Q. A large proportion of oxygen is left unused in the human blood even after its uptake by the body tissues. This $O_{2}$
A) Raises the $p_{CO_{2}}$ of blood to 75 mm of Hg
B) Is enough to keep oxyhaemoglobin
C) Helps in releasing more $O_{2}$ to the epithelial tissues
D) Acts as a reserve during muscular exercises
Explanation
Our tissue are able to utilized only 25% of $O_{2}$ carried by arterial blood. The venous blood is stil 75% saturated with$O_{2}$. This $O_{2}$ acts as a reserve during muscular exucise.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.