Root pressure- It is a pressure developed in the xylem due to metabolic activity of the root cells. It is a hydrostatic pressure developed in the root system that pumps the water or sap in the root xylem.

Transpiration- Transpirationis the evaporation of water into the atmosphere from the leaves and stems of plants.Transpirationis the process of water movement through a plant and its evaporation from aerial parts especially from leaves but also from stems and flowers.

Nerve cell- Nerve cells are also known as neurons. These are the primary building blocks of the nervous system in humans and animals. Its main function is transmitting and receiving electrochemical messages.

Human Brain- A human brain is the largest, the developed structure in the anatomy of human beings and other well-organizedorganisms. The brain is made up of about 100 billion neurons and it weighs about 1300g or 3lbs

Reflex action- Reflex actions are sudden, involuntary reactions of the body in response to stimuli. They occur without the involvement of the conscious areas of the brain. Therefore, all reflex actions are unconscious actions.