Biology 101 (Chapter 7)

Which of the following substances would be most likely to pass through the plasma membrane without the help of a transport protein? 1. A nonpolar molecule, such as a hydrocarbon 2. A large polar molecule 3. A negatively charged ion 4. Water 5. Glucose

1. A nonpolar molecule, such as a hydrocarbon

Which of the following is a correct difference between active transport and facilitated diffusion? 1.Active transport requires energy from ATP, and facilitated diffusion does not. 2. Active transport involves transport proteins, and facilitated diffusion does not. 3. Facilitated diffusion can move solutes against a concentration gradient, and active transport cannot. 4. Active transport can move solutes in either direction across a membrane, but facilitated diffusion can only move in one direction. 5. Facilitated diffusion involves transport proteins, and active transport does not.

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

How does cholesterol affect membrane fluidity? 1. At body temperature, it makes the membrane less fluid. 2. It has no effect on membrane fluidity. 3. At body temperature, it makes the membrane more fluid. 4. At lower temperatures, it makes the membrane more fluid. 5. It allows phospholipids to pack tightly together.

1. At body temperature, it makes the membrane less fluid.

Why is energy required for active transport? 1. Because it moves solutes against their concentration gradient 2. To allow the movement of solutes down their concentration gradient 3. To allow the movement of water from a hypotonic solution to a hypertonic solution 4. To allow the movement of water from a hypotonic solution to a hypertonic solution 5. Because it helps maintain water balance in cells without walls

1. Because it moves solutes against their concentration gradient

Which of the following statements about diffusion is true? 1. It is a passive process. 2. It is very rapid over long distances. 3. It requires expenditure of energy by the cell. 4. It occurs when molecules move from a region of lower concentration to a region of higher concentration. 5. It always requires integral proteins of the cell membrane.

1. It is a passive process.

Which of the following statements about passive transport is correct? 1. 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. 2. Passive transport operates independently of diffusion. 3. Passive transport operates independently of the concentrations of the moving solute. 4. In passive transport, solute movement stops when the solute concentration is the same on both sides of the membrane. 5. Passive transport does not occur in the human body.

1. 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? 1. Phospholipids 2. Proteins 3. Carbohydrates 4. Cholesterol 5. Water

1. Phospholipids

Which of the following is correct regarding integral proteins? 1. These proteins exhibit both hydrophilic and hydrophobic properties. 2. These proteins are found only on the surface of the plasma membrane. 3. They exhibit only hydrophilic properties. 4. They exhibit only hydrophobic properties. 5. They have no specific function in the plasma membrane.

1. These proteins exhibit both hydrophilic and hydrophobic properties.

The sodium-potassium pump __________. 1. transports sodium ions out of the cell and transports potassium ions into the cell 2. transports sodium ions out of the cell 3. transports glucose into the cell 4. transports potassium ions into the cell 5. does not require energy to function

1. 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? 1. A large nonpolar molecule 2. A large polar molecule 3. Dissolved gases such as oxygen or carbon dioxide 4. A small nonpolar molecule 5. Any of the above would easily diffuse through the membrane.

2. A large polar molecule

What function do carbohydrates fulfill in the plasma membrane? 1. Transport of molecules across the membrane 2. Cell-to-cell recognition 3. They contribute to its selective permeability. 4. They facilitate enzymatic processes. 5. They contribute to its "fluid" characteristic.

2. Cell-to-cell recognition

Which of the following cell structures exhibits selective permeability between a cell and its external environment? 1. Mitochondria 2. Plasma membrane 3. Chloroplasts 4. Endoplasmic 5. Lysosomes

2. Plasma membrane

How does the "fluid mosaic model" describe the structure of the plasma membrane? 1. The plasma membrane is a rigid structure that exhibits little flexibility. 2. Proteins in the membrane contribute to the mosaic quality of the membrane while the lateral and rotational movements of phospholipids contribute to its fluidity. 3. The fluid characteristic is due to the presence of carbohydrates, and the mosaic characteristic is due to the presence of phospholipids. 4. Only the proteins in the membrane contribute to its fluidity. 5. None of the listed responses is correct.

2. 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? 1. Nothing will happen because the solution and the cell are isotonic to each other. 2. The cell will decrease in size as water flows out of it. 3. The cell will increase in size as water flows into it. 4. The solutes will diffuse into the cell. 5. The solutes will diffuse out of the cell.

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

Which of the following is correct regarding peripheral proteins? 1. They span the entire phospholipid bilayer. 2. These proteins are found only on the surface of the plasma membrane. 3. They exhibit only hydrophobic properties. 4. They have no specific function in the plasma membrane. 5. These proteins exhibit both hydrophilic and hydrophobic properties.

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

Which of the following plant cells would exhibit the most turgor pressure? 1. A cell placed in an isotonic solution 2. A cell placed in a hypertonic solution 3. A cell placed in a hypotonic solution 4. None of the listed responses is correct. 5. All of the listed responses are correct.

3. A cell placed in a hypotonic solution

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 __________. 1. A; the diffusion gradient there is shallower 2. A; its membrane transport proteins will not be saturated 3. B; the diffusion gradient in cell B is steeper 4. B; the oxygen molecules inside cell B have a higher kinetic energy 5. B; the gradient of oxygen is oriented in the opposite direction compared to cell A

3. B; the diffusion gradient in cell B is steeper

Which of these statements describes some aspect of facilitated diffusion? 1. Facilitated diffusion is another name for osmosis. 2. Facilitated diffusion of solutes occurs through phospholipid pores in the membrane. 3. Facilitated diffusion of solutes may occur through channel or transport proteins 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.

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

A cell is placed into a solution and the cell shrinks. Which of the following is true regarding the solution? 1. The solution has the same solute concentration as the cell. 2. The solution is hypotonic. 3. The solution is hypertonic. 4. The cell is hypertonic. 5. None of the listed responses is correct.

3. The solution is hypertonic.

All cells have voltages across their membranes. This voltage is called a(n) __________ and is often maintained by __________. 1. concentration gradient; osmosis 2. iotonic solution; diffusion 3. membrane potential; electrogenic pumps 4. electrochemical gradient; diffusion 5. None of the listed responses is correct.

3. membrane potential; electrogenic pumps

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

4. 1.0M

Which of the following molecules is most likely to passively diffuse across the plasma membrane? 1. Glucose 2. Sodium ion 3. DNA 4. Carbon dioxide 5. Hemoglobin

4. Carbon dioxide

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? 1. Osmosis 2. Passive transport 3. Exocytosis 4. Endocytosis 5. Active transport

4. Endocytosis

Which of the following processes and organelle(s) accounts for the replacement of lipids and proteins lost from the plasma membrane? 1. Endocytosis and Golgi 2. Active transport and the rough endoplasmic reticulum 3. Receptor-mediated endocytosis and smooth ER and Golgi 4. Exocytosis and smooth and rough ER 5. Flip-flop of phospholipids from one side of the plasma membrane to the other and the Golgi

4. Exocytosis and smooth and rough ER

Which of the following statements concerning carbohydrates associated with the plasma membrane is correct? 1. Carbohydrates are only found associated with the membranes of prokaryotic cells. 2. The carbohydrate composition of most eukaryotic plasma membranes is quite similar. 3. Carbohydrates on the plasma membrane are typically short chains of between two and five monosaccharides. 4. Membrane carbohydrates function primarily in cell-cell recognition. 5. Carbohydrates associated with the plasma membrane are located on both surfaces of the membrane.

4. Membrane carbohydrates function primarily in cell-cell recognition.

The plasma membrane exhibits selective permeability. This means that __________. 1. the plasma membrane allows any substance to flow through it easily 2. the plasma membrane does not allow any substance to flow through it 3. the structure of the plasma membrane does not affect its permeability 4. the plasma membrane allows some substances to flow through it more easily than others 5. proteins in the membrane do not affect its permeability

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

If a red blood cell and a plant cell were placed in seawater, what would happen to the two types of cells? 1. The red blood cell would burst, and the plant cell would shrink. 2. 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. 3. Both cells would gain water by osmosis; the red blood cell would burst, and the plant cell would increase in turgor pressure. 4. The red blood cell would shrink, and the plant cell would gain water. 5. Both cells would lose water; the red blood cell would shrivel, and the plant plasma membrane would pull away from the cell wall.

5. 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 statements about the role of phospholipids in the structure and function of biological membranes is correct? 1. Phospholipids are completely insoluble in water. 2. Phospholipids form a single sheet in water. 3. Phospholipids form a structure in which the hydrophobic portion faces outward. 4. They are triacylglycerols, which are commonly available in foods. 5. Phospholipids form a selectively permeable structure.

5. 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? 1. Proteins sandwiched between two layers of phospholipids 2. A layer of protein coating a layer of phospholipid 3. Phospholipids sandwiched between two layers of protein 4. A phospholipid bilayer with proteins scattered on the surfaces of the membranes 5. Proteins embedded in two layers of phospholipids

5. Proteins embedded in two layers of phospholipids

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. carrier; channel 2. peripheral; enzymatic 3. active transport; signal transduction 4. receptor; channel 5. channel; carrier

5. channel; carrier