Where are $Nissl$ granules absent?

The most appropriate definition of Neuroglial cells is that they are:

Which one of the following pairs of structures distinguishes a nerve cell from other types of cell?

Which of the following statements are correct?
$I$. Dendrites are long fibres with branched distal ends.
$II$. Axons are short fibres which arise from the cell body.
$III$. The cell body of a neuron contains cytoplasm,a nucleus with cell organelles,and Nissl's granules.
$IV$. Dendrites transmit nerve impulses away from the cell body to a synapse.
The correct option is:

Which of the following parts of a neuron is covered by a fatty sheath?

The medullary sheath of the nerve fibre is interrupted at intervals by