What are some characteristics that classify an organism as living?

your body is trying to warm itself up. or more precisely, sensors in your skin send messages to your brain to generate heat to your body.

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.