Bio Exam 2

1.     Which best describes a biological membrane?

a.     two layers of phospholipids with proteins either spanning the layers or on the surface of the layers

Which molecule will diffuse most quickly across a lipid bilayer membrane

o2

1.     A correct distinction between facilitated diffusion and active transport is that

a.     facilitated diffusion depends on an existing energy gradient acting on the transported substance, while active transport makes such a gradient.

1.     At a cocktail party with people moving around a large room, the doors to the room are like _____.

membrane proteins

1.     You are studying a pump protein in the lab. What should you order to make sure that the pump will operate?

atp

1.     How do membrane phospholipids interact with water?

a.     The polar heads interact with water; the nonpolar tails do not.

1.     Which of the following factors would tend to increase membrane fluidity?

a.     a greater proportion of unsaturated phospholipids

1.     Based on our model of the membrane, which statement would lose points on an exam?

a.     Transmembrane proteins often bind with cytoplasmic proteins, but not with extracellular molecules.

1.     What is the function of cholesterol in membrane structure?

a.     stabilization of the phospholipids

1.     Aquaporins are

channel proteins

1.     Energy is required in type of transport?

active

1.     Solutes are transported against their gradient in

active transport

1.     Solutes are transported down their gradient in

passive transport

1.     Which transport protein changes shape during transport?

carrier protein

1.     Which transport protein participates in active transport?

carrier

1.     Are most chemical reactions in living cells at equilibrium?

no

1.     A reaction has a ∆G of –5.6 kcal/mol. Which of the following would most likely be true?

a.     The reaction would proceed by itself but might be very slow.

1.     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

1.     The form of energy that is most often least useful to life is energy in

the form of heat

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

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

1.     The combination of ATP with water, leading to the formation of ADP and free inorganic phosphate ion,

has neither the smallest nor the largest ∆G seen in reactions in life.

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

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

1.     A change in the coding region of a gene can lead to a new allele for that gene. Which property of the protein, coded for by this new allele, could be changed as a result?

a.     its affinity for its substrate

b.     the amino acid sequence in it

c.      its ability to be affected by allosteric factors

d.     the pH that is optimal for its activity

All of the above could be altered by mutations

1.     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?

a.     Enzymes would probably denature.

Enzymatic activity would decline

1.     Which cellular location might contain many enzymatic activities?

a.     mitochondrion

b.     vacuole

c.      cytoplasm

d.     nucleus

e.     all of the above

1.     What can cause a reaction to occur spontaneously?

a.     ​–∆G

1.     Enzymes speed up chemical reaction by

a.     Decreasing activation energy barrier

1.     The initial energy needed to break the bonds of the reactants in a chemical reaction is called

activation energy

1.     Which of the following metabolic processes can occur without a net influx of energy from some other process?

a.     C₆H₁₂O₆+6 O₂→6 CO₂+6 H₂O

1.     If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to

add more of the enzyme

1.     If an enzyme is added to a solution where its substrate and product are in equilibrium, what will occur?

Nothing; the reaction will stay at equilibrium

1.     The hydrogens taken from glucose or a breakdown product of glucose are added to oxygen, releasing energy to

a.     actively transport H+ into the intermembrane space.

1.     ATP synthase at the inner mitochondrial membrane makes ATP and water from ADP and phosphate by coupling this to which other process?

a.     allowing H⁺ to move down its electrochemical gradient

1.     Which of the following is not an immediate net product of the typical mitochondrial electron transport chain?

atp

1.     If you removed the inner membrane of the mitochondrion, could the cell produce any ATP from glucose?

yes, by glycolysis

1.     You are handed a biochemical extract from cells that were performing cellular respiration. You detect cytochromes in one fraction, so it was probably used for the study of

electron transport

1.     If your cells were in need of ATP, what could help you?

a.     substrate-level phosphorylation

b.     ATP synthase

c.      glycolysis

d.     all of the above

1.     ATP gets hydrolyzed in two enzymatic chemical reactions during glycolysis. What are the names of the two enzymes?

a.     Hexokinase and phosphofructokinase

1.     ATP molecules are formed in two enzymatic chemical reactions during glycolysis. What are the names of the two enzymes?

Phosphoglycerokinase and pyruvate kinase

1.     Shape changes are important in the working of enzymes and other parts of biochemistry. In ATP production, what changes shape?

rotor

1.     Which statement about the citric acid cycle is true?

a.     It makes ATP through substrate-level phosphorylation.

42. The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is

o2

1.     When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs?

The pH of the matrix increases.

1.     In mitochondria, exergonic redox reactions

a.     provide the energy that establishes the proton gradient.

1.     Cellular respiration can best be described as

taking electrons from food and giving them to oxygen to make water, using the energy released to drive ATP formation

1.     Of these events from the light reactions, which occurs first?

a.     Light-induced reduction of the primary electron acceptor in the reaction center of PS II.

1.     When donating its activated electron, the chlorophyll in photosystem II is a very powerful oxidizing agent. This is best shown by its ability to

a.     force the oxidation of oxygen in water to oxygen gas.

1.     One reason for carrying out the production of oxygen gas in the space surrounded by the thylakoid membranes, and not in the stroma of the chloroplasts, is

a.     that the hydrogen ions released can contribute to the H+ electrochemical gradient being generated.

1.     The enzyme rubisco catalyzes the fixation of carbon. Considering all the carbons involved, is the production of 3-PGA a net oxidation, reduction, or neither? Why?

a.     Neither. There is no change in the total C–O and C–H bonds between the products and reactants.

If a cell contained a radioactive version of rubisco, where would the radioactivity be located

stroma

1.     Suppose you were preparing to visit a space station that uses photosynthesis to provide you with oxygen. What color lightbulbs should you take with you?

red and blue

1.     Which best links photosynthesis and cellular respiration?

chemiosmosis

1.     Which of the following sequences correctly represents the flow of electrons during photosynthesis?

b. H2O→NADPH→Calvin cycle

1.     In mechanism, photophosphorylation is most similar to

oxidative phosphorylation in cellular respiration

1.     Which process is most directly driven by light energy?

a.     transfer of energy from pigment molecule to pigment molecule