Deck 6: Energy for Life

Question 1

During photosynthesis, ___________ is oxidized, while ___________ is reduced.

A) water; carbon dioxide
B) carbon dioxide; water
C) carbohydrate; carbon dioxide
D) carbon dioxide; carbohydrate
E) carbon dioxide; oxygen

Answer 1

A
Explanation: Photosynthesis can be simplified to a redox reaction in which electrons are removed from water (it is oxidized), and transferred to carbon dioxide, which is then reduced.

Question 2

Replacement electrons for the reaction center of photosystem II are derived from __________.

A) H₂O
B) NADP⁺
C) G3P
D) NADPH
E) CO₂

Answer 2

A
Explanation: Electrons to replace the ones lost from the reaction center of photosystem II are derived from water as it is split into an oxygen atom and two H⁺ ions.

Question 3

The light reactions of photosynthesis are said to be similar to a battery because they form a current. In which direction do the electrons of this circuit flow?

A) H₂O → PSII → electron transport chain → PSI → electron transport chain → NADPH
B) H₂O → PSII → chlorophyll b → PSI → chlorophyll a → NADPH
C) NADPH → PSII → electron transport chain → PSI → electron transport chain → NADP⁺
D) NADP⁺ → PSII → electron transport chain → PSI → electron transport chain → NADPH
E) PSI → electron transport chain → PSII → electron transport chain → NADPH

Answer 3

A
Explanation: The overall process is much like a battery where the electrons (and energy) flow from water through the components of the thylakoid membrane, and are stored in NADPH and ATP to power the Calvin cycle. This energy is derived ultimately from the sun.

Question 4

The reaction center of each photosystem

A) splits water to release electrons.
B) funnels electrons to a central chlorophyll a molecule.
C) produces NADPH.
D) gives off oxygen when stimulated by light.
E) combine hydrogen ions with an electron to form water.

Question 5

Inside the chloroplasts, chlorophyll is found in the

A) mesophyll.
B) thylakoid space.
C) thylakoid membrane.
D) stroma.
E) cytoplasm.

Question 6

Which of the following events does NOT take place in the light reactions?

A) transfer of electrons to the reaction center of photosystem I
B) generation of ATP from ADP + P_i
C) splitting of water, releasing an electron
D) generation of NADPH from NADP⁺
E) conversion of 3PG to G3P

Question 7

The chlorophyll a molecules in the reaction center of a photosystem participate directly in the capture of solar energy. What is the purpose of the accessory pigments?

A) They participate in the Calvin cycle.
B) They funnel solar energy to chlorophyll a in the reaction center.
C) They split the water molecule to supply electrons to the chlorophyll a in the reaction center.
D) They change the color of the leaves to discourage predators.
E) They have no purpose.

Question 8

In a redox reaction, reduction means _________, and oxidation means _________.

A) loss of electrons; gain of electrons
B) gain of water; loss of water
C) gain of electrons; loss of electrons
D) loss of water; gain of water
E) gain of protons; loss of protons

Question 9

The light reactions produce __________, which are used in the Calvin cycle. The Calvin cycle produces __________, which are in turn used in the light reactions.

A) ATP and NADPH; ADP and NADP
B) CO₂ and H₂O; glucose and O₂
C) ATP and CO₂; glucose and O₂
D) glucose and O₂; CO₂ and H₂O
E) ADP and NADH; ATP and NADPH

Question 10

As climate change leads to drier and drier summers in the southeastern U.S., more and more homeowners find that they have crabgrass growing in their yards. The reason for this is that

A) Crabgrass is a type of cactus, so it grows better in dry climates.
B) As the climate changes, homeowners are not caring for their yards as well.
C) Crabgrass is a tropical plant that likes hot, dry climates.
D) Crabgrass is a type of C₃ plant that does well in dry climates.
E) Crabgrass is a type of C₄ plant that does well in dry climates.

Question 11

Why do plants contain other pigments besides chlorophyll?

A) The additional pigments are able to absorb other light wavelengths that chlorophyll cannot.
B) The additional pigments can only absorb violet or ultraviolet light.
C) Chlorophyll is unable to absorb visible light.
D) When chlorophyll breaks down, the additional pigments can absorb the same wavelengths of light.
E) When the additional pigments break down, the chlorophyll can absorb other wavelengths of light.

Question 12

The innermost compartment of a chloroplast formed by the interconnected thylakoids is the

A) stroma.
B) thylakoid membrane.
C) chlorophyll.
D) thylakoid space.
E) leaf space.

Question 13

In photosynthesis, the light reactions ____________ while the Calvin cycle ____________.

A) capture solar energy; converts the captured energy to chemical potential energy
B) can occur only in the light; can occur only in the dark
C) require the presence of ATP; makes ATP
D) can only function if the stomata are open; can only occur if the stomata are closed
E) use products manufactured in the dark reactions; creates products used in the dark reactions

Question 14

The production of glyceraldehyde-3-phosphate (G3P) in the Calvin cycle requires 6 molecules each of ATP and NADPH. Another 3 molecules of ATP are then used in the cycle. What is the purpose of the 3 additional ATP molecules?

A) To regenerate the starter molecule RuBP.
B) To attract the next CO₂ molecule to enter the Calvin cycle.
C) To reduce the molecules of G3P to form glucose.
D) To join acetyl CoA into pyruvate, preparing it to enter the citric acid cycle.
E) To fix carbon dioxide to RuBP.

Question 15

How does ATP synthase obtain the energy to produce ATP?

A) Hydrogen ions flow down a concentration gradient from the thylakoid space to the stroma through ATP synthase, releasing energy that can be used to produce ATP from ADP + P_i.
B) Water splits, releasing electrons that flow from the stroma to the thylakoid space and attach to the active site of ATP synthase.
C) Electrons from the reaction site center of photosystem II are funneled to ATP synthase, which uses the energy to produce ATP from ADP + P_i.
D) Hydrogen ions in the thylakoid space combine with electrons from the stroma at ATP synthase, releasing energy that can be used to produce ATP from ADP + P_i.
E) A hydrogen ion from NADPH is used by ATP synthase to power the production of ATP from ADP + P_i, and an electron is released, splitting water.

Question 16

The enzyme-rich solution found within the chloroplast is called the ________.

A) granum
B) chlorophyll
C) cytoplasm
D) stroma

Question 17

Which compounds link the light reactions with the Calvin cycle reactions?

A) ATP and NADPH
B) H⁺ and ATP
C) G3P and ATP
D) H⁺ and G3P
E) G3P and NADPH

Question 18

The light reactions act much as a battery to power the reactions of the Calvin cycle. This energy is stored as

A) ATP and NADP⁺.
B) ADP + P_i.
C) ADP + P_i and NADP⁺.
D) ATP and NADPH.
E) NADPH and NADP⁺.

Question 19

Which of the following organisms can perform photosynthesis?

A) algae
B) fungi
C) animals
D) invertebrates
E) vertebrates

Question 20

Chlorophyll is to the light reactions as ___ is to the Calvin cycle.

A) NADP⁺
B) carbon dioxide
C) ATP
D) ATP synthase
E) RuBP

Question 21

The end product of the Calvin cycle reactions is ___________.

A) glucose
B) glyceraldehyde-3-phosphate (G3P)
C) sucrose
D) 3-phosphoglycerate (3PG)
E) ribulose 1,5-bisphosphate (RuBP)

Question 22

In C₄ plants, chloroplasts are located

A) in mesophyll cells.
B) in the stomata.
C) in both mesophyll and bundle sheath cells.
D) in bundle sheath cells.
E) in epidermal cells of the leaf.

Question 23

The difference between bundle sheath cells in C₃ and C₄ plants is that

A) the bundle sheath cells in C₃ plants have chloroplasts while those in C₄ plants do not.
B) the bundle sheath cells in C₄ plants have chloroplasts while those in C₃ plants do not.
C) the bundle sheath cells in C₃ plants are arranged in columns just beneath the upper epidermis while those in C₄ plants are arranged in a ring around veins.
D) the bundle sheath cells in C₄ plants are arranged in columns just beneath the upper epidermis while those in C₃ plants are arranged in a ring around veins.
E) There is no difference in bundle sheath cells in C₃ and C₄ plants.

Question 24

The O₂ given off during photosynthesis is derived from which compound?

A) CO₂ and H₂O
B) RuBP
C) CO₂
D) NADP⁺
E) H₂O

Question 25

CAM photosynthesis limits CO₂ fixation to nighttime hours in order to

A) allow water to enter leaf spaces during the daylight hours.
B) open stomata only at night, limiting water loss because of heat and low humidity.
C) allow NADPH and ATP to enter leaf spaces.
D) limit the Calvin cycle reactions to nighttime only.
E) limit water uptake from the soil during daytime hours.

Question 26

The reaction center of photosystem I consists of what type of molecule?

A) chlorophyll a
B) chlorophyll b
C) carotenoids
D) NADP⁺
E) electron transport proteins

Question 27

The Calvin cycle reactions only occur in bundle sheath cells in a C₄ plant

A) to shield the Calvin cycle reactions from O₂ in the leaf spaces.
B) to allow O₂ to enter bundle sheath cells.
C) because rubisco is only found in mesophyll cells.
D) so that they are adjacent to stomata.
E) so that H₂O is not available to mesophyll cells.

Question 28

A new species of plant is discovered and you are asked to help classify it. Upon examination under a microscope, you find that there is a layer of bundle sheath cells containing chloroplasts around the vein of the leaf of the plant. What can you tell about the plant from this?

A) This plant is unlike any other plant that has ever been discovered and is a completely new category of plant.
B) This plant very likely carries out C₄ photosynthesis.
C) This plant falls into the category of CAM type plants.
D) This plant uses chemosynthesis rather than photosynthesis.
E) This is a C₃ type of plant.

Question 29

Energy to drive the formation of ATP in photosynthesis is derived from ____________.

A) H⁺ gradient
B) NADP⁺
C) G3P
D) NADPH
E) CO₂

Question 30

ATP and NADPH are both used during the Calvin cycle. What is the function of each?

A) ATP supplies energy and NADPH supplies electrons for reducing power.
B) ATP supplies energy and NADPH fixes CO₂ so it can enter the cycle.
C) Both ATP and NADPH supply energy to the Calvin cycle.
D) NADPH supplies energy and ATP supplies electrons for reducing power.
E) ATP and NADPH are joined into the starter molecule, RuBP, to form glucose.

Question 31

The three stages of the Calvin cycle reactions are

A) NADPH reduction, CO₂ fixation, and NADP⁺ regeneration.
B) NADPH reduction, CO₂ fixation, and RuBP regeneration.
C) CO₂ fixation, CO₂ reduction, and RuBP regeneration.
D) CO₂ fixation, CO₂ reduction, and NADP⁺ regeneration.
E) CO₂ reduction, NADPH reduction, and CO₂ regeneration.

Question 32

A poison that disrupts the H⁺ gradient in the thylakoid space would most likely cause which of the following to accumulate during the Calvin cycle reactions?

A) 3-phosphoglycerate (3PG)
B) ribulose 1,5-bisphosphate (RuBP)
C) glyceraldehyde-3-phosphate (G3P)
D) NADPH
E) 1,3 bisphosphoglycerate (BPG)

Question 33

In C4 plants, the light reactions will stop during the daytime when the supply of what compound is limited?

A) chlorophyll a
B) NADP⁺
C) H₂O
D) CO₂
E) O₂

Question 34

Which steps of photosynthesis does C4 photosynthesis partition in space?

A) carbon fixation and Calvin cycle reactions
B) carbon fixation and light reactions
C) light reactions and Calvin cycle reactions
D) glyceraldehyde-3-phosphate (G3P) formation and glucose phosphate formation
E) 1,3 bisphosphoglycerate (BPG) formation and glucose phosphate formation

Question 35

Which of the following is a coenzyme?

A) glyceraldehyde-3-phosphate (G3P)
B) chlorophyll a
C) electron transport protein
D) rubisco
E) NADP⁺

Question 36

Before being converted into sucrose, starch, or cellulose, G3P must first be converted into which compound?

A) glucose
B) galactose
C) glucose phosphate
D) fructose
E) 3PG

Question 37

A small, low-growing plant found on the surface of a sun-exposed rock on a dry hillside would most likely use which type of photosynthesis?

A) CAM
B) C3
C) C4
D) both C4 and CAM
E) both C3 and CAM

Question 38

In a high latitude rainforest, the dominant type of photosynthesis is most likely to be

A) both C3 and CAM.
B) C4.
C) CAM.
D) both C4 and CAM.
E) C3.

Question 39

A plant that uses CAM photosynthesis is most likely to be successful in what type of environment?

A) cool, moist
B) hot, moist
C) cool, dry
D) hot, dry
E) semi-tropical

Question 40

Sucrose, cellulose, amino acids, and starch are all made from what starter molecule in plants?

A) Glucose
B) Fructose
C) Glyceraldehyde-3-phosphate (G3P)
D) ATP
E) RuBP carboxylase

Question 41

ATP synthase derives energy for the generation of ATP from

A) The movement of hydrogen ions against their concentration gradient into the thylakoid space.
B) The splitting of H₂O which releases electrons.
C) Solar energy captured by the light reactions changing the shape of the enzyme.
D) Electrons transferred from NADPH causing the enzyme to change shape.
E) The movement of hydrogen ions down their concentration gradient from the thylakoid space to the stroma.

Question 42

Grana are

A) Interconnecting stomata.
B) Flattened sacs of thylakoid membrane.
C) Pores that open to allow gas exchange.
D) The sites of the Calvin cycle and production of sugars.
E) Enzymes that bind CO₂.

Question 43

Which of the labeled cells of a C3 leaf does not perform photosynthesis?

A) A and B
B) A and D
C) B and D
D) B and C
E) C and D

Question 44

Which complex or enzyme of photosynthesis consumes H₂O?

A) Photosystem I
B) Photosystem II
C) rubisco
D) electron transport chain
E) ATP synthase

Question 45

What is the major disadvantage of CAM photosynthesis relative to C3 or C4 photosynthesis?

A) lower G3P yield
B) less water loss
C) less CO₂ availability
D) fewer electrons available from chlorophyll
E) fewer NADPH molecules from the light reactions

Question 46

What two things are added to NADP⁺ to convert it into NADPH?

A) H⁺ and electrons
B) electrons and ATP
C) H⁺ and ATP
D) H⁺ and CO₂
E) electrons and CO₂

Question 47

Which of the following is not derived from G3P?

A) starch
B) cellulose
C) glucose phosphate
D) NADP⁺
E) sucrose

Question 48

Which stages of the Calvin cycle reactions require the use of energy from ATP?

A) CO₂ fixation and CO₂ reduction
B) RuBP regeneration and CO₂ reduction
C) CO₂ reduction and RuBP regeneration
D) CO₂ fixation and RuBP regeneration
E) CO₂ fixation, CO₂ reduction, and RuBP regeneration

Question 49

Not all molecules contain the same amount of chemical energy. The energy relationship between G33P and CO₂ is

A) G3P and CO₂ have the same amount of energy.
B) G3P has less energy than CO₂.
C) Neither G3P nor CO₂ contain any chemical energy.
D) G3P has more energy than CO₂.

Question 50

What of the following is a disadvantage of C4 photosynthesis relative to C3 photosynthesis?

A) inability of rubisco to obtain O₂
B) need for energy to move fixed carbon in C4 compound into bundle sheath cells
C) need for stomata to close to conserve H₂O
D) need for energy to move H₂O into bundle sheath cells
E) inability of ATP synthase to utilize H⁺ gradient for energy

Question 51

How many turns of the Calvin cycle would be required for a plant to make one molecule of glucose?

A) 1
B) 2
C) 3
D) 6
E) 12

Question 52

In which of the labeled cells of a C4 leaf are the Calvin cycle reactions performed?

A) A and B
B) B and C
C) A and D
D) B only
E) C only

Question 53

The _______ from the light reactions is used to reduce CO₂ to a carbohydrate using energy derived from ______.

A) NADPH; ATP
B) NADP⁺; ATP
C) RuBP; ATP
D) NADPH; RuBP
E) rubisco; RuBP

Question 54

How many times must the Calvin cycle turn to yield a single molecule of glyceraldehydes-3-phosphate (G3P).

A) 2
B) 3
C) 4
D) 5
E) 6

Question 55

The light-harvesting complexes of a chloroplast are located in the ______; the enzymes of the Calvin cycle reactions are located in the _________.

A) thylakoid membrane; stroma
B) stroma; thylakoid space
C) thylakoid space; thylakoid membrane
D) stroma; thylakoid membrane
E) thylakoid space; stroma

Question 56

Carotenoids are found in high concentrations in yellow and orange leaves or vegetables. This color is seen because the carotenoid pigments

A) Reflect and transmit yellow and orange wavelengths of light.
B) Absorb yellow and orange wavelengths of light.
C) Absorb or transmit yellow and orange wavelengths of light.
D) Absorb or reflect yellow and orange wavelengths of light.
E) Absorb all wavelengths of light and then transmit yellow and orange wavelengths.

Question 57

Which of the following correctly describes CO₂ fixation in a C3 plant?

A) Rubisco combines CO₂ with RuBP to form a 6-carbon compound that then breaks down into two 3-carbon compounds.
B) Rubisco combines CO₂ with a 2-carbon compound to form G3P.
C) Rubisco combines CO₂ with a 2-carbon compound to form 3PG, which is then reduced to G3P.
D) Rubisco combines 6 CO₂ molecules to form RuBP, which breaks down into two 3-carbon compounds.
E) Rubisco combines 3 CO₂ molecules to form 3PG, which is then reduced to G3P.

Question 58

The localization of the electron transport chains to the thylakoid membrane ensures that

A) the energy released can be used to establish an H⁺ ion gradient.
B) the energy released is stored in the stroma.
C) NADP⁺ does not enter the thylakoid space.
D) CO₂ remains in the stroma for the Calvin cycle reactions and does not enter the thylakoid space.
E) glyceraldehyde-3-phosphate (G3P) is produced in the thylakoid space.

Question 59

RuBP carboxylase (rubisco) is able to bind with both

A) Carbon dioxide and water.
B) Carbon dioxide and oxygen.
C) Carbon dioxide and NADPH.
D) Oxygen and water.
E) NADPH and ATP.

Question 60

A coenzyme is defined as

A) a non-protein helper that works with an enzyme.
B) another enzyme that assists an enzyme with a chemical reaction.
C) another enzyme in the same biochemical pathway.
D) a carbohydrate that assists an enzyme.
E) a protein that is not an enzyme.