Question 1

Replacement electrons for the reaction center of photosystem II are derived from A) H₂O. B) NADP⁺. C) G3P. D) NADPH. E) CO₂.

Accepted Answer

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 2

The function of a photosystem is to
A) split water to release electrons.
B) funnel electrons to a central chlorophyll a molecule.
C) produce NADPH.
D) give off oxygen when stimulated by light.
E) combine hydrogen ions with an electron to form water.

Accepted Answer

Electrons are passed from one chlorophyll molecule to another until they ultimately end up in one central chlorophyll a molecule.

Question 3

The enzyme-rich solution found within the chloroplast is called the
A) granum.
B) chlorophyll.
C) cytoplasm.
D) stroma.
E) christae

Accepted Answer

Among other things, the stroma contains enzymes that participate in the Calvin cycle reactions.

Question 4

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. Plants use a variety of pigments in order to absorb a broader portion of the visible light spectrum.

Accepted Answer

The additional pigments are able to absorb other light wavelengths that chlorophyll cannot, allowing the plant to absorb a broader portion of the visible light spectrum.

Question 5

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

Accepted Answer

Solar energy is captured during the light reactions and used to make ATP and NADPH, which are used in the Calvin cycle to make sugars.

Question 6

Chlorophyll is to the light reactions as ________ is to the Calvin cycle. A) NADP⁺ B) carbon dioxide C) ATP D) ATP synthase E) RuBP

Accepted Answer

Chlorophyll accepts input solar energy) and funnels that energy in the form of electrons into production of the end products of the light reactions ATP and NADPH). In the process, chlorophyll is regenerated. Likewise, RuBP accepts input CO₂) and energy from the light reactions to produce the end product of the Calvin cycle G3P). RuBP is then regenerated.

Question 7

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

Accepted Answer

The final three molecules of ATP are necessary to reform the starter molecule of RuBP, so the Calvin cycle can continue.

Question 8

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

Accepted Answer

The light reactions and the Calvin cycle reactions are dependent upon one another. If the Calvin cycle stops, the NADP⁺ and ADP needed to derive energy from the light reactions are depleted, and the light reactions stop too.

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

Accepted Answer

The products of the light reactions, ATP and NADPH, supply energy and reducing power to the Calvin cycle.The byproducts of the Calvin cycle, ADP, inorganic P, and NADP, are returned to the light reactions.

Question 10

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

Accepted Answer

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 11

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.

Accepted Answer

The inner space inside each thylakoid is the thylakoid space. The thylakoid spaces of neighboring thylakoids in a granum are connected to make one large thylakoid space.

Question 12

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.

Accepted Answer

The chlorophyll a in the reaction center is only able to accept certain wavelengths of light. The accessory pigments capture other wavelengths and pass them from one pigment to another until the correct wavelength is reached, and then pass them to the chlorophyll a in the reaction center.

Question 13

As climate change leads to drier and drier summers in the southeastern United States, 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.

Accepted Answer

Since it is a C₄ plant, crabgrass is able to outcompete the C₃ grasses that are commonly grown in yards.

Question 14

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⁺.

Accepted Answer

Solar energy is stored as ATP and NADPH and used to power the Calvin cycle reactions.

Question 15

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

Accepted Answer

The light reactions of photosynthesis convert sunlight to ATP and NADPH that are then used in the synthesis reactions.

Question 16

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

Accepted Answer

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 17

Inside the chloroplasts, chlorophyll is found in the
A) mesophyll.
B) thylakoid space.
C) thylakoid membrane.
D) stroma.
E) cytoplasm.

Accepted Answer

Chlorophyll molecules are found within the photosystem complexes that are embedded within the thylakoid membrane.

Question 18

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 + Pi.
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 + Pi.
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 + Pi.
E) A hydrogen ion from NADPH is used by ATP synthase to power the production of ATP from ADP + Pi, and an electron is released, splitting water.

Accepted Answer

Energy is derived from electrons moving down energy levels through the electron carriers of the electron transport chain, and this is used by some of these proteins to move protons against their concentration gradient to the inside of the thylakoid. The protons exit at the ATP synthase, and as they move down energy levels, the energy released is used to make ATP.

Question 19

Which of the following organisms can perform photosynthesis?
A) algae
B) fungi
C) animals
D) invertebrates
E) vertebrates

Accepted Answer

Plants, cyanobacteria, algae, and some protists are capable of photosynthesis.

Question 20

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

Accepted Answer

A compound is reduced when it gains electrons. A compound is oxidized when it loses electrons. Redox reactions couple these processes together, whereby one compound is oxidized, and the other reduced.

Quiz 6: Energy for Life

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

The function of a photosystem is to

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

Why do plants contain other pigments besides chlorophyll?

In photosynthesis, the light reactions while the Calvin cycle .

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

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

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

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

During photosynthesis, is oxidized, while is reduced.

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

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?

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

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

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

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?

Inside the chloroplasts, chlorophyll is found in the

How does ATP synthase obtain the energy to produce ATP?

Which of the following organisms can perform photosynthesis?

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