Chapter 8: Physiology and Sports

NCERT Solutions Physical Education Class 12. Download CBSE Study Materials on in pdf format.

NCERT books Solutions

1 Mark Questions

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Question 1:

What do you mean by ‘Cardiac Output’? [Delhi 2016]

Answer 1:

Cardiac output is the volume of the blood pumped by the heart, measured in litres per minute. It is a product of stroke volume and heart rate.


Question 2:

What is “Stroke Volume”? [Delhi Outside 2016]

Answer 2:

Amount of blood pumped by left ventricle in per beat.

At rest period – 50 to 70 ml/beat

During Exercise – 110 to 130 ml/beat


Amount of blood ejected by heart in one stroke.


Question 3:

Explain the term ‘hypertrophy of muscles’. [Delhi 2015]

Answer 3:

Hypertrophy of muscles: Due to training the heart muscle fibers become thicker and stronger and thus help to have more forceful contractions of the heart. Strength training results in high degree of muscle hypertrophy, i.e. Increase in muscle size.


Question 4:

Why does involvement in regular exercise delay the onset of fatigue? [All India 2015]

Answer 4:

Regular exercise increases our cardio-respiratory endurance/efficiency which delays the onset of fatigue.


Question 5:

Define physical fitness. [Delhi 2014]

Answer 5:

Physical fitness to perform various activities in life depends mainly on three undermentioned components:

(i) Anatomic fitness

(ii) Physiological fitness

(iii) Psychological fitness


Question 6:

Define respiratory system [Delhi 2010]

Answer 6:

The respiratory system enables us to breathe. The act of breathing includes inhaling and exhaling of air in the body. In the process of respiration, oxygen is absorbed and carbon dioxide is discharged.

3 Marks Questions

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Question 1:

What are the changes that take place in cardiovascular system by doing regular exercise? [CBSE Sample Paper 2017]

Answer 1:

The cardio-vascular system undergoes various changes if exercises are performed. During exercise, the cardiovascular system begins to meet the increased demands of the body in many ways. The cardio-vascular system rushes oxygen to the working muscles, returns the blood to the lungs to be re-oxygenated and delivers fuel (nutrients and oxygen) to the active tissues of the body.

In fact, the effects of exercise can be studied in the following ways:

Immediate Effects of Exercises

(i) Increase in heart rate: Generally the resting heart rate of an adult remains at 72 beats per minute. The elite endurance athletes usually have 28 to 40 treats per minute. Even before the beginning of exercise the heart rate increases in anticipation. It is known as anticipatory response. When an individual starts exercise his heart rate increases as per the intensity and duration of the exercise.

(ii) Increase in stroke volume: Stroke volume is the amount of blood ejected per the left beat from ventricle. It is measured in ml/beat. Stroke volume increases proportionally with exercise intensity. In untrained individuals the stroke volume at rest remains at 50 to 70 ml/beat. It increases up to 110 to 130 mm/beat during intense exercise. The stroke volume of experienced athletes at rest remains at 90 to 110 ml/beat. It increases up 150 to 220 ml/beat during intensive exercise.

(iii) Increase in cardiac output: Cardiac output is the amount of blood pumped by the heart in one minute. It is measured in litre/minute. Cardiac output is a product of stroke volume and heart rate. If either heart rate or stroke volume increases or both, the cardiac output increases also. The cardiac output increases proportionally with the intensity of exercise. At rest the cardiac output is about 5 litre/minute but during intense exercise it can increase up to 20 to 40 litre/minute.

Long Term Effects of Exercises

(i) Increase in the size of heart: When we perform regular exercise the muscles of the heart increase in size and strength. In fact, the left ventricle adapts to the greatest extent. The heart wall grow stronger and thicker. The recent studies show that the myocardial wall thickness also increases.

(ii) Decrease in resting heart rate: Regular exercise decreases the resting heart rate. If a 10 week training programme is given to an individual whose initial resting heart rate is 72 beats per minute after this duration his resting heart rate may reduce up to lb beats per minute. After regular exercise the heart finally becomes more efficient. It does not require to beat as quickly to supply the body with blood while at rest. It has been noted that highly conditioned athletes can have their resting heart rates in the 30 seconds.

Question 2

Sports are good for all age groups. Competitive sports are a showcase of power at the international arena. Supremacy over the other country is indirectly shown by standing at the top of medal tally. To achieve their target few countries are imparting very strict training to growing children. Over the years many organizations have raised their voice against the intensity with which training is scheduled for making an international athlete.

(a). What are the disadvantages of giving high intensity training to the growing children?

(b). Elaborate any two physiological benefits of exercise in children. [Delhi Outside 2016]

Answer 2:

(a). Role of physical activities in improving the quality of life as follows:

  1. Exercise controls weight
  2. Strength the bones
  3. Strength the lungs
  4. Promote changes in the brain structure
  5. Strength the Heart
  6. Boost energy level
  7. Reduce blood sugar level
  8. Builds strong and healthy muscles
  9. Motor development
  10. Helps in digestive process
  11. Improves neuro muscular co-ordination
  12. Help in staying healthy

(Elaborate any two from above)


  1. Stress/fatigue
  2. Chances of overload
  3. Early maturity
  4. Can reach too early top form
  5. Less flexibility
  6. Chances of injury

(Explain any two)

Question 3:

Regular physical activities cannot stop the clock of ageing; but definitely it can slow the process. Justify. [CBSE Sample Paper 2015]


“Regular physical activity can delay your ageing process.” Justify your answer in light of the effect of activities on physiological changes. [All India 2015]

Answer 3:

Regular exercise always promotes healthy aging process. Getting older is a regular cycle of life. Regular exercise delays the changes which occur due to ageing. The role of regular exercise is as follows.

(i) Muscles lose strength due to ageing. But we can maintain their strength for longer period if we exercise regularly.

(ii) With increase in age cardio-respiratory fitness decreases but those who continue to exercise keep their cardio system efficient which slows down the process of ageing.

(iii) Muscles and joints become less flexible and agile with age. But regular exercise removes various joint problems and keeps the person healthy and fit, saves from osteoporosis.

(iv) More severe changes in ageing are on skin which lead to wrinkles and decreased elasticity. Regular exercise tones up the muscles and because of aerobic consumption and better flow of circulation to all the parts of the body, there is glow on the skin with less wrinkles.

Definitely Regular physical activities slow down the ageing process. One day each one of us is going to grow old but regular exercises become an asset to live a good quality life.

Question 4:

What are Arteries? [Delhi 2013]

Answer 4:

Arteries: Arteries carry highly oxygenated blood from the heart to the various body parts. They are more elastic and muscular with thick walls. Arterioles are narrower arteries that branch off from the ends of arteries and carry blood to capillaries.

5 Marks Questions

Download Long Answer Type Questions

Question 1:

Explain in detail about the effects of regular exercise on Respiratory System. [Delhi 2016]

Answer 1:

Regular exercises have following effects on respiratory system:

(i) Increase in size of lungs and chest: When a person performs exercise regularly, he requires more amount of oxygen. He inhales more amount of air during exercise. Gradually in a long period, the size of his lungs and chest increases.

(ii) Increase in residual air volume: Residual air is that amount of air, which is left in the lungs after exhalation. If an individual performs regular exercise, his residual air capacity increases in comparison to an individual who does not perform regular exercise.

(iii) Strong will-power: Regular exercises increase will-power of the individual. As Pranayama, i.e. specific exercise for lungs, increases the will-power of the doer.

(iv) Unused alveolus become active: Regular exercise activates the unused alveolus, because much amount of oxygen, is required in vigorous and prolonged exercise of daily routine. The passive’ alveolus become active.

(v) Decrease in rate of respiration: Itis certain that when a beginner starts exercise, his rate of respiration increases. But when the same individual performs exercise daily, his rate of respiration decreases in comparison to the beginning stage at rest.

(vi) Avoids second wind: For a beginner, the stage of second wind is, indeed, a crucial stage. But for a regular exerciser, it is hardly felt. Sometimes, a well-experienced athlete does not feel it in his course of activity.

(vii) Increase in tidal air capacity: Tidal air is the amount of air that flows in and out of the lungs in each quiet respiratory movement. But tidal air capacity is the amount of air that can be breathed in and breathed out, over and above the tidal air by the deepest possible inspiration/expiration respectively.

(viii) Strengthens diaphragm and muscles: Regular exercise strengthens the diaphragm and the muscles of the chest.

(ix) Increase in endurance: If exercise is performed regularly and for a longer period, it increases endurance. An activity can be done for a longer period without taking any rest. Those who do not perform exercise, have less endurance. They cannot continue exercise for a long duration.

Hence, it can be alluded that exercise increases the endurance of an individual.

Question 2:

Describe the changes in circulatory system after training [Delhi 2015]

Answer 2:

Training have following effects on circulatory system:

Increase in oxygen circulation to muscles: Blood contains three different types of cells i.e. white blood cells which fight infection, red blood cells that transport oxygen and platelets which help in blood clotting. All these cells float in blood plasma. When you exercise your red blood cells are saturated with oxygen and increases the transportation of enough oxygen to the muscles.

Return of normal pulse quickly: The pulse/heart rate returns to normal quickly after exercise. Thus, body feels relaxed after sometime.

Blood pooling: When you exercise, blood is diverted from non-essential organs like digestive system or reproductive system to the working muscles. This is called blood pooling. When the strenuous exercise is over, the pooled blood moves out of the muscles back into general circulation, particularly after cooling down.

Faster Adaptation to working load: In a trained person, the heart can adapt to working load quickly 1.e., quick adjustment of heart according to body needs.

Increase in blood circulation: Due to the muscles squeezing in the veins, more blood is sent back to the heart. As the heart fills up, its stretches. As the muscle fibres stretch, they contact more strongly and pump out more blood. As a result, there is increase in blood circulation.

Cardiovascular system improves: Regular exercises improve cardiovascular system thus blood travels faster through blood vessels.

Faster healing: The increased circulation of blood makes healing faster, therefore, there is faster recovery from injuries.

Cardiorespiratory system improves: With improved circulation, the efficiency of respiratory system also improves.

Increase in number of RBC: The number of RBC (Red Blood Corpuscles) increases when exercises are taken on regular basis. These RBCs are the carriers of nutrients including haemoglobin and oxygen, to the muscles.

Increase in number of WBC: It has also been noted that regular exercises increase the number of WBC (White Blood Corpuscles).

Hypertrophy of Heart: With regular exercise the hypertrophy of heart take place. With this effect, there is an increase in stroke volume and cardiac output.

Question 3:

What are the important functions of our skeletal system? [Delhi Outside 2015]

Answer 3:

Important functions of skeletal system

The hard and rigid structure of bone makes the skeletal system to act as a framework, which supports the body and gives it a shape. The major functions are as follows:

(i) It serves as a supporting framework.

(ii) It acts as liner and allows the movement of the body.

(iii) It protects and supports many of the internal organs.

(iv) It releases calcium when there is lack of calcium in the body fluids.

(v) It produces, maintains and repairs itself.

(vi) It stores the marrow which produces the blood cells.

(vii) It provides surface for the attachment of skeletal muscles.

(Explain any three)

Question 4:

What are the various factors affecting physiological fitness? Explain. [All India 2015]

Answer 4:

The following are the factors that affect the physiological fitness:

Anatomical structure: An individual must be appropriate in body size, shape and structure essential for the performance. Sometimes genetic impaired organs are responsible for weakness in structure which limits individual performance.

Psychological factors or stress tension: This can become a barrier to performance by contributing tension and anxiety which affect the fitness level of a person. One must be mentally tough/strong and prepared to perform better.

Climate: Physical fitness also gets influenced by different climatic conditions such as summer, winter and humid. Exercise must be done early morning or late evening. Drink plenty of fluid. Wear light loose fitting, comfortable clothes. In winter dress in layers. Stop if you experience dizziness, shivering, cramp, etc.

Diet: Plays an important role in maintaining physical fitness level. Diet requirement varies from individual to individual game wise. Therefore, while planning fitness programme diet factor must also be given due consideration.

Healthy surroundings: A healthy environment at home/school/playfields is helpful in proper growth and development of an individual which creates a better learning situation. There is a need for proper working environment for participation in sports activities, otherwise it will affect the fitness of individual.

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