Biology 110 Practice Exam - Chapter 5 - Biological Membranes

Arrange the following molecules in order from most likely to least likely to pass through a biomembrane.

2. carbon dioxide 3. water 1. glucose 4. potassium ion

Which of the following is a characteristic feature of a carrier protein in a plasma membrane?

It exhibits a specificity for a particular type of molecule.

You observe plant cells under a microscope that have just been placed in an unknown solution. First the cells plasmolyze; after a few minutes, the plasmolysis reverses and the cells appear normal. What would you conclude about the unknown solution?

It is hypertonic to the plant cells, but its solute can cross the plant cell membranes.

Which of the following membrane activities require energy from ATP hydrolysis?

Na+ ions moving out of the cell

Bacteria invading a mammalian host are often removed when the host's immune system cells engulf the bacteria and fuse with lysosomes, which provide the enzymes for destruction of the bacteria.

T

Existing proton (H+) gradients frequently provide the energy required to move nutrients against their concentration gradients.

T

A patient has had a serious accident and lost a lot of blood. In an attempt to replenish body fluids, distilled water, equal to the volume of blood lost, is transferred directly into one of his veins. What will be the most probable result of this transfusion?

The patient's red blood cells will swell because the blood fluid is hypotonic compared to the cells.

A plant cell placed in a hypotonic environment will

become turgid.

The sodium-potassium pump is called an electrogenic pump because

contributes to the membrane potential (electrical gradient across the membrane).

Ions diffuse across membranes down their (choose the most precise answer)

electrochemical gradient.

Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small intestine, however, rapidly move large quantities of glucose from the glucose-rich food into their glucose-poor cytoplasm. Using this information, which transport mechanism is most probably functioning in the intestinal cells?

facilitated diffusion

The technique most commonly used to study the interior of a biomembrane is known as

freeze-fracture electron microscopy.

This term is used to describe the carbohydrate-rich zone on the surface of certain animal cells that shields them from mechanical and physical damage.

glycocalyx

What are the membrane structures that function in active transport?

integral proteins

Water passes quickly through certain cell membranes because

it moves through aquaporins in the membrane.

Which of the following processes includes all others?

passive transport

White blood cells engulf bacteria through what process?

phagocytosis

A single layer of phospholipid molecules coats the water in a beaker. Which part of the molecules will face the air?

the hydrocarbon tails

Pinocytosis involves

the pinching in of the plasma membrane around small droplets of external fluid.

Facilitated diffusion across a cellular membrane requires ___________ and moves a solute _______ its concentration gradient.

transport proteins; down