Deck 6: Harvesting Energy

Question 1

The metabolic pathway that involves the oxidation of glucose to pyruvate is called

A) glycolysis.
B) the electron transport chain.
C) oxidative phosphorylation.
D) the citric acid cycle.
E) fermentation.

Answer 1

glycolysis.

Question 2

On balance, for every molecule of glucose processed, glycolysis produces

A) two molecules of ATP and two molecules of NAD⁺.
B) two molecules of ATP and two molecules of NADH.
C) four molecules of ATP and two molecules of NADH.
D) four molecules of ATP and two molecules of NAD⁺.
E) only two molecules of NADH as the ATP produced is used in glycolysis.

Answer 2

two molecules of ATP and two molecules of NADH.

Question 3

Before lipids can be used in respiratory ATP production, they must first be converted to

A) pyruvate.
B) glucose.
C) acetyl CoA.
D) citric acid.
E) lactic acid.

Answer 3

acetyl CoA.

Question 4

Before entering the citric acid cycle, carbohydrates are processed by glycolysis while lipids are processed by ß-oxidation. Although different, both of these metabolic pathways result in the production of

A) CO₂.
B) NADH.
C) ATP.
D) acetyl CoA.
E) NAD⁺.

Question 5

The oxidation of pyruvate to acetyl CoA occurs in the

A) mitochondrial matrix during aerobic respiration.
B) intermembrane space of the mitochondrion.
C) cytosol during anaerobic respiration.
D) cytosol during aerobic respiration.
E) inner mitochondrial membrane during aerobic respiration.

Question 6

In the metabolism of glucose, acetyl CoA is produced

A) via alcoholic fermentation in anaerobic conditions.
B) by the addition of CO₂ to pyruvate in the final step of glycolysis.
C) in the citric acid cycle, coupled with the production of ATP.
D) by the decarboxylation of lactate in aerobic respiration.
E) by the decarboxylation of pyruvate in mitochondria.

Question 7

The metabolic pathway that involves reduced electron carriers and cytochrome proteins associated with the inner mitochondrial membrane is called

A) glycolysis.
B) oxidative phosphorylation.
C) the citric acid cycle.
D) the electron transport system.
E) photosynthesis.

Question 8

The electron carriers of the respiratory electron transport chain are

A) embedded in the plasma membrane of aerobically respiring prokaryotic cells.
B) embedded in the plasma membrane in all prokaryotic cells.
C) free in the cytoplasm of prokaryote cells.
D) absent in all prokaryotic cells.
E) embedded in the inner mitochondrial membrane of aerobically respiring prokaryotic cells.

Question 9

NAD⁺ and FAD are

A) oxidised to NADH and FADH during glycolysis and the citric acid cycle.
B) reduced to NADH and FADH by the electron transport system.
C) converted to NADH and FADH coupled to the breakdown of pyruvate to acetyl-CoA.
D) recycled from NADH and FADH by the electron transport system.
E) converted to NADH and FADH in reactions coupled to the synthesis of ATP.

Question 10

In aerobic respiration, the energy released from reduced electron carriers is used to

A) catalyse the synthesis of ATP from ADP.
B) create a proton gradient across the mitochondrial inner membrane.
C) restore NAD⁺ molecules for further use in the citric acid cycle.
D) oxidise NADH and FADH₂.
E) move electrons along a chain of electron carriers to the final electron acceptor, oxygen.

Question 11

Most of the ATP produced during aerobic cellular respiration is produced by

A) glycolysis.
B) the citric acid cycle.
C) chemiosmosis.
D) ß-oxidation.
E) electron transport chain.

Question 12

The compound 2,4-dinitrophenol (DNP) destroys the proton concentration gradient across the inner mitochondrial membrane. If isolated mitochondria are incubated in a solution of DNP, you would expect

A) no reduced electron carriers to be produced.
B) no ATP to be generated.
C) no NADH to be oxidised.
D) extra ATP to be generated.
E) the mitochondria to switch to anaerobic fermentation.

Question 13

In alcoholic fermentation, NAD⁺ is regenerated when

A) phosphorylated glucose is split into two 3-carbon molecules.
B) glyceraldehyde 3-phosphate is oxidised to pyruvate.
C) CO₂ is split from pyruvate to generate acetaldehyde.
D) ethanol is oxidised to CO₂.
E) acetaldehyde is reduced to ethanol.

Question 14

Chlorophyll is a pigment that shows strong absorption of

A) red and blue light.
B) infra-red light.
C) green light only.
D) white light.
E) UV light.

Question 15

Thylakoid membranes contain protein complexes for

A) the light-harvesting system.
B) the electron transport system.
C) the ATP synthesising system.
D) the absorption of photons for the transport of electrons across the membrane.
E) All of the answers are correct.

Question 16

The primary function of the light-dependent reactions of photosynthesis is to

A) produce oxygen by removing electrons from water.
B) produce carbohydrates from carbon dioxide and water.
C) produce energy-rich ATP and NADPH.
D) activate rubisco for the synthesis of sucrose.
E) create an electron gradient that drives ATP synthesis.

Question 17

Which of the following statements about Photosystems I and II in non-cyclic photosynthesis is CORRECT?

A) Photosystem I passes high-energy electrons to NADPH whereas Photosystem II passes high-energy electrons to the cytochrome b/f complex.
B) Both photosystem I and photosystem II recycle oxidised NADP⁺ to NADPH.
C) The reaction centre of Photosystem I contains a pair of chlorophyll a molecules whereas the reaction centre of Photosystem II contains a pair of chlorophyll b molecules.
D) Photosystem I is located on granal lamellae whereas Photosystem II is located on stromal lamellae.
E) The light-absorbing pigments of Photosystem I absorb blue light whereas the light-absorbing pigments of Photosystem II absorb red light.

Question 18

During the light-dependent reactions in photosynthetic eukaryotes, the flow of electrons in non-cyclic phosphorylation is from

A) PS II - cytochrome b/f complex - PS I - NADP⁺.
B) PS II - cytochrome b/f complex - NADP⁺ - PS I.
C) PS II - NADP⁺ - cytochrome b/f complex - PS I.
D) PS I - cytochrome b/f complex - PS II - NADP⁺.
E) PS I - cytochrome b/f complex - NADP⁺ - PS II.

Question 19

If 25 per cent of the photosystems in a chloroplast change from non-cyclic to cyclic photophosphorylation, this will

A) increase the rate of production of ATP and NADPH.
B) decrease the rate of production of ATP and NADPH.
C) increase ATP production relative to NADPH production.
D) increase NADP⁺ production relative to ATP production.
E) increase NADPH production relative to ATP production.

Question 20

As in mitochondria, the protein complexes of the electron transport system of chloroplasts

A) synthesise ATP from ADP and phosphate.
B) pass electrons to O₂ as the final electron acceptor.
C) accept high-energy electrons from reduced electron carriers.
D) transport electrons to recycle NADPH to NADP⁺.
E) create a proton gradient that drives ATP synthesis.

Question 21

Green and purple bacteria do not produce O₂ because

A) they lack chloroplasts.
B) the enzymes associated with light harvesting are on the plasma membrane.
C) they lack the enzymes for photosystem II.
D) they lack the cytochrome b/f complex which splits water.
E) they lack the enzymes for photosystem I.

Question 22

In photosynthetic eukaryotes the enzymes for carbon fixation are found in the

A) chloroplast stroma.
B) plasma membrane.
C) chloroplast grana.
D) stromal lamellae.
E) cytosol.

Question 23

ATP and NADPH produced in the light-dependent reactions of photosynthesis

A) are concentrated in the thylakoid spaces.
B) supply the energy to fix CO₂ to produce sugars.
C) supply the energy to fix CO₂ to produce Rubisco.
D) are used primarily for the general energy requirements of plant cells.
E) are produced in the thylakoid lumen of the chloroplast.

Question 24

In the Calvin-Benson cycle, Rubisco catalyses the

A) synthesis of ATP.
B) formation of RuBP.
C) rearrangement of 2 PGAL into fructose and glucose.
D) fixing of CO₂ to RuBP.
E) oxidation of NADPH.

Question 25

Photorespiration lowers the efficiency of the Calvin-Benson cycle by reducing the number of

A) carbon dioxide molecules fixed.
B) oxygen molecules released.
C) rubisco molecules synthesised.
D) ATP molecules synthesised.
E) NADPH molecules reduced.

Question 26

A C₄ plant

A) fixes CO₂ to form oxaloacetate in mesophyll cells.
B) requires more energy for photosynthesis than a C₃ plant.
C) usually has Kranz anatomy.
D) produces a 4-carbon organic acid as the first stable product of photosynthesis.
E) All of the answers are true.

Question 27

A green plant is placed in an enclosed CO₂-free atmosphere containing 21 per cent O₂ in the light. The CO₂ concentration remains zero. Which of the following statements about this plant is true?

A) The plant is a C₃ plant.
B) The primary carboxylating enzyme in the plant is Rubisco.
C) Photorespiration is undetectable.
D) The plant has very few grana in its mesophyll chloroplasts.
E) The plant is able to carry out photorespiration in the light.

Question 28

CAM plants are like other types of C₄ plants in that

A) CO₂ fixation occurs mostly at night.
B) there is no Rubisco in the mesophyll cells.
C) the C₄ pathway and Calvin-Benson cycle occur in the same cell.
D) CO₂ for the Calvin-Benson cycle comes from the decarboxylation of malate.
E) they are able to carry out photorespiration in the light.

Question 29

If a C4 plant was exposed to radioactive CO₂, which of the following compounds would be the first labelled by the radioactive carbon?

A) Malate.
B) Phosphoenolpyruvate.
C) Pyruvate.
D) Oxaloacetate.
E) Ribulose-1, 5-bisphosphate.

Question 30

What is an electron transport system?

A) A system of light absorbing pigments, including chlorophyll, which makes it possible for photosynthetic organisms to absorb light.
B) A sequence of membrane-bound molecules which allow the passage of H⁺ into the matrix.
C) A series of cytochromes with the ability to reduce NAD⁺.
D) A series of membrane bound proteins and smaller compounds that have the ability to accept and donate electrons.
E) The biological system for the production of ATP.

Question 31

Which of the following do not occur in both mitochondria and chloroplasts?

A) The generation of ATP
B) The ability to generate an electrochemical gradient across an inner membrane
C) The use of O₂ to produce water
D) The transport of electrons by protein complexes
E) The ability to recycle reduced nucleotides

Question 32

The flow of electrons in photosynthesis is

A) PS II $\rightarrow$ cytochrome b/f complex $\rightarrow$ PS I $\rightarrow$ NADP⁺.
B) PS I $\rightarrow$ NADP⁺ $\rightarrow$ cytochrome b/f complex $\rightarrow$ PS II $\rightarrow$ NADP⁺.
C) PS I $\rightarrow$ cytochrome b/f complex $\rightarrow$ PS II $\rightarrow$ NADP⁺.
D) cytochrome b/f complex $\rightarrow$ PS II $\rightarrow$ PS I $\rightarrow$ NADP⁺.
E) PS II $\rightarrow$ cytochrome b/f complex $\rightarrow$ NADP⁺ $\rightarrow$ PS I.

Question 33

Fats are degraded by the process $\beta$ -oxidation. What is the end product of this process?

A) ATP.
B) Glucose.
C) Acetyl-CoA.
D) Pyruvate.
E) Lactate.

Question 34

When the first autotrophic photosynthetic prokaryotes evolved, they metabolised CO₂ and H₂O by utilising energy from the sun. Based on your knowledge of photosynthesis and evolution, what would the end products of these early reactions have been?

A) Pyruvate
B) Sucrose, fructose and NAD⁺
C) O₂ and carbohydrates
D) ATP and H⁺
E) Fatty acids

Question 35

Using only glycolysis, a cell is able to produce 2 ATP from one glucose molecule. When combined with oxidative respiration, how many ATP can a cell produce from one glucose molecule?

A) None, glycolysis and oxidative respiration are mechanisms to produce NAD⁺
B) 38
C) 2
D) 36
E) 34

Question 36

Which of the following statements in relation to fermentation is INCORRECT?

A) Fermentation only occurs when O₂ is present.
B) Lactate and methanol are products of fermentation.
C) Fermentation consumes NADH and is independent of glycolysis.
D) During fermentation, glucose is converted into pyruvate.
E) All of the options listed here are incorrect.

Question 37

How do carotenoids and phycobilins assist in photosynthesis?

A) They bind to the chlorophyll and increase the surface area for photon absorption.
B) They absorb wavelengths of light not readily absorbed by chlorophyll.
C) They produce chemical energy and release solutes to rapidly open and close stomata.
D) They have a lower absorption efficiency but a higher tolerance to adverse environmental conditions, allowing the plant to continue some photosynthesis even under extremely harsh conditions.
E) Being structurally distinct from chlorophyll, carotenoids and phycobilins do not compete with chlorophyll for the same limited enzyme capacity.

Question 38

Phycobilins can be found in

A) some primitive cyanobacteria and red marine algae.
B) all higher plants.
C) conifers exclusively.
D) some angiosperms.
E) mosses and liverworts.

Question 39

Which of the following are NOT found in chloroplasts?

A) stroma lamellae.
B) granum.
C) thylakoid tonoplast.
D) thylakoid membrane.
E) thylakoid lumen.

Question 40

When a chlorophyll molecule absorbs a photon, how is the energy generated transferred from the chlorophyll in the first instance?

A) Electrons are transferred to neighbouring acceptor molecules via an electron chain
B) By generating ATP
C) By the synthesis of energy-rich carbohydrates
D) Via photosynthesis assistance molecules such as phycobilins and carotenoids
E) Excitation transfer

Question 41

A plant scientist is examining a transverse section of a leaf taken from a grass species growing in a tropical climate. He thinks he sees a tight wreath of cells with very thick walls surrounding the vascular tissue. What type of C-fixation anatomy would this specimen most likely have?

A) C₃
B) Reductive citric acid cycle
C) 3-Hydroxypropionate cycle
D) C₄
E) Crassulacean acid metabolism

Question 42

Why are plants that use the CAM system of C-fixation more efficient at tolerating hot and dry climates?

A) They have no stomata. Instead they use a slower but more water efficient system of CO₂ diffusion across the epidermis for gas exchange.
B) They have evolved a system independent of phosphoenolpyruvate, the most water inefficient step in C₃ and C₄ C-fixation.
C) Their enzyme efficiency is optimal when the internal cellular environment is warmer and drier than other plants.
D) They only open their stomata at night, thus minimising transpiration loss.
E) The initial 3-carbon compound they produce in darkness is stored in the vacuole, before then being decarboxylated when light appears.