Answer:
Sperm motility
Explanation:
Sperm motility is the property of the sperms to move properly through the woman's reproductive system during the process of fecundation. The sperms need to move into the female reproductive tract to fertilize the ovum and thus form the egg cell.
Producers provide oxygen gas as a result from photosynthesis - something that almost all other organisms at high trophic levels need
Flash floods are population independent, and are therefore NOT dependent upon population density
It some back to earth since gravity pulls it down
