Free Respiration MCQs with Answers
446 Respiration MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
The human respiratory system includes the air passages, lungs, alveoli and breathing muscles, while gaseous exchange explains how oxygen enters blood and carbon dioxide leaves it by diffusion. The effects of smoking include damage to cilia and alveoli, reduced gas exchange, chronic bronchitis, emphysema and increased risk of lung cancer.
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- A. Cancer
- B. Asthma
- C. Tuberculosis
- D. Emphysema
Explanation: Tuberculosis is an infectious respiratory disease caused mainly by Mycobacterium tuberculosis and can spread through airborne droplets.
Correct answer: Tuberculosis- A. I only
- B. II only
- C. I and III
- D. II and III
Explanation: The correct answer is I and III. Emphysema is primarily caused by long-term exposure to airborne irritants, including tobacco smoke and…
Correct answer: I and III- A. Lower levels of oxygen in the blood
- B. Higher levels of oxygen in the blood
- C. Lower levels of carbon dioxide in the blood
- D. No effect
Explanation: Emphysema can lead to decreased gas exchange efficiency in the lungs due to the destruction of alveoli.
Correct answer: Lower levels of oxygen in the blood- A. Bacterial infection
- B. Pollution
- C. Smoking
- D. Drinking
- E. Radiations
Explanation: Smoking is the most important cause of many respiratory disorders, including chronic bronchitis, emphysema, and lung cancer.
Correct answer: Smoking- A. Lungs
- B. Trachea
- C. Bronchus
- D. Body tissue
Explanation: The correct answer is the lungs. In the context of respiratory physiology, the lungs play a crucial role in gas exchange.
Correct answer: Lungs- A. I
- B. III
- C. I and III
- D. II and III
Explanation: The correct answer is Option B: IIIThe secretion of surfactant by the epithelial cells of alveoli is the main adaptation that prevents the…
Correct answer: III- A. A
- B. B
- C. C
- D. D
Explanation: The only artery with greater CO₂ concentration is the pulmonary artery, as it carries deoxygenated blood, so B is correct.
Correct answer: B- A. Low in tissues, high in lungs
- B. High in tissues, low in lungs
- C. Equal in tissues and lungs
- D. Varies independently of tissues and lungs
Explanation: The correct answer is that the relative oxygen concentration is low in body tissues and high in the lungs.
Correct answer: Low in tissues, high in lungs- A. High concentration of oxygen in blood
- B. Lower pressure of nitrogen in atmosphere
- C. Higher pressure of carbon dioxide in blood
- D. Low temperature of body in cold environment
Explanation: The correct answer is Option C:higher pressure of carbon dioxide in blood.This is because an increase in carbon dioxide levels in the…
Correct answer: Higher pressure of carbon dioxide in blood- A. Frog
- B. Hydra
- C. Cockroach
- D. Earthworm
Explanation: The correct answer is frog. Frogs have adapted to their environment by developing a moist skin that allows for cutaneous respiration…
Correct answer: Frog- A. Lungs
- B. Trachea
- C. Body tissue
- D. Diaphragm
Explanation: The correct answer is the lungs. In the context of respiratory physiology, the lungs play a crucial role in gas exchange.
Correct answer: Lungs- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: In fish, countercurrent exchange is a highly efficient system for gas exchange in the gills, where water and blood flow in opposite…
Correct answer: Option D- A. Has more affinity with oxygen
- B. Loses oxygen at PO2 60mmHg
- C. Transports oxygen
- D. Has four iron atoms in molecule
Explanation: Hemoglobin indeed releases oxygen to tissues when the partial pressure of oxygen (PO2) decreases, which typically happens around 40 mmHg…
Correct answer: Loses oxygen at PO2 60mmHg- A. O2
- B. CO2
- C. CO
- D. H2
Explanation: If the pH of blood is lower than normal (normal physiological pH is 7.4), then the haemoglobin does not bind oxygen as well.
Correct answer: O2- A. 19.6 ml/100 ml of blood
- B. 50 ml/100 ml of blood
- C. 54 ml/100 ml of blood
- D. 96 ml/100 ml of blood
Explanation: The venous blood in tissues has 54 ml carbondioxide/100 ml of blood.
Correct answer: 54 ml/100 ml of blood- A. 21%
- B. 16%
- C. 79%
- D. 4%
Explanation: The amount of oxygen in exhaled air is 16% whereas in inhaled air it is 21% as the body absorbs oxygen for aerobic respiration to occur.
Correct answer: 16%- A. As bicarbonate ions
- B. In the form of dissolved gas molecules
- C. By binding to R.B.C
- D. As carbamino haemoglobin.
Explanation: The correct option is a) as bicarbonate ions.Explanation of each option:A.
Correct answer: As bicarbonate ions- A. Myoglobin
- B. Globin
- C. Haemoglobin
- D. Hemocyanin
Explanation: Myoglobin is a pigment that has the highest affinity to bind with oxygen.
Correct answer: Myoglobin- A. Moving their ribs upward and out
- B. Actively creating higher pressure in their mouth
- C. Maintaining higher pressure in their internal nostrils
- D. Using their diaphragms to create lower pressure in their lungs
Explanation: Frogs utilize a positive pressure breathing mechanism, which is different from the negative pressure mechanism seen in mammals.
Correct answer: Actively creating higher pressure in their mouth- A. Cuticle
- B. Trachea
- C. Spiracle
- D. Tracheole
Explanation: In cockroaches, the respiratory system consists of a network of tubes called tracheae, which branch into finer tubes called tracheoles.
Correct answer: Tracheole