Compare the structure and mechanism of alveoli in the lung and nephron in the kidney.

What is the difference between transport of materials in xylem and phloem?

Describe the double circulation in human beings. Why is it necessary?

What can be the consequences of the deficiency of hemoglobin in our body?

How are alveoli designed for maximum exchange of gases?

What is the difference between aerobic and anaerobic respiration? Name some organisms which have anaerobic respiration.