Ch 7 Campbell Biology Quiz

Which of the following statements is most likely true of a protein that cotransports glucose and sodium ions into the intestinal cells of an animal?

A substance that blocks sodium ions from binding to the cotransport protein will also block the transport of glucose.

Which of the following statements correctly describes osmosis?

In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.

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

It exhibits a specificity for a particular type of molecule.

Which of the following statements about diffusion is true?

It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.

When a plant cell, such as one from a tulip leaf, is submerged in a hypertonic solution, what is likely to occur?

Plasmolysis will shrink the interior of the cell.

What will happen to a red blood cell (RBC), which has an internal ion content of about 0.9%, if it is placed into a beaker of pure water?

The cell would swell because the water in the beaker is hypotonic relative to the cytoplasm of the RBC.

Which of the following statements is a reasonable explanation for why unsaturated fatty acids help keep a membrane more fluid at lower temperatures?

The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.

Why are lipids and proteins free to move laterally in membranes?

There are only weak hydrophobic interactions in the interior of the membrane.

The force driving simple diffusion is ________, while the energy source for active transport is ________.

a concentration gradient; ATP hydrolysis

In which of the following environments would there be the greatest need for osmoregulation?

a salmon moving from a river into an ocean

According to the fluid mosaic model of cell membranes, phospholipids ________.

can move laterally along the plane of the membrane

In some cells, there are many ion electrochemical gradients across the plasma membrane even though there are usually only one or two proton pumps present in the membrane. The gradients of the other ions are most likely accounted for by ________.

cotransport proteins

Based on Figure below, which of these experimental treatments would increase the rate of sucrose transport into a plant cell?

decreasing extracellular pH

Familial hypercholesterolemia is characterized by _______

defective LDL receptors on the cell membranes

The membranes of winter wheat are able to remain fluid when it is extremely cold by ________.

increasing the proportion of unsaturated phospholipids in the membrane

Celery stalks that are immersed in fresh water for several hours become stiff. Similar stalks left in a 0.15 M salt solution become limp. From this we can deduce that the fresh water ________.

is hypotonic and the salt solution is hypertonic to the cells of the celery stalks

A bacterium engulfed by a white blood cell through phagocytosis will be digested by enzymes contained in ________.

lysosomes

A sodium-potassium pump ________.

move three sodium ions out of a cell and two potassium ions into a cell while consuming an ATP for each cycle

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

movement of Na+ ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid

In receptor-mediated endocytosis, receptor molecules initially project to the outside of the cell. Where do they end up after endocytosis?

on the inside surface of the vesicle

Which of the following processes includes all of the others?

passive transport

Which of the following types of molecules are hydrophilic and therefore excluded from the hydrophobic portion of the phospholipid bilayer?

peripheral membrane proteins

White blood cells engulf bacteria using ________.

phagocytosis

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

small and hydrophobic

Which of the following are least likely to diffuse through the phospholipid bilayer of a cell membrane?

small ions