Modifying Biology Chapter 7 Quiz

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

Active transport requires energy from ATP, and facilitated diffusion does not.

Why is energy required for active transport?

Because it moves solutes against their concentration gradient

If a red blood cell and a plant cell were placed in seawater, what would happen to the two types of cells?

Bother cells would lose water; the red blood cell wold shrivel, and the plant plasma membrane would pull away form the cell wall.

Which of the following processes and organelle(s) accounts for the replacement of lipids and proteins lost from the plasma membrane?

Exocytosis and smooth and rough ER

Which of the following statements about the role of phospholipids in the structure and function of biological membranes is correct?

Phospholipids form a selectively permeable structure.

How does the "fluid mosaic model" describe the structure of the plasma membrane?

Proteins in the membrane contribute to the mosaic quality of the membrane while the lateral and rotational movements of phospholipids contribute to its fluidity.

Which of the following is correct regarding integral proteins?

These proteins exhibit both hydrophilic and hydrophobic properties.

In facilitate diffusion, _________ proteins provide openings in the plasma membrane for substances to flow through without changing structure, and _________ proteins allow passage of substances thought the plasma membrane after undergoing a subtle change in shape.

channel; carrier

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

1.0M

Which of the following plant cells would exhibit the most turgor pressure?

A cell placed in a hypotonic solution

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

A large polar molecule

Which of the following substances would be most likely to pass through the plasma membrane without the help of a transport protein?

A non polar molecule, such as a hydrocarbon

How does cholesterol affect membrane fluidity?

At body temperature, it makes the membrane less fluid.

Cells A and B are the same size, shape, and temperature, but cell A is metabolically less active the cell B; cell B is actively converting oxygen to water in cellular respiration. Oxygen will diffuse more rapidly into cell ___________ because _________.

B; the diffusion gradient in cell B is steeper

Which of the following molecules is most likely to passively diffuse across the plasma membrane?

Carbon dioxide

What function do carbohydrates fulfill in the plasma membrane?

Cell-to-cell recognition

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 which process?

Endocytosis

Which of these statements describes some aspect of facilitates diffusion?

Facilitated diffusion of solutes may occur through channel or transport proteins in the membrane.

Which of the following statements about diffusion is true?

It is a passive process.

Which of the following statements concerning carbohydrates associated with the plasma membrane is correct?

Membrane carbohydrates function primarily in cell-cell recognition.

Which of the following statements about passive transport is correct?

Passive transport permits the solute to move in either direction, but the net movement of the population of solute molecules occurs down the concentration gradient of the molecule.

Which of the following molecules are most abundant in the plasma membrane?

Phospholipids

Which of the following cell structures exhibits selective permeability between a cell and its external environment?

Plasma membrane

Which of the following structural arrangements of the components in biological membranes facilitates the cell membrane's property of selective permeability?

Proteins embedded in two layers of phospholipids

Red blood cells contain approximately a 2% concentration of solutes. A red blood cell is placed into a solution that contains a 4% concentration of solutes to which the cells is not permeable. What will happen to the red blood cell?

The cell will decrease in size as water flows out of it.

A cell is placed into a solution and the cell shrinks. Which of the following is true regarding the solution?

The solution is hypertonic. To explain the behavior of a cell in a solution, we must consider both solute concentration and membrane permeability. Both factors are taken into account in the concept of tonicity, the ability of a surrounding solution to cause a cell to gain or lose water. The tonicity of a solution depends in part on its concentration of solutes that cannot cross the membrane (nonpenetrating solutes) relative to the concentration inside the cell. If there is a higher concentration of nonpenetrating solutes in the surrounding solution, water will tend to leave the cell, and vice versa. Since the cell shrinks, the concentration of the solution cannot be the same as that in the cell.If the solution were hypotonic, the cell would increase in size. If the cell were hypertonic, it would increase in size.

Which of the following is correct regarding peripheral proteins?

These proteins are found only on the surface of the plasma membrane. Somewhat like a tile mosaic, a membrane is a collage of different proteins, often clustered together in groups and embedded in the fluid matrix of the lipid bilayer. Integral proteins penetrate the hydrophobic interior of the lipid bilayer. The majority of the transmembrane proteins, which stand the membrane; other integral proteins extend only partway into the hydrophobic interior. The hydrophobic regions of an integral protein consists of one or more stretches of non polar amino acids, usually coiled into helices. The hydrophilic parts of the molecule are exposed to the aqueous solutions on either side of the membrane. Peripheral proteins are not embedded in the lipid bilayer at all; they are appendages loosely bound to the surface of the membrane, often to exposed parts of integral proteins. Peripheral proteins are found on the surfaces of the plasma membrane and do not span the entire phospholipid bilayer. Peripheral proteins tend to exhibit only hydrophilic properties. Peripheral proteins carry out a variety of functions in the plasma membrane. Peripheral proteins do not tend to exhibit hydrophobic properties.

All cells have voltages across their membranes. This voltage is called a(n) __________ and is often maintained by __________.

membrane potential; electrogenic pumps

The plasma membrane exhibits selective permeability. This means that __________.

the plasma membrane allows some substances to flow through it more easily than others

The sodium-potassium pump __________.

transports sodium ions out of the cell and transports potassium ions into the cell