Mastering Biology Ch. 7 review

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. 1.0M 2. distilled water 3. 0.4M 4. 0.8M 5. 150m

1

Which of these statements describes some aspect of facilitated diffusion? 1. Facilitated diffusion of solutes may occur through channel or transport proteins in the membrane. 2. Facilitated diffusion is another name for osmosis. 3. Facilitated diffusion of solutes occurs through phospholipid pores in the membrane. 4. Facilitated diffusion requires energy to drive a concentration gradient. 5. There is only one kind of protein pore for facilitated diffusion.

1

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

1. Channel; Carrier

A cell is placed into a solution and the cell shrinks. Which of the following is true regarding the solution? A. The solution is hypertonic. B. The solution has the same solute concentration as the cell. C. The solution is hypotonic. D. The cell is hypertonic.

A

Which of the following is correct regarding peripheral proteins? A. These proteins are found only on the surface of the plasma membrane. B. They span the entire phospholipid bilayer. C. They exhibit only hydrophobic properties. D. They have no specific function in the plasma membrane. E. These proteins exhibit both hydrophilic and hydrophobic properties.

A

Which of the following substances would be most likely to pass through the plasma membrane without the help of a transport protein? A. A nonpolar molecule, such as a hydrocarbon B. A large polar molecule C. A negatively charged ion D. Water E. Glucose

A

Which of the following plant cells would exhibit the most turgor pressure? A cell placed in a hypotonic solution A cell placed in an isotonic solution A cell placed in a hypertonic solution

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 A large nonpolar molecule Dissolved gases such as oxygen or carbon dioxide A small nonpolar molecule

A large polar molecule

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. Active transport involves transport proteins, and facilitated diffusion does not. Facilitated diffusion can move solutes against a concentration gradient, and active transport cannot. Active transport can move solutes in either direction across a membrane, but facilitated diffusion can only move in one direction. Facilitated diffusion involves transport proteins, and active transport does not.

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

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 than 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 A; the diffusion gradient there is shallower A; its membrane transport proteins will not be saturated B; the oxygen molecules inside cell B have a higher kinetic energy B; the gradient of oxygen is oriented in the opposite direction compared to cell A

B; the diffusion gradient in cell B is steeper

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?

Both cells would lose water; the red blood cell would shrivel, and the plant plasma membrane would pull away from the cell wall.

Which of the following molecules is most likely to passively diffuse across the plasma membrane? Carbon dioxide Glucose Sodium ion DNA Hemoglobin

Carbon Dioxide

What function do carbohydrates fulfill in the plasma membrane? Cell-to-cell recognition Transport of molecules across the membrane They contribute to its selective permeability. They facilitate enzymatic processes. They contribute to its "fluid" characteristic.

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 Osmosis Passive transport Exocytosis Active transport

Endocytosis

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 Endocytosis and Golgi Active transport and the rough endoplasmic reticulum Receptor-mediated endocytosis and smooth ER and Golgi Flip-flop of phospholipids from one side of the plasma membrane to the other and the Golgi

Exocytosis and smooth and rough ER

Which of the following statements about diffusion is true? It is a passive process. It is very rapid over long distances. It requires expenditure of energy by the cell. It occurs when molecules move from a region of lower concentration to a region of higher concentration. It always requires integral proteins of the cell membrane.

It's 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. Carbohydrates are only found associated with the membranes of prokaryotic cells. The carbohydrate composition of most eukaryotic plasma membranes is quite similar. Carbohydrates on the plasma membrane are typically short chains of between two and five monosaccharides. Carbohydrates associated with the plasma membrane are located on both surfaces of the membrane.

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. Passive transport operates independently of diffusion. Passive transport operates independently of the concentrations of the moving solute. In passive transport, solute movement stops when the solute concentration is the same on both sides of the membrane. Passive transport does not occur in the human body.

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 Proteins Carbohydrates Cholesterol Water

Phospholipids

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. Phospholipids are completely insoluble in water. Phospholipids form a single sheet in water. Phospholipids form a structure in which the hydrophobic portion faces outward. They are triacylglycerols, which are commonly available in foods.

Phospholipids form a selectively permeable structure.

Which of the following cell structures exhibits selective permeability between a cell and its external environment? Plasma membrane Mitochondria Chloroplasts Endoplasmic Lysosomes

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 Proteins sandwiched between two layers of phospholipids A layer of protein coating a layer of phospholipid Phospholipids sandwiched between two layers of protein A phospholipid bilayer with proteins scattered on the surfaces of the membranes

Proteins embedded in two layers of phospholipids

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.

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 cell is not permeable. What will happen to the red blood cell?

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

Which of the following is correct regarding integral proteins? These proteins exhibit both hydrophilic and hydrophobic properties. These proteins are found only on the surface of the plasma membrane. They exhibit only hydrophilic properties. They exhibit only hydrophobic properties. They have no specific function in the plasma membrane.

These proteins exhibit both hydrophilic and 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