Chapter 5 General Biology

Most of the functions of a cell membrane, including transport and enzymatic function, are performed by -glycolipids. -cholesterol. -phospholipids. -proteins.

proteins.

The molecules responsible for membrane transport are -carbohydrates. -steroids. -proteins. -phospholipids.

proteins.

Cells acquire low-density lipoproteins (LDLs) by -receptor-mediated endocytosis. -diffusion. -phagocytosis. -pinocytosis.

receptor-mediated endocytosis.

A cell that has neither a net gain of water nor net loss of water when it is immersed in a solution must be -metabolically inactive. -isotonic to its environment. -hypertonic to its environment. -hypotonic to its environment.

sotonic to its environment.

Which of the following processes can move a solute against its concentration gradient? -active transport -facilitated diffusion -passive transport -osmosis

active transport

Which of the following direct energy transfers is impossible in living systems? -chemical energy to kinetic energy -heat to light energy -light energy to chemical energy -light energy to potential energy

-heat to light energy

Which of the following statements regarding active transport is false? -Active transport can move a solute against its concentration gradient. -Active transport requires the cell to expend energy. -Active transport is driven by the concentration gradient. -Active transport uses ATP as an energy source.

Active transport is driven by the concentration gradient.

Which of the following statements regarding diffusion is false -Diffusion is a result of the thermal energy of atoms and molecules. -Diffusion occurs when particles spread from areas where they are less concentrated to areas where they are more concentrated. -Diffusion requires no input of energy into the system. -Diffusion occurs even after equilibrium is reached and no net change is apparent.

Diffusion occurs when particles spread from areas where they are less

Which of the following statements regarding enzyme function is false? -Enzymes emerge unchanged from the reactions they catalyze. -Enzymes are very specific for certain substrates. -An enzyme's function depends on its three-dimensional shape. -Enzymes are used up when they catalyze a chemical reaction so must be synthesized for each new chemical reaction.

Enzymes are used up when they catalyze a chemical reaction so must be synthesized for each new chemical reaction.

What is the basic difference between exergonic and endergonic reactions? -In exergonic reactions, the reactants have less chemical energy than the products; in endergonic reactions, the opposite is true. -Exergonic reactions involve the breaking of bonds; endergonic reactions involve the formation of bonds. -Exergonic reactions involve ionic bonds; endergonic reactions involve covalent bonds -Exergonic reactions release energy; endergonic reactions absorb it.

Exergonic reactions release energy; endergonic reactions absorb it.

Which of the following statements about the ATP molecule is true? -It contains the sugar glucose. -It contains five phosphate groups. -It releases energy when one phosphate group leaves ATP. -Extremely stable bonds link the second and third phosphate groups.

It releases energy when one phosphate group leaves ATP.

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. Which of the following will occur? -Sucrose will leave the balloon. -Sucrose will enter the balloon. -Water will leave the balloon. -Water will enter the balloon.

Water will leave the balloon.

Which of the following substances could be a cofactor? -a polypeptide -a ribosome -a zinc atom -a protein

a zinc atom

A plant cell in a hypotonic solution -bursts because of an inflow of water. -wilts because of an outflow of water. -becomes turgid because of an inflow of water. -shrivels because of an outflow of water.

becomes turgid because of an inflow of water.

Glucose molecules provide energy to power the swimming motion of sperm. In this example, the sperm are changing -chemical energy into potential energy. -kinetic energy into potential energy. -kinetic energy into thermal energy. -chemical energy into kinetic energy.

chemical energy into kinetic energy.

The fluid mosaic model describes the plasma membrane as consisting of -carbohydrates and phospholipids that can drift in the membrane. -a phospholipid bilayer with embedded carbohydrates. -two layers of phospholipids with cholesterol sandwiched between them. -diverse proteins embedded in a phospholipid bilayer.

diverse proteins embedded in a phospholipid bilayer.

Phagocytosis is to eating as pinocytosis is to -drinking -chewing -osmosis -lysis

drinking

small, non polar, hydrophobic molecules such as fatty acids -very slowly diffuse through a membrane's lipid bilayer -are actively transported across cell membranes -easily pass through a membrane's lipid bilayer -require transport proteins to pass through a membranes lipid bilayer

easily pass through a membrane's lipid bilayer

When a cell uses chemical energy to perform work, it uses the energy released from a/an ________ reaction to drive a/an ________ reaction. -exergonic; spontaneous -exergonic; endergonic -endergonic; exergonic -spontaneous; exergonic

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 higher free water concentration. -exhibit a net movement to the side with lower solute concentration. -exhibit a net movement to the side with lower free water concentration. -exhibit an equal movement in both directions across the membrane.

exhibit a net movement to the side with lower free 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? -pinocytosis -endocytosis -diffusion -exocytosis

exocytosis

The cholesterol associated with animal cell membranes -is an abnormality resulting from a diet high in cholesterol. -helps solidify the membranes when the room temperature is below freezing. -is attached to membrane proteins and extends into the watery environment surrounding the cell. -helps to keep phospholipids from being too close to one another.

helps to keep phospholipids from being too close to one another.

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. -is hypertonic to the protozoan. -contains a higher concentration of solutes than the protozoan. -is isotonic to the protozoan.

is hypotonic to the protozoan.

When an enzyme catalyzes a reaction, -it lowers the activation energy of the reaction. -it acts as a reactant. -it raises the activation energy of the reaction. -it is used once and discarded.

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. -chemical energy is a particular form of kinetic energy. -kinetic energy can be converted into various forms of energy, whereas chemical energy can only be converted into heat. -kinetic energy is stored energy that has the potential to do work, and chemical energy is the energy of movement.

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 -neither gain nor lose water. -experience turgor. -shrivel. -lyse.

lyse.

All cells are enclosed by a plasma membrane that is similar in________and__________. -lucidity;texture -structure;function -permeability;content -thickness;composition

structure;function

Osmosis can be defined as -active transport. -the diffusion of a solute. -the diffusion of nonpolar molecules. -the diffusion of water.

the diffusion of water.

According to ________, energy cannot be created or destroyed. -the first law of thermodynamics -the third law of thermodynamics -the second law of thermodynamics -Aristotle's first principle

the first law of thermodynamics

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

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

If placed in tap water, an animal cell will undergo lysis, whereas a plant cell will not. What accounts for this difference? -the expulsion of water by the plant cell's central vacuole -the fact that plant cells are isotonic to tap water -the relative inelasticity and strength of the plant cell wall -the relative impermeability of the plant cell wall to water

the relative inelasticity and strength of the plant cell wall

Which of the following processes is endergonic? -cellular respiration -the breakdown of glucose -the synthesis of glucose from carbon dioxide and water -the burning of wood

the synthesis of glucose from carbon dioxide and water

Facilitated diffusion across a biological membrane requires ________ and moves a substance ________ its concentration gradient. -energy and transport proteins; against -energy and transport proteins; down -transport proteins; against -transport proteins; down

transport proteins; down

An energy barrier -can only be overcome with the use of enzymes. -prevents the spontaneous breakdown of molecules in the cell. -is the amount of energy that must be produced by the reactants to end a chemical reaction. -is higher than the activation energy of a reaction.

prevents the spontaneous breakdown of molecules in the cell.

Which of the following processes is classified as a metabolic pathway? -passive diffusion -osmosis -cell lysis -protein synthesis

protein synthesis

Most of a cell's enzymes are -lipids. -amino acids. -carbohydrates. -proteins.

proteins.

Which of the following is a coenzyme? -iron -zinc -vitamin B6 -iodine

vitamin B6

Which of the following statements regarding membrane protein function is false? -Membrane proteins act as receptors to molecules like hormones. -Membrane proteins form junctions between cells. -Membrane proteins transfer genetic information to the cytoplasm. -Membrane proteins serve as enzymes.

Membrane proteins transfer genetic information to the cytoplasm.

Which of the following substances would have the most trouble crossing a biological membrane diffusing through the lipid bilayer? -CO2 -O2 -Na+ -a small nonpolar molecule such as butane (c4H10)

Na+

Which of the following statements is true for all types of passive transport? -The concentration gradient is the driving force. -Proteins are needed to transport molecules across the membrane -Only small polar molecules are able to cross the plasma membrane. -Ions never cross the plasma membrane by passive transport.

The concentration gradient is the driving force.

Which of the following statements regarding membrane function is false? -the plasma membrane plays a role in transferring signals to the cell's interior. -The plasma membrane is the control center of the cell. -the plasma membrane forms a selective barrier around the cell -the plasma membrane has receptors for chemical messages

The plasma membrane is the control center of the cell.

Relaying a message from a membrane receptor to a molecule that performs a specific function within a cell occurs when -a protein receptor on the interior of the membrane become bounds by a signaling molecule. -a signaling molecule binds to a protein that extends to the outside of the cell. -the extracellular matrix is moved to the inside of the cell. -glycoproteins are recognized by other cells.

a signaling molecule binds to a protein that extends to the outside of the cell.

The energy required to initiate an exergonic reaction is called -exergonic energy. -input energy. -activation energy. -endergonic energy.

activation energy.

Substrates bind to an enzyme's ________ site. -phosphate -allosteric -active -inhibitory

active

Aquaporins -allow water to cross the plasma membrane via facilitated diffusion. -allow for the active transport of water. -allow water to cross the plasma membrane against its concentration gradient -are found in all cells.

allow water to cross the plasma membrane via facilitated diffusion.

Diffusion does not require the cell to expend ATP. Therefore, diffusion is considered a type of -passive transport. -active transport. -exocytosis. -endocytosis.

passive transport.

Oxygen crosses a plasma membrane by -active transport -pinocytosis -passive transport. -osmosis.

passive transport.

The process of a white blood cell engulfing a bacterium is -osmosis. -phagocytosis. -receptor-mediated endocytosis. -pinocytosis.

phagocytosis.