Question 1

Where does the Calvin cycle take place?
A)stroma of the chloroplast
B)thylakoid membrane
C)cytoplasm surrounding the chloroplast
D)interior of the thylakoid (thylakoid space)
E)outer membrane of the chloroplast

Accepted Answer

The Calvin cycle takes place in the stroma of the chloroplast, which is the fluid-filled space surrounding the thylakoid membranes where light-independent reactions occur.

Question 2

Which of the following are directly associated with photosystem I?
A)harvesting of light energy by ATP
B)receiving electrons from the thylakoid membrane electron transport chain
C)generation of molecular oxygen
D)extraction of hydrogen electrons from the splitting of water
E)passing electrons to the thylakoid membrane electron transport chain

Accepted Answer

Photosystem I receives electrons from the thylakoid membrane electron transport chain, making option B the correct answer. Harvesting of light energy by ATP is associated with photosystem II, extraction of hydrogen electrons from the splitting of water produces oxygen and is associated with photosystem II, and passing electrons to the thylakoid membrane electron transport chain is also associated with photosystem II.

Question 3

Some photosynthetic organisms contain chloroplasts that lack photosystem II, yet are able to survive. The best way to detect the lack of photosystem II in these organisms would be
A)to determine if they have thylakoids in the chloroplasts.
B)to test for liberation of O₂ in the light.
C)to test for CO₂ fixation in the dark.
D)to do experiments to generate an action spectrum.
E)to test for production of either sucrose or starch.

Accepted Answer

Photosystem II is responsible for the liberation of O₂ in the light during photosynthesis. Therefore, testing for liberation of O₂ in the light would be the best way to detect the lack of photosystem II in these organisms.

Question 4

In the thylakoid membranes, what is the main role of the antenna pigment molecules?
A)split water and release oxygen to the reaction-centre chlorophyll
B)harvest photons and transfer light energy to the reaction-centre chlorophyll
C)synthesize ATP from ADP and  ᵢ
D)transfer electrons to ferredoxin and then NADPH
E)concentrate photons within the stroma

Accepted Answer

The main role of the antenna pigment molecules in the thylakoid membranes is to harvest photons and transfer light energy to the reaction-centre chlorophyll, which is then used for photosynthesis. The antenna pigments are arranged in such a way that they can effectively capture a wide range of wavelengths of light and transfer the energy to the reaction center. This process of light energy transfer is known as resonance energy transfer.

Question 5

Halobacterium has a photosynthetic membrane that is coloured purple. Its photosynthetic action spectrum is exactly complementary (opposite to)the action spectrum for green plants. What wavelengths of light do the Halobacterium photosynthetic pigments absorb?
A)red and yellow
B)blue, green, and red
C)green and yellow
D)red and green
E)blue and red

Accepted Answer

Since the photosynthetic action spectrum of Halobacterium is complementary to that of green plants, it suggests that Halobacterium absorbs the wavelengths of light that green plants do not absorb effectively. Green plants absorb mainly blue and red light, but not much in the green range. Therefore, the best choice is E, which includes blue and red light.

Question 6

In any ecosystem, terrestrial or aquatic, what group(s)is (are)always necessary?
A)autotrophs and heterotrophs
B)producers and primary consumers
C)photosynthesizers
D)autotrophs
E)green plants

Accepted Answer

The answer of In any ecosystem, terrestrial or aquatic, what...

Question 7

Which of the events listed below occurs in the light reactions of photosynthesis?
A)NADP is produced.
B)NADPH is reduced to NADP⁺.
C)Carbon dioxide is incorporated into PGA.
D)ATP is phosphorylated to yield ADP.
E)Light is absorbed and funnelled to reaction-centre chlorophyll a.

Accepted Answer

The event that occurs in the light reactions of photosynthesis is the absorption of light energy by pigments such as chlorophyll and the transfer of that energy to reaction-center chlorophyll a. This is required as a source of energy to charge the electrons that will later be used in the production of ATP and NADPH. Therefore, the option E is the best choice. Options A, B, C, and D pertain to events in the dark reactions (Calvin cycle) of photosynthesis.

Question 8

In a plant cell, where are the ATP synthase complexes located?
A)thylakoid membrane only
B)plasma membrane only
C)inner mitochondrial membrane only
D)thylakoid membrane and inner mitochondrial membrane
E)thylakoid membrane and plasma membrane

Accepted Answer

ATP synthase complexes are located in the thylakoid membrane of chloroplasts and in the inner mitochondrial membrane of mitochondria. Therefore, the best choice is D, which includes both of these membranes.

Question 9

What does the chemiosmotic process in chloroplasts involve?
A)establishment of a proton gradient across the thylakoid membrane
B)diffusion of electrons through the thylakoid membrane
C)reduction of water to produce ATP energy
D)movement of water by osmosis into the thylakoid space from the stroma
E)formation of glucose, using carbon dioxide, NADPH, and ATP

Accepted Answer

The chemiosmotic process in chloroplasts involves the establishment of a proton gradient across the thylakoid membrane, which drives the synthesis of ATP through the action of ATP synthase. This occurs during the light-dependent reactions of photosynthesis.

Question 10

Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will have the most direct effect on which of the following processes?
A)the splitting of water
B)the absorption of light energy by chlorophyll
C)the flow of electrons from photosystem II to photosystem I
D)the synthesis of ATP
E)the reduction of NADP⁺

Accepted Answer

The synthesis of ATP occurs in the thylakoid membrane and requires a proton gradient to be maintained across this membrane. If the thylakoid is punctured and the interior is no longer separated from the stroma, the proton gradient will be disrupted and this will directly affect the synthesis of ATP. Choices A, B, C, and E occur within the thylakoid membrane but are not directly dependent on the maintenance of the proton gradient.

Question 11

What are the products of linear photophosphorylation?
A)heat and fluorescence
B)ATP and P700
C)ATP and NADPH
D)ADP and NADP
E)P700 and P680

Accepted Answer

The products of linear photophosphorylation are ATP and NADPH. Heat and fluorescence are not products of this process. P700 and P680 are the names of the reaction centers in photosystems I and II, respectively. ATP and P700 are not products of linear photophosphorylation, but rather products of cyclic photophosphorylation. Similarly, ADP and NADP are not products of linear photophosphorylation, but rather substrates.

Question 12

In autotrophic bacteria, where are the enzymes located that can carry on carbon fixation (reduction of carbon dioxide to carbohydrate)?
A)in chloroplast membranes
B)in chloroplast stroma
C)in the cytosol
D)in the nucleoid
E)in the infolded plasma membrane

Accepted Answer

The answer of In autotrophic bacteria, where are the enzymes...

Question 13

As a research scientist, you measure the amount of ATP and NADPH consumed by the Calvin cycle in 1 hour. You find 30 000 molecules of ATP consumed, but only 20 000 molecules of NADPH. Where did the extra ATP molecules come from?
A)photosystem II
B)photosystem I
C)cyclic electron flow
D)linear electron flow
E)chlorophyll

Accepted Answer

Cyclic electron flow can produce additional ATP without consuming NADPH, which could explain the excess ATP measured.

Question 14

Which statement describes the functioning of photosystem II?
A)Light energy excites electrons in the thylakoid membrane electron transport chain.
B)Photons are passed along to a reaction-centre chlorophyll.
C)The P680 chlorophyll donates a pair of protons to NADP⁺, which is thus converted to NADPH.
D)The electron vacancies in P680⁺ are filled by electrons derived from water.
E)The splitting of water yields molecular carbon dioxide as a by-product.

Accepted Answer

Photosystem II functions by using light energy to excite electrons in the thylakoid membrane electron transport chain. These electrons are then passed along to a reaction-centre chlorophyll (P680), where they are used to fill electron vacancies in P680⁺, which are derived from water. Through this process, oxygen is released as a by-product. The P680 chlorophyll does not donate protons to NADP⁺; this occurs in photosystem I. Additionally, photosystem II does not directly produce CO2 as a by-product; this occurs in the Calvin cycle.

Question 15

If photosynthesizing green algae are provided with CO₂ synthesized with heavy oxygen (¹⁸O), later analysis will show that all but one of the following compounds produced by the algae contain the ¹⁸O label. That one is
A)3-phosphoglycerate.
B)glyceraldehyde 3-phosphate (G3P).
C)glucose.
D)ribulose bisphosphate (RuBP).
E)O₂.

Accepted Answer

During photosynthesis, the oxygen atoms in the CO₂ molecules do not end up in the O₂ produced. Instead, the O₂ released comes from the splitting of water (H₂O) molecules in the light-dependent reactions, not from the carbon dioxide (CO₂) used in the Calvin cycle. Therefore, if CO₂ with ¹⁸O is used, the ¹⁸O would be incorporated into the carbon fixation products (3-phosphoglycerate, glyceraldehyde 3-phosphate (G3P), glucose, and ribulose bisphosphate (RuBP)) but not in the molecular oxygen (O₂) released.

Question 16

Suppose the interior of the thylakoids of isolated chloroplasts were made acidic and then transferred in the dark to a pH 8 solution. What would be likely to happen?
A)The isolated chloroplasts will make ATP.
B)The Calvin cycle will be activated.
C)Cyclic photophosphorylation will occur.
D)The isolated chloroplasts will generate oxygen gas.
E)The isolated chloroplasts will reduce NADP⁺ to NADPH.

Accepted Answer

The acidification of the thylakoid interior, followed by placement in a basic solution, creates a proton gradient across the thylakoid membrane. This gradient drives ATP synthesis through chemiosmosis, similar to the process occurring during the light reactions of photosynthesis, but without the need for light in this experimental setup.

Question 17

Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?
A)CO₂ and glucose
B)H₂O and O₂
C)ADP,  ᵢ, and NADP⁺
D)electrons and H⁺
E)ATP and NADPH

Accepted Answer

ATP and NADPH are the products of the light reactions that are utilized in the Calvin cycle to power the synthesis of glucose. CO₂ is used in the Calvin cycle as a substrate, while glucose is the end product of the cycle. H₂O and O₂ are reactants and products of the light reactions, respectively. Electrons and H⁺ are also involved in the light reactions but are not directly utilized in the Calvin cycle. ADP and NADP⁺ are also involved in the light reactions but are not products that are utilized in the Calvin cycle.

Question 18

Photosynthesis is not responsible for
A)oxygen in the atmosphere.
B)the ozone layer.
C)most of the organic carbon on Earth's surface.
D)atmospheric CO₂.
E)fossil fuels.

Accepted Answer

The answer of Photosynthesis is not responsible for
A)oxygen in the...

Question 19

When oxygen is released as a result of photosynthesis, it is a direct by-product of
A)reducing NADP⁺.
B)splitting water molecules.
C)chemiosmosis.
D)the electron transfer system of photosystem I.
E)the electron transfer system of photosystem II.

Accepted Answer

Oxygen is released during photosynthesis as a direct by-product of the splitting of water molecules during the light-dependent reactions. This process occurs in photosystem II and involves the transfer of electrons from water to the electron transport chain, ultimately resulting in the generation of oxygen gas.

Question 20

A plant has a unique photosynthetic pigment. The leaves of this plant appear to be reddish yellow. What wavelengths of visible light are being absorbed by this pigment?
A)red and yellow
B)blue and violet
C)green and yellow
D)blue, green, and red
E)green, blue, and yellow

Accepted Answer

The color of the leaves is determined by the wavelengths of light that are reflected, not absorbed. Since the leaves appear reddish yellow, it means that red and yellow wavelengths are being reflected, while the complementary colors, such as blue and violet, are being absorbed by the pigment.

Quiz 10: Photosynthesis

Where does the Calvin cycle take place?

Which of the following are directly associated with photosystem I?

Some photosynthetic organisms contain chloroplasts that lack photosystem II, yet are able to survive. The best way to detect the lack of photosystem II in these organisms would be

In the thylakoid membranes, what is the main role of the antenna pigment molecules?

Halobacterium has a photosynthetic membrane that is coloured purple. Its photosynthetic action spectrum is exactly complementary (opposite to) the action spectrum for green plants. What wavelengths of light do the Halobacterium photosynthetic pigments absorb?

In any ecosystem, terrestrial or aquatic, what group(s) is (are) always necessary?

Which of the events listed below occurs in the light reactions of photosynthesis?

In a plant cell, where are the ATP synthase complexes located?

What does the chemiosmotic process in chloroplasts involve?

Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will have the most direct effect on which of the following processes?

What are the products of linear photophosphorylation?

In autotrophic bacteria, where are the enzymes located that can carry on carbon fixation (reduction of carbon dioxide to carbohydrate) ?

As a research scientist, you measure the amount of ATP and NADPH consumed by the Calvin cycle in 1 hour. You find 30 000 molecules of ATP consumed, but only 20 000 molecules of NADPH. Where did the extra ATP molecules come from?

Which statement describes the functioning of photosystem II?

If photosynthesizing green algae are provided with CO₂ synthesized with heavy oxygen (¹⁸O) , later analysis will show that all but one of the following compounds produced by the algae contain the ¹⁸O label. That one is

Suppose the interior of the thylakoids of isolated chloroplasts were made acidic and then transferred in the dark to a pH 8 solution. What would be likely to happen?

Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?

Photosynthesis is not responsible for

When oxygen is released as a result of photosynthesis, it is a direct by-product of

A plant has a unique photosynthetic pigment. The leaves of this plant appear to be reddish yellow. What wavelengths of visible light are being absorbed by this pigment?