A2 Biology nervous system

A nerve is

• a neurone
• a cell which always has a dendron
• a bundle of neurones
• all options are incorrect

This diagram shows a

• sensory neurone
• motor neurone
• relay neurone
• association neurone

The myelin sheath around an axon is made

• of ions
• of carbohydrates
• from Schwann cells
• of cytoplasm

In a motor neurone there is

• a dendron but no axon
• a dendron and an axon
• an axon but no dendron
• none of these options is correct

When the neurone is not conducting a nerve impulse the membrane is

• polarised
• depolarised
• repolarised
• action potential

When an action potential is generated, the inside of the membrane becomes

• positive relative to the outside
• negative relative to the outside
• polarised
• filled with potassium ions

Threshold stimulus means that

• the size of the action potential does not change
• only one impulse is conducted at a time
• a certain level of stimulus is required to generate an action potential
• the membrane becomes repolarised quickly after an action potential passes

The time following an action potential in which no new action potential can be generated is called

• the refractory period
• the nerve impulse
• the stationary phase
• the threshold period

The speed of nerve transmission is greatest when there is 

• a myelin sheath
• saltatory conduction
• thick axon
• all options are correct

A motor neurone is used to

• link the eye to the brain
• connect the spinal cord to the thigh muscle
• communicate within the brain
• detect a stimulus