KJ

Biological Membranes and Energy Processes

Exam Practice Questions Notes

Biological Membranes

  • Question 1: Best description of a biological membrane?

    • a. Two layers of phospholipids with proteins embedded between the two layers.

    • b. A mixture of covalently linked phospholipids and proteins regulating solute transport.

    • c. Two layers of phospholipids with proteins either spanning or on the surface of the layers.

    • d. A fluid structure in which phospholipids and proteins move freely across the membrane.

    • e. Two layers of phospholipids (with opposite orientations), each layer covered on the outside with proteins.

Transport Across Membranes

  • Question 2: Which molecule diffuses most quickly across a lipid bilayer?

    • a. H2O

    • b. O2

    • c. H2PO4–

    • d. Glucose

    • e. Na+

  • Question 3: Difference between facilitated diffusion and active transport:

    • a. Active transport requires protein conformational changes; facilitated diffusion does not.

    • b. Active transport requires an integral membrane protein; facilitated diffusion does not.

    • c. Facilitated diffusion requires a protein-lined pore; active transport does not.

    • d. Facilitated diffusion depends on an energy gradient; active transport creates it.

    • e. Facilitated diffusion uses cellular energy; active transport does not.

  • Question 4: Analogy for doors to a room at a cocktail party?

    • a. Energy

    • b. Membrane proteins

    • c. DNA

    • d. Organelles

    • e. None of the above

Membrane Dynamics and Structure

  • Question 5: Order what is needed for pump protein operation:

    • a. Salt

    • b. Glucose

    • c. DNA

    • d. Pure water

    • e. ATP

  • Question 6: Interaction of membrane phospholipids with water:

    • a. Phospholipids do not interact with water, being hydrophobic.

    • b. Hydrophilic tails face outward; hydrophobic heads face inward.

    • c. Polar heads have no affinity for water; nonpolar tails do.

    • d. Polar heads interact with water; nonpolar tails do not.

Factors Affecting Membrane Fluidity

  • Question 7: Factors increasing membrane fluidity:

    • a. Greater proportion of unsaturated phospholipids.

    • b. Greater proportion of saturated phospholipids.

    • c. Lower temperature.

    • d. High protein content in the membrane.

Membrane Composition & Function

  • Question 8: Which statement would lose points on an exam about membranes?

    • a. Glycoproteins have oligosaccharides on their outward-facing side.

    • b. Transmembrane proteins bind with cytoplasmic proteins only.

    • c. The composition of phospholipids differs between the two faces of the membrane.

    • d. Phospholipids move faster laterally than proteins.

    • e. Some transmembrane proteins function as active transport systems.

  • Question 9: Function of cholesterol in membrane structure:

    • a. Stabilization of phospholipids.

    • b. Cell-cell communication.

    • c. Structural support of the cell.

    • d. Transport across the plasma membrane.

    • e. Detection of environmental change.

  • Question 10: Aquaporins are:

    • a. Channel proteins.

    • b. Carrier proteins.

    • c. Both.

Types of Transport

  • Question 11: Energy requirement in transport types:

    • a. Passive

    • b. Active

  • Question 12: Solutes transported against their gradient:

    • a. Active transport

    • b. Passive transport

  • Question 13: Solutes transported down their gradient:

    • a. Active transport

    • b. Passive transport

  • Question 14: Transport protein changing shape during transport:

    • a. Channel protein

    • b. Carrier protein

  • Question 15: Transport protein participating in active transport:

    • a. Channel

    • b. Carrier

Chemical Reactions and Enzymes

  • Question 16: Are most chemical reactions in living cells at equilibrium?

    • a. Yes

    • b. No

    • c. Only exergonic reactions

    • d. All except those powered by ATP hydrolysis

  • Question 17: Implication of a reaction having a ∆G of –5.6 kcal/mol:

    • a. Could couple to power an endergonic reaction with ∆G of +8.8 kcal/mol.

    • b. The reaction is nonspontaneous.

    • c. Needs to couple to ATP hydrolysis.

    • d. Results in products with greater free energy.

    • e. Proceeds by itself, possibly slowly.

Enzyme Inhibition

  • Question 18: Vioxx and NSAIDs as inhibitors:

    • a. Competitive inhibitors.

    • b. Noncompetitive inhibitors.

    • c. Allosteric regulators.

    • d. Prosthetic groups.

    • e. Feedback inhibitors.

Energy and Cellular Processes

  • Question 19: Least useful form of energy to life:

    • a. Concentration gradients.

    • b. Electrical gradients.

    • c. Differences between distinct forms of molecules.

    • d. Heat.

    • e. Electromagnetic radiation.

  • Question 20: Coupling ATP hydrolysis to ion transport:

    • a. Energy alters the free energy of another reaction.

    • b. Cofactors transfer energy and matter between reactions.

    • c. Phosphate groups temporarily donated to ions.

    • d. Both processes are exergonic.

    • e. Changes in ATP hydrolysis alter enzyme shape.

  • Question 21: ATP and water reaction:

    • a. Very large ∆G compared to other reactions.

    • b. Exergonic reaction due to bonds in water.

    • c. Neither smallest nor largest ∆G.

    • d. Occurs rapidly without an enzyme.

    • e. Very small ∆G compared to other reactions.

Feedback Mechanisms in Enzyme Activity

  • Question 22: Similarities between feedback inhibition, allosteric factors, and enzyme coupling:

    • a. All can drive an endergonic reaction forward.

    • b. All involve structural changes influencing enzyme activity.

    • c. Permanent changes made to bound items.

    • d. All lead to new covalent bond formation.

    • e. All lower activation energy barriers.

Genetic Variation and Enzymatic Activity

  • Question 23: Impact of coding region change in a gene:

    • a. Altered affinity for substrate.

    • b. Changed amino acid sequence.

    • c. Ability affected by allosteric factors.

    • d. Optimal pH for activity could change.

    • e. All could be altered by mutations.

  • Question 24: Effect of changing cytoplasmic pH in a cell:

    • a. Little or no change.

    • b. Enzymes would likely denature.

    • c. Decline in enzymatic activity.

    • d. Enzymes add ATP to reactions.

    • e. b and c.

Cellular Locations with Enzymatic Activities

  • Question 25: Location containing many enzymatic activities:

    • a. Mitochondrion

    • b. Vacuole

    • c. Cytoplasm

    • d. Nucleus

    • e. All of the above.

Spontaneous Reactions and Energy Dynamics

  • Question 26: Cause of a reaction to occur spontaneously:

    • a. –∆G

    • b. –∆S

    • c. +∆H

    • d. ∆T

  • Question 27: How enzymes speed up chemical reactions:

    • a. Decrease activation energy barrier.

    • b. Increase activation energy barrier.

    • c. Both.

    • d. None.

  • Question 28: Initial energy to break reactant bonds (activation energy):

    • a. Free energy.

    • b. Thermal energy.

    • c. Heat.

    • d. Activation energy.

Metabolic Processes

  • Question 29: Metabolic processes occurring without energy influx:

    • a. ADP + Pi → ATP + H2O

    • b. C6H12O6 + 6 O2 → 6 CO2 + 6 H2O

    • c. 6 CO2 + 6 H2O → C6H12O6 + 6 O2

    • d. Amino acids → Protein.

  • Question 30: Effective way to increase product yield with saturated enzyme:

    • a. Add more enzyme.

    • b. Heat to 90°C.

    • c. Add more substrate.

    • d. Add a noncompetitive inhibitor.

  • Question 31: Adding enzyme to solution at equilibrium:

    • a. Additional substrate produced.

    • b. Reaction changes from endergonic to exergonic.

    • c. Free energy of the system changes.

    • d. Nothing; it remains at equilibrium.

Mitochondrial Function and Cellular Respiration

  • Question 32: Function of hydrogen from glucose:

    • a. Actively transport H+ into intermembrane space.

    • b. Actively transport NAD+.

    • c. Actively transport Na+ into matrix.

    • d. Power facilitated diffusion of H+ into matrix.

    • e. Actively transport H+ into matrix.

  • Question 33: ATP synthase at the inner mitochondrial membrane function:

    • a. Allows H+ to move down its electrochemical gradient.

    • b. Allows H+ to move against its electrochemical gradient.

    • c. Synthesizes H+.

    • d. Active transport of H+.

  • Question 34: Not an immediate net product of the mitochondrial electron transport chain:

    • a. ATP.

    • b. Water.

    • c. NAD+.

    • d. FAD.

    • e. Proton electrochemical gradient.

  • Question 35: Could the cell produce ATP from glucose without the inner mitochondrial membrane?

    • a. Yes, by glycolysis.

    • b. Yes, by the citric acid cycle.

    • c. Yes, using ATP synthase.

    • d. Yes, by electron transport.

  • Question 36: Cytochromes in a biochemical extract indicate:

    • a. Glycolysis.

    • b. Fermentation.

    • c. Electron transport.

    • d. ATP synthase function.

  • Question 37: Need for ATP solutions:

    • a. Substrate-level phosphorylation.

    • b. ATP synthase.

    • c. Glycolysis.

    • d. All of the above.

  • Question 38: Enzymes hydrolyzing ATP in glycolysis:

    • a. Phosphoglycerokinase and pyruvate kinase.

    • b. Phosphofructokinase and pyruvate kinase.

    • c. Hexokinase and phosphoglycerokinase.

    • d. Hexokinase and phosphofructokinase.

  • Question 39: ATP formation enzymes during glycolysis:

    • a. Phosphoglycerokinase and pyruvate kinase.

    • b. Phosphofructokinase and pyruvate kinase.

    • c. Hexokinase and phosphoglycerokinase.

    • d. Hexokinase and phosphofructokinase.

  • Question 40: Shape changes important in enzyme function:

    • a. Stator.

    • b. Protons.

    • c. Rotor.

    • d. ADP.

    • e. Membrane lipids.

  • Question 41: True statement about the citric acid cycle:

    • a. Occurs during movement from cytosol through mitochondrial membranes.

    • b. Makes ATP through substrate-level phosphorylation.

    • c. Makes more ATP compared to other steps in glucose breakdown.

    • d. Occurs in eukaryotic cytoplasm.

    • e. Splits glucose.

  • Question 42: Final electron acceptor in aerobic oxidative phosphorylation:

    • a. O2

    • b. Water

    • c. NAD+

    • d. Pyruvate

  • Question 43: Changes during electron transport along mitochondrial chains:

    • a. pH of the matrix increases.

    • b. ATP synthase pumps protons actively.

    • c. Electrons gain free energy.

    • d. NAD+ oxidized.

  • Question 44: Exergonic redox reactions in mitochondria:

    • a. Source of energy for prokaryotic ATP synthesis.

    • b. Establish proton gradient.

    • c. Reduce carbon atoms to carbon dioxide.

  • Question 45: Best description of cellular respiration:

    • a. Using energy from breaking high-energy covalent bonds in organic molecules to drive ATP formation.

    • b. Taking electrons from food to give to phosphate for ATP formation.

    • c. Taking electrons from food and giving to oxygen to make water, using energy to drive ATP formation.

    • d. Converting higher-energy organic molecules to lower-energy ones, using released energy to drive ATP formation.

Photosynthesis and Light Reactions

  • Question 46: First event in light reactions:

    • a. Light-induced reduction of primary electron acceptor in PS II.

    • b. Electrons taken from water.

    • c. Donation of electrons from reduced Pq to cytochrome complex.

    • d. Acceptance of electrons by Pc from cytochrome complex.

    • e. Pq gets electrons from reduced primary electron acceptor of PS II.

  • Question 47: Chlorophyll in photosystem II as oxidizing agent:

    • a. Uses proton gradient to drive ATP formation.

    • b. Forces oxidation of oxygen in water to gas.

    • c. Donates electron to plastoquinone (Pq).

    • d. Absorbs light energy for redox reactions.

    • e. Forces reduction of NADP+ to NADPH.

  • Question 48: Oxygen production location in chloroplasts:

    • a. Makes it easier for O2 to exit chloroplast.

    • b. Hydrogen ions can contribute to H+ electrochemical gradient.

    • c. Reduces O2 concentration in stroma to prevent organic matter oxidation.

    • d. High concentration of water in space makes oxygen formation easier.

  • Question 49: Is the production of 3-PGA a net oxidation, reduction, or neither?

    • a. Oxidation: Adding CO2 makes products more oxidized.

    • b. Reduction: Adding hydrogens from water results in more reduced condition.

    • c. Reduction: Carbon in CO2 has been slightly reduced.

    • d. Neither: No change in C–O and C–H bonds.

    • e. Oxidation: RuBP acts as oxidizing agent.

  • Question 50: Location of radioactivity in a radioactive version of rubisco:

    • a. Cytoplasm.

    • b. Stroma.

    • c. Thylakoid space.

    • d. Outer membrane.

    • e. Ribosomes.

  • Question 51: Color lightbulbs for space station photosynthesis:

    • a. Red.

    • b. Green.

    • c. Blue.

    • d. Green and blue.

    • e. Red and blue.

  • Question 52: Best link between photosynthesis and cellular respiration:

    • a. Four carbon compounds.

    • b. Chemiosmosis.

    • c. Thylakoid membrane.

    • d. Photosystems.

  • Question 53: Correct sequence for electron flow in photosynthesis:

    • a. NADPH→O2→CO2.

    • b. H2O→NADPH→Calvin cycle.

    • c. H2O→photosystem I→photosystem II.

    • d. NADPH→electron transport chain→O2.

  • Question 54: Similarity of photophosphorylation mechanism:

    • a. Similar to substrate-level phosphorylation in glycolysis.

    • b. Similar to oxidative phosphorylation in cellular respiration.

    • c. Similar to carbon fixation.

  • Question 55: Process directly driven by light energy:

    • a. Creation of pH gradient by proton pumping across thylakoid membrane.

    • b. Reduction of NADP+ molecules.

    • c. Transfer of energy between pigment molecules.

    • d. ATP synthesis.

  • Question 56: Effect of cyanide on ATP production:

    • a. Most will be in mitochondria.

    • b. Ribosomes.

    • c. Peroxisomes.

    • d. Lysosomes.