state gov BSSC Laboratory Assistant Mock Test Series 2025 Biology Human Physiology Circulatory System
The concentration gradient for O2 is from ______, while the concentration gradient for CO2 is from ______.
1
Alveoli to tissues; tissues to blood
2
Alveoli to blood; tissues to blood
3
Tissues to blood; blood to alveoli
4
Blood to alveoli; tissues to blood