Which of the following limit cell size? Select all of the answers that apply. ratio of surface area to volume
. rate of moving materials across the cell's membrane
- efficiency of using the information in a cell's DNA
efficiency of DNA replication and cell division

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.

voluntary muscles are controlled by the cerebellum.