Which of the following does not require energy?

a. diffusion

b. endocytosis

c. active transport

d. sodium-potassium pump

Tlymphocytes mature in the? a. thyroid gland. b. bone marrow. c. spleen. d. thymus.

Why is it important to reduce the number of chromosomes in half when forming gametes for sexual reproduction?

Why do leaves change color in the fall? green pigments break down and no longer mask the color of chlorophyll. chlorophyll breaks down and no longer masks the colors of other pigments. red- and yellow-colored pigments grow and mask green-colored chlorophyll. green-colored chlorophyll breaks down and turns red and yellow.