Ch 5-8 Review

Phospholipids spontaneously form a bilayer in an aqueous solution. Why do the heads of the phospholipids point out and the tails point toward one another?

• The tails are nonpolar and form hydrogen bonds with one another.

• The tails are repelled by the aqueous environment, and the heads will directly interact with the aqueous solution.

• The heads are repelled by the water inside and outside the cell.

Within the fluid mosaic of a plasma membrane, what is the role of transport and channel proteins?

• They prevent the passage of amino acids.

• They permit ions and water molecules to move through the plasma membrane.

• They may set off cellular changes such as cell division or hormone secretion.

• They are cell-surface connection sites.

• They identify the cell.

Recognition proteins are most important for

• facilitated diffusion of molecules.

• active transport of molecules.

• maintaining membrane integrity.

• maintaining membrane fluidity.

• distinguishing foreign cells from "self" cells.

The net movement of molecules from a high concentration to a low concentration is best described by which of the following?

• Passive transport

• Active transport

• Osmosis

• Endocytosis

• Exocytosis

Which of the following is an energy-requiring mode of transport that brings substances into a cell?

• Facilitated diffusion

• Osmosis

• Active transport

• Simple diffusion

To say that a cell is "selectively permeable" means

• it has different-sized perforations in the membrane.

• it is permeable to different substances than other cells.

• only certain molecules can pass through.

• sometimes water passes through, and sometimes it can't.

• permeability depends on gradient differences.

If red blood cells are taken from the body and placed in a hypertonic solution, what happens to the cells?

• The cells swell and burst because water moves into them.

• The cells shrivel up because water leaves them.

• The cells remain unchanged due to equal solute concentrations inside and outside the cells.

• The cells remain unchanged due to equal water concentrations inside and outside the cells.

• They become white blood cells.

The process in which white blood cells engulf bacteria is termed

• recognition.

• exocytosis.

• pinocytosis.

• phagocytosis.

• reception.

In an isolated system, all of the following are true of the second law of thermodynamics EXCEPT

• the amount of useful energy decreases.

• reactions cause energy to be converted from more useful to less useful forms.

• all chemical reactions release more energy than they consume.

• there is a natural tendency toward greater disorder in the organization of matter (increase in entropy).

Energy that is not converted to useful energy is usually given off as

• radioactivity.

• electricity.

• light.

• heat.

• entropy.