Which of the following allows a cell to become specialized?
A: different patterns of gene expression

A spring-fed stream forms a pond that contains watercress plants, minnows, and crayfish. The pond receives 5 hours of direct sunlight every day. Which of the following is an abiotic factor in this ecosystem?
A: the pond water

Many cells have a nucleus that contains chromosomes. These chromosomes carry genes that are composed of
A: DNA molecules

Which interaction within an ecosystem is characterized by gradual change from one community of organisms to another?
A:
succession