All of the following membrane activities require energy from ATP hydrolysis except

Celery stalks are immersed in fresh water for several hours and become stiff and hard. Similar stalks left in salt solution become limp and soft. From this we can deduce that the cells of the celery stalks are

A patient has had a serious accident and lost a lot of blood. Equal to the blood volume lost, the patient is given distilled water. What will be the most probable result of this diffusion?

Oxygen crosses a plasma membrane by

The presence of cholesterol in the plasma membranes of some animals

What kinds of molecules pass through the cell membrane most easily?

According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids?

Why is the cell membrane called the fluid mosaic model?

In a hypotonic solution, an animal cell will

What may happen to a person who has too little cholesterol in the cell membranes?

The following pictures are examples of which of the following?

In a hypertonic solution, an animal cell will

You are a biochemist making a new drug. For the drug to work, it must enter the cytoplasm of specific cells. Which of the following is NOT a factor that determines whether the molecule enters the cell?