What is the reason for the growth of the pollen tube towards the ovule?

The main function of abscisic acid in plants is to

Write true or false for the statement: Insulin raises the sugar level in the blood.

Which mechanism controls the timing and amount of hormone released?

Which of the following statements are true about the brain?
$(i)$ The main thinking part of the brain is the hindbrain.
$(ii)$ Centres of hearing,smell,memory,sight,etc.,are located in the forebrain.
$(iii)$ Involuntary actions like salivation,vomiting,and blood pressure are controlled by the medulla in the hindbrain.
$(iv)$ Cerebellum does not control posture and balance of the body.

In what form is the response to a stimulus generally observed in body parts?