At the time of puberty,both boys and girls show many changes in their appearance. Name the hormones responsible for these changes.

Differentiate between estrogen and testosterone.

What is the correct direction of flow of electrical impulses?

How does chemical coordination occur in plants? Explain with the help of three examples.

Name the hormone synthesized at the shoot tips. How does it help the plant to respond to light?

Which of the following statements are true?
$(i)$ Sudden action in response to something in the environment is called reflex action.
$(ii)$ Sensory neurons carry signals from the spinal cord to muscles.
$(iii)$ Motor neurons carry signals from receptors to the spinal cord.
$(iv)$ The path through which signals are transmitted from a receptor to a muscle or a gland is called a reflex arc.