Explain briefly how a large quantity of dead organic materials dumped into a river can be harmful to aquatic life.

Name the physical processes responsible for the following (a) entry of carbon dioxide into the leaf through the stomata (b) entry of soil water into the root hair (c) shrinkage of plant tissue in hypertonic sugar solution

Name the blood vessel that carries digested food to the liver.

List three harmful effects of noise pollution.

Name one example of symbiotic relationship in animals