Chapter 5 Practice Questions

Which of the following is a typical feature of an ATP-driven active transport mechanism?

The solute moves against the concentration gradient.

Anything that prevents ATP formation will most likely

result in cell death

Anything that prevents ATP formation will most likely

result in cell death.

Plasma membranes are selectively permeable. This means that

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

In the reaction A → B + C + heat,

the potential energy of the products is less than that of the reactant.

The active site of an enzyme is

the region of an enzyme that attaches to a subsrate.

The active site of an enzyme is

the region of an enzyme that attaches to a substrate.

If placed in tap water, an animal cell will undergo lysis, whereas a plant cell will not. What accounts for this difference?

the relative inelasticity and strength of the plant cell wall

A steer must eat at least 100 pounds of grain to gain less than 10 pounds of muscle tissue. This illustrates

the second law of thermodynamics.

Which one of the following processes is endergonic

the synthesis of glucose from carbon dioxide and water

Facilitated diffusion across a biological membrane requires _________ and moves a substance _________ its concentration gradient.

transport proteins.....down

Most of the functions of a cell membrane are preformed by

proteins

Most of a cell's enzymes are

proteins.

Most of the functions of a cell membrane are performed by

proteins.

The molecules responsible for membrane transport are

proteins.

Cells acquire LDLs by

receptor-mediated endocytosis.

Americans spend up to $100 billion annually for bottled water (41 billion gallons). The only beverages with higher sales are carbonated soft drinks. Recent news stories have highlighted the fact that most bottled water comes from municipal water supplies (the same source as your tap water), although it may undergo an extra purification step called reverse osmosis. Imagine two tanks that are separated by a membrane that's permeable to water, but not to the dissolved minerals present in the water. Tank A contains tap water and Tank B contains the purified water. Under normal conditions, the purified water would cross the membrane to dilute the more concentrated tap water solution. In the reverse osmosis process, pressure is applied to the tap water tank to force the water molecules across the membrane into the pure water tank. If you shut the system off and pressure was no longer applied to Tank A, you would expect

A) the water movement to follow the concentration gradient. B) the water to revers flow from B to A. both a and b above to occur. (correct answer)

Which of the following statements regarding active transport is false?

Active transport is driven by the concentration gradient.

Which of the following can affect the rate of an enzyme-catalyzed reaction?

All of the choices are correct.

Which of the following statements regarding thermodynamics is false?

An automobile engine is an example of a closed system.

How does inhibition of an enzyme-catalyzed reaction by a competitive inhibitor differ from inhibition by a noncompetitive inhibitor?

Competitive inhibitors bind to the active site of the enzyme; noncompetitive inhibitors bind to a different site.

Which of the following statements regarding diffusion is false?

Diffusion occurs when particles spread from areas where they are less concentrated to areas where they are more concentrated.

A child is brought to the hospital with a fever of 107°F. Doctors immediately order an ice bath to lower the child's temperature. Which explanation offers the most logical reason for this action?

Elevated body temperatures may denature enzymes. This would interfere with the cell's abilities to catalyze various reactions

A child is brought to the hospital with a fever of 107 degrees F. Doctors immediately order an ice bath to lower the child's temperature. Which of the following statements offers the most logical explanation for this action?

Elevated body temperatures may denature enzymes. This would interfere with the cell's abilities to catalyze various reactions.

Which of the following statements regarding enzyme function is false?

Enzymes are used up in chemical reactions.

Which one of the following is false?

Enzymes are used up in chemical reactions.

What is the role of enzymes?

Enzymes catalyze specific reactions.

Which of the following statements regarding enzymes is true?

Enzymes catalyze specific reactions.

What is the basic difference between exergonic and endergonic reactions?

Exergonic reactions release energy; endergonic reactions absorb it

What is the basic difference between exergonic and endergonic reactions?

Exergonic reactions release energy; endergonic reactions absorb it.

Which one of the following is true about the ATP molecule?

It contains a nitrogenous base molecule called adenine

Which of the following statements about the ATP molecule is true?

It contains a nitrogenous base molecule called adenine.

Which of the following statements regarding membrane protein function is false?

Membrane proteins transfer genetic information to the cytoplasm.

White blood cells (WBCs) are more resistant to lysis than red blood cells (RBCs). When looking at a sample of blood for WBCs, what could you do to reduce interference from RBCs?

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

Which of the following substances would have the most trouble crossing a biological membrane by diffusing through the lipid bilayer?

Na+

In 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. Which of the following will occur?

Water will leave the balloon.

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 and 60% water. Which of the following will occur?

Water will leave the balloon.

Which of the following substances could be a cofactor?

a zinc atom

Substrates bind to an enzyme's _________ site.

active

Substrates bind to an enzyme's __________ site.

active

Which of the following processes can move a solute against its concentration gradient?

active transport

Which of the following processes could result in the net movement of a substance into a cell, if the substance is more concentrated in the cell than in the surroundings?

active transport

Which one of the following processes could result in the net movement of a substance into a cell, if the substance is more concentrated in the cell than in the surroundings?

active transport

A major function of glycoproteins and glycolipids in the cell membrane is to

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

Americans spend up to $100 billion annually for bottled water (41 billion gallons). The only beverages with higher sales are carbonated soft drinks. Recent news stories have highlighted the fact that most bottled water comes from municipal water supplies (the same source as your tap water), although it may undergo an extra purification step called reverse osmosis. Imagine two tanks that are separated by a membrane that's permeable to water, but not to the dissolved minerals present in the water. Tank A contains tap water and Tank B contains the purified water. Under normal conditions, the purified water would cross the membrane to dilute the more concentrated tap water solution. In the reverse osmosis process, pressure is applied to the tap water tank to force the water molecules across the membrane into the pure water tank. After the reverse osmosis system has been operating for 30 minutes, the solution in tank A would

be hypertonic to tank B

Which of the following examples is classified as a metabolic pathway?

protein synthesis

Which figure depicts an animal cell placed in a solution hypotonic to the cell? (see figure)

cell A

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?

cell-surface carbohydrates

When physicians preform an organ transplant, they choose a donor whose tissues match those of the recipients as closely as possible. Which of the following cell components are being matched?

cell-surface carbohydrates

Heating inactivates enzymes by

changing the enzyme's three-dimensional shape.

Glucose molecules provide energy to power the swimming motion of sperm. In this example, the sperm are changing

chemical energy into kinetic energy.

What type of bond joins the phosphates of ATP?

covalent

Living systems

decrease their entropy while increasing the entropy of the universe.

Phagocytosis is to eating as pinocytosis is to

drinking

Phagocytosis is to eating as pinocytosis is to

drinking.

Small, nonpolar, hydrophobic molecules such as fatty acids

easily pass through a membrane's lipid bilayer.

When a cell uses chemical energy to preform work, it couples a(n) _________ reaction with a(n) _________ reaction.

exergonic....endergonic

When two aqueous solutions that differ in solute concentration are placed on either side of a semipermeable membrane, and osmosis is allowed to take place, the water will

exhibit a net movement to the side with lower water concentration

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?

exocytosis

Bacterial production of the enzymes needed for the synthesis of the amino acid tryptophan declines with increasing levels of tryptophan and increases as tryptophan levels decline. This is an example of

feedback inhibition.

The more heat released by a reaction, the

greater the increase in entropy

The cholesterol associated with cell membranes

helps to stabilize the cell membrane at body temperature

The cholesterol associated with animal cell membranes

helps to stabilize the cell membrane at body temperature.

In the lab, you use a special that is permeable to water but not to 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.

hypotonic

Many of the enzymes that control a firefly's ability to produce light energy from chemical energy are located

in membranes.

Where in are eukaryotic cell enzymes typically located?

in plasma membranes and inside organelles

The fluid mosaic model describes the plasma membrane as consisting of

individual proteins and phospholipids that can drift in a phospholipid bilayer

The fluid mosaic model describes the plasma membrane as consisting of

individual proteins and phospholipids that can drift in a phospholipid bilayer.

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

is hypotonic to the protozoan

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

is hypotonic to the protozoan.

Which one of the following is not a function of the plasma membrane? The plasma membrane

is the control center of the cell.

A plant cell in a hyotonic solution

is turgid.

A cell that neither gains nor loses water when it is immersed in a solution is

isotonic to its environment.

When an enzyme catalyzes a reaction

it lowers the activation energy of the reaction.

When an enzyme catalyzes a reaction,

it lowers the activation energy of the reaction.

Kinetic energy differs from chemical energy in that

kinetic energy is the energy of a moving object, whereas chemical energy is the potential energy of molecules.

In a hypotonic solution, an animal cell will

lyse.

Which of the following is not a true statement about diffusion? Diffusion

occurs when particles spread from areas where they are less concentrated to areas where they are more concentrated.

Membrane phospholipids

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

Diffusion does not require the cell to expend ATP. Therefore, diffusion is considered a type of

passive transport.

Oxygen crosses a plasma membrane by

passive transport.

The act of a white blood cell engulfing a bacterium is

phagocytosis

The process of a white blood cell engulfing a bacterium is

phagocytosis

The transfer of a phosphate group to a molecule or compound is called

phosphorylation.

Ultimately, nearly all animals are dependent on __________ as their source of energy.

photosynthesis

An energy barrier

prevents the spontaneous decomposition of molecules in the cell.

Relaying a message from a membrane receptor to a molecule that preforms a specific function within a cell is called

signal transduction.

The ultimate source of nearly all energy available to life on Earth is

sunlight.

Osmosis can be defined as

the diffusion of water across a membrane.

Osmosis can be defined as

the diffusion of water.

The energy required to initiate an exergonic reaction is called

the energy of activation

The energy required to initiate an exergonic reaction is called

the energy of activation.

According to __________, energy cannot be created or destroyed.

the first law of thermodynamics

You are adrift in the Atlantic Ocean, and, being thirsty, drink the surrounding seawater. As a result,

you dehydrate yourself.