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Class 8 Science Chapter 8 Force And Pressure Long Answer Type Questions And Answers

Question 1. Two groups of students are playing tug-of-war.

1. Choose the correct direction of force applied by Group Land Group 2.

Answer: 4.

2. Group1 is pulling with a 250 N force, and Group 2 is pulling with a 300 N force. What would be the likely position of the two groups after a minute of pulling?

Answer: 1.  Net 50n Force Demonstration Winning Team Movement

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Question 2. Rishi drops a metal block from the same height onto different wooden blocks of the same mass but different contact areas. The teacher was also watching this activity. He asked Rish some questions to Rish, which are listed below.

Explain the relationship between the contact area of the wooden block and how deeply the wooden block would sink into the soft ground.

A force of 100 N is applied on an area of 4 m 2. Calculate the pressure applied to the area.

The contact area of one of the wooden blocks is 9 cm2. Calculate the force acting on it if the pressure is 900 Pa.

Question 3. Four students wanted to find out who could kick a football the strongest. Each student kicked the football. The table shows the distance the football travelled in the air before hitting the ground.

1. Which student kicked the ball with the greatest force?

1. Student 1
2. Student 2
3. Student 3
4. Student 4

2. Which of these factors must remain the same when each student kicks the football? Choose ‘Yes’ or ‘No’ for the correct response.

Shade the columns in the graph to correctly show the data in the table.

Answer:

As pressure is equal to force divided by area, hence as the contact area of the wooden block increases, the depth to which block would sink into the soft ground decreases.

⇒ \(\text { Pressure }=\frac{\text { Force }}{\text { Area }}\)

Force = 100 N, Area = 4 m2

⇒ \(\text { Pressure }=\frac{\text { Force }}{\text { Area }}=\frac{100}{4}=25Pa\)

The relation between pressure and force is

⇒ \(\text { Pressure }=\frac{\text { Force }}{\text { Area }}\)

Force = Pressure X Area

= (900) (0.0009) ( v 9 cm 2 = 0.0009 m 2 )

= 0.81 N

Question 3. It is much easier to burst an inflated balloon with a needle than with a finger. Explain.
Answer:

Because the needle tip has a very small area of cross-section in comparison to that of our finger, and we know that pressure exerted by a force is inversely proportional to the area where it has been applied, the pressure exerted will be more by the needle tip than the finger.

CBSE Class 8 Science Chapter 4 Combustion And Flame Short Answer Questions

Question 1. We were told that food is a fuel for our bodies. Why?
Answer: The food that we eat is broken down in our body by reaction with oxygen, and energy is produced, which is utilised by our body as a fuel.

Question 2. We have read that the Sun produces its heat and light. Is it also some kind of combustion?
Answer: No, it is not combustion. The heat and light in the Sun are produced by nuclear reactions.

Read And Learn More CBSE Class 8 Science Short Answer Questions

Question 3. Why is it important to know the telephone number of the fire service in your area?
Answer: It is important to know the telephone number of the fire service so that, in case of a fire, the fire brigade can reach on time and extinguish the fire.

Question 4. Why should we never sleep in a room with a burning or smouldering coal fire?
Answer: It is because carbon monoxide gas produced can kill persons sleeping in the room with a burning or smouldering coal fire.

Question 5. If you hold a piece of iron wire with a pair of tongs inside a candle flame or a Bunsen burner flame, what will you observe? Will it produce a flame?
Answer: The Iron wire will become red hot and glow. It will not produce a flame.

Question 6. Boojho wants to separate the following materials as combustible and non-combustible. Can you help him? Charcoal, chalk, stone, iron rod, copper coin, straw, cardboard, glass, paper, candle, wood,
Answer:

1. Combustible — charcoal, straw, cardboard, paper, candle, wood.
2. Non-Combustible- Chalk, Stone, iron rod, copper coil, glass.

CBSE Class 8 Science Chapter 8 Force And Pressure Short Answer Type Questions

Question 1. Two people are applying forces on two opposite sides of a moving cart. The cart still moves with the same speed in the same direction. What do you infer about the magnitudes and direction of the forces applied?
Answer: The magnitude of forces will be equal, and they act in opposite directions, so that they cancel each other. We can understand this by using the following

Question 2. A man is pushing a cart down a slope. Suddenly, the cart starts moving faster, and he wants to slow it down. What should he do?

Answer:

The man can do the following things

1. He can start pulling the cart instead of pushing it to balance the downward force due to gravity.
2. He can go to the other side by moving himself very fast in the direction of motion and try to slow down the speed of the cart by giving an opposite force to the moving cart.

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Question 3. A soccer ball flew towards a goalkeeper standing at the goalpost. He tried to grab it, but it slipped from his hands. Describe the action of the force at the point when the goalkeeper grabbed the ball.

Answer:

When the goalkeeper tried to grab the ball coming towards him, the force he applied caused it to change direction. At the same time, the force caused the ball to decrease in its speed. The force applied did not stop the ball from moving or increase its speed.

Question 4. The figure shows a man with a parachute. Name the force that is responsible for his downward motion. Will he come down with the same speed without the parachute?

Answer:

1. The name of the force responsible for the downward motion of the parachute is called force of gravity.
2. No, because the air friction will become less.

Question 5. In the circuit shown in the figure, when the key is closed, the compass needle placed in the match box deflects. Name the force that causes this deflection.

Answer: On closing the switch, the current starts flowing in the wire, and due to this current, a magnetic field is established around the wire, which exerts a magnetic force on the needle, and it gets deflected.

Question 6. Does the force of gravitation exist between two astronauts in space?
Answer: Yes, there will be a gravitational force between the astronauts because every object in the universe, whether small or large, exerts a force on every other object; it is the universal law of gravitation.

Question 7. The figure shows a car stuck to an electromagnet. Name the forces acting on the car. Which one of them is larger?
Answer:

1. The forces working on the object (car) are
2. Force of gravity (downwards)
3. Magnetic force (upwards)

Since the car is moving upwards, so magnetic force due to the electromagnet is greater.

Class 8 Science Chapter 8 Force And Pressure Very Short Answer Type Questions

Question 1. Where do we apply a force while walking?
Answer: We apply a force on the ground while walking, and the ground applies a reaction force on our foot, due to which we can move forward.

Question 2. Does the palm apply any force on the ball when we place our palm in front of a moving ball?
Answer: Yes, when we place our palm in front of a moving ball, then the palm applies a force on the moving ball and stops it.

Question 3. Name an activity that does not involve any pushing force.
Answer: When a person swims freestyle, he is pulling themselves forward in the water.

Question 4. A ball of dough is rolled into a flat chapati. Name the force exerted to change the shape of the dough.
Answer: The shape of the dough is changed due to the muscular force applied by the hand.

Question 5. In ‘tug of war’, when two teams pull equally hard, what happens?
Answer: In ‘tug of war’, when two teams pull equally hard, then the rope does not move in any direction.

Question 6. A girl is pushing a box towards the East. In which direction should her friend push the box, so that it moves faster in the same direction?
Answer: Her friend should push the box towards the East direction, so that it will start moving faster towards the East because the magnitude of force increases.

Question 7. During dry weather, clothes made of synthetic fibre often stick to the skin. Which type of force is responsible for this phenomenon?
Answer: The electrostatic force starts working between the cloth made of synthetic fibre and sticks to the skin.

Question 8. Two thermocol balls are held close to each other, but they move away from each other when they are released. Name the force which might be responsible for this phenomenon. Explain.
Answer: This is an electrostatic force which is created due to the rubbing, and since the same charges are induced on two balls, they move away from each other.

Question 9. While sifting grains, small pieces fall. Which force pulls them down?
Answer: It is the force of gravity that is responsible for the grains to fall.

Question 10. Does the force of gravity act on dust particles?
Answer: Yes, the force of gravity acts on the dust particles.

Question 11. A gas-filled balloon moves up. Is the upward force acting on it larger or smaller than the force of gravity?
Answer: The upward force will be greater than the force of gravity, then the balloon will be able to lift against this gravitational force.

Question 12. Fruits detached from a tree fall due to the force of gravity. We know that a force arises due to the interaction between two objects. Name the objects interacting in this case.
Answer: The interacting objects in this case are: Earth and fruit. Earth applies a force of gravity on the fruit towards its centre, so the fruit falls.

Question 13. Rahul is pushing a magnet along his table when some paper clips on his table suddenly move. In which direction does the force act on the paper clips?

Answer: As the magnet will attract the paper clips, the force acting on them will be towards the magnet.

Question 14. Under which circumstances, a person not experience any gravitational force?
Answer: A person who is in a space that is too far away from Earth’s gravitational force will not suffer any gravitational force.

Question 15. An astronaut travels from Earth to the moon. How does his weight and mass change?
Answer: The Mass of an object remains constant at all places, so the mass of the astronaut will not change. The weight of an object depends on the gravity; on the moon, gravity is less than on Earth, so the weight of an astronaut will decrease.

Question 16. Have you ever wondered what makes an object slow down or go faster or change its direction of motion?
Answer: Force makes an object slow down or go faster, or change its direction of motion.

Question 17. Paheli remembers that a magnet attracts a piece of iron towards it. Is attraction also a pull? What about repulsion between similar poles of two magnets? Is it a pull or a push?
Answer: The Attraction or repulsion between the poles of a magnet can be seen as another form of pull or push.

Question 18. Does it mean that the net force on an object is zero if the two forces acting on it in opposite directions are equal?
Answer: Yes, when two forces of equal magnitude act in opposite directions, the net force is zero on that body.

Question 19. Boojho has seen children competing with one another in moving a rubber tyre or a ring by pushing it. Why does the speed of the tyre or ring increase whenever it is pushed?
Answer: With every push, they are applying a little more force on the moving tyre in the direction of motion. Hence, the speed of the tyre increases continuously.

Question 20. Does the application of a force always result in a change in the state of motion of the object?
Answer: No, sometimes a heavy material may not move at all, even if you apply the maximum force that you can exert.

Example: When you try to push a wall, no effect of force is observed.

Simple Magnetic Force Activity Using Paperclips For CBSE Class 8 Science Activity 1

Aim: To identify push or pull by observing the motion of objects.

Material Required: Pen and paper.

Read And Learn More CBSE Class 8 Science Activities

Procedure:

1. Take a familiar situation of moving objects.
2. Draw a table as shown below.
3. Now, identify the action involved in each case and categorise it into push or pull.

Where To Find Class 8 Force And Pressure Lab Manual NCERT-Aligned Activity 2

Aim: To learn more about forces by exploring them.

Material Required: A heavy object like a table or box.

Procedure:

1. Push the box by yourself.
2. Now, ask your friend to help you in pushing it in the same direction. You will find that it is easier to move than before.
3. Now, ask your friend to push it from the opposite side. You will find that the box moves in the direction where the stronger push is applied.
4. Note the direction of motion in each case

Conclusion: When force is applied in the same direction, then the movement of the box increases, and when forces are applied from the opposite direction, the box moves slowly.

Common Viva Questions On Pressure Activities Class 8 Activity 3

Aim: To show that when a force is applied to an object at rest, it begins to move.

Material Required: A rubber ball and a table.

Procedure:

1. Place the rubber ball on the level surface of the table.
2. Push the ball very slowly along the level surface.
3. The ball will start moving, push the moving ball in the direction of its motion. You will observe that the speed of the moving ball increases.
4. Now, place your palm in front of the moving ball.
5. Remove your palm as soon as the ball touches it.
6. You will observe that the speed of the moving ball decreases.

Conclusion: Force can increase or decrease the speed of the object.

Common Viva Questions On Pressure Activities Class 8 Activity 4

Aim: To determine whether force can change the direction. Material Required: A ruler and a ball.

Procedure:

1. Place the ball on a level surface and push it.
2. Now, place a ruler in its path as shown in the figure

Note the motion of the ball when it strikes the ruler.

Repeat the activity by placing the ruler at different angles.

How To Calculate Force And Pressure In Class 8 Activities Activity 5

Aim: To study the effect of force on objects.

Material Required: Pen and paper.

Procedure:

1. List some phenomena as mentioned in the table.
2. Now, categorise them by observing the action of force.

Class 8 Science Chapter 8 Force And Pressure Activity 6

Aim: To study the type of force applied by the magnet.

Material Required: A pair of bar magnets and 3 round-shaped pencils.

Procedure:

1. Place the longer side of a magnet on the 3 rounded shape pencil as shown in the figure.
2. Now, bring one end of the other magnet near the end of the magnet placed on the pencil.
3. Do not touch the ends of a magnet, then observe the motion of the magnet.
4. Now, bring the other end ofthe magnet near the same end of the magnet placed on the pencil.
5. Again, observe the motion of the magnet.

Class 8 Science Chapter 8 Force And Pressure Activity 7

Aim: To identify the type of force (contact or non-contact) applied by electrically charged objects.

Material Required: A table, a long thread, a straw, and scissors.

Procedure:

1. Cut the plastic straw into nearly two equal pieces.
2. Suspend one of the pieces from the edge of the table with the help of a thread.
3. Now, take the other piece of straw and rub it with a sheet or paper.
4. Bring the rubbed end of the straw near the suspended straw.
5. Observe the movement in suspended straw. You will find that it will attract towards it.
6. Now, rub the free end of the suspended straw with the paper.
7. Again, bring the straw that was earlier rubbed with the paper.
8. Again, observe the motion of the suspended straw. You will find that it will repel each other.

Conclusion: Electrostatic force is a non-contact force.

Class 8 Science Chapter 8 Force And Pressure Activity 8

Aim: To demonstrate that liquid exerts pressure at the bottom of its container.

Material required: A transparent plastic pipe of length 25 cm and diameter about 5-7.5 cm, a balloon, and water.

Procedure:

1. Fix the rubber balloon at one end of the pipe.
2. Now, hold the pipe in a vertical position and ask your friend to pour some water into the pipe.
3. Note the height of the water column and the change in shape of the balloon.
4. Now, pour some more water and note the increase in the balloon.
5. Repeat the same process 2-3 times and try to find the relation between the bulge and the height of the water column.

Conclusion

1. A liquid exerts pressure at the bottom of its container.
2. The pressure exerted by a liquid depends on the height of the liquid column

Class 8 Science Chapter 8 Force And Pressure Activity 9

Aim: To demonstrate that the liquid exerts pressure on the walls of its container.

Material Required: A plastic bottle, a cylindrical glass tube of a few cm long, a balloon, and water.

Procedure:

1. Make a hole near the bottom of the bottle.
2. Fix the tube into the hole and attach a balloon (fixed tightly) on the other end of the tube. See the figure.
3. Now, fill the bottle upto half with water and note the bulge of the balloon.
4. Add some more water and again observe the change in the bulge.

Conclusion: From this activity, we can also conclude that

A liquid exerts pressure on the walls of its container.

The pressure exerted by the liquid on the walls of its container depends on the height liquid level from the bottom.

Class 8 Science Chapter 8 Force And Pressure Activity 10

Aim: To demonstrate that liquid exerts equal pressure at the same depth.

Material required: Empty plastic bottle and water.

Procedure:

1. Drill four holes all around near the bottom of the bottle.
2. Make sure the holes are at the same height from the bottom.
3. Pour the water into the bottle and measure the distance where the water jet falls from the bottle. You will find that the different streams of water coming out of the holes fall at the same distance from the bottle.

Conclusion Liquid: Exert equal pressure if they are at the same depth.

Class 8 Science Chapter 8 Force And Pressure Activity 11

Aim: To show the effect of pressure due to air.

Material Required: A rubber sucker.

Procedure:

1. Hold a good Quality of rubber sucker.
2. Try to press it on a flat, smooth surface, so most of the air between its cup and the surface escapes out.
3. We will notice that the sucker sticks to the surface.
4. Now, try to pull the sucker off the surface, you will find little hard to pull it off.
5. To pull the sucker off the surface, the applied force should be large enough to overcome the atmospheric pressure.

Conclusion: We have concluded that the sucher sticks to the surface because the pressure of the atmosphere acts on it.

Class 8 Science Chapter 4 Combustion And Flame Very Short Answer Questions

Question 1. Which type of substances produce flame? Does charcoal burn with flame?
Answer: The substances that vaporise during burning produce flame. No, charcoal does not burn with flame; it glows only.

Question 2. What are the products obtained when combustion takes place?
Answer: The products of combustion are carbon dioxide, water vapour, heat, and light.

Read And Learn More CBSE Class 8 Science Very Short Questions And Answers

Question 3. Name the substance that gives heat and light after combustion.
Answer: The substance that provides heat and light is called fuel

Question 4. If you burn a candle and a coal, what is the difference in their burning?
Answer: A Candle burns with a flame, whereas coal burns by producing light in the form of a glow.

Question 5. How is heat produced in our body?
Answer: In our body, food is broken down by reaction with oxygen. During such reactions, heat is produced. This heat keeps our body warm.

Question 6. Name two fuels that we use in our homes for cooking food.
Answer: Two fuels which we use in our homes for cooking food are LPG and kerosene oil.

Question 7. Like fuels, the Sun also provides heat and light. What is the source of heat and light in the Sun?
Answer: In the Sun, heat and light are produced by nuclear reactions.

Question 8. Out of kerosene oil or wood, which has a higher ignition temperature?
Answer: Wood has a higher ignition temperature than kerosene oil.

Question 9. In what form can CO2 be stored in cylinders?
Answer: CO2 can be stored in cylinders in liquid form.

Question 10. Do all the substances catch fire at the same temperature?
Answer: No, different substances need different temperatures to catch fire due to their different ignition temperature.

CBSE Class 8 Science Chapter 7 Reaching The Age Of Adolescence Multiple Choice Questions

Question 1. The most conspicuous visible change that occurs in boys during puberty is

1. Development in the voice box
2. Increase in height
3. Production of sperm
4. Increased sweating

Answer: Increase in height

Question 2. Pimples and acne are formed due to the increased activity of

1. Adrenal glands
2. Sebaceous glands
3. Thyroid gland
4. Sweat glands

Read And Learn More CBSE Class 8 Science Multiple Choice Questions

Choose the correct option

1. 1 and 2
2. 2 and 2
3. 1 and 3
4. 2 and 4

Answer: 2 and 4

CBSE Class 8 Science Chapter 7 Reaching The Age Of Adolescence MCQ with answers

Question 3. The dramatic changes in body features associated with puberty are mainly because of the secretions of

1. Thyroxine
2. Oestrogen
3. Adrenaline
4. Testosterone

Choose the correct Option 

1. (1) and (2)
2. (2) and (3)
3. (1) and (3)
4. (2) and (4)

Answer: 4. (2) and (4)

Question 4. The male hormone is

1. Oestrogen
2. Progesterone
3. Testosterone
4. All of these

Answer: 3. Testosterone

Question 5. How do the endocrine glands’ hormones secreted during puberty induce changes in the body?

1. It decreases the muscle mass
2. It reduces the metabolism, increasing the food intake
3. It stimulates changes in different parts of the body
4. It doubles the capability of body parts to function

Answer: 3. It stimulates changes in different parts of the body

Question 6. The beginning of menstruation at puberty is called

1. Ovulation
2. Menstruation
3. Menarche
4. Menopause

Answer: 3. Menarche

Question 7. Given below are events that lead to pregnancy and the development of the embryo.

1. Fertilisation of the egg
2. Maturation of the egg
3. Release of egg
4. Embedding of the embryo in the uterus

Which of the following options gives the correct order of sequence in which they occur?

1. (1). (2). (3), (4)
2. (2), (1), (3), (4)
3. (1), (4), (2), (3)
4. (2), (1) (3) (4)

Answer: (4). (2), (1). (4)

Question 8. Structures present in a cell which Is responsible for determining the sex of a baby are

1. Cytoplasm
2. Cell membrane
3. Nucleus
4. Chromosome

Answer: 4. Chromosome

Question 9. The number of chromosomes present in a human cell

1. 22 pairs
2. 23 pairs
3. 24 pairs
4. 26 pairs

Answer: 2. 23 pairs

Question 10. The belief that the mother is completely responsible for the sex of the child is wrong because the child

1. Gets sex chromosome only from the mother
2. Develops in the body of the mother
3. Gets one sex chromosome from the mother and the other from the father
4. Gets sex chromosome only from the father

Answer: 3. Gets one sex chromosome from the mother and the other from the father

Real-Life Examples To Explain Adolescence Changes: Class 8 Long Answer Type Questions

Question 1. During adolescence, the body of boys and girls undergoes critical changes. Given below of those changes

1. Broad shoulders
2. Wider chosts
3. Wider region below the waist
4. Development of muscles
5. Development of mammary glands
6. Growth of facial hair
7. Acne and pimples on the face
8. Development of sex organs
9. High-pitched voice
10. Growth of pubic hair

Categorise these changes into those that occur in boys and those that occur in girls, and fill in the table given below.

Body changes during adolescence

Answer: Body changes during adolescence are given below

Question 2. In the figure, mark the position of the endocrine glands that release the hormones that control the release of sex hormones.
Answer: Pituitary gland. It releases hormones that control the release of sex hormones, i.e., testosterone in males and oestrogen in females.

Answer:

Testis. It releases testosterone, which is responsible for the secondary sexual characteristics in boys prevents diabetes.

The Pancreas releases insulin, which prevents diabetes

Maintain the correct salt balance in the blood.

The adrenal gland releases aldosterone, which maintains the correct salt balance in the blood.

Read And Learn More CBSE Class 8 Science Long Answer Questions

Question 3. Choose the correct option.

1. Adolescents should be careful about what they eat, because

1. A proper diet develops their brains
2. A proper diet is needed for the rapid growth taking place in their body
3. Adolescents feel hungry all the time
4. Taste buds are well developed in teenagers

2. Reproductive age in women starts when their

1. Menstruation starts
2. Breasts start developing
3. Body weight Increases
4. Height increases

The right meal for adolescents consists of

1. Chips, noodles, cake
2. Chapati, dal, vegetables
3. Rice, noodles, and a burger
4. Vegetable cutlets, chips and lemon drink

Answer: Adolescents should be careful about what they eat because a proper diet is needed for the rapid growth taking place in their bodies.

1. Reproductive age in women starts when their menstruation starts.
2. The right meal for adolescents consists of chapati, dal and vegetables
3. Question 8 Write notes on
4. Adam’s apple.
5. Secondary sexual characteristics.
6. Sex determination of the unborn baby.

Answer:

Adam’s apple: In males, the protruding part of the growing voice box is called Adam’s apple. In boys, the voice box (larynx) develops larger than in girls, and this protruding part is seen as a bulge in the neck area.

Secondary sexual characteristics: The physical features that help to distinguish males from females are called secondary sexual characteristics. These characters develop at the time of puberty. The secondary sexual characteristics in humans are given below. In males,

1. Growth of pubic hair, beard, and moustaches.
2. Hair on chest and underarms.

In females,

1. Enlargement of breasts.
2. Appearance of pubic hair, hair underarms.

Sex determination of the unborn baby. The Sex of the unborn baby is determined by the sex chromosomes, i.e., X and Y.

In females, the gamete (i.e., egg) has only one X chromosome, but in males, the gamete (i.e. sperm) may have an X chromosome or Y chromosome.

If the egg fertilises with sperm containing an X chromosome, the zygote will develop into a female (XX), and if the egg fertilises with sperm containing a Y chromosome, the zygote will develop into a male (XY)

Question 4. The table given below shows the trend in likely heights of boys and gills os they grow in age. Draw graphs showing height and Ago for both boys and girls on the same graph paper. What conclusions can be drawn from this graph?

Answer: We conclude that initially. Girls grow faster than boys, hitting about 18 years of age. Both reach their maximum height. The rate of growth in brightness varies in Different individuals.

Question 4. The heights of students of four different sections of grade 8 are measured. The table shows the percentage of maximum height up to which the students in each section have grown

In which class have both the boys and the girls reached the end of puberty?

1. Section A
2. Section B
3. Section C
4. Section D

Answer: Section B.

What can be concluded from the table?

1. Girls are taller than boys in all four classes
2. Girls attain their maximum height earlier than boys
3. Girls grow faster than boys throughout their childhood
4. Girls and boys attain their maximum height at the same age

Answer: Girls attain their maximum height earlier than boys.

Question 5. An ovum contains one X chromosome. A sperm contains an X or a Y chromosome. A sperm can fertilise an ovum to produce two different zygotes.

1. Which chromosome does the female zygote receive from the mother and the father?

Answer: 1. Mother X-chromosome, father X-chromosome

Which of those stntomonts is supported by the picture?

Circle ‘Yes’ or ‘No’ for the correct response

Answer: A. Yes B. Yes C. No

Question 6. Diabetes is a condition in which the blood sugar level of a person rises above the normal level. The table below shows the average range of blood sugar levels at fasting

Doctors prescribe insulin injections for patients with high blood sugar levels. However, glucagon is injected in an emergency if the blood sugar level of a person drops too low.

Which of these is true about the gland that secretes insulin in the human body?

1. It has no ducts
2. It is located on the skin
3. It controls the function of all other glands
4. It releases hormones that help in growth

Answer: It has no ducts

Under what conditions of blood sugar level is glucagon likely to be injected?

1. Below 60 mg/dL
2. 80-100 mg/dL
3. 100-120 mg/dL
4. Above 120 mg/dL

Answer: Below 60 mg/dL

CBSE Class 8 Science Chapter 7 Reaching The Age Of Adolescence Short Answer Questions

Question 1. Define adolescence as stated by the WHO. Why is adolescence also called teenage?
Answer: The World Health Organisation (WHO) defines adolescence as the period of life between 11 and 19 years of age. Since adolescence covers the teen period, i.e., 13-19 years of age, adolescence is also called ‘teenage’.       

Question 2. Salma had very soft and smooth skin during her childhood. As she entered adolescence, she developed pimples on her face. The skin specialist advised her to wash her face at regular intervals. Can you explain the reasons for the appearance of pimples on her face and suggest ways to prevent them? Competency-Based Question
Answer: During adolescence, the secretion of sweat glands and sebaceous glands increases, leading to acne and pimples. Regular face wash keeps the face clean and dry and helps to reduce pimples.

Read And Learn More CBSE Class 8 Science Short Answer Questions

Question 3. Mention any two features that are seen in boys and girls, each to distinguish them from each other at puberty.
Answer: Two features seen in boys at puberty are

• Growth of facial hair.
• Voice becomes hoarse.
• Two features seen in girls at puberty are
• Development of breasts.
• The region below the waist becomes wider

Question 4. In human females, each time during maturation and release of an egg, the Inner wall of the uterus thickens. Is this thickening permanent? Give reasons.
Answer: No, this thickening of the uterine wall is not permanent. If the egg gets fertilised, it starts developing and gets embedded in the uterine wall, resulting in pregnancy. During pregnancy, no more eggs are released, and the thickened lining is discharged only when the baby Is born. However, if fertilisation does not occur, the released egg and the thickened lining are shed off, resulting in menstruation.

Question 5. Fill the blank circles in the figure and identify the sex of child A and B

Answer:

Question 6. Name the hormone that would be released during the following situations.

• A frightened person
• Growth of a child into an adult
• Development of the caterpillar into the moth
• Development of tadpole to frog

Answer: Adrenaline is secreted from the adrenal gland during stress conditions like fright or fear, anger, worry or embarrassment.

• Growth hormone is secreted from the pituitary gland to regulate the normal growth ofa person, i.e., growth of a child to adult.
• Insect hormones control the development of the caterpillar and the lo moth.
• Thyroxine is produced by the thyroid gland to control the development of a tadpole into a frog.

Question 7. A tadpole is kept in a lagoon with deficient water. How will it affect its growth? Explain
Answer: Tadpoles growing in Iodine deficient water have retarded growth. This is because the growth and development is regulated by thyroxine hormone which is produced by thyroid gland As loodine required for thyroxine production, retarded growth Is seen In tadpoles When kept In Water.

Question 8. Liia always eats only dal and rice in everyday meals; she often falls and has become prone to diseases. Can you suggest changes in her diet Which can make her healthy and free from diseases?
Answer: Lila’s diet is not balanced because her meals do not contain (lie adequate nutrition. She likes only proteins mid airliohydriilcn In every mail. She requires vitamins mid minerals in her meal to protect her from various diseases, Thus, I would suggest her lo include fruits and vegetables in her meal as a source of vitamins and minerals.

CBSE Class 8 Chapter 7 Reaching The Age Of Adolescence Very Short Answer Type Questions

Question 1. Adolescence is the period from 13-19 years of age. Is there any other term for this period?
Answer: Yes, the other term for adolescence is teenage.

Question 2. Do all the parts of the body grow at the same rate? State yes or no.
Answer: No, all parts of the body do not grow at the same rate.

Question 3. What is the common name of the bulge (or projection) at the front of the throat in grown-up boys?
Answer: Adam’s apple.

Question 4. Some characters distinguish a boy from a girl. What are they called?
Answer: Secondary sexual characteristics distinguish a boy from a girl

Question 5. Name the hormone that is released by the testes at the onset of puberty.
Answer: Testosterone is the male hormone that is released from the testes at the onset of puberty.

Question 6. Name the female hormone produced by the ovaries that helps in the development of mammary glands.
Answer: Oestrogen is the female hormone produced by the ovaries that helps in the development of breasts/mammary glands.

Question 7. State the function of the male sex hormone testosterone.
Answer: Testosterone is involved in the development of the reproductive organs and controls secondary sexual characteristics.

Question 8. Give a suitable word for each of the following statements.

1. The site that responds to a hormone.
2. Name of a gland which transports secretions through ducts.
3. Chemicals that control changes at the adolescent stage.
4. It marks the beginning of the reproductive period.

Answer:

1. Target site
2. Sweat glands
3. Hormones
4. Puberty

Question 9. Out of the two sexes of humans, which one has a longer reproductive phase of life?
Answer: Men have a longer reproductive phase oflife than women.

Question 10. What is the name of the process in which the thickened uterus lining along with its blood vessels is removed from the body of a woman through vaginal bleeding.
Answer: Menstruation cycle.

Question 11. Which comes earlier in the life of a woman, menarche or menopause?
Answer: The reproductive life of a woman starts at menarche and ends at menopause. Thus, menarche comes earlier.

Question 12. What is menstruation? Explain.
Answer: Menstruation is the monthly reproductive cycle that occurs in women once in about 28-30 days.

It is the release of unfertilised eggs along with blood. If the egg released from the ovary does not get fertilised, the released egg and the thickened lining of the uterus, along with its blood, are released from the body.