Question 1

What is another name for ribulose 1,5-bisphosphate carboxylase/oxygenase?

Accepted Answer

Rubisco is the common name for ribulose 1,5-bisphosphate carboxylase/oxygenase, an enzyme involved in the first major step of carbon fixation in the Calvin cycle of photosynthesis.

Question 2

When NADPH is abundant, the nonoxidative phase of the pentose phosphate pathway may still be used to produce _______________.

Accepted Answer

ribose 5-phosphate

Question 3

In C₄ plants, carbon dioxide is added to ____________________ to form oxaloacetate, which is reduced to malate, which carries CO₂ to the bundle-sheath cells.

Accepted Answer

phosphoenolpyruvate

Question 4

The binding site of Mg²⁺ to rubisco requires the formation of a ________________ group between lysine 201 and CO₂.

Accepted Answer

The answer of The binding site of Mg²⁺ to rubisco...

Question 5

Hemolytic anemia is caused by a deficiency of the enzyme ______________________.

Accepted Answer

The answer of Hemolytic anemia is caused by a deficiency...

Question 6

A _______________ intermediate is formed between the carbonyl group of the ketose substrate and the ε-amino group of a lysine residue of transaldolase.

Accepted Answer

The answer of A _______________ intermediate is formed between the...

Question 7

Which of the following types of organisms can synthesize glucose from carbon dioxide and water?

Accepted Answer

Autotrophs are organisms that can synthesize glucose from carbon dioxide and water, typically through photosynthesis or chemosynthesis.

Question 8

What prosthetic group is tightly bound to the enzyme transketolase?

Accepted Answer

Thiamine pyrophosphate (TPP) is the prosthetic group that is tightly bound to the enzyme transketolase, playing a crucial role in the catalytic process.

Question 9

What pathway ensures that sufficient amounts of CO₂ are available to minimize wasteful photorespiration by transporting CO₂ from the mesophyll cells to the bundle sheath cells?

Accepted Answer

The C4 pathway ensures that sufficient amounts of CO2 are available to minimize wasteful photorespiration by transporting CO2 from the mesophyll cells to the bundle sheath cells.

Question 10

The enzymes that catalyze the dark reactions of photosynthesis are located in the ___________ of the chloroplasts.

Accepted Answer

The answer of The enzymes that catalyze the dark reactions...

Question 11

The first step of the Calvin cycle involves the addition of CO₂ to _______________________ to produce two molecules of 3-phosphoglycerate.

Accepted Answer

The answer of The first step of the Calvin cycle...

Question 12

The enzyme transketolase transfers a ________-carbon fragment from a ketose to an aldose.

Accepted Answer

The answer of The enzyme transketolase transfers a ________-carbon fragment...

Question 13

Which of the following enzymes is involved in both the Calvin cycle and the pentose phosphate pathway?

Accepted Answer

Transaldolase is involved in both the Calvin cycle and the pentose phosphate pathway, playing a key role in the transfer of three-carbon units.

Question 14

What metabolic adaptation is employed by plants living in hot dry climates to prevent water loss and decrease photorespiration?

Accepted Answer

Crassulacean acid metabolism (CAM) is a metabolic adaptation employed by plants living in hot, dry climates to prevent water loss and decrease photorespiration. CAM plants fix CO2 at night, when temperatures are cooler and humidity is higher, reducing water loss. This adaptation allows them to open their stomata at night and close them during the day, which minimizes water loss while still enabling photosynthesis.

Question 15

Which of the following is a readily mobilized sugar that is commonly used to transport carbohydrates through a plant?

Accepted Answer

Sucrose is the sugar most commonly used by plants for transport through the phloem because it is less reactive and more stable than glucose or fructose, making it better suited for long-distance transport.

Question 16

What intermediate is formed in the oxygenase reaction catalyzed by rubisco?

Accepted Answer

Rubisco, the enzyme responsible for carbon fixation in photosynthesis, can also act as an oxygenase, incorporating oxygen into RuBP (ribulose-1,5-bisphosphate). This reaction produces one molecule of 3-phosphoglycerate and one molecule of phosphoglycolate, the latter being the intermediate formed in the oxygenase reaction.

Question 17

What thiol-containing molecule in its reduced state is critical to reducing reactive oxygen species?

Accepted Answer

Glutathione in its reduced state (GSH) plays a crucial role in protecting cells from oxidative stress by reducing reactive oxygen species (ROS) and maintaining other antioxidants in their active forms.

Question 18

The oxidative phase of the pentose phosphate pathway produces __________, which is required for lipid biosynthesis.

Accepted Answer

The answer of The oxidative phase of the pentose phosphate...

Question 19

In photorespiration, the oxidation of glycolate to glyoxylate occurs in the __________ .

Accepted Answer

The answer of In photorespiration, the oxidation of glycolate to...

Question 20

Which of the following types of organisms obtain their energy from chemical fuels produced by other organisms?

Accepted Answer

Heterotrophs obtain their energy from consuming other organisms or organic matter, unlike autotrophs which produce their own food through photosynthesis or chemosynthesis.

Quiz 20: The Calvin Cycle and the Pentose Phosphate Pathway