Proteins that are found on the cell membrane: a allow water through b allow large amino acids through c allow charged ions through d all of the above

Natural selection changes allele frequencies because some survive and reproduce more successfully than others.

What process decreases the salinity of ocean water? decreased precipitationdecreased melting of glaciersincreased evaporationincreased runoff from rivers

Abird flies by moving its wings up and down. which two systems are most directly responsible for the movement of a bird's wings? a. skeletal and muscular systems b. respiratory and muscular systems c. skeletal and digestive systems d. respiratory and digestive systems