work?
Answer:
Soapy’s first plan was to eat to his heart’s content in a fine restaurant and then not pay the bill. The restaurant staff would call the police, and he would have to appear before a judge, who would sentence him for three months. It did not work because the staff at the restaurant did not let him enter the restaurant on account of his broken old shoes and tom pants.

Question 4.
“But the cop s mind would not consider Soapy ”. What did the cop not consider, and why?
Answer:
The cop did not consider that Soapy was the one who broke the glass of the shop window because he did not think that the culprit would keep standing after breaking the window. Logically, if Soapy had broken the window, he would have mn away instead of standing there and talking to the cop.

Question 5.
“We have orders to let them shout”. What is the policeman referring to?
Answer:
The policeman is referring to college students doing a protest and shouting on the streets. But he had misidentified Soapy as being one of the college boys.

Question 6.
Write ‘True’or ‘False’ against each of the following.

• Soapy stole a man s umbrella. True
• The owner of the umbrella offered to give it to Soapy. True
• The man had stolen the umbrella that was now Soapy’s. False
• Soapy threw away the umbrella. True

Question 7.
“There was a sudden and wonderful change in his soul”. What brought about the change in Soapy?
Answer:
As Soapy was passing over his old childhood home, he heard music wafting from one of the rooms. In that peaceful moment, he remembered his mother and his childhood. He remembered flowers and high hopes and friends, and clean thoughts and clean clothes. This nostalgic moment brought about a change in him.

Discuss the following topics in groups.

Question 1.
Suppose no cop came at the end. What would Soapy s life be like through the winter?
(Encourage the students to express their opinions clearly on the given topics.)
Answer:
If no cop had come at the end, Soapy would be a free man who would have made something out of himself after his realization. He would probably get a new job and would be able to afford rent to a small apartment. He would surely have kept warm in the winter and would have turned over a new leaf. He would have met his old friends and shared his life experience with them.

Question 2.
Retell an episode in the story which is a good example of irony in a situation.
Answer:
The most ironic episode in the entire story is its end. When Soapy is passing over his childhood home, he has an epiphanous moment. He resolves to change his life, and do something meaningful with it. He pictures himself finding a new job and going to work.

He is just lost in such thoughts when a cop’s hand lands on his shoulder and asks him what he is doing. He is arrested immediately. The irony here is that just when Soapy is ready for a real change, that opportunity is taken away from him. Through that entire day, he tries to get arrested by doing petty crimes, but each time the cops are indifferent to them. But just when he is doing nothing, and only staring at the Church and listening to music playing through its windows, the policeman arrests him.

These NCERT Solutions for Class 6 Maths Chapter 6 Integers Ex 6.1 Questions and Answers are prepared by our highly skilled subject experts.

NCERT Solutions for Class 6 Maths Chapter 6 Integers Exercise 6.1

Question 1.
Write opposites of the following:
(a) Increase in weight
(b) 30 km north
(c) 80 m east
(d) Loss of? 700
(e) 100 m above sea level
Answer:
(a) Decrease in weight
(b) 30 km south
(c) 80 m west
(d) Profit of ₹ 700
(e) 100 m below sea level

Question 2.
Represent the following numbers as integers with appropriate signs.
(a) An aeroplane is flying at a height two thousand metre above the ground.
(b) A submarine is moving at a depth, eight hundred metre below the sea level.
(c) A deposit of rupees two hundred.
(d) Withdrawal of rupees seven hundred.
Answer:
(a) (+) 2000 meters
(b) (-) 800 meters
(c) (+) 200?
(d) (-) 700 ?

Question 3.
Represent the following numbers on a number line:
(a) +5
(b) -10
(c) +8
(d) -1
(e) -6
Answer:

Question 4.
Adjacent figure is a vertical number line, representing integers. Observe it and locate the following points:
(a) If point D is + 8, then which point is -8?
(b) Is point G a negative integer or a positive integer?
(c) Write integers for points B and E.
(d) Which point marked on this number line has the least value?
(e) Arrange all the points in decreasing order of value.
Answer:
(a) F
(b) Negative integer
(c) B = (+) 4; E = (-) 10
(d) E
(e) D, C, B, A, O, H, G, F, E

Question 5.
Following is the list of temperatures of five places in India on a particular day of the year.

(a) Write the temperatures of these places in the form of integers in the blank column.
(b) Following is the number line representing the temperature in degree Celsius.
Plot the name of the city against its temperature.

(c) Which is the coolest place?
(d) Write the names of the places where temperatures are above 10°C.
Answer:
Place – Temperature
Siachen – (-) 10° C
Shimla – (-) 2° C
Ahmedabad – (+) 30° C
Delhi – (+) 20° C
Srinagar Number line – (-) 5° C

(c) Siachen (-10°C) is the coolest place.
(d) Ahmedabad (+30°C) and Delhi (+20°C).

Question 6.
In each of the following pairs, which number is to the right of the other on the number line?
(a) 2,9
(b) -3, -8
(c) 0,-1
(d) -11, 10
(e) -6,6
(f) 1,-100
Answer:
(a) 9 is right to 2.
(b) -3 is right to -8.
(c) 0 is right to-1.
(d) 10 is right to-11.
(e) 6 is right to -6.
(f) 1 is right to-100.

Question 7.
Write all the integers between the given pairs (write them in the increasing order.)
(a) 0 and -7
(b) -4 and 4
(c) -8 and -15
(d) -30 and -23
Answer:
(a) -6, -5, -4, -3, -2,-1
(b) -3, -2,-1,0, 1,2,3
(c) -14,-13,-12,-11,-10, -9
(d) -29, -28, -27, -26, -25, -24

Question 8.
(a) Write four negative integers greater than -20.
(b) Write four integers less than -10.
Answer:
(a) -19, -18, -17, -16
(b) -11, -12, -13, -14

Question 9.
For the following statements, write True (T) or False (F). If the statement is false, correct the statement.
(a) -8 is to the right of-10 on a number line.
(b) -100 is to the right of -50 on a number line.
(c) Smallest negative integer is -1.
(d) -26 is greater than -25.
Answer:
(a) True
(b) False
(c) False
(d) False

Question 10.
Draw a number line and answer the following:
(a) Which number will we reach if we move 4 numbers to the right of -2.
(b) Which number will we reach if we move 5 numbers to the left of 1.
(c) If we are at -8 on the number line, in which direction should we move to reach -13?
(d) If we are at -6 on the number line, in which direction should we move to reach -1?
Answer:

(c) On left side
(d) On right side

These NCERT Solutions for Class 9 Maths Chapter 9 Areas of Parallelograms and Triangles Ex 9.1 Questions and Answers are prepared by our highly skilled subject experts.

NCERT Solutions for Class 9 Maths Chapter 9 Areas of Parallelograms and Triangles Exercise 9.1

Question 1.
Which of the following figures lie on the same base and between the same parallels. In such a case, write the common base and the two parallels.

Solution:
(i) In figure 9.8(i), trapezium ABCD and triangle PCD have a common base CD and between seine parallels AB and CD.

(ii) In fig 9.8 (ii), parallelogram PQRS and trapezium MNRS have common base RS, but they are not in the same parallels.

(iii) In figure 9.8(iii), parallelogram PQRS and triangle TQR have a common base QR and between same parallels QR and PS.

(iv) In figure 9.8(iv), parallelogram ABCD and triangle PQR have no common base but they are in between the same parallels AD and BC.

(v) In figure 9.8(v), parallelogram ABCD and parallelogram APQD have a common base AD, and between same parallels AD and BQ.

(vi) In figure 9.8(vi), parallelograms PBCS and PBAD lie on the same base PS, but not in the same parallels.

These NCERT Solutions for Class 6 Maths Chapter 11 Algebra Ex 11.4 Questions and Answers are prepared by our highly skilled subject experts.

NCERT Solutions for Class 6 Maths Chapter 11 Algebra Exercise 11.4

Question 1.
Answer the following:
(a) Take Sarita’s present age to be y years
(i) What will be her age 5 years from now?
(ii) What was her age 3 years back?
(iii) Sarita’s grandfather is 6 times her age. What is the age of her grandfather?
(iv) Grandmother is 2 years younger than grandfather. What is grandmother’s age?
(v) Sarita’s father’s age is 5 years more than 3 times Sarita’s age. What is her father’s age?

(b) The length of a rectangular hall is 4 meters less than 3 times the breadth of the hall. What is the length, if the breadth is b meters?

(c) A rectangular box has height h cm. Its length is S times the height and breadth is 10 cm less than the
length. Express the length and the breadth of the box in terms of the height.

(d) Meena, Beena and Leena are climbing the steps to the hill top. Meena is at step s, Beena is 8 steps ahead and Leena 7 steps behind. Where are Beena and Meena? The total number of steps to the hill top is 10 less than 4 times what Meena has reached. Express the total number of steps using s.

(e) A bus travels at v km per hour. It is going from Daspur to Beespur. After the bus has travelled 5 hours, Beespur is still 20 km away. What is the distance from Daspur to Beespur? Express it using v.
Answer:
(a)
(i) y + 5
(ii) y – 3
(iii) 6 y
(iv) 6y – 2
(v) 3y + 5

(b) Length = 3b and Breadth
= (3b – 4) meters

(c) Height of the box = h cm
Length of the box
= 5 times the height = 5h cm
Breadth of the box
= 10 cm less than length
= (5h – 10) cm

(d) Meena’s position = s
Beena’s position
= 8 steps ahead = s + 8
Leenas position
= 7 steps behind = s – 7
Total number of steps = 4s – 10

(e) Speed of the bus = v km/h
Distance travelled in 5 hours = 5v km
Remaining distance = 20 km
Therefore, total distance = (5v + 20) km

Question 2.
Change the following statements using expressions into statements in ordinary language.
(For example, Given Salim scores r runs in a cricket match, Nalin scores
(r + 15) runs. In ordinary language- Nalin scores 15 runs more than Salim.)

(a) A note book costs ₹ p. A book costs ₹ 3 p.
(b) Tony puts q marbles on the table. He has 8 q marbles in his box.
(c) Our class has n students. The school has 20 n students.
(d) Jaggu is z years old. His uncle is 4 z years old and his aunt is (4z – 3) years old.
(e) In an arrangement of dots there are r rows. Each row contains 5 dots.
Answer:
(a) A book cost 3 times the cost of a notebook.
(b) The number of marbles in box is 8 times the marble on the table.
(c) Total number of students in the school is 20 times that in our class.
(d) Jaggu’s uncle’s age is 4 times the age of Jaggu. Jaggu’s aunt is 3 years younger than his uncle.
(e) The total number of dots is 5 times the number of rows.

Question 3.
(a) Given Munnu’s age to hex years, can you guess what (x – 2) may show? (Hint: Think of Mannu’s younger brother.)
Can you guess what (x + 4) may show? What (3x + 7) may show?

(b) Given Sara’s age today to be y years.
Think of her age in the future or in the past.
What will the following expression indicate?
y + 7, y – 3, y + 4\(\frac { 1 }{ 2 }\), y – 2 \(\frac { 1 }{ 2 }\)

(c) Given n students in the class like football, what may 2n show? What may \(\frac { n }{ 2 }\) show? (Hint: Think of games other than football).

Answer:
(a) Munnu’s age = × years
His younger brother is 2 years younger than him = (x – 2) years
His elder brother’s age is 4 years more than his age = (x + 4) years
His father is 7 year’s more than thrice of his age = (3x + 7) years

(b) Her age in past = (y = 3),\(\left(y=2 \frac{1}{2}\right)\)
Her age in future = (y + 7),\(\left(y=4 \frac{1}{2}\right)\)

(c) Number of students like hockey is twice the students liking football, i.e., 2n
Number of students like tennis is half the students like football, i.e.,\(\frac{n}{2}\)

These NCERT Solutions for Class 9 Maths Chapter 8 Quadrilaterals Ex 8.2 Questions and Answers are prepared by our highly skilled subject experts.

NCERT Solutions for Class 9 Maths Chapter 8 Quadrilaterals Exercise 8.2

Question 1.
ABCD is a quadrilateral in which P, Q, R, and S are midpoints of the sides AB, BC, CD, and DA (see fig. 8.29). AC is a diagonal. Show that
(i) SR || AC and SR = \(\frac {1}{2}\) AC
(ii) PQ = SR
(iii) PQRS is a parallelogram.

Solution:
Given. ABCD is a quadrilateral in which P, Q, R, and S are the midpoints of side AB, BC, CD, and AD respectively.
To prove that:
(i) SR || AC and SR = \(\frac {1}{2}\) AC
(ii) PQ = SR
(iii) PQRS is a parallelogram.
Proof:
(i) In ΔADC
S and R are the mid-point of side AD and DC respectively.
We know that the line segment joining the midpoints of any two sides of a triangle is parallel to the third side and is half of it.
SR || AC and SR = \(\frac {1}{2}\) AC ……(i)

(ii) In ΔABC,
P and Q are the mid points of side AB and BC respectively.
Therefore, PQ || AC and PQ = \(\frac {1}{2}\) AC …….(ii)
From equation (i) and (ii),
PQ || SR and PQ = SR

(iii) We have
PQ = SR (Prove above)
and PQ || SR (Prove above)
We know that if one pair of opposite sides of a quadrilateral are parallel and equal then the quadrilateral is a parallelogram.
∴ PQRS is parallelogram.

Question 2.
ABCD is a rhombus and P, Q, R, and S are the midpoints of the sides AB, BC, CD, and DA respectively. Show that the quadrilateral PQRS is a rectangle.
Solution:
Given: Arhmbus ABCD in which P, Q, Rand S are the midpoints of sides AB, BC, CD, and DA respectively. PQ, QR, RS, and SP are joined.
To prove that: PQRS is a rectangle.
Construction: Join AC and BD.

Proof: In order to prove that PQRS is a rectangle, it is sufficient to show that it is a parallelogram whose one angle is a right angle. First, we shall prove that PQRS is a parallelogram.
In ΔABC,
P and Q are the mid points of AB and BC respectively.
∴ PQ || AC and PQ = \(\frac {1}{2}\) AC ……(i)
In ΔADC,
R and S are the mid points of CD and AD respectively.
∴ RS || AC and RS = \(\frac {1}{2}\) AC ……(ii)
From equation (i) and (ii) we have
PQ || RS and PQ = RS
Thus, PQRS is a quadrilateral such that one pair of opposite sides PQ and SR is equal and parallel. So, PQRS is a parallelogram.
PQ || AC (Opposite sides of || gm)
∴ MQ || ON
QR || BD (Opposite sides of || gm)
∴ QN || OM
Therefore, OMQN is a parallelgram.
and ∠NOM = 90°
[Diagomals of a rhombus bisects each other at a right angle]
So, ∠MQN = 90°
[Opposite angles of || gm are equal]
Therefore, PQRS is a parallelogram in which ∠Q is a right angle.
∴ PQRS is a rectangle.

Question 3.
ABCD is a rectangle and P, Q, R, and S are midpoints of the sides AB, BC, CD, and DA respectively. Show that the quadrilateral PQRS is a rhombus.

Solution:
Given: A rectangle ABCD in which P, Q, R, and S are the midpoints of sides AB, BC, CD, and DA respectively. PQ, QR, RS, and SP are joined.
To prove that: PQRS is a rhombus.
Construction: Join AC and BD.
Proof: In ∆ABC,
P and Q are mid points of AB and BC respectively.
∴ PQ || AC and PQ = \(\frac {1}{2}\) AC …..(i)
Similarly in ∆ACD,
SR || AC and SR = \(\frac {1}{2}\) AC ……(ii)
From equation (i) and (ii) we have
PQ || SR and PQ = SR
Therefore, PQRS is a parallelogram
∴ SR || PQ (Opposite sides of || gm PQRS)
and SR = PQ
Now, in ∆BCD,
Q and R are mid points of side BC & CD.
∴ QR || AC and QR = \(\frac {1}{2}\) BD
But, AC = BD (In rectangle diagonals are equal)
QR = \(\frac {1}{2}\) AC ……(iii)
From equation (i) and (iii) we have
PQ = QR
but PQ = SR and PS = QR
Therefore, PQ = QR = RS = PS
∴ PQRS is a rhombus.

Question 4.
ABCD is a trapezium in which AB || DC, BD is a diagonal, and E is the midpoint of AD. A line is drawn through E parallel to AB intersecting BC at F (see fig. 8.30). Show that F is the midpoint of BC.

Solution:
In ∆ABD,
E is the midpoints of AD and EF || AB
∴ EF || CD
We know that a line through the midpoint of a side of a triangle parallel to another side bisects the third side. So, G is the midpoint of DB.
Now, in ∆DBC
G is the midpoint of DB and GF || CD
∴ F is the midpoint of BC.

Question 5.
In a parallelogram ABCD, E and F are the midpoints of sides AB and CD respectively (see fig. 8.31). Show that the line segment AF and EC trisect the diagonal BD.

Solution:
We have,
ABCD is a parallelogram
∴ AB || CD
So, AE || FC ……(i)
Again, AB = CD (Opposite sides of ||gm ABCD)
∴ \(\frac {1}{2}\) AB = \(\frac {1}{2}\) CD
or, AE = FC …….(ii)
From equation (i) and (ii)
Therefore, AFCE is a parallelogram.
Now, in ΔDQC,
F is the mid point of CD,
and FP || CQ
We know that a line through the midpoint of a side of a triangle parallel to another side bisects the third side.
So, P is the midpoint of DQ
or, DP = PQ ……(i)
Similarly in ΔAPB, Q is midpoint of BP
i.e. PQ = BQ …..(ii)
From equation (i) and (ii)
PQ = DP = BQ
∴ AF and CE trisect the diagonal BD.

Question 6.
Show that the line segments joining the midpoints of the opposite sides of a quadrilateral bisect each other.
Solution:
Given: ABCD is a quadrilateral in which P, Q, R, and S are the midpoints of side AB, BC, CD, and AD respectively.
To prove that: PR & QS bisect each other. Construction: Join PQ, QR, RS, and SP and join BD.
Proof: In ΔABD,
S and P are the midpoint of side AD and AB respectively we know that the line segment joining the midpoints of any two sides of a triangle is. parallel to the third side and is half of it.

Therefore, SP || BD and SP = \(\frac {1}{2}\) BD …….(i)
Similarly,
In ΔBCD,
Q and R is the mid points of side BC & CD
∴ QR || AC and QR = \(\frac {1}{2}\) AC ……(ii)
From equation (i) and (ii)
SP || QR and SP = QR
We know that if one opposite pair of a quadrilateral are parallel and equal, then the quadrilateral is a parallelogram.
∴ SPQR is a parallelogram.
So, PR and QS bisect each other.
[Because diagonal of a parallelogram bisects each other]

Question 7.
ABC is a triangle right angled at C. A line through the midpoint M of hypotenuse AB and parallel to BC intersects AC at D. Show that
(i) D is the mid point of AC
(ii) MD ⊥ AC
(iii) CM = MA = \(\frac {1}{2}\) AB
Solution:
Given: ABC is a right-angled triangle right angle at C. M is the midpoint of side AB and DM || BC.
To prove that:
(i) D is the mid point of AC
(ii) MD ⊥ AC
(iii) CM = MA = \(\frac {1}{2}\) AB

Construction: Join CM.
Proof: (i) In ΔABC,
M is the mid point of side AB and MD || BC
We know that a line through the midpoint of a side of a triangle parallel to another side bisects the third side.
So, D is the midpoint of AC.

(ii) We have DM || CB
∴ ∠MDC + ∠DCB = 180°
(Sum of interior angles of the same side of transveralsi)
or, ∠MDC + 90° = 180°
or, ∠MDC = 90°
Therefore, MD ⊥ AC

(iii) In ΔAMD and ΔCMD
AD = CD (Prove above)
∠ADM = ∠CDM, (Each 90°)
DM = DM (Common)
By S-A-S congruency condition
ΔAMD ≅ ΔCMD
∴ AM = CM …..(i) (By CPCT)
But AM = AB ……(ii)
(Given M is the mid point of AB)
From (i) and (ii)
CM = MA = \(\frac {1}{2}\) AB