ICSE Solutions for Chapter 14 The Respiratory System Class 9 Biology Selina

Progress Check

1. Given below is the definition of respiration with a few blanks to be filled in. Write suitable words in the blanks:
Respiration is a process of releasing ____ by breaking down _____ for carrying out _____ processes.

Solution

Energy, glucose, life.

2. Write the overall chemical equation representing the above definition of respiration.

Solution

The chemical equation is as follows:

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy

3. In what form is the energy liberated in respiration?

Solution

A large part of the energy liberated is in the form of ATP (adenosine triphosphate).

4. Give two examples of life activities which need energy.

Solution

We need energy because:
• We require to synthesize proteins from amino acids
• Production of new cells and enzymes
• To keep the body warm

5. State whether the following statements are true(T) or false(F):

(i) Strenuous physical exercise may cause fatigue due to accumulation of CO₂ in the blood. T/F
(ii) No, CO₂ is produced in anaerobic respiration in the human body. T/F
(iii) Breathing and gaseous transport are and the same thing. T/F
(iv) CO₂ is transported to the lungs by the blood in two forms: as bicarbonates and as carbamino-haemoglobin. T/F
(v) Tissue respiration means chemical changes occurring inside the cell. T/F

Solution

(i) False. Strenuous physical exercise may cause fatigue due to accumulation of lactic acid in the blood.

(ii) True.

(iii) False. Breathing and gaseous transport are two separate processes.

(iv) True.

(v) The statement is true.

6. Match the items in Column I with those in Column II.

Column I	Column II
a) Nasal chamber	(i) Production of voice
b) Epiglottis	(ii) C-shaped rings
c) Air-sacs	(iii) Warms air
d) Lungs	(iv) Drives mucus
e)Larynx	(v) Closes wind-pipe during swallowing
f) Trachea	(vi) Network of capillaries
g) Cilia	(vii) Spongy and elastic

Solution

Column I	Column II
a)Nasal chamber	Warms air
b)Epiglottis	Closes wind-pipe during swallowing
c)Air-sacs	Network of capillaries
d)Lungs	Spongy and elastic
e)Larynx	Production of voice
f)Trachea	C-shaped rings
g)Cilia	Drives mucus

7. How do the following contribute in inspiration during breathing?
(i) Ribs
(ii) Diaphragm

Solution

The following is the contribution of these structures during breathing:

(i) Ribs – they move upwards and outwards
(ii) Diaphragm – contracts and flattens downwards

8. Match the lung capacities in Column I with the quantities given in Column II.

Column I	Column II
Residual air	4500 mL
Vital capacity	6000 mL
Total lung capacity	1500 mL
Dead air space	150 mL

Solution

Column I	Column II
Residual air	1500 mL
Vital capacity	4500 mL
Total lung capacity	6000 mL
Dead air space	150 mL

9. Mention any two points of difference in the quality of inspired and expired air.

Solution

Difference in the quality of inspired and expired air

Inspired air	Expired air
Amount of oxygen absorbed at the alveolar surface is 20.96%	Amount of oxygen absorbed at the alveolar surface is 16.4%
Amount of carbon dioxide released at the alveolar surface is 0.04%	Amount of carbon dioxide released at the alveolar surface is 4%

10. Give reasons for:

(i) People climbing to high altitudes may suffer from dizziness and unsteady vision.
(ii) Use of lime water in most experiments on respiration
(iii) Respiration rate is higher in animals than in plants.

Solution

(i) As we go up higher, the air we breathe decreases in pressure along with a gradual decrease in oxygen content. Lack of oxygen leads to dizziness and unsteady vision.

(ii) Lime water is used in most of the experiments on respiration as lime water turns milky in the presence of carbon dioxide.

(iii) Respiration rate is higher in animal than in plants because animals require more energy as compared to plants because animals move one place to another in search of food and water they are not stationary. Plants are stationary and requires less energy.

11. Given alongside is an experiment intended to demonstrate the action of diaphragm, but something has gone wrong.

(i) What is the mistake in the diagram? Explain.

Solution

(i) The mistake in the diagram is that when the sheet is pushed upwards, the volume of the rubber balloons inside the bell jar does not increase as shown in the diagram, instead it decreases. The pressure increases and the balloons should collapse as the air rushes out. The balloon represents the two lungs.

Review Questions

A. Multiple Choice Type

1. During inspiration, the diaphragm

(a) Relaxes
(b) Contracts
(c) Expands
(d) Gets folded

Solution

(b) Contracts
The diaphragm contracts and flattens downwards during inspiration.

2. The ultimate end parts of the respiratory system in humans is known as

(a) Alveoli
(b) Bronchioles
(c) Tracheoles
(d) Bronchi

Solution

(a) Alveoli
The bronchioles ultimately end in a cluster of tiny air chambers known as air sacs or alveoli.

3. During respiration there is

(i) Gain in dry weight
(ii) Loss in dry weight
(iii) No change in dry weight
(iv) Increase in the overall weight

Solution

(b) Loss in dry weight.
Respiration causes loss in dry weight.

B. Very short answer type

1. Choose the odd one out in each of the following groups of four items each:

(a) Trachea, Bronchus, Alveolus, Diaphragm
(b) Ethyl alcohol, Carbon dioxide, Starch, Oxygen absence
(c) Diffusion, Respiratory gases, Alveoli, Capillary network
(d) Trachea, ciliated epithelium, mucus, diffusion
(e) Oxyhaemoglobin, carbaminohaemoglobin, Hypoxia, Carboxyheamoglobin
(f) Hairy, Moist, Nostril, Vocal cord

Solution

(a) Diaphragm
(b) Ethyl alcohol
(c) Diffusion
(d) Diffusion
(e) Hypoxia
(f) Vocal cord

2. Name the body structure concerned with the given functional activity:

(a) Prevents food from entering the trachea during swallowing
(b) Transports oxygen to the body cells
(c) Helps to increase the volume of the chest activity lengthwise
(d) Combines with the oxygen in the lungs
(e) Protects the lungs from mechanical injuries
(f) Provides actual diffusion of respiratory gases in lungs.

Solution

(a) Prevents food from entering the trachea during swallowing – Epiglottis
(b) Transports oxygen to the body cells – Capillaries
(c) Helps to increase the volume of the chest activity lengthwise – Diaphragm
(d) Combines with the oxygen in the lungs – Bronchioles
(e) Protects the lungs from mechanical injuries – Ribs
(f) Provides actual diffusion of respiratory gases in lungs – Air sacs/alveoli

3. What is the normal percentage composition of gases in inspired air and expired air respectively?

Solution

The following table depicts the gas composition in percentage:

Name of the gas	Inspiration	Expiration
Oxygen	20.96%	16.4%
Carbon dioxide	0.04%	4%
Nitrogen	79.00%	79.6%

4. Which chemical compound inside a cell can be termed “Currency of Energy”.

Solution

ATP or Adenosine Triphosphate is termed as “Currency of Energy" of the cell.

5. Match the items in Column I with the ones most appropriate in Column II. Rewrite the matching pairs:

Column I	Column II
(a) Alveoli	(i) where aerobic respiration takes place
(b) Bronchioles	(ii) Lined with hair
(c) Nasal chamber	(iii) Diffusion of gases
(d) Bronchi	(iv) small air tubes
	(v) An inverted Y-shaped tube
	(vi) A common passage for food and air

Solution

Column I	Column II
Alveoli	Diffusion of gases
Bronchioles s	mall air tubes
Nasal chamber	Lined with hair
Bronchi	An inverted Y-shaped tube

C. Short Answer Type

1. Given below is an example of a certain structure and its special functional activity:
“Kidney and excretion”

Fill in the blanks on a similar pattern.

(a) Alveoli and ___
(b)Mitochondria and ___
(c) Epiglottis and ___
(d) Pleura and ___
(e) Diaphragm and ___
(f) ‘C’ shaped cartilage rings and ____

Solution

(a) Alveoli and gaseous diffusion
(b) Mitochondria and power house (respiration)
(c) Epiglottis and guard of entrance to trachea
(d) Pleura and lung covering
(e) Diaphragm and differentiate thoracic cavity and abdominal cavity
(f) 'C shaped cartilage rings and support

2. State one function of each of the following:

(a) Ciliated epithelium lining the respiratory tract
(b) Mitochondria
(c) Diaphragm
(d) Intercostal muscles
(e) Pleural fluid

Solution

(a) Ciliated epithelium: It is the protective Inner lining of the respiratory passage. It helps in motion, driving any fluid that is on them.

(b) Mitochondria: In mitochondria, pyruvic acid is further broken down step by step in a cyclic manner In the presence of oxygen.

(d) Intercostal muscles: The muscles help the inward and outward movement of ribs enlarging the chest cavity all around.

(e) Pleural fluid: It provides lubrication for free movement of the expanding and contracting lungs.

3. Match the items in Column A with those in Column B.

Column I	Column II
Cartilaginous	Epiglottis
Large surface area	Diaphragm
Breathing movements	Bronchi
Voice	Alveoli
Complemented air	larynx
Swallowing	Extra inhalation

Solution

Column I	Column II
Cartilaginous	Bronchi
Large surface area	Alveoli
Breathing movements	Diaphragm
Voice	Larynx
Complemented air	Extra inhalation
Swallowing	Epiglottis

4. Under what conditions would the breathing rate increase?

Solution

Breathing rate can increase under the following circumstances:

Accumulation of carbon dioxide in blood
• Vigorous physical exercise

5. How would you prove that the air you breathe out is warmer?

Solution

During breathing, the air expelled out is always warmer or at body temperature. It can be felt by breathing out the air on our own hand. One can feel the warmth of the air expelled out during breathing.

6. How is the respiratory passage kept free of dust particles?

Solution

T The nasal cavity is lined by ciliated epithelium and mucous glands. The mucous glands secrete mucous. The ciliated epithelium is present on the entire lining of larynx, trachea, bronchi and bronchioles. The constant motion of cilia and mucous trap dust, micro-organisms, pollen and other minute particles present in the air. In this way, the respiratory passage is kept free of dust particles.

7. What is wrong in the statement “We breathe in oxygen and breathe out carbon dioxide”?

Solution

We inhale air which contains more of oxygen and less of carbon dioxide. We exhale air which contains more of carbon dioxide and less of oxygen. Therefore, the statement "We breathe in oxygen and breathe out carbon dioxide" is wrong.

D. Long Answer Type

1. Differentiate between the following pairs on the basis of the aspect given in the brackets.

(a) Aerobic and anaerobic respiration (end products of the process)
(b) Respiration and photosynthesis (gas released)
(c) Photosynthesis and respiration (reactants)
(d) Inspired air and alveolar air (carbon dioxide content)
(e) Respiration and breathing (organs involved)
(f) Tidal volume and residual volume (quantity of air)

Solution

(a) Aerobic and anaerobic respiration (end products of the process)

Aerobic respiration	Anaerobic respiration
CO₂, H₂O, ATP, Heat energy	Lactic acid, ATP, heat energy

(b) Respiration and photosynthesis (gas released)

Respiration	Photosynthesis
CO₂	O₂

Photosynthesis	Respiration
CO₂ + sunlight + H₂O	Glucose (with or without oxygen)

(d) Inspired air and alveolar air (carbon dioxide content)

Inspired air	Alveolar air
0.04%	4%

(e) Respiration and breathing (organs involved)

Respiration	Breathing
Lungs, bronchi, alveoli	Nasal cavity, trachea, diaphragm

(f) Tidal volume and residual volume (quantity of air)

Tidal volume	Residual volume
500mL	1500mL

2. Give suitable explanations for the following:

(a) Breathing through the nose is said to be healthier than through the mouth.
(b) Why does gaseous exchange continue in the lungs even during expiration?
(c) Why does a person feel breathlessness at higher altitudes?
(d) Why do you shiver and why do your teeth chatter when it is very cold in winter?

Solution

(a) Breathing through the nose is said to be healthier than through the mouth because the hair present in the nostrils prevent large dust particles from entering inside the respiratory system.

(b) Gaseous exchange continues in the lungs even during expiration because expiration is the result of reverse movements of the ribs and diaphragm. As consequence of the movements of the ribs and the diaphragm, the thoracic cavity is diminished and the lungs are compressed, forcing the air out into the atmosphere.

(d) We shiver and our teeth chatter when it is very cold in order to increase the heat production in the body. To maintain the temperature of the body constant in extremely cold conditions, the production of heat is increased through heightened metabolic rate and greater muscular activity and shivering and teeth chattering involves a lot of muscular activity.

3. With regard to the respiratory system and the process of respiration in man, answer the following questions:

(a) Name any two muscles that help in breathing.
(b) Briefly describe how the above mentioned muscles help in the inspiration of air.
(c) Give the overall chemical equation to represent the process of respiration in humans.
(d) What is meant by:

Residual air
Dead air space

Solution

(a) (i) Abdominal muscles (ii) Intercostal muscles

(b) (i) The ribs are moved inwards and outwards by the intercostal muscles stretched between them and thereby, enlarges the chest cavity.
(ii) The diaphragm flattens and presses the organs inside the abdomen. When the abdominal muscles relax, the abdominal wall moves outwards.

(d) 1. Residual air: Some air is always left in the lungs even after forcibly breathing out. This is the left over or residual air. This volume is 1500 mL.

Dead air space: Some tidal air is left in the respiratory passages such as trachea and bronchi, where no diffusion of gases can occur. This volume is called dead air space. It is 150 mL.

4. Starting from the nostrils, trace the path in sequence which the transpired air takes until it reaches the air sacs.

Solution

The path taken by the transpired air through the nostrils until it reaches the air sacs is as follows:

Nose→ Pharynx →Larynx →Trachea →Bronchi

5. What are the functions of the following in breathing?

(a) Ribs
(b) Diaphragm
(c) Abdominal muscles

Solution

(a) Ribs: The ribs move inwards and outwards by the muscles stretched between them, thus enlarging the chest cavity all around.

(b) Diaphragm: On contraction, the diaphragm falls or flattens from the dome-shaped outline to an almost horizontal plane and thus, contributes to the enlargement of the chest cavity lengthwise.

(c) Abdominal muscles: Abdominal muscles help to increase the size of the thoracic cavity by the movement of diaphragm and therefore, aids in inspiration.

E. Structured/Application/Skill Type

1. Given alongside is a diagrammatic sketch of a part in human lungs

(i) Name the parts numbered 1-4
(ii) What do the arrows 5 and 6 indicate?

Solution

(i) 1: Thin walls of capillary;
2: RBCs (Red blood corpuscles);
3: Plasma;
4: Thin wall of the alveolus

(ii) 5: CO₂diffuses out; 6: O₂ diffuses in

2. Given below is an overall chemical reaction of a certain process:

C₆H₁₂O₆ + lactic acid → 2ATP+ heat energy
(a) Name the process.
(b) Is this reaction applicable to animals or to plants or to both animals and plants?
(c) Name one tissue in which this reaction may occur.

Solution

(a) Anaerobic respiration

(b) This reaction is applicable to animals only.

3. Given below are chemical reactions (1 to 5) involving glucose and five other chemical products (A-E).

(a) Write the reaction number of the following:
(i) Anaerobic respiration in plants ____
(ii) End-products in aerobic respiration ____
(iii) Reaction occurring in liver ____
(iv) Anaerobic respiration in animals ___
(v) Storage in the liver ________

(b) Which reactions (1-5) in the above correspond to the following (write the corresponding number of reaction next to them).
(i) Aerobic respiration
(ii) Change taking place in the liver
(iii) Anaerobic respiration in yeast
(iv) Change taking place in a plant storage organ – e.g. potato.
(v) Anaerobic respiration in animals

Solution

(a) (i) Anaerobic respiration in plants: 5
(ii) End products in aerobic respiration: 4
(iii) Reaction occurring in liver: 2
(iv) Anaerobic respiration in animals: 1
(v) Storage in the liver: 3

(b) (i) Aerobic respiration: 4
(ii) Change taking place in the liver: 3
(iii) Anaerobic respiration in yeast: 5
(iv) Change taking place in a plant storage organ, e.g., potato: 2
(v) Anaerobic respiration in animals: 1

4. The volume of air in the lungs and the rate at which it is exchanged during inspiration and expiration was measured.
The following diagram shows a group of the lung volumes and capacities:

Study the diagram carefully and explain briefly the following:
(a) Tidal volume
(b) Inspiratory reserve volume
(c) Expiratory reserve volume
(d) Vital capacity
(e) Residual volume

Solution

(a) Tidal volume (TV): Air breathed in and out, in a normal quiet breathing is called tidal volume. It is 500 mL.

(b) Inspiratory reserve volume (IRV): Air that can be drawn in forcibly over and above the tidal air is called inspiratory reserve volume. It is also known as complemental air. It is 3000 mL.

(c) Expiratory reserve volume (ERV): Air that can be forcibly expelled out after a normal expiration is called expiratory reserve volume. It is also called supplemental air. It is 1000 mL.

(d) Vital capacity (VC): Volume of air that can be taken in and expelled out by maximum inspiration and expiration is called vital capacity. It is 4500 mL.

(e) Residual volume (RV): Air left in the lungs, even after forcible expiration is called residual volume. It is 1500 mL.

ICSE Solutions for Chapter 14 The Respiratory System Class 9 Biology Selina

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Selina Concise Ch 14 The Respiratory System ICSE Solutions Class 9 Biology

ICSE Solutions for Chapter 14 The Respiratory System Class 9 Biology Selina

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