Biology Multiple Choice Questions on “Transport of Gases”.
1. One haemoglobin carries __________ molecules of oxygen.
a) 6
b) 3
c) 4
d) 2
Answer: c
Clarification: Haemoglobin is made up of 4 units. Each unit has 1 Fe in +2 state. Each haemoglobin molecules can carry a maximum of four molecules of oxygen. 1 gm haemoglobin transports 1.34 ml of oxygen.
2. How the majority of oxygen gets transported?
a) In dissolved form in blood plasma
b) In form of oxyhaemoglobin
c) In form of methaemoglobin
d) In form of carbamino haemoglobin
Answer: b
Clarification: Approximately 3% of oxygen dissolves in the blood plasma. Remaining 97% oxygen combines with haemoglobin to form oxyhaemoglobin. Oxygen can bind with Hb in a reversible mannner to form oxyhaemoglobin.
3. Formation of oxyhaemoglobin is a/an ________
a) oxygenation
b) oxidation
c) reduction
d) deoxygenation
Answer: a
Clarification: Oxygen does not oxidize haemoglobin. Formation of oxyhaemoglobin is a process of oxygenation. The valency of iron is 2 in oxyhaemoglobin. Some gases like ozone oxidise haemoglobin. This oxidized Hb is called methamoglobin.
4. What is the shape of Haemoglobin-oxygen dissociation curve?
a) Straight
b) Constant
c) Hyperbolic
d) Sigmoid
Answer: d
Clarification: A graph is plotted between oxygen concentration and percentage saturation of haemoglobin with this curve is called dissociation curve. Dissociation curve is sigmoid in shape.
5. Every 100 ml deoxygenated blood delivers around _______ carbon dioxide to alveoli.
a) 20 ml
b) 25 ml
c) 5 ml
d) 4 ml
Answer: d
Clarification: Every 100 ml deoxygenated blood delivers around 4 ml carbon dioxide to alveoli, whereas every 100 ml oxygenated blood can deliver around 5 ml of oxygen to tissues under physiological conditions.
6. What is chloride shift?
a) Movement of chloride ion from plasma to WBC
b) Movement of chloride ion from plasma to RBC
c) Movement of chloride ion from WBC to plasma
d) Movement of chloride ion from RBC to plasma
Answer: b
Clarification: In response of bicarbonate ion, chloride ions diffuse from plasma into the erythrocyte to maintain the ionic balance. Thus, electrochemical neutrality is maintained. This is called chloride shift or Hamburger phenomenon.
7. Chloride shift occurs in response to _____
a) H+
b) K+
c) HCO3-
d) Na+
Answer: c
Clarification: Chloride shift occurs in response to HCO3-. In response of bicarbonate ion, chloride ions diffuse from plasma into the erythrocyte to maintain the ionic balance. Thus, electrochemical neutrality is maintained. This is called chloride shift or Hamburger phenomenon.
8. Bulk of carbon dioxide is transported by __________
a) dissolved state
b) plasma as bicarbonate
c) carbamino haemoglobin
d) methamoglobin
Answer: b
Clarification: Nearly 70% carbon dioxide is transported by plasma as sodium bicarbonate. Approximately, 5-7% of carbon dioxide is transported in dissolves form in plasma. About 20-25% carbon dioxide react with the amine group of haemoglobin and form carbamino-haemoglobin.
9. Oxygen dissociation curve will shift to right on decrease of________
a) temperature
b) acidity
c) pH
d) carbon dioxide concentration
Answer: c
Clarification: Shift to the right means that decrease in affinity between oxygen and Hb and dissociation of oxyhaemoglobin. Low oxygen, high carbon dioxide, high hydrogen ion, low pH and high temperature are responsible for this.
10. What percentage of carbon dioxide transport in the form of carbamino haemoglobin?
a) 20-25%
b) 5-7%
c) 3%
d) 97%
Answer: a
Clarification: About 20-25% carbon dioxide react with the amine group of haemoglobin and form carbamino-haemoglobin. Approximately 5-7% of carbon dioxide is transported in dissolves form in plasma.