Which lobe of the cerebrum contains the centers for voluntary muscle movement?

$(i)$ Differentiate between sensory neurons and motor neurons.
$(ii)$ How is the brain protected in our body?
$(iii)$ Name the part of the brain responsible for the precision of voluntary actions and maintaining body posture and balance of the body.

In a neuron,conversion of electrical signal to a chemical signal occurs at/in

What is the correct direction of flow of electrical impulses?

What is meant by hydrotropism? Give an example.

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