Biology · Gaseous Exchange

Passive diffusion is the type of diffusion which takes place down the concentration gradient and there’s no need of any channel protein moreover passive diffusion only occurs in gases. Since the concentration of Oxygen entering the alveoli is greater whereas the concentration of oxygen entering the lungs through blood is lower, thus a concentration gradient created and oxygen diffuse from alveoli into the blood through the plasma membrane. Vice versa happens for Carbon dioxide. Since, Oxygen and Carbon dioxide are small, soluble polar molecules, they can easily cross the plasma membrane via Passive transport, marking this option to be correct.

This is incorrect. Oxygen and carbon dioxide cross the plasma membrane by simple diffusion, moving along their concentration gradients. Active transport, which requires energy, is not involved in their movement.

No, facilitated diffusion is also not the main mechanism for oxygen and carbon dioxide. These gases are small and nonpolar, so they pass directly through the lipid bilayer by simple diffusion without needing protein channels.

Passive diffusion is the type of diffusion which takes place down the concentration gradient and there’s no need of any Channel protein therefore passive diffusion occurs only within gases. Since the concentration of Oxygen entering the alveoli is greater whereas the concentration of oxygen entering the lungs through blood is lower, thus a concentration gradient created and oxygen diffuse from alveoli into the blood through the plasma membrane. Vice versa happens for Carbon dioxide. Since, Oxygen and Carbon dioxide are small, soluble polar molecules, they can easily cross the plasma membrane via Passive transport, marking this option to be correct.

There is no specific term as ‘Random Diffusion’ thus marking it as incorrect.