Which statement does not describe cell cycle checkpoints? A.
Normal checkpoints assess damage to DNA.

B.
Faulty checkpoints may lead to abnormal cell growth.

C.
Cell checkpoints can fail in mitosis and meiosis.

D.
Cells that bypass the G2 checkpoint move to the synthesis stage.

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.