Chapter 5

Membrane phospholipids A)form impermeable layers for cells . B) remain fluid because they are tightly packed against one another. C) often have "kinks" in their tails caused by the presence of a double bond between carbons. D) have hydrophobic heads that face the center of the membrane and are shielded from water. E) have hydrophilic tails that face outward and are exposed to water.

C) often have "kinks" in their tails caused by the presence of a double bond between carbons

Which characteristic promoted the utilization of lipids as the first cell membrane? A)utilization of the hydrophilic nature of lipids B)spontaneous degradation of the intracellular environment C)self-assembly into a simple membrane D)ability to form an impermeable membrane E)formation of a semi-solid membrane

C)self-assembly into a simple membrane

A steer must eat at least 100 pounds of grain to gain less than 10 pounds of muscle tissue. This illustrates A)that some energy is destroyed in every energy conversion. B)that thermal energy can be transformed into chemical energy. C)the second law of thermodynamics. D)the first law of thermodynamics. E)that energy transformations are typically 100% efficient.

C)the second law of thermodynamics.

In a hypotonic solution, an animal cell will A)experience turgor. B) shrivel. C) lose water. D) neither gain nor lose water. E) lyse.

E) lyse.

Oxygen crosses a plasma membrane by A) pinocytosis. B) active transport. C) phagocytosis. D)osmosis. E) passive transport.

E) passive transport.

Facilitated diffusion across a biological membrane requires ________ and moves a substance ________ its concentration gradient. A) energy and transport proteins . . . against B) transport proteins . . . against C) energy . . . down D) energy and transport proteins . . . down E) transport proteins . . . down

E) transport proteins . . . down

Some protozoans have special organelles called contractile vacuoles that continually eliminate excess water from the cell. The presence of these organelles tells you that the environment A)contains a higher concentration of solutes than the protozoan. B)is contaminated with pollutants. C)is isotonic to the protozoan. D)is hypertonic to the protozoan. E)is hypotonic to the protozoan.

E)is hypotonic to the protozoan.

Plasma membranes are selectively permeable. This means that A)cholesterol cannot enter the cell. B)glucose cannot enter the cell. C)anything can pass into or out of a cell as long as the membrane is intact and the cell is healthy. D)plasma membranes must be very thick. E)the plasma membrane allows some substances to enter or leave a cell more easily than others.

E)the plasma membrane allows some substances to enter or leave a cell more easily than others.

A cell that neither gains nor loses water when it is immersed in a solution is A) isotonic to its environment. B) hypertonic to its environment. C) dead. D) hypotonic to its environment. E) metabolically inactive.

A) isotonic to its environment.

The transfer of a phosphate group to a molecule or compound is called A) phosphorylation. B)hydrogenation. C)ionization. D)carboxylation. E)hydrogen bonding.

A) phosphorylation.

ATP can be used as the cell's energy exchange mechanism because A)endergonic reactions can be fueled by coupling them with the hydrolysis of high-energy phosphate bonds in ATP. B)ATP is a disposable form of chemical energy, used once and then discarded by the cell. C)endergonic reactions can be fueled by coupling them with the formation of ATP from ADP. D)ATP is the most energy-rich small molecule in the cell. E)the regeneration of ATP from ADP can be fueled by coupling it with endergonic reactions.

A)endergonic reactions can be fueled by coupling them with the hydrolysis of high-energy phosphate bonds in ATP.

Diffusion does not require the cell to expend ATP. Therefore, diffusion is considered a type of A)passive transport. B)endocytosis. C)exocytosis. D)active transport. E)phagocytosis.

A)passive transport.

You are adrift in the Atlantic Ocean, and, being thirsty, drink the surrounding seawater. As a result, A)you dehydrate yourself. B)your cells become turgid. C)your cells lyse from excessive water intake. D)your cells lyse, due to the excessive intake of salt. E)you quench your thirst.

A)you dehydrate yourself.

Which of the following processes is endergonic? A) the breakdown of glucose B) the synthesis of glucose from carbon dioxide and water C) the burning of wood D) cellular respiration E) the release of heat from the breakdown of glucose

B) the synthesis of glucose from carbon dioxide and water

White blood cells (WBCs) are more resistant to lysis than red blood cells (RBCs). When looking at a sample of blood for WBCs, would could you do to reduce interference from RBCs? A)Mix the blood with a dye that stains the proteins in the cytoplasm. B)Mix the blood in a hypotonic solution, which will cause the RBCs to lyse. C) Mix the blood in a hypertonic solution, which will cause the RBCs to lyse. D) Mix the blood in an isotonic solution and allow the WBCs to float to the top. E) Mix the blood in a salty solution to cause the RBCs to lyse.

B)Mix the blood in a hypotonic solution, which will cause the RBCs to lyse.

When physicians perform an organ transplant, they choose a donor whose tissues match those of the recipient as closely as possible. Which of the following cell components are being matched? A)plasma membrane proteins B)cell-surface carbohydrates C)cytoskeletal elements D)plasma membrane phospholipids E)plasma membrane cholesterols

B)cell-surface carbohydrates

Certain cells that line the stomach synthesize a digestive enzyme and secrete it into the stomach. This enzyme is a protein. Which of the following processes could be responsible for its secretion? A)pinocytosis B)exocytosis C)endocytosis D)diffusion E)passive transport

B)exocytosis

Which of the following statements regarding enzyme function is false? A)Enzymes emerge unchanged from the reactions they catalyze. B) An enzyme binds to its substrate at the enzyme's active site. C)Enzymes are used up in chemical reactions. D)An enzyme's function depends on its three-dimensional shape. E)Enzymes are very specific for certain substrates.

C)Enzymes are used up in chemical reactions.

A major function of glycoproteins and glycolipids in the cell membrane is to A) glue cells together to form tissues. B) help the cell resist swelling. C) allow the cells of an embryo to sort themselves into tissues and organs. D) attach the cell membrane to the cytoskeleton. E) help the cell retain its shape.

C) allow the cells of an embryo to sort themselves into tissues and organs.

Living systems A) violate the second law of thermodynamics. B) are only compelled to follow the first law of thermodynamics. C) decrease their entropy while increasing the entropy of the universe. D) are examples of a closed system. E) violate the first law of thermodynamics.

C) decrease their entropy while increasing the entropy of the universe.

A plant cell in a hypotonic solution A) is flaccid. B) shrivels. C) is turgid. D) wilts. E)lyses.

C) is turgid.

Which of the following examples is classified as a metabolic pathway? A) osmosis B) passive diffusion C) protein synthesis D) spontaneous combustions E) cell lysis

C) protein synthesis

Which of the following statements regarding membrane protein function is false? A) Membrane proteins act as receptors to molecules like hormones. B) Membrane proteins serve as enzymes. C)Membrane proteins transfer genetic information to the cytoplasm. D) Membrane proteins form junctions between cells. E)Membrane proteins provide cellular identification tags.

C)Membrane proteins transfer genetic information to the cytoplasm.

Which of the following statements about the ATP molecule is true? A)It contains the six-carbon sugar hexose. B)It contains two phosphate groups. C)It can be coupled with an exergonic reaction. D) It contains a nitrogenous base molecule called adenine. E)Extremely stable bonds link the second and third phosphate groups.

D) It contains a nitrogenous base molecule called adenine.

In the lab, you use a special balloon that is permeable to water but not sucrose to make an "artificial cell." The balloon is filled with a solution of 20% sucrose and 80% water and is immersed in a beaker containing a solution of 40% sucrose and 60% water. The solution in the balloon is ________ relative to the solution in the beaker. A) hydrophobic B) hydrophilic C) hypertonic D) hypotonic E) isotonic

D) hypotonic

Which of the following statements regarding thermodynamics is false? A)An open system exchanges both energy and matter with its surroundings. B)The collection of matter under study is called the system. C)Thermodynamics is the study of energy transformations that occur in a collection of matter. D)An automobile engine is an example of a closed system. E)A single cell or the planet Earth could be a thermodynamic system.

D)An automobile engine is an example of a closed system.

Most of the functions of a cell membrane are performed by A)Glycolipids. B)cholesterol. C)phospholipids. D)proteins. E)nucleotides.

D)proteins

The active site of an enzyme is A) the highly changeable portion of an enzyme that adapts to fit the substrates of various reactions. B) the region of the enzyme composed of only a few specific nucleic acids. C) the region of a product that detaches from the enzyme. D) the region of a substrate that is changed by an enzyme. E) the region of an enzyme that attaches to a substrate.

E) the region of an enzyme that attaches to a substrate.