1. Mammals respire by :
(a) Gills
(b) Trachea
(c) Skin
(d) Lungs
[M.P. P.C.S. (Pre) 2016]
Ans. (d) Lungs
- The lungs are the main organs used for breathing in mammals and most other animals with a spine.
- In mammals, there are two lungs located close to the spine on either side of the heart.
- The lungs take oxygen from the air and put it in the blood and take carbon dioxide from the blood and let it out into the air, which is a way of exchanging gases.
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2. The amount of which of the following components in the air does not change in the process of respiration?
(a) Carbon dioxide (CO2)
(b) Oxygen
(c) Water vapours
(d) Nitrogen
[R.A.S./R.T.S. (Pre) 2003]
Ans. (d) Nitrogen
- Breathing in and out is called respiration. It is something that all living things do.
- The air we breathe in is made up of five main gases – Nitrogen, Oxygen, Argon, Carbon Dioxide, and other small amounts of gases.
- As we breathe out, the same amount of nitrogen is released as was taken in when we breathed in.
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3. Oxygen transportation in a human body takes place through :
1. Blood
2. Lungs
3. Tissue
The correct sequence of transportation is :
(a) 1, 2, 3
(b) 3, 1, 2
(c) 2, 1, 3
(d) 1, 3, 2
[I.A.S. (Pre) 1997]
Ans. (c) 2, 1, 3
- Getting oxygen to the body’s cells requires three major
events:
• Uptaking oxygen from the air to the lungs;
• Transporting that oxygen in the blood;
• Delivering the oxygen to cells and tissues throughout the
body.
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4. Site of gaseous exchange in lungs is :
(a) Tracheoles
(b) Bronchioles
(c) Pulmonary vein
(d) Alveoli
[U.P. P.C.S. (Pre) 2021]
Ans. (d) Alveoli
- The respiratory system’s job is to transport oxygen and carbon dioxide. In the lungs, millions of alveoli and the capillaries around them exchange these two gases.
- Oxygen goes from the alveoli to the capillaries, and carbon dioxide goes from the capillaries to the alveoli.
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5. When there is a decrease in the concentration of oxygen in the blood, the rate of breathing :
(a) Decreases
(b) Increases
(c) Does not change
(d) First decreases, then increases
[U.P.P.C.S. (Pre) 2000]
Ans. (b) Increases
- The body needs a certain amount of oxygen in the blood to work correctly. When this amount is lower than normal, it’s called hypoxemia and can cause shortness of breath.
- This happens because there is less oxygen in the blood, which causes you to breathe faster.
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6. Carbon monoxide poisoning affects mainly which one of the following?
(a) Digestive activity
(b) Liver functioning
(c) Kidney functioning
(d) Oxygen carrying capacity of blood
[M.P.P.C.S. (Pre) 2012]
Ans. (d) Oxygen carrying capacity of blood
- Carbon monoxide harms people by combining with haemoglobin, a type of protein in the blood, to form carboxyhaemoglobin.
- This stops haemoglobin from taking oxygen to the body’s tissues, which leads to a lack of oxygen.
- It might also affect myoglobin and cytochrome oxidase in the mitochondria.
- Carboxyhaemoglobin can be changed back to haemoglobin, but it takes time because the HbCO complex is strong.
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7. Which one of the following biotransformations provides maximum energy to the human body?
(a) ADP ĺ AMP
(b) ATP ĺ ADP
(c) ADP ĺ ATP
(d) AMP ĺ ADP
[U.P.P.C.S. (Mains) 2015]
Ans. (b) ATP ĺ ADP
- Adenosine triphosphate (ATP) is a molecule that holds energy.
- Changing ATP into ADP is essential for giving energy for things like muscle movement, electrical work, and necessary building blocks of life.
- The energy from food or sunlight is turned into useful work by breaking down ATP.
ATP + H2
O → ADP + Pi + energy
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8. During respiration energy is produced in the form of :
(a) ADP
(b) ATP
(c) NADP
(d) CO2
[U.P. P.C.S. (Mains) 2016]
Ans. (b) ATP
- Respiration is a set of chemical reactions that happen in living cells.
- It turns energy from food into a form that the body can use (ATP) and also produces waste products.
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9. The complete conversion of glucose, in the presence of oxygen, into carbon dioxide and water with release of energy is called :
(a) Aerobic respiration
(b) Anaerobic respiration
(c) Glycolysis
(d) Hydrolysis
[I.A.S. (Pre) 1998]
Ans. (a) Aerobic respiration
- Aerobic respiration is the process of releasing energy from glucose or other organic substances when oxygen is present.
- During this process, glucose is changed into carbon dioxide and water, and a lot of energy is created. Animals and plants constantly use aerobic respiration in their cells.
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10. Which part of human body maintains the body temperature?
(a) Heart
(b) Lungs
(c) Liver
(d) Kidney
[M.P.P.C.S. (Pre) 1991]
Ans. (b) Lungs
- The lungs are the main organs of respiration, which keep the body temperature steady by taking in oxygen-rich air and releasing air full of carbon dioxide, a waste gas.
- This process also creates energy in the body’s tissues by burning food and evaporating the body’s water, which also helps keep the body’s temperature normal.
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