Which part of the brain does the hypothalamus belong to?

Which is the correct sequence of the components of a reflex arc?

When a person is suffering from severe cold,he or she cannot :

$A$ protective and an insulating sheath of myelin found around the axon is made up of ..........

Describe an activity to illustrate the phenomenon of phototropism and explain why this occurs.

$(a)$ How are the movement of leaves of touch-me-not and the growth of a stem towards light different?
$(b)$ What is chemotropism? Give one example.
$(c)$ What is tropism?