8: Metabolism, Cell Respiration, and Photosynthesis Kognity Strength Tests

Which of the following is needed in order to regenerate RuBP? A. Two molecules of reduced NADP B. Phosphate groups C. Rubisco D. Phosphorylation of ADP

B. Phosphate groups The regeneration of RuBP from triose phosphates involves the use of ATP to provide the phosphate groups needed for its formation.

Which of the following statements is correct about the structure of mitochondria? A. They have their own DNA and 80S ribosomes. B. The matrix contains enzymes vital for the link reaction and Krebs cycle. C. The outer membrane is folded to increase surface area. D. The space between the inner and outer membrane is large to provide a high concentration gradient of protons.

B. The matrix contains enzymes vital for the link reaction and Krebs cycle.

Which of the following statements is a characteristic of enzymes? A. They supply the energy for a reaction. B. They lower the activation energy for a reaction. C. They are used up in the reactions they catalyse. D. Allosteric inhibitors bind to the active site.

B. They lower the activation energy for a reaction

Which of the following is not a product of glycolysis? A. ATP B. Reduced NAD+ C. Acetyl CoA D. Pyruvate

C. Acetyl CoA

Which option is correct when comparing the Krebs cycle with the Calvin cycle ? (Krebs cycle; Calvin cycle) A. Requires CO2 reduces NAD; Requires Acetyl CoA, oxidizes NADPH B. Requires Acetyl CoA, oxidizes NADPH; Requires CO2, reduces NADP C. Requires CO2, oxidizes NADH; Requires Acetyl CoA, reduces NADP D. Requires Acetyl CoA, reduces NAD; Requires CO2, oxidizes NADPH

D

Which of the following enzymes is involved in the light-dependent reactions? A. Polymerase B. Ligase C. RuBisCO D. ATP synthase

D. ATP synthase

Which of the following is not true with regard to both competitive and non-competitive inhibition? A. Both involve a decrease in the activity of the enzyme B. Both prevent the substrate from binding to the active site. C. Both involve a decrease in the rate of reaction. D. Both could reach the maximum rate of reaction when the substrate concentration increases.

D. Both could reach the maximum rate of reaction when the substrate concentration increases.

Which of the following processes is not part of the light-dependent reactions? A. Photoactivation B. Chemiosmosis C. Photolysis D. Carbon fixation

D. Carbon fixation

Which of the following takes place during the link reaction of aerobic respiration? A. Oxidation of NADH B. Regeneration of NAD+ C. Reduction of pyruvate D. Decarboxylation of pyruvate

D. Decarboxylation of pyruvate

What does chemiosmosis in photosynthesis involve? A. Diffusion of electrons into the thylakoid space. B. Diffusion of protons into the thylakoid space. C. Diffusion of electrons into the stroma. D. Diffusion of protons into the stroma.

D. Diffusion of protons into the stroma.

Where are carbohydrates made in the chloroplast? A. On the inner membrane. B. In the intermembrane space. C. In the thylakoid space. D. In the stroma.

D. In the stroma. The Calvin cycle takes place in the stroma of the chloroplasts. Carbohydrates are formed from the condensation of triose phosphate molecules.

In the mitochondrial electron transport chain, what is the last electron acceptor? A. H2O B. NAD+ C. CO2 D. O2

D. O2

What is chemiosmosis? A. Protons pumping into the space between the inner and outer mitochondrial membranes. B. Phosphorylation of glucose in the matrix. C. Protons pumping into the matrix through ATP synthase. D. Protons moving down a concentration gradient into the matrix.

D. Protons moving down a concentration gradient into the matrix.

Which of the following is a key component required for the synthesis of acetyl-CoA? A. Galactose B. Urea C. Glucose D. Pyruvic acid

D. Pyruvic acid

Which statement is correct about chloroplasts? A. The inner membrane is folded to increase surface area. B. The thylakoid space is small, to allow rapid accumulation of electrons. C. The stroma contains many enzymes needed for the Krebs cycle. D. The thylakoid membrane has a large surface, for more light-dependent reactions to occur.

D. The thylakoid membrane has a large surface, for more light-dependent reactions to occur.

Which row of the table describes the first stage of cellular respiration? (Substrate, Location, Product, Product) i. pyruvate, mitochondria, oxygen, water ii. pyruvate, cytoplasm, carbon dioxide, ATP iii. glucose, mitochondria, oxygen, water iv. glucose, cytoplasm, pyruvate, ATP A. i B. ii C. iii D. iv

D. iv

What does oxidation involve? A. A loss of electrons. B. A gain of hydrogen. C. A loss of oxygen. D. A gain of electrons.

A. A loss of electrons. Oxidation is loss of electrons/loss of hydrogen/gain of oxygen. Reduction is gain of electrons/gain of hydrogen/loss of oxygen. OIL RIG: Oxidation Is Loss (of electrons) and Reduction Is Gain (of electrons)

Which of the following explains why each step in the metabolic pathway often requires a separate enzyme? A. Enzymes are specific for their substrate. B. Metabolic pathways are not often controlled. C. The same substrate would be used at each step. D. The substrate is continually regenerated in all reactions.

A. Enzymes are specific for their substrate.

What happens during glycolysis? A. Glucose is broken down into two pyruvate molecules. B. Lactic acid is produced. C. Carbon dioxide is produced. D. More ATP is consumed than is produced.

A. Glucose is broken down into two pyruvate molecules.

Which of the following comes first in cellular respiration? A. Glucose is broken down to pyruvate in the cytoplasm. B. Acetyl-CoA generates FADH2 and NADH + H+. C. Acetyl-CoA enters into the mitochondrion. D. FADH2 and NADH + H+ are oxidized in the electron transport chain.

A. Glucose is broken down to pyruvate in the cytoplasm.

Which of the following is correct with regard to end-product inhibition? (Inhibition, Site of Binding, Reaction) A→1B→2C→3D I. D inhibits 1, Allosteric site, Reversible II. D inhibits 1, Allosteric site, Irreversible III. 1 inhibits D, Allosteric site, Reversible IV. 1 inhibits D, Active site, Reversible A. I B. II C. III D. IV

A. I

In the graph below, which curve(s) represents inhibition? I on the top II in the middle III on the bottom with a flatter line A. II and III B. Only II C. I and II D. Only III

A. II and III I represents no inhibition, #2 is therefore wrong. II represents competitive inhibition as it reaches the maximum rate of reaction when the substrate concentration increases. III represents non-competitive inhibition as it never reaches the maximum rate of reaction even when the substrate concentration increases.

What can reduce the effect of a competitive inhibitor on enzyme activity? A. Increase the substrate concentration. B. Decrease the temperature at which the reaction takes place. C. Increase the temperature at which the reaction takes place. D. Add a non-competitive inhibitor.​

A. Increase the substrate concentration.

The following shows a metabolic pathway: (Arrows represent different enzymes) Substrate -> Intermediate X -> Intermediate Y -> Final Product What would be the effect on the reaction of adding a competitive inhibitor to enzyme 2? A. The concentration of intermediate X would increase. B. Intermediate Y would not be formed. C. The concentration of intermediate Y would increase. D. No final product would be formed.

A. The concentration of intermediate X would increase.

Which statement is correct about Calvin's lollipop experiment? A. Triose phosphate had a high percentage of radioactivity after 30 seconds. B. Triose phosphate was the first molecule to contain radioactive 14C. C. A radioactive isotope (14C) was introduced into E.coli. D. Large amounts of glycerate 3-phosphate contained 14C and were produced after 30 seconds.

A. Triose phosphate had a high percentage of radioactivity after 30 seconds.

In the diagram of a chloroplast below, where will the Calvin cycle take place? i. Open space ii. Long Thylakoid iii. One of the thylakoids iv. Membrance A. i B. ii C. iii D. iv

A. i

The diagram below shows the link reaction and the Krebs cycle. Which molecules are represented by the letters W, X, Y and Z? (W, X, Y, Z) i. Pyruvate, Acetyl CoA, CO2, ADP ii. Acetyl CoA, CO2, Pyruvate, ATP iii. Glucose, Acetyl CoACO2, ADP iv. Glucose, CO2, Pyruvate, ATP A. i B. ii C. iii D. iv

A. i W can only be pyruvate as in the next step CO2 is lost and CoA is added generationg acetyl CoA (X), which enters the Krebs cycle and loses CoA. Z can only be ADP as it binds to a phosphate group to generate ATP. Y can only be CO2 because the products of the Krebs cycle include NADH, FADH2, ATP and CO2.

The diagram below shows the energy levels of a reaction in the presence or absence of an enzyme. What is the best explanation of the processes labelled I and II? (I, II) i. Absence of an enzyme, Presence of an enzyme ii. Presence of an enzyme, Absence of an enzyme iii. Absence of an enzyme, Low concentration of reactants iv. High concentration of reactants, Presence of an enzyme A. i B. ii C. iii D. iv

A. i. The graph shows that in the absence of an enzyme (I) the activation energy that is needed is much higher than when an enzyme is present (II). Options #3 and #4 are not possible because the graph indicates the energy level of a reaction and not the concentration of reactants.

Name a protein in the thylakoids that generates ATP using the proton gradient.

ATP synthase

What happens in the light-dependent reactions of photosynthesis? A. Photolysis of carbon dioxide. B. A proton gradient is generated in the thylakoid space. C. Hydrogen gas is produced as a byproduct. D. Electrons are pumped into the thylakoid space.

B. A proton gradient is generated in the thylakoid space.

What is required for mitochondrial ATP production? A. Accumulation of protons in the matrix. B. Accumulation of protons in the intermembrane space. C. Diffusion of protons out of the matrix. D. Active pumping of protons into the matrix.

B. Accumulation of protons in the intermembrane space.

Which of the following is correct about non-competitive inhibition? (Structure of the inhibitor, Site to which the inhibitor binds) I. Does not resemble substrate, Allosteric site II. Resembles substrate, Allosteric site III. Does not resemble substrate, Active site IV. Resembles substrate, Active site A. II B. I C. III D. IV

B. I

The amino acid threonine is converted to isoleucine through a chain of reactions. When there is a high amount of isoleucine, it binds to the enzyme threonine deaminase, which is responsible for the first step in this reaction. What is the role of isoleucine in this reaction? A. Speeds up the rate of reaction B. Non-competitive inhibitor C. Competitive inhibitor D. Catalyst

B. Non-competitive inhibitor

Ethylene glycol (antifreeze) is broken down in the liver by alcohol dehydrogenase to form toxic substances that cause severe damage to the kidneys. Alcohol can be used in treating ethylene glycol poisoning as it binds to alcohol dehydrogenase and prevents the conversion of ethylene glycol by the liver. However, the more ethylene glycol, the higher the rate of the reaction. What is the role of alcohol in this reaction? A. Catalyst B. Non-Competitive Inhibitor C. Competitive Inhibitor D. End Product Inhibitor

C. Competitive inhibitor

Fatty acids can be a source of energy in cell respiration. Which of the following processes in cell respiration will fatty acids not go through? A. Krebs cycle B. Electron transport chain C. Glycolysis D. Link reaction

C. Glycolysis

Where precisely in the cell do the reactions of the Krebs cycle take place? A. In the thylakoid space. B. On the surface of cristae in the mitochondria. C. In the matrix of the mitchondria. D. In the stroma of the chloroplast.

C. In the matrix of the mitchondria.

In the liver, alcohol breaks down to acetaldehyde, which is broken down by aldehyde dehydrogenase to acetic acid. Disulfiram is a drug that binds to aldehyde dehydrogenase and prevents acetaldehyde from being converted to acetic acid. What is the effect of disulfiram? A. Increases aldehyde dehydrogenase in blood. B. Increases alcohol concentration in blood. C. Increases acetaldehyde concentration in blood D. Increases acetic acid concentration in blood.

C. Increases acetaldehyde concentration in blood

What happens to oxygen in aerobic cell respiration? A. It is oxidized, by accepting hydrogen at the end of the electron transport chain. B. It is reduced, by accepting hydrogen at the start of the electron transport chain. C. It is reduced, by accepting electrons at the end of the electron transport chain. D. It is oxidized, by accepting electrons at the end of the electron transport chain.

C. It is reduced, by accepting electrons at the end of the electron transport chain.

Which of the following describes an allosteric site? A. It is the area on the enzyme to which a competitive inhibitor binds. B. It is the area on the substrate to which an enzyme binds. C. It is the area on the enzyme to which the end-product binds. D. It is the area on the enzyme to which a substrate binds.

C. It is the area on the enzyme to which the end-product binds.

Serotonin is needed for the synthesis of the hormone melatonin as indicated below: Serotonin -> N-acetylserotonin -> Melatonin Serotonin-N-acetyltransferase and hydroxindole-0-methytransferase What will happen once the body produces enough melatonin? A. Serotonin production is lowered. B. Melatonin production is increased C. Melatonin binds to serotonin-N-acetyltransferase. D. Melatonin binds to N-acetylserotonin.

C. Melatonin binds to serotonin-N-acetyltransferase.

In glycolysis, glucose is broken down to produce two molecules of pyruvate. Which of the following processes is not part of glycolysis? A. Reduction of NAD B. ATP formation C. Reduction of a triose D. Phosphorylation of a hexose

C. Reduction of a triose

What occurs during the light-independent reactions of photosynthesis? A. Glycerate 3-phosphate is oxidized. B. ATP is produced. C. Ribulose bisphosphate reacts with carbon dioxide to form a 6 carbon compound. D. Reduction of NADP.

C. Ribulose bisphosphate reacts with carbon dioxide to form a 6 carbon compound.

Which of the following is not true about light-dependent reactions? A. Involves the reduction of NADP into NADPH B. Involves the production of ATP. C. Take place in the stroma. D. Require the presence of light.

C. Take place in the stroma.

Which of the following is false about the Calvin cycle? A. The Calvin cycle is the name for the light-independent reactions. B. The Calvin cycle is conceptually comparable to the Krebs cycle. C. The Calvin cycle is a cycle of chemical reactions where O2 is the starting material for the production of carbohydrates. D. The Calvin cycle occurs in the stroma of chloroplasts.

C. The Calvin cycle is a cycle of chemical reactions where O2 is the starting material for the production of carbohydrates.

What describes a competitive inhibitor? A. The inhibitor competes with the substrate for the allosteric site. B. The inhibitor causes a conformational change in the active site of the enzyme. C. The inhibitor resembles the substrate. D. The inhibitor binds to the active site permanently.

C. The inhibitor resembles the substrate.

Name the process which is the first stage of cell respiration in all living organisms. (one word)

glycolysis

Name one product of the light-dependent reactions which is not needed for the light-independent reactions.

oxygen

Name the process that generates electrons for use in the light-dependent reactions.

photolysis Photolysis of water generates electrons for use in the light-dependent reactions, as it constantly replaces electrons lost by photosystem II.

What is the name of the enzyme that is involved in the carboxylation of RuBP?

rubisco