Question 1

In the Calvin cycle,the three-carbon molecule that will be immediately formed after carbon dioxide fixation occurs is

Accepted Answer

3PG (3-phosphoglycerate) is the first stable product formed in the Calvin cycle after the fixation of carbon dioxide.

Question 2

Why does the chloroplast utilize a cyclic electron pathway as well as the noncyclic electron pathway?

Accepted Answer

The Calvin cycle requires more ATP than NADPH, and the cyclic electron pathway helps produce additional ATP without producing NADPH.

Question 3

How much of the protein content in chloroplasts is made up of the enzyme RuBP carboxylase? Why?

Accepted Answer

RuBP carboxylase, also known as ribulose-1,5-bisphosphate carboxylase/oxygenase or RuBisCO, is the most abundant enzyme on Earth and makes up 20-50% of the protein content in chloroplasts. This high proportion is because the enzyme is very slow, necessitating a large amount of it to meet the photosynthetic demand of plants.

Question 4

What is the function of ribulose bisphosphate (RuBP)during photosynthesis?

Accepted Answer

Ribulose bisphosphate (RuBP) combines with carbon dioxide (CO2) to form a 6-carbon compound during the initial steps of the Calvin cycle, which is an important process in photosynthesis. This 6-carbon compound then breaks down into two 3-carbon compounds, which can be used to eventually produce glucose.

Question 5

The hydrocarbon skeleton used to form fatty acids,glycerol,and amino acids (when N is added)is derived from

Accepted Answer

The hydrocarbon skeleton used to form fatty acids, glycerol, and amino acids (when N is added) is derived from G3P, which is produced during both photosynthesis and cellular respiration. Starch, sucrose, and cellulose are all carbohydrates and do not contain hydrocarbon skeletons. Glucose phosphate does contain a hydrocarbon skeleton, but it is not the primary source for the ones used to form fatty acids, glycerol, and amino acids.

Question 6

Plants need other molecules besides glucose.Where do these molecules,such as cellulose and fructose,come from?

Accepted Answer

G3P, which is produced through photosynthesis, can be used as a precursor molecule for the synthesis of a variety of organic molecules such as cellulose, fructose, and other carbohydrates, lipids, and amino acids. Therefore, plants do not need to produce glucose first and then convert it to other molecules, but they can directly produce a variety of molecules from G3P.

Question 7

The formation of carbohydrate occurs within the

Accepted Answer

The stroma is where the Calvin cycle occurs, which is the process by which carbohydrates (e.g. glucose) are formed from carbon dioxide during photosynthesis.

Question 8

Some herbicides inhibit the electron transport chain in the thylakoid membrane.Without the movement of electrons,hydrogen ions would not be pumped from the stroma to the thylakoid space and the hydrogen ion gradient would not be established.How would this affect the Calvin cycle reactions?

Accepted Answer

Without the establishment of a hydrogen ion gradient, ATP would not be produced during photophosphorylation. ATP is needed for the Calvin cycle reactions to occur, so without it, the reactions would not take place.

Question 9

One of the products of the Calvin cycle is

Accepted Answer

G3P, or glyceraldehyde-3-phosphate, is a product of the Calvin cycle. This molecule can be used to create glucose, which is essential for plant growth and metabolism.

Question 10

What will cycle the energized electrons from the reaction center of PS I back to the reaction center in PS I?

Accepted Answer

The cyclic electron pathway is responsible for cycling the energized electrons from the reaction center of PS I back to the reaction center in PS I. This process generates ATP without producing NADPH or releasing O2.

Question 11

Which of the following statements comparing the ATP synthase complex in cellular respiration and photosynthesis is not true?

Accepted Answer

In photosynthesis, the movement of H+ ions (protons) from inside the thylakoid compartment to the outside of the compartment generates the gradient that drives ATP synthesis by ATP synthase. However, in cellular respiration, the movement of H+ ions (protons) from outside the mitochondrial matrix to the inside generates the gradient that drives ATP synthesis by ATP synthase. Therefore, only cellular respiration requires the movement of H⁺ from inside a compartment to outside of the compartment.

Question 12

The Calvin cycle reactions are dependent upon a supply of

Accepted Answer

The Calvin cycle reactions require a supply of carbon dioxide, NADPH, and ATP to occur. These are the products of the light-dependent reactions that occur in the thylakoid membranes of the chloroplasts. The carbon dioxide is fixed into organic molecules during the Calvin cycle, while the NADPH and ATP are used to power the cycle's reactions. Thus, choice C is the best answer.

Question 13

During photosynthesis,CO₂ is reduced.This means that

Accepted Answer

Reduction is the gain of one or more electrons by a molecule, atom or ion. Therefore, if CO₂ is reduced during photosynthesis, it means that it gains electrons.

Question 14

Most major food plants such as wheat,oats,and rice are in the group of

Accepted Answer

C₃ plants are the most common type of plant, and they include most major food plants such as wheat, oats, and rice.

Question 15

NADPH and ATP are used in the

Accepted Answer

NADPH and ATP are both utilized in the Calvin cycle reactions to reduce carbon dioxide and create glucose. The noncyclic and cyclic electron pathways, as well as the citric acid cycle, also use ATP and NADPH, but not exclusively. The light reactions use these molecules to generate energy and electron carriers for further use in the plant.

Question 16

The H⁺ (protons)accumulate in the thylakoid space during electron transport between photosystems I and II.The excess of protons in the thylakoid space

Accepted Answer

The excess of protons in the thylakoid space moves from the thylakoid space to the stroma through the ATP synthase complex, where it is used to generate ATP in the process of chemiosmosis. This movement of protons down their concentration gradient is facilitated by the ATP synthase complex, which acts as a proton channel and an enzyme that catalyzes the synthesis of ATP from ADP and inorganic phosphate. This process is known as photophosphorylation and is an essential part of the light-dependent reactions of photosynthesis.

Question 17

What are the stages of the Calvin cycle?

Accepted Answer

The Calvin cycle involves three main stages: carbon dioxide fixation, carbon dioxide reduction, and regeneration of RuBP (ribulose-1,5-bisphosphate). These processes are essential for the synthesis of glucose in plants during photosynthesis.

Question 18

Biologists are fairly certain that oxygen was built up in the atmosphere by the development of photosynthesis.The production of oxygen and,therefore,the beginning of extensive aerobic life was made possible by the evolution of

Accepted Answer

Photosystem II is responsible for the production of oxygen during photosynthesis.

Question 19

The reservoir for hydrogen ions for chemiosmotic ATP synthesis during photosynthesis is the

Accepted Answer

The thylakoid space is the reservoir for hydrogen ions (H+) during photosynthesis. This concentration gradient is established by the splitting of water during the light-dependent reactions and is then used to drive chemiosmotic ATP synthesis.

Question 20

How many total carbons are involved in carbon dioxide fixation with 3 molecules of carbon dioxide and 3 molecules of RuBP?

Accepted Answer

Each molecule of RuBP contains 5 carbons, so 3 molecules of RuBP contain a total of 15 carbons. Three molecules of CO2 each contribute one carbon, for a total of 3 carbons. Therefore, the total number of carbons involved in carbon dioxide fixation is 18.

Quiz 8: Photosynthesis

In the Calvin cycle,the three-carbon molecule that will be immediately formed after carbon dioxide fixation occurs is

Why does the chloroplast utilize a cyclic electron pathway as well as the noncyclic electron pathway?

How much of the protein content in chloroplasts is made up of the enzyme RuBP carboxylase? Why?

What is the function of ribulose bisphosphate (RuBP) during photosynthesis?

The hydrocarbon skeleton used to form fatty acids,glycerol,and amino acids (when N is added) is derived from

Plants need other molecules besides glucose.Where do these molecules,such as cellulose and fructose,come from?

The formation of carbohydrate occurs within the

Some herbicides inhibit the electron transport chain in the thylakoid membrane.Without the movement of electrons,hydrogen ions would not be pumped from the stroma to the thylakoid space and the hydrogen ion gradient would not be established.How would this affect the Calvin cycle reactions?

One of the products of the Calvin cycle is

What will cycle the energized electrons from the reaction center of PS I back to the reaction center in PS I?

Which of the following statements comparing the ATP synthase complex in cellular respiration and photosynthesis is not true?

The Calvin cycle reactions are dependent upon a supply of

During photosynthesis,CO₂ is reduced.This means that

Most major food plants such as wheat,oats,and rice are in the group of

NADPH and ATP are used in the

The H⁺ (protons) accumulate in the thylakoid space during electron transport between photosystems I and II.The excess of protons in the thylakoid space

What are the stages of the Calvin cycle?

Biologists are fairly certain that oxygen was built up in the atmosphere by the development of photosynthesis.The production of oxygen and,therefore,the beginning of extensive aerobic life was made possible by the evolution of

The reservoir for hydrogen ions for chemiosmotic ATP synthesis during photosynthesis is the

How many total carbons are involved in carbon dioxide fixation with 3 molecules of carbon dioxide and 3 molecules of RuBP?

Quiz 8: Photosynthesis

In the Calvin cycle,the three-carbon molecule that will be immediately formed after carbon dioxide fixation occurs is

Why does the chloroplast utilize a cyclic electron pathway as well as the noncyclic electron pathway?

How much of the protein content in chloroplasts is made up of the enzyme RuBP carboxylase? Why?

What is the function of ribulose bisphosphate (RuBP) during photosynthesis?

The hydrocarbon skeleton used to form fatty acids,glycerol,and amino acids (when N is added) is derived from

Plants need other molecules besides glucose.Where do these molecules,such as cellulose and fructose,come from?

The formation of carbohydrate occurs within the

Some herbicides inhibit the electron transport chain in the thylakoid membrane.Without the movement of electrons,hydrogen ions would not be pumped from the stroma to the thylakoid space and the hydrogen ion gradient would not be established.How would this affect the Calvin cycle reactions?

One of the products of the Calvin cycle is

What will cycle the energized electrons from the reaction center of PS I back to the reaction center in PS I?

Which of the following statements comparing the ATP synthase complex in cellular respiration and photosynthesis is not true?

The Calvin cycle reactions are dependent upon a supply of

During photosynthesis,CO2 is reduced.This means that

Most major food plants such as wheat,oats,and rice are in the group of

NADPH and ATP are used in the

The H+ (protons) accumulate in the thylakoid space during electron transport between photosystems I and II.The excess of protons in the thylakoid space

What are the stages of the Calvin cycle?

Biologists are fairly certain that oxygen was built up in the atmosphere by the development of photosynthesis.The production of oxygen and,therefore,the beginning of extensive aerobic life was made possible by the evolution of

The reservoir for hydrogen ions for chemiosmotic ATP synthesis during photosynthesis is the

How many total carbons are involved in carbon dioxide fixation with 3 molecules of carbon dioxide and 3 molecules of RuBP?

During photosynthesis,CO₂ is reduced.This means that

The H⁺ (protons) accumulate in the thylakoid space during electron transport between photosystems I and II.The excess of protons in the thylakoid space