Asperm must penetrate the exterior of an egg cell in order for the of the sperm and egg cells to combine and contribute chromosomes to the , the first cell of a new individual.

i disagree that there is little difference between adult female development and adult male development. sociological studies comparing female and male pathways to adulthood, revelead that there are sustancial differences between them. particularly, female and male differ from timing of marriage, when they began to live with children and the likelihood of combining wife/husband and parent roles.

answer; observing;

answer; decipher the motives for why people behave the way they do;