Exam 4: Cell Membranes, Transport, and Communication

Signaling molecules can be "tagged" by attaching glow-in-the-dark molecules to them.After adding tagged signaling molecules to the fluid around several cells,you observe the cells with a microscope designed to see the glow-in-the-dark molecules.After a few minutes,you notice that the plasma membrane of some of the cells begins to glow.This observation indicates that some cells

As a biological process,osmosis

Cells suspended in a hypertonic solution will lose water.

If a red blood cell is placed in a hypertonic solution,what happens to it?

Which of the following is found in plants?

Many hormones are large and hydrophilic.Where would you expect the receptor proteins for these hormones to be located?

Which of the following types of molecules could NOT easily diffuse across a plasma membrane?

What best explains the double-headed arrows associated with carbon dioxide and molecular oxygen shown in the following illustration?

Elevated cholesterol and LDL (the particles that transport cholesterol)have been strongly associated with vascular disease; what process(es)lead to the elevated levels?

Several types of lipoproteins exist; the best balance for cardiovascular health is achieved with ________ amount of LDL and ________ amount of HDL.

All movement,including that of diffusing molecules,requires a small expenditure of energy; which of the following small sources of energy is most likely to make diffusion possible across the cell membrane from the cell exterior into the cell interior?

When the solute concentration outside a cell is equal to the solute concentration inside the cell,the cell is in a(n)________ solution.

Receptors in target cells can be located in the plasma membrane,the cytosol,or the ________.

Ingested protein is always degraded to amino acids before absorption in the mature human small intestine,but nursing infants can absorb intact antibodies (large protein molecules)from breast milk.How might this difference in intestinal function be explained?

The fragrance of bread baking in a kitchen spreads to other rooms by

The following figure shows the movement of solutes across a plasma membrane in the direction indicated by the arrows. This movement across the membrane

For a cell to be a target for a particular hormone,it must usually

Active carrier proteins can transfer molecules into areas of higher concentration.

When placed in a 2 percent sucrose solution,red blood cells shrink (lose volume); relative to the red blood cell cytoplasm,a 2 percent solution must be

Active carrier proteins are not found in the same cells as passive carrier proteins.