Biology Chapter 14/15

The sodium-potassium pump __________. transports potassium ions into the cell does not require energy to function transports sodium ions out of the cell and transports potassium ions into the cell transports glucose into the cell transports sodium ions out of the cell

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

Which of the following would be least likely to diffuse through a plasma membrane without the help of a transport protein? Any of the above would easily diffuse through the membrane. A small nonpolar molecule A large nonpolar molecule A large polar molecule Dissolved gases such as oxygen or carbon dioxide

A large polar molecule

Which of the following is a correct difference between active transport and facilitated diffusion? Facilitated diffusion can move solutes against a concentration gradient, and active transport cannot. Active transport requires energy from ATP, and facilitated diffusion does not. Facilitated diffusion involves transport proteins, and active transport does not. Active transport can move solutes in either direction across a membrane, but facilitated diffusion can only move in one direction. Active transport involves transport proteins, and facilitated diffusion does not

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

How does cholesterol affect membrane fluidity? It has no effect on membrane fluidity. At body temperature, it makes the membrane less fluid. At body temperature, it makes the membrane more fluid. At lower temperatures, it makes the membrane more fluid. It allows phospholipids to pack tightly together.

At body temperature, it makes the membrane less fluid.

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

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? Exocytosis Osmosis Passive transport Active transport Endocytosis

Endocytosis

Which of the following processes and organelle(s) accounts for the replacement of lipids and proteins lost from the plasma membrane? Endocytosis and Golgi Flip-flop of phospholipids from one side of the plasma membrane to the other and the Golgi Active transport and the rough endoplasmic reticulum Exocytosis and smooth and rough ER Receptor-mediated endocytosis and smooth ER and Golgi

Exocytosis and smooth and rough ER

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

It is a passive process.

Which of the following statements concerning carbohydrates associated with the plasma membrane is correct? Carbohydrates are only found associated with the membranes of prokaryotic cells. The carbohydrate composition of most eukaryotic plasma membranes is quite similar. Membrane carbohydrates function primarily in cell-cell recognition. 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? In passive transport, solute movement stops when the solute concentration is the same on both sides of the membrane. Passive transport operates independently of the concentrations of the moving solute. Passive transport does not occur in the human body. Passive transport operates independently of diffusion. 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 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 Cholesterol Water Carbohydrates Proteins

Phospholipids

Which of the following statements about the role of phospholipids in the structure and function of biological membranes is correct? Phospholipids form a single sheet in water. Phospholipids form a selectively permeable structure. Phospholipids form a structure in which the hydrophobic portion faces outward. Phospholipids are completely insoluble in water. They are triacylglycerols, which are commonly available in foods.

Phospholipids form a selectively permeable structure.

Which of the following structural arrangements of the components in biological membranes facilitates the cell membrane's property of selective permeability? Phospholipids sandwiched between two layers of protein A layer of protein coating a layer of phospholipid A phospholipid bilayer with proteins scattered on the surfaces of the membranes Proteins sandwiched between two layers of phospholipids Proteins embedded in two layers of phospholipids

Proteins embedded in two layers of phospholipids

How does the "fluid mosaic model" describe the structure of the plasma membrane? None of the listed responses is correct. The fluid characteristic is due to the presence of carbohydrates, and the mosaic characteristic is due to the presence of phospholipids. Only the proteins in the membrane contribute to its fluidity. The plasma membrane is a rigid structure that exhibits little flexibility. Proteins in the membrane contribute to the mosaic quality of the membrane while the lateral and rotational movements of phospholipids contribute to its fluidity.

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 solutes will diffuse out of the cell. The solutes will diffuse into the cell. The cell will decrease in size as water flows out of it. Nothing will happen because the solution and the cell are isotonic to each other. The cell will increase in size as water flows into it.

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

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. carrier; channel receptor; channel peripheral; enzymatic active transport; signal transduction channel; carrier

channel; carrier

All cells have voltages across their membranes. This voltage is called a(n) __________ and is often maintained by __________. iotonic solution; diffusion None of the listed responses is correct. concentration gradient; osmosis electrochemical gradient; diffusion membrane potential; electrogenic pumps

membrane potential; electrogenic pumps

The plasma membrane exhibits selective permeability. This means that __________. the structure of the plasma membrane does not affect its permeability the plasma membrane does not allow any substance to flow through it the plasma membrane allows any substance to flow through it easily proteins in the membrane do not affect its permeability the plasma membrane allows some substances to flow through it more easily than others

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

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

B; the diffusion gradient in cell B is steeper

Why is energy required for active transport? To allow the movement of water from a hypotonic solution to a hypertonic solution To allow the movement of solutes down their concentration gradient Because it moves solutes against their concentration gradient To allow the movement of water from a hypotonic solution to a hypertonic solution Because it helps maintain water balance in cells without walls

Because it moves solutes against their concentration gradient

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

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

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

Plasma membrane

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

These proteins are found only on the surface of the plasma membrane.

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

These proteins exhibit both hydrophilic and hydrophobic properties.

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

A nonpolar molecule, such as a hydrocarbon

If a red blood cell and a plant cell were placed in seawater, what would happen to the two types of cells? The red blood cell would shrink, and the plant cell would gain water. Both cells would lose water; the red blood cell would shrivel, and the plant plasma membrane would pull away from the cell wall. Both cells would gain water by osmosis; the red blood cell would burst, and the plant cell would increase in turgor pressure. Seawater is isotonic to both cells, therefore, neither cell will change as there will be no movement of water into or out of the cells. The red blood cell would burst, and the plant cell would shrink.

Both cells would lose water; the red blood cell would shrivel, and the plant plasma membrane would pull away from the cell wall. Seawater is hypertonic to both red blood cells and plant cells, and in both cases, water would leave the cells due to osmosis. Both cell types will shrivel. The plant cell will undergo plasmolysis as its cell membrane pulls away from the cell wall. Because seawater is not hypotonic to these cells, water will not enter the cells.

A cell is placed into a solution and the cell shrinks. Which of the following is true regarding the solution? The cell is hypertonic. None of the listed responses is correct. The solution is hypotonic. The solution has the same solute concentration as the cell. The solution is hypertonic.

The solution is hypertonic.

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 150m 0.4M 0.8M distilled water

1.0M The internal solute concentration of a plant cell is about 0.8M. To demonstrate plasmolysis, it would be necessary to suspend the cell in a 1.0M solution. Plasmyolysis refers to the shriveling of plant cells when they are placed in a hypertonic environment. Surrounded by a high concentration of non-penetrating solutes, the plant cells lose water to the environment and shrink. The plasma membrane pulls away from the cell wall, leading to wilting and possible death. Distilled water is hypotonic to the plant: in such a solution, water will enter the cells, leading to turgor. For a plant with an internal solute concentration of 0.8M, a solution of 0.4M is hypotonic, leading to increased turgidity. A solution of 0.8M is isotonic to the plant cell, which will become flaccid if immersed, but plasmolysis will not occur. A 1.0M solution is hypertonic to the plant cell and will cause plasmolysis. A 150m solution is the same as a 0.15M solution, which is hypotonic to the plant cell.

Which of the following plant cells would exhibit the most turgor pressure? None of the listed responses is correct. A cell placed in a hypertonic solution A cell placed in an isotonic solution All of the listed responses are correct. A cell placed in a hypotonic solution

A cell placed in a hypotonic solution The plant cell with the most turgor pressure would be the one placed in a hypotonic solution. A hypotonic solution is a solution that has a lower solute concentration than the cell. When a plant cell is placed in a hypotonic solution, water will move into the cell by osmosis in order to equalize the solute concentration on both sides of the cell membrane. This influx of water will increase the turgor pressure of the cell. In contrast, if a plant cell is placed in an isotonic solution, which has the same solute concentration as the cell, there will be no net movement of water across the cell membrane. The turgor pressure of the cell will remain the same. If a plant cell is placed in a hypertonic solution, which has a higher solute concentration than the cell, water will move out of the cell by osmosis in order to equalize the solute concentration on both sides of the cell membrane. This efflux of water will decrease the turgor pressure of the cell and may even cause the cell to plasmolyze, which is when the cell membrane pulls away from the cell wall.

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

Carbon dioxide Nonpolar molecules like carbon dioxide, hydrocarbons, and oxygen are hydrophobic and dissolve in the lipid bilayer, crossing the cell membrane easily through passive diffusion. Ions and polar molecules, however, are hydrophilic and cannot cross the hydrophobic interior of the membrane without a carrier. Glucose is a polar molecule that is covered in water; it requires a transport protein to cross a membrane. Sodium ion is positively charged and also requires a transport protein. DNA is a large charged molecule: it, too, cannot cross the membrane easily. Hemoglobin, too, is large, and this protein does not normally cross the cell membrane.