Chapter 7 Biology

The internal solute concentration of a plant cell is about 0.8 M. To demonstrate plasmolysis, it would be necessary to suspend the cell in what solution?

1.0 M

Which statement best describes phagocytosis?

A cell engulfs a particle by wrapping pseudopodia around it and packaging it within a vacuole.

Which of the following is a difference between active transport and facilitated diffusion?

AT requires energy from ATP, and facilitated diffusion does not

A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. These molecules probably enter the cells lining the baby's digestive tract via

Endocytosis

The concentration of solutes in a red blood cell is about 2%. Sucrose cannot pass through the membrane, but water and urea can. Osmosis would cause red blood cells to shrink the most when immersed in which of the following solutions?

Hypertonic sucrose solution

Select the correct statement concerning membrane carbohydrate

Membrane carbohydrates function primarily in cell-cell recognition

Imagine two solutions separated by a selectively permeable membrane that allows water to pass, but not sucrose or glucose. The membrane separates a 0.2-molar sucrose solution from a 0.2-molar glucose solution. With time, how will the solutions change? 1) Nothing happens because the two solutions are isotonic to one another. 2) Water enters the sucrose solution because the sucrose molecule is a disaccharide and thus larger than the monosaccharide glucose. 3) Water leaves the sucrose solution because the sucrose molecule is a disaccharide and thus larger than the monosaccharide glucose. 4) The sucrose solution is hypertonic and will gain water because the total mass of sucrose is greater than that of glucose. 5) After the sucrose dissociates to two monosaccharides, water will be osmotically drawn to that side of the membrane.

Nothing happens because the two solutions are isotonic to one another

The diffusion of water across a selectively permeable membrane is called

Osmosis

Which of the following enables a cell to pick up and concentrate a specific kind of molecule?

Receptor-mediated endocytosis

A plant cell is placed in a solution whose solute concentration is twice as great as the concentration of the cell cytoplasm. The cell membrane is selectively permeable, allowing water but not the solutes to pass through. Wat will happen to the cell?

The cell will swell because of osmosis

Which of the following would be least likely to diffuse through a cell membrane without the help of a transfer protein?

a large polar molecule

The result of the operation of an electrogenic pump would be

a voltage difference across the membrane

The concentration of calcium in a cell is 0.3%. The concentration of calcium in the surrounding fluid is 0.1%. How could the cell obtain more calcium?

active transport

The movement of molecules from an area of higher concentration to an area of lower concentration is called

diffusion

Which of the following functional processes results form the presence of protein within the plasma membrane?

enzymatic activity, cell-cell recognition, intercellular joining, signal transduction

Phospholipid molecules in a membrane are arranged with their ____ on the exterior and their _____ on the interior.

hydrophilic heads-hydrophobic tails

In osmosis water always moves toward the ____ solution--that is, toward the solution with the ____ solute concentration.

hypertonic...greater

Red blood cells shrivel when placed in a 10% sucrose solution. When first placed in the solution, the solute concentration of the cells is ____ the concentration of the sucrose solution. After the cells shrivel, their solute concentration is _____ the concentration of the sucrose solution.

less than...equal to

One consequence of the sidedness of the plasma membrane is that

molecules begin on the outside face of the ER end up on the inside face of the plasma membrane, the asymmetrical distribution of membrane proteins, lipids, and carbohydrates is determined as the membrane is being constructed, each protein has directional orientation in the membrane, membrane carbohydrates are restriction to the extracellular, surface of the plasma membrane.

Which of the following best describes the general structure of a cell membrane?

proteins embedded in two layers of phospholipid