NEETZoologyBreathing and Exchange of Gases
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Under normal physiological conditions, every 100 ml of oxygenated blood delivers around 20 ml of O ₂ to the tissues. Reason (R): In the tissues, low pO ₂ , high pCO ₂ , high H ^+ concentration and higher temperature exist, which are favourable for dissociation of oxygen from oxyhaemoglobin. In the
Options
- ABoth (A) and (R) are true and (R) is the correct explanation of (A).
- BBoth (A) and (R) are true but (R) is not the correct explanation of (A).
- C(A) is true but (R) is false.
- D(A) is false but (R) is true.
Correct answer
D. (A) is false but (R) is true.
Step-by-step solution
Assertion (A) is false because under normal physiological conditions, every 100 ml of oxygenated blood can deliver around 5 ml of O ₂ to the tissues, not 20 ml . While 100 ml of oxygenated blood carries about 20 ml of O ₂ , it only unloads approximately 25 % (i.e., 5 ml ) to the tissues under resting conditions. Reason (R) is true. In the tissues, conditions such as low pO ₂ , high pCO ₂ , high H ^+ concentration, and higher temperature shift the oxygen dissociation curve to the right. These factors are favourable