Chapter 05: The Working Cell Dynamic Study Module

Select the substances that use facilitated diffusion to cross cell membranes. (Select all that apply) -ions -amino acids -water -sugars -oxygen

-ions -amino acids -water -sugars

Enzymes __________ the activation energy of a reaction. The energy change between products and reactants is __________ for a reaction that is catalyzed versus one that is not. -raise; the same -lower; less -lower; the same -raise; greater -lower; greater

lower; the same

(Match the terms to the correct description of how large molecules are moved into and out of cells.) -A cell engulfs a particle by wrapping extensions around it and packaging it in a vacuole. -pits coated with proteins that have specific binding sites for substances -Vesicles carrying bulky materials from the Golgi apparatus fuse with the cell membrane, releasing their contents into the extracellular fluid.

-phagocytosis -receptor-mediated endocytosis -exocytosis

What is meant by the term "enzyme specificity"? -An enzyme is "used" only once. -An enzyme is specific for one temperature and pH range. -An enzyme catalyzes only one type of reaction. -An enzyme is present in only one cell type. -An enzyme has only one active site.

An enzyme catalyzes only one type of reaction.

__________ energy is the type of __________ energy used to power the work of the cell. -Chemical; potential -Thermal; kinetic -Heat; kinetic -Chemical; kinetic -Thermal; potential

Chemical; potential

Which of the following is a correct statement about aquaporins? -Aquaporin proteins have been identified in animal cells, but not in plants or bacteria. -Each aquaporin molecule allows billions of molecules of water to cross the plasma membrane each second. -Each aquaporin molecule allows thousands of molecules of water to cross the plasma membrane each day. -When injected into frog eggs in a hypotonic solution, aquaporin messenger RNA (mRNA) slows the rate of osmosis. -People whose kidney cells have too many aquaporin proteins have to urinate very often.

Each aquaporin molecule allows billions of molecules of water to cross the plasma membrane each second.

The pesticide malathion and some drugs used as anesthetics both block an enzyme that is critical for transmitting nerve impulses. Why don't patients die like insects when they undergo surgery? -Enzyme inhibition with malathion is irreversible but with anesthetics, reversible. -Enzyme inhibition with both drugs is irreversible but with anesthetics, "rescue" drugs are available. -Enzyme inhibition with malathion is reversible but with anesthetics, irreversible. -Insects are exposed to the enzyme for a long time, but most operations using these drugs are fairly brief. -The dose of enzyme inhibitor in malathion is much greater than in anesthetics.

Enzyme inhibition with malathion is irreversible but with anesthetics, reversible.

Imagine a U-shaped tube with a membrane at the bottom of the "U". The membrane is permeable to glucose, sucrose, and water. You place a concentrated glucose solution on Side A and an equally concentrated sucrose solution on Side B. Describe the movement of each solute across the membrane during the first few hours. -Glucose will move into Side B down its concentration gradient, and sucrose will remain on Side B until the movement of glucose has stopped. -Neither substance will cross the membrane because the concentrations on Sides A and B are the same. -Sucrose will move into Side A down its concentration gradient, and glucose will remain on Side A until the movement of sucrose has stopped. -Glucose will move into Side B down its concentration gradient, and sucrose will move into Side A down its concentration gradient. -Free water will move between Sides A and B through osmosis.

Glucose will move into Side B down its concentration gradient, and sucrose will move into Side A down its concentration gradient.

What is one way of reducing the effectiveness of a competitive enzyme inhibitor? -Increase the concentration of the competitive inhibitor. -Increase the concentration of the enzyme. -Decrease the concentration of the enzyme. -Decrease the concentration of the substrate. -Increase the concentration of the substrate.

Increase the concentration of the substrate.

One model of the cell membrane is that it is a "fluid mosaic." What does this mean? -It consists of nucleotides, proteins, and ions suspended in a fluid phospholipid bilayer. -It consists of small, nonpolar molecules suspended in a fluid phospholipid bilayer. -It consists of phospholipids suspended in a bilayer of proteins. -It consists of ions and carbohydrates suspended in a bilayer of of proteins. -It consists of proteins suspended in a fluid phospholipid bilayer.

It consists of proteins suspended in a fluid phospholipid bilayer.

In what way, if any, does osmosis differ from simple diffusion? -Polar water molecules cluster with hydrophilic molecules, so only free water diffuses down its concentration gradient. -Polar water molecules cluster with hydrophilic molecules, and these are the only water molecules that cross the membrane. -They are the same process: "Osmosis" is used to distinguish the movement of water from that of other molecules. -Nonpolar water molecules cluster with hydrophilic molecules, so only free water diffuses down its concentration gradient. -Polar water molecules avoid hydrophilic molecules, so only free water diffuses down its concentration gradient.

Polar water molecules cluster with hydrophilic molecules, so only free water diffuses down its concentration gradient.

When you hear "Substance X is moved against its concentration gradient," what do you think of? -Substance X has moved from a region of lower to a region of higher concentration with the help of a transport protein. -Substance X has moved from a region of lower to a region of higher concentration with the help of ATP. -Substance X has moved from a region of higher to a region of lower concentration with the help of its concentration gradient. -Substance X has moved from a region of higher to a region of lower concentration with the help of ATP. -Substance X has moved from a region of higher to a region of lower concentration with the help of a transport protein.

Substance X has moved from a region of lower to a region of higher concentration with the help of ATP.

Imagine a metabolic pathway where: Molecule A → Molecule B → Molecule C → Molecule D → Product X. Enzyme 1 catalyzes the first reaction (Molecule A → Molecule B), Enzyme 2 catalyzes the second reaction (Molecule B → Molecule C), and so on. Product X exerts feedback inhibition on Enzyme 2. What is the consequence of this inhibition as Product X accumulates? -The concentration of Molecule C increases. -Molecule B is eliminated. -The concentration of Molecule B decreases. -The concentration of Molecule A increases. -The concentration of Molecule B increases.

The concentration of Molecule B increases.

Researchers used frog eggs to learn more about aquaporins. What characteristic of normal frog eggs was essential in these studies? -They are highly permeable to water. -They contain high levels of aquaporins. -They are largely impermeable to water. -They are surrounded by a hypertonic solution. -They can translate mRNA into protein.

They are largely impermeable to water.

Which of the following statements about coenzymes is correct? -They speed up reactions faster than enzymes. -They are organic and inorganic cofactors with enzymes in reactions. -They are organic cofactors with enzymes in reactions. -They are specific for a particular enzyme. -They are inorganic cofactors with enzymes in reactions.

They are organic cofactors with enzymes in reactions.

A plant cell placed into an isotonic solution __________. An animal cell placed into an isotonic solution __________. -remains turgid; shrivels -neither swells nor shrivels; neither swells nor shrivels -becomes flaccid; shrivels -becomes flaccid; neither swells nor shrivels -remains turgid; bursts

becomes flaccid; neither swells nor shrivels

Before refrigeration, meat was preserved by adding __________. What effect did this have on any contaminating bacteria or fungi? -concentrated sugar solutions; plasmolysis -concentrated salt solutions; swelling and bursting -dilute sugar solutions; swelling and bursting -concentrated salt solutions; plasmolysis -dilute salt solutions; swelling and bursting

concentrated salt solutions; plasmolysis

Building a molecule of ATP is an __________ process. Hydrolyzing a molecule of ATP is an __________ process. This cycle is an example of __________. -endergonic; exergonic; metabolism -endergonic; exergonic; energy coupling -exergonic; endergonic; energy coupling -endergonic; endergonic; energy coupling -exergonic; exergonic; metabolism

endergonic; exergonic; energy coupling

Photosynthesis is an __________ process. Energy from __________ allows the production of products with __________. -exergonic; the sun; higher potential energy than the reactants -endergonic; the sun; lower potential energy than the reactants -exergonic; metabolism; lower potential energy than the reactants -endergonic; the sun; higher potential energy than the reactants -endergonic; mitochondria; about the same potential energy as the reactants

endergonic; the sun; higher potential energy than the reactants

At what stage of active transport is ATP needed? -attachment of the solute to its transport protein -for the transport protein to change its shape -return of the transport protein to its original shape -ATP is not required for active transport. -release of the solute from its transport protein

for the transport protein to change its shape

Which of the following prevents the cells of a freshwater fish from becoming hypotonic and bursting? -tonicity -osmosis -passive diffusion -aquaporins -osmoregulation

osmoregulation

Both a living cell and an automobile convert fuel and __________ to the waste products __________. In the process, __________ is produced, which represents the entropy of the reaction. -oxygen; CO2 and water; energy -oxygen; CO2 and water; heat -energy; CO2 and oxygen; heat -CO2; oxygen and water; heat -oxygen; energy and water; CO2

oxygen; CO2 and water; heat

What is the function of the sodium-potassium pump in nerve cells? -pumping K+ and CO2 out of the cell and Na+ and O2 into the cell -pumping K+ out of the cell and Na+ into the cell -pumping K+ and CO2 out of the cell and Na+ into the cell -pumping Na+ out of the cell and K+ into the cell -pumping Na+ and CO2 out of the cell and K+ into the cell

pumping Na+ out of the cell and K+ into the cell

Which method of transport uses coated pits? -vacuole-mediated endocytosis -phagocytosis -receptor-mediated endocytosis -exocytosis -facilitated diffusion

receptor-mediated endocytosis

Endergonic reactions __________ energy and result in products that have __________ potential energy than the reactants. -release; lower -require; lower -require; higher -release; variable levels of -release; higher

require; higher