AP Bio-Chapter 8

Multiple Choice

How do living organisms create macromolecules, organelles, cells, tissues, and complex higher-order structures?

• The laws of thermodynamics do not apply to living organisms.

• Living organisms create order by recycling and reusing energy from the sun.

• Living organisms create order locally, but the energy transformations generate waste heat that increases the entropy of the universe.

Multiple Choice

A friend tells you that his hamster has reached equilibrium. You

• send a sympathy card since the hamster is dead.

• congratulate your friend on teaching the hamster a trick.

• say that the hamster must produce lots of ATP.

• A catabolic pathway in a cell releases free energy in a series of reactions.

  • For example, in cellular respriation reactions are "pulled" in one direction because the products of each reaction are the reactants in the next step.

  • A steady inflow of glucose and release of waste products ensures that equilibrium is never reached.
    

Multiple Choice

Some enzymes can couple the hydrolysis of ATP to ion transport by having

• energy from ATP hydrolysis alter the free energy changes of another reaction.

• cofactors that act to transfer energy and matter from one reaction to another.

• phosphate groups from the ATP temporarily dontated to the ions.

• the coupled processes both be exergonic.

• changes during ATP hydrolysis alter the enzyme's shape, forcing ionic transport to occur.

Multiple Choice

When a cell breaks down glucose, only about 34% of the energy is captured in ATP molecules. What happens to most of the remaining 66% of the energy?

• It is used to increase the order necessary for life to exist.

• It is lost as heat, in accordance with the second law of thermodynamics.

• It is stored in starch or glycogen for later use by the cell.

• It is released when the ATP molecules are hydrolyzed.

Multiple Choice

Are most chemical reactions in living cells at equilibrium?

• Yes

• No

• Only the exergonic reactions

• All reactions except those powered by ATP hydrolysis.

Multiple Choice

The oxidation of glucose to CO₂ and H₂O is highly exergonic: ΔG=-636 kcal/mole. This is spontaneous, but why is it very slow?

• Few glucose and oxygen molecules have the activation energy at room temperature.

• There is too much CO₂ in the air.

• CO₂ has higher energy than glucose.

• The formation of six CO₂ molecules from one glucose molecule decreases entropy.

• The water molecules quench the reaction.

Multiple Choice

For the reaction shown, which statement is true?

• The greater the activation energy barrier, the slower the reaction rate.

• The less energy released when products form, the slower the reaction rate.

• The more types of reactants involved in the reaction, the faster the reaction.

• The higher the net ΔG of the reaction, the faster the reaction rate.

• The more bonds altered by the reaction, the faster the reaction rate.

Multiple Choice

In the energy diagram, what is the difference between the red and black curves?

• The red curve is for a reaction powered by ATP hydrolysis.

• The black curve occurs at higher temperature.

• The red curve is catalyzed by an enzyme.

• The black curve has a higher activation energy.

• c and d

Multiple Choice

What would happen to cytoplasmic enzyme activity inside a cell with a normal cytoplasmic pH of 7.2 if you injected a chemical that would change the pH to 4.0?

• Little or no change would occur.

• Enzymes would probably denature.

• Enzymatic activity would decline.

• Enzymes would start to add ATP to all reactions.

• b and c

Multiple Choice

Vioxx and other prescription nonsteroidal anti-inflammatory drugs (NSAIDs) are potent inhibitors of the cyclooxygenase-2 (COX-2) enzyme. High substrate concentrations reduce the efficacy of inhibition by these drugs. These drugs are:

• competitive inhibitors

• noncompetitive inhibitors

• allosteric regulators

• prosthetic groups

• feedback inhibitors

Multiple Choice

If you're not getting enough vitamins in your food, what are you missing?

• allosteric regulators

• cofactors

• coenzymes

• minerals

• none of the above

Multiple Choice

How are the effect of feedback inhibition and allosteric factors similar to how enzymes often couple reactions?

• All can drive an endergonic reaction forward by their exergonic energy changes.

• All often involve inducing structural changes in the enzyme, influencing its activities.

• Permanent changes are made to the item(s) bound by the enzyme in each case.

• All lead to the formation of new covalent bonds in the enzyme.

• All can lower the activation energy barrier and speed the rate of a reaction.

Multiple Choice

Which cellular location might contain many enzymatic activities?

• mitochondrion

• vacuole

• cytoplasm

• nucleus

• all of the above