1. Why pancreas is called mixed gland?

2. Why are intestinal villis highly vascular?

3. Why do we get muscle cramp after vigorous exercise?

4. The breathing rate of aquatic animals is high, why?

5. Why does haemoglobin molecule act as efficient carrier of oxygen than diffusion process?

6. Why capillaries are thin walled?

7. Why do plants need less energy than animals?

1. Pancreas functions as both endocrine and exocrine gland. Hence, called as dual function gland or a mixed gland. Exocrine part of pancreas secretes digestive enzymes while, its endocrine part (islets of Langerhans) produce two hormones, i.e. insulin and glucagon.

2. Intestinal villi are highly vascular to increse the surface area for absorption and also provides connection with blood vessels for rapid absorption.