A & P Ch. 4 Biology of the Cell (Homework)

Translation is terminated when a stop codon is presented at the ________ site. 1. A 2. P 3. E 4. B

1. A

A 5% urea solution is hypotonic to a 10% urea solution. A) True B) False

A) True

Facilitated diffusion requires a specific transporter for a specific molecule. A) True B) False

A) True

If a cell is placed in an isotonic medium, there will be no net movement of water. A) True B) False

A) True

If the material the cell takes in is liquid, the process is termed pinocytosis. A) True B) False

A) True

Low-density lipoprotein is brought into the cell by receptor-mediated endocytosis. A) True B) False

A) True

The binding and release of sodium or potassium ions are due to conformational changes in the protein. A) True B) False

A) True

The sodium-potassium pump is a trans-membrane protein. A) True B) False

A) True

What is the source of energy used to power the sodium-potassium pump? A) breakdown of ATP B) formation of ATP C) transport of ATP by the pump D) breakdown of GTP E) transport of GTP by the pump

A) breakdown of ATP

Simple diffusion is defined as the movement of A) molecules from areas of higher concentration to areas of lower concentration. B) molecules from areas of lower concentration to areas of higher concentration. C) water molecules across a membrane. D) gas molecules across a membrane. E) gas or water molecules across a membrane.

A) molecules from areas of higher concentration to areas of lower concentration.

The sodium-potassium pump functions to pump A) sodium ions out of the cell and potassium ions into the cell. B) sodium ions into the cell and potassium ions out of the cell. C) sodium and potassium ions into the cell. D) sodium and potassium ions out of the cell. E) sodium and potassium ions in both directions across the cell membrane.

A) sodium ions out of the cell and potassium ions into the cell.

Facilitated diffusion is used to transport A) sugars and amino acids. B) H2O and O2. C) CO2 and O2. D) CO2 and H2O. E) sugars and H2O.

A) sugars and amino acids

Active transport requires A) An enzyme on the surface of the cell. B) A channel on the surface of the cell. C) A carrier protein on the surface of the cell. D) A pore on the surface of the cell. E) A gate on the surface of the cell.

C) A carrier protein on the surface of the cell.

When a membrane that is permeable to both a solute and water separates water with a high osmolarity from water with a low osmolarity A) The water will only move through the membrane in one direction while the solute will move through the membrane in the other. B) The solute will pass through the membrane in both directions until equilibrium is reached on both sides of the membrane for the solute. C) Both the water and the solute will pass through the membrane in both directions until equilibrium is reached on both sides of the membrane for both water and the solute. D) The motion of the molecules of both the solute and water will cease when equilibrium is reached.

C) Both the water and the solute will pass through the membrane in both directions until equilibrium is reached on both sides of the membrane for both water and the solute.

Which of the following statements is false regarding the sodium-potassium pump? A) After releasing ions into the extracellular fluid, the carrier protein exhibits a new conformation. B) With this new conformation, the carrier protein can now bind to different ions in the extracellular fluid. C) The ions in the extracellular fluid bind to the carrier protein, and the potassium attached to the carrier protein is released. D) The carrier protein then changes shape again. E) The ions from the extracellular fluid are then transported across the cell membrane to the inside of the cell.

C) The ions in the extracellular fluid bind to the carrier protein, and the potassium attached to the carrier protein is released.

The sodium potassium exchange pump is an example of A) diffusion. B) facilitated diffusion. C) active transport. D) osmosis. E) filtration.

C) active transport.

The lysosome contains ________ enzymes. A) photosynthetic B) anabolic C) hydrolytic D) melancholic E) alcoholic

C) hydrolytic

Which of the following statements about receptor-mediated endocytosis is TRUE? A) it is used to transport material out of the cell B) it is not specific C) it involves clathrin-coated pits D) it involves transport of material into the cell through pores in the cell membrane E) none of the above

C) it involves clathrin-coated pits

A red blood cell placed in a hypertonic medium will A) expand. B) burst. C) shrink. D) have no change in shape. E) become a white blood cell.

C) shrink.

When sugar is mixed with water, equilibrium is reached when A) molecules of sugar stop moving. B) water and sugar molecules are moving at the same speed. C) the dissolved sugar molecules are evenly distributed throughout the solution. D) there are the same number of water molecules as dissolved sugar molecules. E) two tablespoons of coffee are added.

C) the dissolved sugar molecules are evenly distributed throughout the solution.

During one cycle, the sodium-potassium pump binds and moves. A) 1 Na+ and 2 K+. B) 2 Na+ and 2 K+. C) 2 Na+ and 3 K+. D) 3 Na+ and 2 K+. E) 3 Na+ and 3 K+.

D) 3 Na+ and 2 K+.

Lysosomes are membrane-bound vesicles that arise from the A) nucleus. B) mitochondria. C) endoplasmic reticulum. D) Golgi apparatus. E) cell membrane.

D) Golgi apparatus.

Facilitated diffusion occurs A) into the cell only. B) out of the cell only. C) in either direction depending on the temperature. D) in either direction depending on the concentration gradient of the molecule. E) in either direction depending on the size of the molecule.

D) in either direction depending on the concentration gradient of the molecule.

Certain white blood cells engulf microorganisms and bring them in to digest them. This process is best described as A) pinocytosis. B) osmosis. C) receptor-mediated exocytosis. D) phagocytosis. E) diffusion.

D) phagocytosis.

Translation is the synthesis of A) mRNA from DNA. B) mRNA from proteins. C) proteins from DNA. D) proteins from mRNA. E) proteins from tRNA.

D) proteins from mRNA.

Diffusion is one of the processes whereby materials are exchanged between a cell and its environment. A) True B) False

True

The molecules in a solid lump of sugar do not move. A) True B) False

FALSE

Active transport moves a solute A) up its concentration gradient; that is, from a low concentration to a high one. B) up its concentration gradient; that is, from a high concentration to a low one. C) down its concentration gradient, that is, from a low concentration to a high one. D) down its concentration gradient; that is, from a high concentration to a low one. E) across its concentration gradient; that is, from a high concentration to a low one.

A) up its concentration gradient; that is, from a low concentration to a high one.

Unlike simple diffusion, facilitated diffusion requires energy expenditure by the cell. A) True B) False

B) False

Facilitated diffusion requires A) enzymes. B) carrier proteins. C) lipid carriers. D) carbohydrate carriers. E) lipid or carbohydrate carriers.

B) carrier proteins.

Active transport requires A) energy in the form of ADP. B) energy in the form of ATP. C) energy in the form of glucose. D) energy in the form of fructose. E) little or no energy to function.

B) energy in the form of ATP.

Exocytosis is a process by which cells A) release substances from the cell through pores in the cell membrane. B) release substances from the cell via vesicles. C) release substances from the cell via carrier proteins. D) bring in substances from the outside via vesicles. E) bring in substances from the outside via pores in the cell membrane.

B) release substances from the cell via vesicles.

Which of the following will pass through a cell membrane most easily? A) small polar molecules B) small nonpolar molecules C) large polar molecules D) large nonpolar molecules E) large neutral molecules

B) small nonpolar molecules

Osmosis is best defined as the movement of A) molecules from an area of high concentration to an area of lower concentration. B) molecules from an area of low concentration to an area of higher concentration. C) water molecules across a membrane from an area of low water to an area of higher concentration. D) water molecules across a membrane from an area of high water concentration to an area of lower concentration. E) water molecules inside a container.

D) water molecules across a membrane from an area of high water concentration to an area of lower concentration.

Which of the following cells will be expected to contain the most active lysosomes? A) Brain cell B) Skin cell C) Kidney cell D) Intestinal cell E) Phagocytosing white blood cell

E) Phagocytosing white blood cell

The rate of diffusion is affected by which of the following? A) Temperature B) Size of molecules C) Steepness of the concentration gradient D) Temperature and size of the molecules only E) Temperature, size of the molecules, and steepness of the concentration gradient

E) Temperature, size of the molecules, and steepness of the concentration gradient

Which of the following occurs as the ribosome shifts down the mRNA by a distance of three nucleotides? A) The tRNA that was in the A site moves into the E site. B) The tRNA that was in the P site moves into the A site. C) The tRNA that was in the E site moves into the P site. D) The tRNA that was in the E site moves into the A site. E) The tRNA that was in the P site moves into the E site.

E) The tRNA that was in the P site moves into the E site.

When a membrane that is only permeable to water separates water with a high osmolarity from water with a low osmolarity A) The water will diffuse through the membrane until there is an equal volume of solute on both sides. B) The water will diffuse through the membrane until there is an equal volume of water on both sides. C) The water will diffuse through the membrane until there is an equal concentration of water on both sides. D) The water will diffuse through the membrane until there is an equal concentration of solute on both sides. E) The water will diffuse through the membrane until there is an equal concentration of solute and water on both sides.

E) The water will diffuse through the membrane until there is an equal concentration of solute and water on both sides.