Compare the functioning of alveoli in lungs and nephrons in the kidneys with respect to their structure and functioning.

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

What are the differences between the transport of materials in xylem and phloem?

Draw a labelled diagram of sectional view of human heart of human digestive system.

What is the role of folowing: (i) Lymph (ii) RBCs?