Cell Transport/Enzymes Honors Biology Test 2022

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

transport proteins; down

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

you dehydrate yourself.

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.

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

passive transport

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

Most of a cell's enzymes are what macromoecule?

proteins

Most of the functions of a cell membrane, including transport and enzymatic function, are performed by...

proteins

The active site of an enzyme is...

the region of an enzyme that attaches to a substrate.

The picture demonstrates an example of which type of cell transport?

Active Trasport

Aquaporins...

allow water to cross the plasma membrane via facilitated diffusion.

What is a concentration gradient?

A difference in concentrations that drives molecules to flow from high to low concentrations

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 an allosteric site.

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 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.

_ is the increase of heat and therefore the disorder of the universe.

Entropy

What type of movement is passive and needs the help of a membrane protein to move through the cell membrane?

Facilitated diffusion

Sodium potassium pump is an example of passive transport. (T/F)

False

Biologists use the _ model to describe the plasma membrane's structure.

Fluid mosaic

_ are proteins that serve as ID tags, they may be recognized by membrane proteins of other cells. These proteins must match in patients that need kidney transplants and their donors.

Glycoproteins

Which of the following statements about ATP is true?

It releases energy when one phosphate group leaves ATP.

_ proteins form intercellular connections that attach adjacent cells.

Junctions

_ is the term used when a plant cell is in a hypertonic solution.

Plasmolysis

what is the driving force of passive transport

The concentration gradient is the driving force.

Which part of the ATP molecule breaks free of the rest when an ATP molecule releases energy?

The last phosphate

The fluid mosaic model describes the plasma membrane as consisting of diverse proteins embedded in a phospholipid bilayer. (T/F)

True

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. What will occur?

Water will leave the balloon

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

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

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

a. The plasma membrane is the control center of the cell.

Which process can move a solute against its concentration gradient?

active transport

Which of the following substances would have the most trouble crossing a biological membrane by diffusing through the lipid bilayer? a. O2 b. Na+ c.d. a small, nonpolar molecule such as butane (C4H10)

b. Na+

All of the following are true about the data in the accompanying figure except? a.The solid line represents a reaction that has not been catalyzed by an enzyme. b. The energy of the products is higher than the energy of the reactants. c. Both lines represent endergonic reactions. d.The dashed line represents a reaction that includes an enzyme.

b. The energy of the products is higher than the energy of the reactants.

A plant cell in a hypotonic solution

becomes turgid because of an inflow of water.

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

c. Active transport is driven by the concentration gradient.

Which of the following statements regarding membrane protein function is false? a. Membrane proteins serve as enzymes. b. Membrane proteins form junctions between cells. c. Membrane proteins produce phospholipids. d. Membrane proteins act as receptors to molecules like hormones.

c. Membrane proteins produce phospholipids.

A group of single-cell organisms collected from the ocean was brought into the lab for examination. The lab assistant was concerned that the water had become full of toxic waste products and so added clean water to the culture. All of the organisms died, and when she looked at them under the microscope, all she could see were bits and pieces of them scattered throughout the water. What likely happened? a. She added too little salt to the seawater she added, and the organisms all lost too much water and shriveled up. b. She added seawater to which she had added too much salt, and they ruptured. c. She added water that was hypotonic to the culture of organisms, and they ruptured. d. She added water isotonic to the organisms, causing too much water to move in and out of the organisms, and they ruptured.

c. She added water that was hypotonic to the culture of organisms, and they ruptured.

Which of the following processes is endergonic? a. the burning of wood b. cellular respiration c. the synthesis of glucose from carbon dioxide and water d. the breakdown of glucose

c. the synthesis of glucose from carbon dioxide and water

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

How do fatty acids travel through a cell membrane?

diffusion

Osmosis can be defined as

diffusion of water

Membrane phospholipids are able to _ in the plasma membrane.

drift about within one monolayer in the plasma membrane.

When a cell uses chemical energy to perform work, it uses the energy released from a(n) ________ reaction to drive a(n) ________ reaction.

exergonic; endergonic

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

Many physiological conditions are related to particular proteins in cell membranes. The number of insulin receptors in membranes is related to the amount of insulin present around those cells. If the presence of increased insulin results in a decrease in receptors and a decrease in insulin results in an increase in insulin receptors, this would be an example of

feedback inhibition.

What is it called when a plant cell is in an isotonic solution? _

flaccid

The cholesterol associated with animal cell membranes aids...

in the fluidity of the membrane.

Enzymatic reactions can only occur if the enzyme's active site binds to or hugs the correct substrate. This is called _

induced fit

A cell that has neither a net gain of water nor a net loss of water when it is immersed in a solution must be

isotonic to its environment.

When an enzyme catalyzes a reaction...

it lowers the activation energy of the reaction.

what happens to an animal cell in a hypotonic solution?

it lyses

List the three types of endocytosis.

receptor mediated endocytosis phagocytosis pinocytosis

In a hypotonic solution, an animal cell will

swell and possibly lyse.

Plasma membranes are selectively permeable. This means that

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