A change over time in the inherited traits of living things is called

Evolution

Explanation:

Evolution is the change over time in the inherited traits of a species. It is based on the principle that individuals of a species that have the best adaptations related to the environment tend to reproduce more and the beneficial traits they have let them out-compete other that are less well adapted to their environment, whose genes eventually die out.

x would be the most and the least would be y because there are more fruit   and seeds than flock z has insects

answer; motor (efferent)neurons;