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BIOLOGY 2 Marks Questions

Breathing and Exchange of Gases · Rajasthan Board (RBSE) STD 11 Science (Rajasthan - English Medium). 55 questions.

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Question 12 Marks
Define vital capacity. What is its significance?
Answer
Vital capacity is the maximum volume of air that can be exhaled after a maximum inspiration. It is about 3.5 – 4.5 liters in the human body. It promotes the act of supplying fresh air and getting rid of foul air, thereby increasing the gaseous exchange between the tissues and the environment.
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Question 22 Marks
Distinguish between:
Inspiratory capacity and Expiratory capacity.
Answer
 
Inspiratory capacity
(IC)
 
Expiratory capacity
(EC)
1.
It is the volume of air that can be inhaled after a normal expiration.
1.
It is the volume of air that can be exhaled after a normal inspiration.
2.
It includes tidal volume and inspiratory reserve volume.
IC = TV + IRV
2.
It includes tidal volume and expiratory reserve volume. 
EC = TV + ERV
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Question 32 Marks
What will be the pO2 and pCO2 in the atmospheric air compared to those in the alveolar air?
  1. pO2 lesser, pCO2 higher.
  2. pO2 higher, pCO2 lesser.
  3. pO2 higher, pCO2 higher.
  4. pO2 lesser, pCO2 lesser.
Answer
  1.  pO2 higher, pCO2 lesser

Solution:

Air that has entered the alveoli through the bronchioles is called alveolar air. It has the same partial pressure of CO2 and O2 as is in the atmospheric air. Then, there occurs gaseous exchange between the adjacent blood capillaries and the alveoli. CO2 diffuses from blood into the alveolar air and O2 diffuse from alveolar air to the blood. As a result, new alveolar air has higher pCO2 and lesser pO2, than the atmospheric air. 

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Question 42 Marks
Distinguish between:
IRV and ERV
Answer
 
Inspiratory reserve volume
(IRV)
 
Expiratory reserve volume (ERV)
1.

It is the maximum volume of air that can be inhaled after a normal inspiration.

 1.

It is the maximum volume of air that can be exhaled after a normal expiration.
2. It is about 2500 – 3500 mL in the human lungs. 2. It is about 1000 – 1100 mL in the human lungs.
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Question 52 Marks
Distinguish between:
Vital capacity and Total lung capacity.
Answer
 
Vital capacity
(VC)
 
Total lung capacity
(TLC)
1.
It is the maximum volume of air that can be exhaled after a maximum inspiration. It includes IC and ERV.
1.
It is the volume of air in the lungs after maximum inspiration. It includes IC, ERV, and residual volume.
2.
It is about 4000 mL in the human lungs.
2.
It is about 5000 – 6000 mL in the human lungs.
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Question 62 Marks
State the volume of air remaining in the lungs after a normal breathing.
Answer
The volume of air remaining in the lungs after a normal breathing is called Functional residual capacity (FRC). This includes expiratory reserve volume (ERV) and residual volume (RV). ERV=1000 to 1100 ml.
RV = 1100 to 1200 ml.
Thus, FRC = 2100 to 2300 ml.
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Question 72 Marks
What is Tidal volume? Find out the Tidal volume (approximate value) for a healthy human in an hour.
Answer
Tidal volume is the volume of air inspired or expired with each normal breath. This is about 500 mL in an adult person. It is composed of about 350 mL of alveolar volume and about 150 mL of dead space volume. The alveolar volume consists of air that reaches the respiratory surfaces of the alveoli and engages in gas exchange.
The dead space volume consists of air that does not reach the respiratory surfaces.
A healthy man can inspire or expire approximately 6000 to 8000 mL of air per minute. Therefore, tidal volume for a healthy human in an hour is 360 – 480 mL of air.
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Question 82 Marks
What is the site of gaseous exchange in an insect?
Answer
In insects, gaseous exchange occurs through a network of tubes collectively known as the tracheal system. The small openings on the sides of an insect’s body are known as spiracles. Oxygen-rich air enters through the spiracles. The spiracles are connected to the network of tubes. From the spiracles, oxygen enters the tracheae. From here, oxygen diffuses into the cells of the body.
The movement of carbon dioxide follows the reverse path. The CO2 from the cells of the body first enters the tracheae and then leaves the body through the spiracles.
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Question 92 Marks
In normal breathing, which is the active process inspiration or expiration Explain. 
Answer
In normal breathing, inspiration is an active process as it is brought about by the contraction of diaphragm and external intercostal muscles, while expiration is a passive process as it simply involves relaxation of inspiratory muscles.
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Question 102 Marks
Give two examples of each of the following:
  1. Animals having internal gills.
  2. Animal groups showing tracheal respiration.
  3. Anaerobes.
Answer
  1. Fishes and Pita, etc.
  2. Insects, centipedes and millipedes, etc.
  3. Certain bacteria, parasitic worms (e.g., Ascaris and  tapeworm), etc.
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Question 112 Marks
Give a chart of partial pressure of oxygen and carbon dioxide at different places in the respiratory system:
Answer
Partial Pressure of Gases Compared to Atmospheric Pressure
Respiratory Gases Atmospheric Air Alveoli Blood (Deoxygrnated) Blood (Oxygenated) Tissue
O2 159 104 40 95 40
CO2 0.3 40 45 40 45

 

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Question 122 Marks
  1. What prevents the trachea and the bronchi from collapsing?
  2. Name the epithelium and the cells present in the walls of trachea, bronchi and bronchioles.
Answer
  1. Cartilaginous rings are incomplete from behind which  supports the walls of the trachea and the bronchi to prevent them from collapsing.
  2. Pseudostratirted ciliated columnar epithelium is rich in mucus secreting cells.
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Question 132 Marks
  1. When does inspiration take place?
  2. When does expiration take place?
Answer
  1. Inspiration occurs when the intra-pulmonary pressure is lower than the atmospheric pressure.
  2. Expiration occurs when the intra-pulmonary pressure is higher than the atmospheric pressure.
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Question 142 Marks
Name the factors that affect the binding of oxygen to haemoglobin to form oxyhaemoglobin.
Answer
  1. Partial pressure of oxygen.
  2. Partial pressure of carbon dioxide.
  3. Hydrogen ion concentration.
  4. Temperature.
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Question 152 Marks
In what form is oxygen carried in the red blood cells? What happens to this form when the blood reaches the tissues?
Answer
  1. Oxygen is carried as oxyhaemoglobin in the RBCs.
  2. When the blood reaches the tissues, whose PO2 is much lower than the blood in the blood vessel, the oxyhaemoglobin dissociates and releases the oxygen into the tissues.
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Question 162 Marks
Why do workers in industries that involve grinding or breaking of stones suffer from inflammation of lungs? How can they be protected?
Answer
  1. In such industries, the production of dust is so much that the defence mechanism of the body cannot cope with the situation.
  2. The workers should wear protective masks to avoid the dust getting into the respiratory system.
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Question 172 Marks
Explain two steps in respiration.
Answer
Two steps of respiration:

  1. Inspiration. When the intrapulmonary pressure is less than the atmospheric pressure then air is inspired

  2. Expiration. When the intrapulmonary pressure is more than the atmospheric pressure then air is expired.

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Question 182 Marks
How does diaphragm help in inspiration?
Answer
  1. The contraction of diaphragm initiates inspiration, as it increases the volume of the thoracic chamber in the antero-posterior axis.
  2. Hence, the intra-pulmonary air pressure decreases to less than the atmospheric pressure; hence, air from outside moves into the lungs.
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Question 192 Marks
Explain the conducting part of the human respiratory system.
Answer
Conducting Part of Respiratory System: The part of respiratory system, starting with the external nostrils up to the terminal bronchioles, constitutes the conducting part. The conducting part transports the atmospheric air to the alveoli, clears it from foreign particles, humidifies and also brings the air to body temperature.
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Question 202 Marks
Mention the cause and the symptoms of Asthma and Emphysema.
Answer
Asthma:

  1. It is due to inflammation of bronchi and bronchioles.
  2. Difficulty in breathing and wheezing are its symptoms.

Emphysema:

  1. It is caused mainly by cigarette smoking.
  2. The alveolar walls are damaged and hence, there is a decrease in the respiratory surface for exchange of gases.
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Question 212 Marks
Differentiate between oxyhaemoglobin and carbaminohaemoglobin.
Answer
Differences between oxyhaemoglobin and carbaminohaemoglobin are:
S.No.
Oxyhaemoglobin
Carbaminohaemoglobin
(i)
It is formed by the combination of oxygen with the Fe2+ part of haemoglobin.
It is formed by the combination of CO2 with the amino group of haemoglobin.
(ii)
Its formation occurs on the alveolar surface.
Its formation occurs in the tissues.
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Question 222 Marks
Give the values of each of the following:
  1. PO2 of:
  1. Alveolar air.
  2. Oxygenated blood and til.
  3. A metabolically active tissue.
  1. PCO2 of:
  1. Alveolar air.
  2. Deoxygenated blood.
  3. Oxygenated blood.
Answer
  1.  
  1. 104mm Hg.
  2. 95mm Hg.
  3. 40mm Hg.
  1.  
  1. 40mm Hg.
  2. 45mm Hg
  3. 40mm Hg.
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Question 232 Marks
Why does oxygen diffuse into the blood capillaries in the lungs, but out of the blood capillaries in the tissues?
Answer
  1. The partial pressure of oxygen (PO­2) of the alveolar air (104mm Hg) is higher than that of the blood (40mm Hg); so oxygen diffuses into the blood vessels in the lungs.
  2. In the tissues, the partial pressure of oxygen (40mm Hg) is less than that of blood (95mm Hg) in the blood vessels; hence, oxygen diffuses out of the capillaries into the tissues.
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Question 242 Marks
The lungs are situated in the thoracic chamber, which is anatomically an air-tight chamber. How is it formed? Why is such a set-up necessary?
Answer
  1. The thoracic chamber is formed dorsally by the vertebral column, ventrally by the sternum, laterally by the ribs and on the lower side by the dome-shapec diaphragm.
  2. It is necessary because any change in the volume of thoracic cavity will be reflected in the pulmonary cavity.
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Question 252 Marks
What are occupational respiratory disorders? What happens in this disorder?
Answer
  1. Occupational disorders are those respiratory disorders caused by the potentially harmful substances/ pollutants present in the air, where a person works. In work places involving breaking or grinding of stones, there is so much of pollutants/ dust that the immune system of the body cannot cope with the situation.
  2. Long exposure to such pollutants leads to inflammation and fibrosis of the lungs and lung damage.
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Question 262 Marks
How is residual volume different from functional residual capacity?
Answer
  Residual Volume Functional Residual Capacity
1 It is the volume of air left in the lungs after forceful expiration. It is the volume of air left in the lungs after normal effortless expkation.
2 This is about 1100-1200ml. It includes RV + ERV = 1100 + 1100ml.
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Question 272 Marks
What is fibrosis in lungs? How is it caused?
Answer
  1. Proliferation of fibrous tissues of lungs due to inflammation, is called fibrosis.
  2. The inflammation may be caused by the pollutants in one's working place, especially cement or glass factories, coal mines, etc.
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Question 282 Marks
Why does CO2 diffuse into the blood vessels in the tissues, but diffuse out of the blood vessels into the alveoli in the lungs?
Answer
  1. In the tissues, the PCO2 (45mm Hg) is higher than that in the blood vessels (40mm Hg); hence, CO2 diffuses into the blood vessels.
  2. In the alveoli; the PCO2 of blood in the blood vessels (45mm Hg) is higher than that of alveolar air, (40mm Hg); hence, CO2 diffuses out of the blood vessels into the alveoli.
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Question 292 Marks
Why is it not advisable to sleep in closed rooms warmed with burning of coals continuously?
Answer
A person sleeping in such room gets carbon monoxide poisoning. CO combines with Hb more readily than oxygen forming carboxyhaemoglobin. This reduces the amount of free rib available for carrying O2. Thus, the tissue is starved of O2. This is the reason why it is not advisable to sleep in closed rooms warmed with coals.
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Question 302 Marks
Mention the components of the diffusion membrane of human respiratory system. What is its total thickness?
Answer
Diffusion membrane consists of:

  1. Squamous epithelium of alveoli.
  2. Endothelium of alveolar capillaries.
  3. Basement membranes between the two.

It's about 0.2mm in thickness.

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Question 312 Marks
How does haemoglobin help in the transport of oxygen from lung to tissues?
Answer
Haemoglobin combines with O2 in a reversible manner to form oxyhaemoglobin.

This oxygenated blood circulates in the body. When, it reaches the tissues having low pO2 , the oxygen is released into the tissues.

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Question 322 Marks
Name the factors that favour the dissociation of oxyhaemoglobin in the tissues.
Answer
Dissociation of oxyhaemoglobin is favoured by:
  1. Low partial pressure of oxygen (PO2).
  2. High partial pressure of carbon dioxide (PCO2).
  3. High temperature.
  4. High H­+ concentration.
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Question 332 Marks
What is the role of carbonic anhydrase in humans?
Answer
Nearly 70% of CO2 enters the RBCs and reacts with water to form carbonic acid in the presence of enzyme carbonic anhydrase. This dissociates to form bicarbonate ions, which are circulated by plasma.
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Question 342 Marks
Give the condition of the following muscles during expiration:
  1. Diaphragm muscles.
  2. Internal intercostal muscles.
Answer
  1. The muscles of the diaphragm are in a relaxed position, making it convex.
  2. The internal intercostal muscles are contracting thus, pulling the ribs downward and inward.
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Question 352 Marks
Rahul's father bought an aquarium to home, while looking at the fishes, Rahul wondered that fishes, though small, can breathe efficiently in water. He wondered why do humans die of drowning. Next day, he asked his biology teacher about the same. The teacher explained that fishes have special respiratory organ, which allow them to breathe inside water. Rahul was amazed to know that even respiratory organs differ in different animal groups.
  1. Give the name of the respiratory organ of fishes.
  2. How do humans swim and breathe inside water?
  3. Give the name of the respiratory organ of humans.
  4. What values are displayed by Rahul?
Answer
  1. Fishes have gills as the respiratory organ (branchial respiration). It allows them to breathe inside water.They use dissolved oxygen in water.
  2. Swimmers resort to repeated deep inhalations and exhalations in rapid succession to store oxygen, so that they can swim under water.
  3. Respiratory organ of humans are lungs.
  4. Rahul is intelligent, good observer, concerned and inquisitive student.
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Question 362 Marks
Give the name of the three major layers of diffusion membrane.
Answer
  1. Thin squamous epithelium of alveoli.
  2. Endothelium of alveolar capillaries.
  3. Basement substance in between.
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Question 372 Marks
State the factors affecting the oxygen haemoglobin binding.
Answer
Factors that affect the oxygen haemoglobin binding are:
  1. Partial pressure of oxygen.
  2. Partial pressure of carbon dioxide.
  3. Hydrogen ion concentration.
  4. Temperature.
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Question 382 Marks
How marine mammals are able to make long underwater dives? Explain.
Answer
Marine mammals (e.g., seals and whales) can make long underwater dives as they have more blood per kg of body weight can store more oxygen in blood and muscles have a large spleen with blood can reduce O2 consumption rate when underwater.
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Question 392 Marks
  1. What is partial pressure of a gas?
  2. List two factors which affect the rate of diffusion of a gas.
  3. Delhi is a highly polluted city and there is a rise in the number of individuals experiencing difficulty in breathing due to inflammation of bronchi and bronchioles. Name the disorder.
Answer
  1. The pressure contributed by an individual gas in a mixture of gases, is called the partial pressure of a gas.
  2. The factors affecting rate of diffusion include.
  1. Solubility of the gas.
  2. Thickness of the membrane.
  1. It is asthma.
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Question 402 Marks
Name the important parts involved in creating a pressure gradient between lungs and the atmosphere during normal respiration.
Answer
Diaphragm and external and internal intercostals muscles of ribs are the important parts involved in creating a pressure gradient between lungs and the atmosphere during normal respiration.
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Question 412 Marks
Differentiate between.
Emphysema and occupational respiratory disorder.
Answer
The differences between emphysema and occupational respiratory disorder are as follows:
 
Emphysema
Occupationl respiratory disorder
(i)
It is a chronic disorder in which alveoler walls are damaged and respiratory surface is reduce.
It is caused by proliferation of fibrous connective tissue of upper part of lung.
(ii)
One of the major causes of this is cigarette smoking.
It is due to exposure to harmful substances, gas fumes, dust etc.
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Question 422 Marks
Human beings have a significant ability to maintain and moderate the respiratory rhythm to suit the demands of the body tissues. How is it achieved?
Answer
The regulation of rate of respiration is carried out by the centres present in the brain (neural system) and also by centres outside the brain:
  1. By centres in the brain:
  1. Respiratory rhythm centre in the medulla is primarily responsible for regulation.
  2. Pneumotaxic centre present in the pons moderates the functioning of the respiratory rhythm centre; signals from this centre can reduce the duration of inspiration and alter the rate of respiration.
  3. Chemosensitive area in the medulla can sense changes in the CO2 and H+ concentration and send signals to rhythm.
  1. By centres outside the brain:
  1. Receptors in the aortic arch and recognise and send necessary signals for remedial action.
  2. Receptors in the carotid artery.
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Question 432 Marks
Differentiate between oxy haemoglobin and carbaminohaemoglobin.
Answer
Differences:
 
Oxyhaemoglobin
Carbaminohaemoglobin
1
It is a compound formed when oxygen binds to the ferrous atoms of haemoglobin.
It is a compound formed when CO2 binds to the globin part of haemoglobin.
2
It is formed in the alveolar surface and dissociates in the tissues.
It is formed in the tissues and dissociates in the alveolar surface.
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Question 442 Marks
Differentiate between.
Inspiratory and expiratory reserve volume.
Answer
The differences between inspiratory reserve volume and expiratory reserve volume are as follows:
  Inspiratory reserve volume Expiratory reserve volume
(i) It is additional volume of air a person can inspire by a forcible inspiration after normal inspiration. It is additional volume of air a person can expire by forcible expiration after normal expiration.
(ii) It averages 2500 - 3000ml of air. It averages 1000 - 1100ml of air.
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Question 452 Marks
State the route of foul air from the lungs to outside. Also state whether TV increases or decreases during excitement and activity.
Answer
The foul air follows the route given below:
Alveoli→ Alveolar ducts → Bronchioles → Bronchi→ Trachea → Larynx → Glottis Pharynx → Internal nares →Nasal chambers → 4 External nares → Atmosphere.
The tidal volume increases 4-10 times during excitement and activity.
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Question 462 Marks
Why is breathing of women regarded as thoracic, while that of male as abdominal? Also state who among the two has higher vital capacity.
Answer
In males, the lateral movement of thorax constitutes 25% of breathing, while the abdominal movement accounts for 75% breathing. Thus, it is regarded as abdominal breathing.
In women, particularly in pregnant women, the entire breathing is through lateral movement of thorax. Thus, breathing in women is regarded as thoracic.
The VC is higher in men than in women and in the young ones than in the old persons.
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Question 472 Marks
What is partial pressure of a gas?
Answer
The pressure contributed by an individual gas in a mixture of gases, is called partial pressure of gases.
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Question 482 Marks
How is CO2 transported in human body?
Answer
CO2 is transported in the human body in the following ways:
  1. In dissolved form about 7%.
  2. As bicarbonate ions about 70%.
  3. As carbaminohaemoglobin about 20-25%.
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Question 492 Marks
Compared to O2, diffusion rate of CO2 through the diffusion membrane, unit difference in partial pressure is much higher. Explain.
Answer
Solubility is an important factor deciding diffusion rate. As the solubility of CO2 is 20-25 times higher than O2, diffusion of CO2 through the diffusion membrane per unit difference in partial pressure is much higher.
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Question 502 Marks
Differentiate between.
Vital capacity and total lung capacity.
Answer
The differences between vital capacity and total lung capacity are as follows:
  Vital capacity Total lung capacity
(i) It is the maximum volume of air a person can breathe in after a forced expiration of the maximum volume of air a person can breathe out after a forced inspiration. It is the total volume of air accomodated in the lungs and respiratory passage after forced inspiration.
(ii) It is sum of tidal volume, inspiratory reserve volume and expiratory reserve volume. It is sum of vital capacity and residual volume.
(iii) It averages 3400 - 4800 ml. Il averages 4500 - 6200ml.
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Question 512 Marks
Which of the regulatory centre of respiration can reduce the inspiratory duration when it is stimulated?
Answer
Respiratory process is regulated by certain specialised, centres present in hindbrain. Amongst them, pneumotaxis centre is located in the dorsal part of pons varoli of the brain, can reduce the duration of inspiration and thus, alter the respiratory rate.
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Question 522 Marks
What makes carbon monoxide more harmful to animals than carbon dioxide?
Answer
Haemoglobin consists of a protein globin and pigment haem. The four portions of iron in haem combine with molecule of oxygen. It is an easy reversible reaction to form oxyhaemoglobin.
$\text{Hb}+\text{O}_2\rightleftharpoons\text{HbO}_2$
Whereas, the complex formed by the reaction of carbon monoxide and haemoglobin is incredibly strong:
$\begin{matrix}\text{Hb}+\text{CO}\xrightarrow{\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ }\text{HbCO}\\^\text{(Haemoglobin)}\ ^\text{(Carboxy haemoglobin)}\end{matrix}$
As a result of this strong bonding between the haemoglobin and carbon monoxide, the haemoglobin looses its affinity to oxygen thus, may lead to choking or even death.
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Question 532 Marks
Write about Haldane effect. How does Haldane effect and Bohr effect complement each other?
Answer
Haldane effect states that binding of oxygen with haemoglobin tends to displace CO, from the blood. It is quantitatively more important in promoting CO2 transport than the Bohr effect in O2 transport. Thus, Haldane effect and Bohr effect complement each other.
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Question 542 Marks
State the different modes of CO2 transport in blood.
Answer
A major part (70%) of carbon dioxide is transported in the form of bicarbonate, 20-25% of CO2 is transported through haemoglobin by the formation of carbamino-haemoglobin and the rest is transported by the plasma in the dissolved state.
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Question 552 Marks
What is the role of oxyhaemoglobin after releasing molecular oxygen in the tissues?
Answer
Amino group of reduced haemoglobin combines with CO2, forming carbaminohaemoglobin to transport CO2.
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