Question 1

Light dependent ATP production is called _____ and occurs in the _____ of chloroplasts.

Accepted Answer

Photophosphorylation is the process of ATP production driven by light energy, and it occurs in the thylakoid membrane of chloroplasts.

Question 2

In the Calvin cycle, ______ is "fixed" to generate carbohydrate molecules.

Accepted Answer

In the Calvin cycle, carbon dioxide (CO2) is "fixed" into organic molecules, ultimately leading to the production of carbohydrates. This process is a key part of photosynthesis in plants.

Question 3

The most abundant biological catalyst is ______.

Accepted Answer

RuBisCO is the most abundant enzyme on Earth, primarily because it plays a critical role in the process of carbon fixation during photosynthesis in plants.

Question 4

In the rubisco mechanism, what performs the nucleophilic attack on carbon dioxide?

Accepted Answer

The enediolate intermediate performs the nucleophilic attack on carbon dioxide in the rubisco mechanism. This is a key step in the process of carbon fixation during photosynthesis.

Question 5

Why does rubisco make up about half of the protein content in a typical chloroplast?

Accepted Answer

Rubisco is a relatively slow enzyme, which means it can only catalyze a few reactions per second. This inefficiency necessitates a higher concentration of the enzyme within chloroplasts to meet the photosynthetic demands of the plant.

Question 6

If carbon dioxide is used as a substrate, the major products of rubisco are _____; if oxygen is used as a substrate, the major products of rubisco are _____.

Accepted Answer

Rubisco catalyzes the carboxylation of ribulose-1,5-bisphosphate into two molecules of 3-phosphoglycerate when carbon dioxide is used as a substrate. When oxygen is used, it catalyzes the oxygenation of ribulose-1,5-bisphosphate, leading to one molecule of 3-phosphoglycerate and one molecule of 2-phosphoglycolate.

Question 7

In C₄ plants, CO₂ (as bicarbonate) is condensed with _____ to yield _____ in the mesophyll cells.

Accepted Answer

In C4 plants, CO2 (as bicarbonate) is condensed with phosphoenolpyruvate (PEP) to yield oxaloacetate in the mesophyll cells. This is the first step in the C4 photosynthetic carbon fixation pathway.

Question 8

In C₄ plants, _____ is found in the mesophyll cells to capture CO₂ while _____ is found in the bundle sheath cells to which releases CO₂.

Accepted Answer

Phosphoenolpyruvate carboxylase is found in the mesophyll cells of C4 plants to capture CO2, and malate is then transported to the bundle sheath cells, where it releases CO2 for the Calvin cycle.

Question 9

Regeneration of the rubisco substrate, ribulose-1,5-bisphosphate involves which of the following sugars?

Accepted Answer

The regeneration of ribulose-1,5-bisphosphate, the substrate for rubisco in the Calvin cycle, involves a complex series of reactions that include the use of sugars of various lengths: tetrose-phosphates, pentose-phosphates, hexose-phosphates, and heptose-phosphates. These sugars are intermediates in the rearrangement and phosphorylation processes that ultimately regenerate ribulose-1,5-bisphosphate from the products of the carbon fixation reaction.

Question 10

The production of one molecule of glucose requires _____.

Accepted Answer

The production of one molecule of glucose through the Calvin cycle requires 6 CO2, 18 ATP, and 12 NADPH.

Question 11

What causes carboxylation of a critical lysine residue that coordinates Mg²⁺ in the rubisco active site to occur?

Accepted Answer

The carboxylation of the critical lysine residue in the rubisco active site is promoted by a high pH, which occurs when the light reactions of photosynthesis are highly active. This is because the light reactions generate ATP and NADPH, leading to proton consumption in the Calvin cycle and an increase in stromal pH.

Question 12

Fixation of one molecule of CO₂ in the Calvin cycle requires ___ ATP and ___ NADPH.

Accepted Answer

The answer of Fixation of one molecule of CO₂ in...

Question 13

Diazotrophs

Accepted Answer

Diazotrophs are a diverse group of bacteria, including free-living cyanobacteria and symbionts in root nodules of legumes, that fix atmospheric nitrogen into ammonia, which is then available for plant use in synthesizing essential biomolecules.

Question 14

Nitrogenase contains ___, unusual electron carrier(s).

Accepted Answer

Nitrogenase, the enzyme responsible for fixing atmospheric nitrogen into a form usable by plants, contains multiple unusual electron carriers, including the FeMo cluster, 8Fe:7S cluster, and 4Fe:4S cluster. These clusters play crucial roles in the complex process of nitrogen fixation.

Question 15

Reduction of N2 requires

Accepted Answer

The reduction of N2 (nitrogen gas) to ammonia in biological systems requires both energy and ATP hydrolysis. Energy is needed to break the strong triple bond in N2, and ATP hydrolysis provides the necessary energy for this process.

Question 16

Which is true about nitrogenase?
I. Holds N2 to a metal ion during catalysis
II. Has N2 as its only substrate
III. Cleaves a triple bond
IV. Generates ammonia

Accepted Answer

Nitrogenase holds N2 to a metal ion during catalysis, cleaves the triple bond of N2, and generates ammonia as a product. N2 is not its only substrate, as it also requires electrons and ATP for the reduction process.

Question 17

How is ammonia toxic to many species?
I. Its effect on choline production makes it neurotoxic
II. It acidifies physiologic fluids
III. It depletes citric acid cycle intermediates
IV. It can interfere with nucleotide biosynthesis

Accepted Answer

The answer of How is ammonia toxic to many species?
I....

Question 18

The overall reduction of one N2 molecule requires

Accepted Answer

The overall reduction of one N2 molecule in the process of nitrogen fixation requires 8 protons, 8 electrons, and 16 ATP. This is because the conversion of N2 into 2NH3 (ammonia) involves the addition of protons and electrons to break the triple bond in N2, and the process is energy-intensive, requiring a significant amount of ATP.

Question 19

Although not completely clear, nitrogenase moves electrons from

Accepted Answer

Nitrogenase moves electrons from the 4Fe:4S center to the P center and then to the FeMo cluster. This electron transfer is part of the process that enables nitrogenase to reduce atmospheric nitrogen (N2) to ammonia (NH3).

Quiz 25: Photosynthesis Nitrogen

Light dependent ATP production is called _ and occurs in the _ of chloroplasts.

In the Calvin cycle, ______ is "fixed" to generate carbohydrate molecules.

The most abundant biological catalyst is ______.

In the rubisco mechanism, what performs the nucleophilic attack on carbon dioxide?

Why does rubisco make up about half of the protein content in a typical chloroplast?

If carbon dioxide is used as a substrate, the major products of rubisco are _; if oxygen is used as a substrate, the major products of rubisco are _.

In C₄ plants, CO₂ (as bicarbonate) is condensed with _ to yield _ in the mesophyll cells.

In C₄ plants, _ is found in the mesophyll cells to capture CO₂ while _ is found in the bundle sheath cells to which releases CO₂.

Regeneration of the rubisco substrate, ribulose-1,5-bisphosphate involves which of the following sugars?

The production of one molecule of glucose requires _____.

What causes carboxylation of a critical lysine residue that coordinates Mg²⁺ in the rubisco active site to occur?

Fixation of one molecule of CO₂ in the Calvin cycle requires _ ATP and _ NADPH.

Diazotrophs

Nitrogenase contains ___, unusual electron carrier(s) .

Reduction of N2 requires

Which is true about nitrogenase? I. Holds N2 to a metal ion during catalysis II. Has N2 as its only substrate III. Cleaves a triple bond IV. Generates ammonia

How is ammonia toxic to many species? I. Its effect on choline production makes it neurotoxic II. It acidifies physiologic fluids III. It depletes citric acid cycle intermediates IV. It can interfere with nucleotide biosynthesis

The overall reduction of one N2 molecule requires

Although not completely clear, nitrogenase moves electrons from

Quiz 25: Photosynthesis Nitrogen

Light dependent ATP production is called _____ and occurs in the _____ of chloroplasts.

In the Calvin cycle, ______ is "fixed" to generate carbohydrate molecules.

The most abundant biological catalyst is ______.

In the rubisco mechanism, what performs the nucleophilic attack on carbon dioxide?

Why does rubisco make up about half of the protein content in a typical chloroplast?

If carbon dioxide is used as a substrate, the major products of rubisco are _____; if oxygen is used as a substrate, the major products of rubisco are _____.

In C4 plants, CO2 (as bicarbonate) is condensed with _____ to yield _____ in the mesophyll cells.

In C4 plants, _____ is found in the mesophyll cells to capture CO2 while _____ is found in the bundle sheath cells to which releases CO2.

Regeneration of the rubisco substrate, ribulose-1,5-bisphosphate involves which of the following sugars?

The production of one molecule of glucose requires _____.

What causes carboxylation of a critical lysine residue that coordinates Mg2+ in the rubisco active site to occur?

Fixation of one molecule of CO2 in the Calvin cycle requires ___ ATP and ___ NADPH.

Diazotrophs

Nitrogenase contains ___, unusual electron carrier(s) .

Reduction of N2 requires

Which is true about nitrogenase? I. Holds N2 to a metal ion during catalysis II. Has N2 as its only substrate III. Cleaves a triple bond IV. Generates ammonia

How is ammonia toxic to many species? I. Its effect on choline production makes it neurotoxic II. It acidifies physiologic fluids III. It depletes citric acid cycle intermediates IV. It can interfere with nucleotide biosynthesis

The overall reduction of one N2 molecule requires

Although not completely clear, nitrogenase moves electrons from

Light dependent ATP production is called _ and occurs in the _ of chloroplasts.

If carbon dioxide is used as a substrate, the major products of rubisco are _; if oxygen is used as a substrate, the major products of rubisco are _.

In C₄ plants, CO₂ (as bicarbonate) is condensed with _ to yield _ in the mesophyll cells.

In C₄ plants, _ is found in the mesophyll cells to capture CO₂ while _ is found in the bundle sheath cells to which releases CO₂.

What causes carboxylation of a critical lysine residue that coordinates Mg²⁺ in the rubisco active site to occur?

Fixation of one molecule of CO₂ in the Calvin cycle requires _ ATP and _ NADPH.