This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
Which parameter is almost same at apex and base of lung: March 2013 
Select and explain. 
A. pCO2, B. O2 concentration in blood, C. Ventilation, D. Perfusion
B: O2 concentration in blood
Answer: B: O2 concentration in blood 
Explanation: Ans. B i.e. O2 concentration in blood At apex the O2 concentration is 20 ml/ 100 ml and at base the value is 19.2 ml/ 100 ml