Define fixed factor as it applies to production.

A fixed factor of production is one who quantity can not be changed. Examples include major pieces of equipment, suitable factory space. A       variable factor of production is one whose usage rate can be changed easily.

Synaptic vesicle

Explanation:

It is also known as the Neurotransmitter vesicle, it can be found inside the axon close to the pre-synaptic membrane, it plays the role of releasing it content into the synaptic cleft, this is achieved only by fusing with the membrane, whenever impulse goes down to the axon of a neuron and gets to the axon terminal, the synaptic vesicle is stimulated.