I am the part of central nervous system. I am the centre for reflex arcs. Who am I ?

I am the state tree of Tamilnadu.Who am I____?

I am the excretory organ, present in flatworms. Who am I ?

I am the part of the brain. I act as the centre for water balance, blood pressure, body temperature, sleep and hunger. Who am I ?

I am a part of brain. I am the site of mental abilities and memory. Who am I ?

I am known as "energy currency " Who am I ?

I am a phytohormone. I am in gaseous state. I am helpful in ripening of fruit. Who am I ?

I am a plant. I am making the soil nitrogen rich. Who am I ?

I am present in gut and coordinates the reactions in the digestive system. I have 100 millions of neurons . Who am I ?

I am the outer most layer of an animal cell. Who am I?

I am an alkaloid. I am present in root. I am used in the treatment of snake bite. Who am I ?