Chapters 7&8 Mastering Biology

Which of the following is the most correct interpretation of the figure? ATP is a molecule that acts as an intermediary to store energy for cellular work. Energy from catabolism can be used directly for performing cellular work. ADP + i are a set of molecules that store energy for catabolism. i acts as a shuttle molecule to move energy from ATP to ADP.

ATP is a molecule that acts as an intermediary to store energy for cellular work.

Active and passive transport of solutes across a membrane typically differ in which of the following ways? Active transport is usually down the concentration gradient of the solute, whereas passive transport is always against the concentration gradient of the solute. Active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy. Active transport is always faster than passive transport. Active transport uses protein carriers, whereas passive transport uses carbohydrate carriers. Active transport is used for ions, passive transport is used for uncharged solutes.

Active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy.

Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics? Life obeys the second law of thermodynamics because the decrease in entropy as the organism grows is exactly balanced by an increase in the entropy of the universe. Living organisms do not obey the second law of thermodynamics, which states that entropy must increase with time. As a consequence of growing, organisms cause a greater increase in entropy in their environment than the decrease in entropy associated with their growth. Living organisms are able to transform energy into entropy.

As a consequence of growing, organisms cause a greater increase in entropy in their environment than the decrease in entropy associated with their growth.

Which of these cannot rapidly pass directly through the phospholipids of the plasma membrane? a)Lipid Soluble Molecule b)Water c)Glucose d)Hydrogen Ion Answer Choices:A only C only B only D only B, C, and D

B, C, D

You have discovered an enzyme that can catalyze two different chemical reactions. Which of the following is most likely to be correct? The enzyme contains α-helices and β-pleated sheets. Either the enzyme has two distinct active sites or the reactants involved in the two reactions are very similar in size and shape. Two types of allosteric regulation occur: The binding of one molecule activates the enzyme, while the binding of a different molecule inhibits it. The enzyme is subject to competitive inhibition and allosteric regulation.

Either the enzyme has two distinct active sites or the reactants involved in the two reactions are very similar in size and shape.

When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated? It is used to power yet more cellular work. It is used to store energy as more ATP. It is used to generate ADP from nucleotide precursors. It is lost to the environment.

It is lost to the environment.

Which of the following statements about osmosis is correct? Osmosis is the diffusion of water from a region of lower water concentration to a region of higher water concentration. If a cell is placed in an isotonic solution, more water will enter the cell than leaves the cell. Osmotic movement of water into a cell would likely occur if the cell accumulates water from its environment. If a solution outside the cell is hypertonic compared to the cytoplasm, water will move into the cell by osmosis. The presence of aquaporins (proteins that form water channels in the membrane) should speed up the process of osmosis.

The presence of aquaporins (proteins that form water channels in the membrane) should speed up the process of osmosis.

Which of the following is true for all exergonic reactions? A net input of energy from the surroundings is required for the reactions to proceed. The reaction proceeds with a net release of free energy. The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants. The products have more total energy than the reactants.

The reaction proceeds with a net release of free energy.

When a cell is in equilibrium with its environment, which of the following occurs for substances that can diffuse through the cell? All movement of molecules is directed by active transport. There is random movement of substances into and out of the cell. There is directed movement of substances into and out of the cell. There is no movement of substances into and out of the cell.

There is random movement of substances into and out of the cell.

In facilitated diffusion, what is the role of the transport protein? Transport proteins provide a protein site for ATP hydrolysis, which facilitates the movement of a solute across a membrane. Transport proteins provide the energy for diffusion of the solute. Transport proteins provide a low-resistance channel for water molecules to cross the membrane. Transport proteins provide a hydrophilic route for the solute to cross the membrane. Transport proteins organize the phospholipids to allow the solute to cross the membrane.

Transport proteins provide a hydrophilic route for the solute to cross the membrane.

Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's _____. entropy equilibrium point activation energy free-energy content

activation energy

If the concentration of phosphate in the cytosol is 2.0 mM and the concentration of phosphate in the surrounding fluid is 0.1 mM, how could the cell increase the concentration of phosphate in the cytosol? passive transport diffusion active transport osmosis facilitated diffusion

active transport

For a protein to be an integral membrane protein, it would have to be _____. exposed on only one surface of the membrane hydrophilic hydrophobic amphipathic, with at least one hydrophobic region

amphipathic, with at least one hydrophobic region

Which of the following types of reactions would decrease the entropy within a cell? anabolic reactions digestion hydrolysis catabolic reactions

anabolic reactions

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones? metabolism anabolism (anabolic pathways) dehydration catabolism (catabolic pathways)

catabolism (catabolic pathways)

A noncompetitive inhibitor decreases the rate of an enzyme reaction by _____. changing the free energy change of the reaction acting as a coenzyme for the reaction binding at the active site of the enzyme changing the shape of the enzyme's active site

changing the shape of the enzyme's active site

Anabolic pathways _____. release energy as they degrade polymers to monomers are usually highly spontaneous chemical reactions consume energy to build up polymers from monomers consume energy to decrease the entropy of the organism and its environment

consume energy to build up polymers from monomers

The phosphate transport system in bacteria imports phosphate into the cell even when the concentration of phosphate outside the cell is much lower than the cytoplasmic phosphate concentration. Phosphate import depends on a pH gradient across the membrane (more acidic outside the cell than inside the cell). Phosphate transport is an example of _____. active transport cotransport passive diffusion facilitated diffusion

cotransport

A chemical reaction that has a positive ΔG is best described as _____. spontaneous enthalpic endergonic exergonic

endergonic

Enzymes are described as catalysts, which means that they _____. increase the rate of a reaction without being consumed by the reaction increase the free energy of the reactants to make the reaction go faster provide activation energy for the reactions they facilitate can alter the free energy change (ΔG) for a chemical reaction are proteins

increase the rate of a reaction without being consumed by the reaction

Endocytosis moves materials _____ a cell via _____. out of ... diffusion out of ... membranous vesicles into ... facilitated diffusion into ... membranous vesicles into ... a transport protein

into ... membranous vesicles

An enzyme _____. is an organic catalyst increases the EA of a reaction can bind to nearly any molecule is a inorganic catalyst is a source of energy for endergonic reactions

is an organic catalyst

The active site of an enzyme is the region that _____. binds allosteric regulators of the enzyme is inhibited by the presence of a coenzyme or a cofactor binds noncompetitive inhibitors of the enzyme is involved in the catalytic reaction of the enzyme

is involved in the catalytic reaction of the enzyme

As a result of its involvement in a reaction, an enzyme _____. permanently alters its shape. loses a phosphate group is used up is unchanged loses energy

is unchanged

A bacterium engulfed by a white blood cell through phagocytosis will be digested by enzymes contained in _____. Golgi vesicles secretory vesicles lysosomes vacuoles

lysosomes

Which of the following membrane activities requires energy from ATP? movement of Na+ ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid movement of glucose molecules into a bacterial cell from a medium containing a higher concentration of glucose than inside the cell movement of carbon dioxide out of a paramecium facilitated diffusion of chloride ions across the membrane through a chloride channel

movement of Na+ ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid

In receptor-mediated endocytosis, receptor molecules initially project to the outside of the cell. Where do they end up after endocytosis? on the inside surface of the cell membrane on the outside of vesicles on the outer surface of the nucleus on the inside surface of the vesicle

on the inside surface of the vesicle

Which of these are NOT embedded in the hydrophobic portion of the lipid bilayer at all? peripheral proteins integral proteins transmembrane proteins All of these are embedded in the hydrophobic portion of the lipid bilayer.

peripheral proteins

A white blood cell engulfing a bacterium is an example of _____. receptor-mediated endocytosis facilitated diffusion pinocytosis exocytosis phagocytosis

phagocytosis

In general, enzymes are what kinds of molecules? proteins nucleic acids carbohydrates lipids minerals

proteins

What kinds of molecules pass through a cell membrane most easily? large and hydrophobic ionic small and hydrophobic large polar

small and hydrophobic

What name is given to the reactants in an enzymatically catalyzed reaction? reactors products substrate active sites EA

substrate

Enzymes work by _____. adding a phosphate group to a reactant decreasing the potential energy difference between reactant and product reducing EA adding energy to a reaction increasing the potential energy difference between reactant and product

reducing EA

You are working on a team that is designing a new drug. For this drug to work, it must enter the cytoplasm of specific target cells. Which of the following would be a factor that determines whether the molecule selectively enters the target cells? lack of charge on the drug molecule lipid composition of the target cells' plasma membrane hydrophobicity of the drug molecule similarity of the drug molecule to other molecules transported by the target cells

similarity of the drug molecule to other molecules transported by the target cells

Catabolic pathways _____. are endergonic are spontaneous and do not need enzyme catalysis supply energy, primarily in the form of ATP, for the cell's work combine molecules into more energy-rich molecules

supply energy, primarily in the form of ATP, for the cell's work

Energy is observed in two basic forms: potential and kinetic. Which of the following correctly matches these forms with a source of energy? the energy related to the height of a bird above the ground: kinetic energy the energy associated with a gradient of ions across a membrane: kinetic energy the heat released from a living organism: potential energy the covalent bonds of a sugar molecule: potential energy the motion of individual molecules: potential energy

the covalent bonds of a sugar molecule: potential energy

The permeability of a biological membrane to a specific polar solute may depend on which of the following? the amount of cholesterol in the membrane the types of transport proteins in the membrane the phospholipid composition of the membrane the presence of unsaturated fatty acids in the membrane the types of polysaccharides present in the membrane

the types of transport proteins in the membrane

Which part of the adenosine triphosphate molecule is released when it is hydrolyzed to provide energy for biological reactions? α -phosphate (the phosphate closest to ribose) β-phosphate (the middle phosphate) γ-phosphate (the terminal phosphate) adenine group ribose sugar

γ-phosphate (the terminal phosphate)