Which of the following describes the main role of the electron transport chain in cellular respiration?
A. It produces molecules of ATP.
B. It produces the energy carriers.
C. It breaks down glucose molecules.
D. It pumps hydrogen ions inside the cell.

Astudent wants to test the hypothesis that fertilizer improves the growth rate of grass seeds. to test this hypothesis, the student put the same amount of grass seed in 3 containers with the same type of soil. the student measured the growth at the end of the week. all plants received equal amounts of water and sunlight. if you were asked to graph this data, what would you place on the x-axis? a. fertilizer b. water c. plant growth d. week one

Which of the following cell structures is significantly different between gram- positive and gram-negative bacteria?

How do the sperm cells get from the stigma to the ovules? a. they slide down the petals to the bottom of the flower. b. they travel through pollen tubes. c. they travel along filaments. d. insects carry the sperm cells from the stigma to the ovules.