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

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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 + 6 O₂ 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):
   1. Strenuous physical exercise may cause fatigue due to accumulation of CO₂ in the blood. T/F
   2. No CO₂ is produced in anaerobic respiration in the human body. T/F
   3. Breathing and gaseous transport are and the same thing. T/F
   4. CO₂ is transported to the lungs by the blood in two forms: as bicarbonates and as carbamino-haemoglobin. T/F
   5. Tissue respiration means chemical changes occurring inside the cell. T/F

   Solution:

   1. The statement is false. Strenuous physical exercise may cause fatigue due to accumulation of lactic acid in the blood.
   2. The statement is true.
   3. The statement is false. Breathing and gaseous transport are two separate processes.
   4. The statement is true.
   5. The statement is true.
6. Match the items in Column I with those in Column II.
   

   Column I	Column I
   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 I
   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?
   1. Ribs
   2. Diaphragm

   Solution:

   The following is the contribution of these structures during breathing:

   1. Ribs – they move upwards and outwards
   2. Diaphragm – contracts and flattens downwards
8. Match the lung capacities in Column I with the quantities given in Column II.
   

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

   Solution:

   Column I	Column I
   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:

   Listed below are the differences:

   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:
    1. People climbing to high altitudes may suffer from dizziness and unsteady vision.
    2. Use of lime water in most experiments on respiration
    3. Respiration rate is higher in animals than in plants.

    Solution:

    1. 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.
    2. Lime water is used in most of the experiments on respiration as lime water turns milky in the presence of carbon dioxide.
11. Given alongside is an experiment intended to demonstrate the action of diaphragm, but something has gone wrong.
    1. What is the mistake in the diagram? Explain.

    

    Solution:

    1. 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.

Multiple Choice Type

1. During inspiration, the diaphragm
   1. Relaxes
   2. Contracts
   3. Expands
   4. 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
   1. Alveoli
   2. Bronchioles
   3. Tracheoles
   4. 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
   1. Gain in dry weight
   2. Loss in dry weight
   3. No change in dry weight
   4. Increase in the overall weight

   Solution:

   b)Loss in dry weight.

   Respiration causes loss in dry weight.

Very short answer type

1. Choose the odd one out in each of the following groups of four items each:
   1. Trachea, Bronchus, Alveolus, Diaphragm
   2. Ethyl alcohol, Carbon dioxide, Starch, Oxygen absence
   3. Diffusion, Respiratory gases, Alveoli, Capillary network
   4. Trachea, ciliated epithelium, mucus, diffusion
   5. Oxyhaemoglobin, carbaminohaemoglobin, Hypoxia, Carboxyheamoglobin
   6. Hairy, Moist, Nostril, Vocal cord

   Solution:

   1. Diaphragm
   2. Ethyl alcohol
   3. Diffusion
   4. Diffusion
   5. Hypoxia
   6. Vocal cord
2. Name the body structure concerned with the given functional activity:
   1. Prevents food from entering the trachea during swallowing
   2. Transports oxygen to the body cells
   3. Helps to increase the volume of the chest activity lengthwise
   4. Combines with the oxygen in the lungs
   5. Protects the lungs from mechanical injuries
   6. Provides actual diffusion of respiratory gases in lungs.

   Solution:

   1. Prevents food from entering the trachea during swallowing – Epiglottis
   2. Transports oxygen to the body cells – Capillaries
   3. Helps to increase the volume of the chest activity lengthwise – Diaphragm
   4. Combines with the oxygen in the lungs – Bronchioles
   5. Protects the lungs from mechanical injuries – Ribs
   6. 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 – adenosine triphosphate

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

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

   Solution:

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

Short Answer Type

1. 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.

1. 1. 1. Alveoli and ___________
      2. Mitochondria and ___________
      3. Epiglottis and ___________
      4. Pleura and ___________
      5. Diaphragm and ___________
      6. ‘C’ shaped cartilage rings and __________

Solution:

1. 1. Alveoli and gaseous diffusion
   2. Mitochondria and powerhouse
   3. Epiglottis and Trachea(guard of entrance)
   4. Pleura and Lung covering
   5. Diaphragm and Distinguishes abdominal cavity and thoracic cavity
   6. ‘C’ shaped cartilage rings and support
2. State one function of each of the following:
   1. Ciliated epithelium lining the respiratory tract
   2. Mitochondria
   3. Diaphragm
   4. Intercostal muscles
   5. Pleural fluid

   Solution:

   1. Ciliated epithelium lining the respiratory tract – it forms the protective inner thing of the respiratory passage and assists in motion, driving any fluid that is on them
   2. Mitochondria – In the presence of oxygen, pyruvic acid is disintegrated stepwise in a cyclic manner.
   3. Diaphragm – It causes the enlargement of the chest cavity in length.
   4. Intercostal muscles – it facilitates the downward and upward rib movement causing the enlargement of the chest cavity all around.
   5. Pleural fluid – It renders lubrication for free movement of the contracting and expanding lungs.
3. Match the items in Column A with those in Column B.
   

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

   Solution:

   Column I	Column I
   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:

   The air that we breathe out is warmer or as per the temperature of the body as it can be felt when breathing out the air on your hands. We can feel the warmth of the air that is exhaled during breathing.

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

   The respiratory passage is kept free of dust particles as the nasal cavity is lined by ciliated epithelium and mucous glands which secretes mucus. This ciliated epithelium is present through the lining of the trachea, larynx, bronchioles and bronchi. The constant motion of mucous and cilia traps micro-organisms, dust, pollen and other tiny particles existing in the air.

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

   The statement is wrong. The air we inhale has more of oxygen and less of carbon dioxide. The air we exhale has higher concentration of carbon dioxide and lesser concentration of oxygen.

Long Answer Type

1. Differentiate between the following pairs on the basis of the aspect given in the brackets.
   1. Aerobic and anaerobic respiration (end products of the process)
   2. Respiration and photosynthesis (gas released)
   3. Photosynthesis and respiration (reactants)
   4. Inspired air and alveolar air (carbon dioxide content)
   5. Respiration and breathing (organs involved)
   6. Tidal volume and residual volume (quantity of air)

   Solution:

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

   Aerobic respiration	Anaerobic respiration
   Carbon dioxide, water, ATP, Heat energy	Lactic acid, ATP, heat energy

   b) Respiration and photosynthesis (gas released)

   Respiration	Photosynthesis
   Carbon dioxide	Oxygen

   c) Photosynthesis and respiration (reactants)

   Photosynthesis	Respiration
   Water, carbon dioxide, sunlight	Glucose (with/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:
   1. Breathing through the nose is said to be healthier than through the mouth.
   2. Why does gaseous exchange continue in the lungs even during expiration?
   3. Why does a person feel breathlessness at higher altitudes?
   4. Why do you shiver and why do your teeth chatter when it is very cold in winter?

   Solution:

   1. It is because the hair in the nostrils checks and prevents the large/tiny dust particles from entering the respiratory system.
   2. It is because expiration is the outcome of reverse movements of the diaphragms and ribs. As a result of the movements of the diaphragm and the ribs, the thoracic cavity shrinks and the lungs compress causing the air to be forced out of the body into the environment.
   3. A person feels breathlessness at higher altitudes because as we go up higher, the content of oxygen is lower in the air.
   4. 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:
   1. Name any two muscles that help in breathing.
   2. Briefly describe how the above mentioned muscles help in the inspiration of air.
   3. Give the overall chemical equation to represent the process of respiration in humans.
   4. What is meant by:
   5. 1. Residual air 2. Dead air space

   Solution:

   1. The two muscles that help in breathing are: intercostal muscles and abdominal muscles
   2. When the intercostal muscles stretch between the ribs, they move outwards and inwards causing them to enlarge the chest cavity.
   3. The overall chemical equation for the process of respiration in humans is as given below:
   4. 
   5. 1. Residual Air – Even after forcibly breathing out, some air always remains in the lungs. This air is referred to as residual air. The volume of this air is 1500mL.
      2. Dead air space – Some tidal air is remaining in the respiratory passages such as bronchi and trachea. Here no gas diffusion takes place. This volume is referred to as dead air space and its volume is 150mL.
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?
   1. Ribs
   2. Diaphragm
   3. Abdominal muscles

   Solution:

   The functions of the respective structures are as follows:

   1. Ribs – The intercostal muscles stretch between the ribs which causes its outward and inward movement which enlarges the chest cavity all around.
   2. Diaphragm – The diaphragm flattens from the dome-shaped outline to an almost horizontal plane upon contraction
   3. Abdominal muscles – it helps to increase the size of the thoracic cavity through the motion of the diaphragm which assists in inspiration.

Structured/Application/Skill Type

1. Given alongside is a diagrammatic sketch of a part in human lungs
   1. Name the parts numbered 1-4
   2. What do the arrows 5 and 6 indicate?

   

   Solution:

   1. The parts numbered 1-4 are:1 – thin walls of capillary

      2 – Red blood corpuscles

      3 – Plasma

      4 – Thin wall of alveoli

   2. Arrows at 5 & 6 indicate diffusion of carbon dioxide outside and diffusing of oxygen inside respectively.
2. Given below is an overall chemical reaction of a certain process:

   C₆H₁₂O₆ + lactic acid →2ATP+ heat energy

   1. Name the process.
   2. Is this reaction applicable to animals or to plants or to both animals and plants?
   3. Name one tissue in which this reaction may occur.

   Solution:

   1. The process is anaerobic respiration
   2. The reaction is applicable to animals only.
   3. The reaction may occur in muscular tissues
3. Given below are chemical reactions ( 1 to 5) involving glucose and five other chemical products (A-E).

   

   1. Write the reaction number of the following:
      1. Anaerobic respiration in plants _________
      2. End-products in aerobic respiration __________
      3. Reaction occurring in liver _________
      4. Anaerobic respiration in animals __________
      5. Storage in the liver ________
   2. Which reactions (1-5) in the above correspond to the following (write the corresponding number of reaction next to them).
      1. Aerobic respiration
      2. Change taking place in the liver
      3. Anaerobic respiration in yeast
      4. Change taking place in a plant storage organ – e.g. potato.
      5. Anaerobic respiration in animals

   Solution:

   1. The reaction number of the following are:
      1. Anaerobic respiration in plants – 5
      2. End-products in aerobic respiration – 4
      3. Reaction occurring in liver – 2
      4. Anaerobic respiration in animals – 1
      5. Storage in the liver – 3
   2. The corresponding reaction number is as follows:
      1. Aerobic respiration – 4
      2. Change taking place in the liver – 3
      3. Anaerobic respiration in yeast – 5
      4. Change taking place in a plant storage organ – e.g. potato – 2
      5. 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:

   1. Tidal volume
   2. Inspiratory reserve volume
   3. Expiratory reserve volume
   4. Vital capacity
   5. Residual volume

   Solution:

   1. Tidal volume – it is the air breathed in and out in a normal quiet breathing is known as tidal volume. The tidal volume(TV) is 500mL
   2. Inspiratory reserve volume – air that can be drawn in forcibly over and above the tidal air is known as inspiratory reserve volume. It is referred to as IRV or complemental air and is 3000mL.
   3. Expiratory reserve volume – it is the air that can be expelled out forcibly after a normal expiration. It is referred to as ERV or supplemental air and is 1000mL.
   4. Vital capacity (VC) – it is the volume of air that can be inhaled and exhaled by maximum inspiration and expiration respectively and is about 4500mL.
   5. Residual volume (RV) – Even after forcible expiration, there is some air left in the lungs and is referred to as residual volume. It is about 1500mL.

Selina Solutions for class 9 Biology Chapter 14 – The Respiratory System

ICSE Class 9 Biology Chapter 14 – The Respiratory System chapter is classified under Unit – V – Human anatomy and physiology. Human anatomy is the science of the different structures of the human body. The consequence of reductionist approach to study life forms caused an increase in the use of Physico-chemical techniques and concepts. Most of these studies employed either surviving straightaway cell-free systems or surviving tissue model. It deals with the major human physiological processes such as respiration, digestion, blood circulation, movement and locomotion are discussed in cellular and molecular terms.

Human anatomy and physiology discuss the chapters listed below in class 9:

• Nutrition
• Digestive system
• Skeleton – Movement and locomotion
• Skin – The jack of all trades
• The respiratory system.

The chapter – The respiratory system discusses the respiratory system in detail along with the organs, mechanism of breathing, tissue respiration and heat production.

The different types of questions that are covered in this chapter are:

• Multiple-choice questions
• State whether true/false
• Fill ups
• Short answer type questions
• Long answer type questions
• Match items in Column I & II
• Structured/application type of questions

List of subtopics covered in Chapter 14 – The Respiratory System

List of Exercise

Selina Solutions for class 9 Biology Chapter 14 – The Respiratory System

The unit discusses the different organs involved in carrying out the process of respiration along with the functions, working mechanism of these structures. Breathing is an essential part of the survival of living entities.

Two types of respiration such as aerobic and anaerobic respiration are discussed in detail so that students get a clear idea of the differences between both the processes in animals and plants. Respiration has different parts such as : Breathing, Gaseous transport, Tissue respiration, Cellular respiration

The different respiratory organs briefed are as follows:

• The nose
• The pharynx
• The larynx
• The trachea
• The bronchi

Lastly, students are enlightened about the blood supply mechanism to the lungs and the respiratory cycle in order to clearly understand the inspiration and expiration processes. Capacities of the lungs and experiments on breathing and respiration are also presented towards the end of the chapter.

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