Question 1

Using structures draw out the reactions of the oxidative phase of the pentose phosphate pathway.

Accepted Answer

The answer of Using structures draw out the reactions of...

Question 2

Which sugar(s) is (are) converted into ribulose 5-phosphate by a single enzymatic step?

Accepted Answer

A)  ribose 5-phosphate 
B)  xylulose 5-phosphate 
C)  erythrose 4-phosphate 
D)  A and B 
E)  B and C 
A)  ribose 5-phosphate 
B)  xylulose 5-phosphate 
C)  erythrose 4-phosphate 
D)  A and B 
E)  B and C

Question 3

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 4

What prosthetic group is tightly bound to the enzyme transketolase?

Accepted Answer

A)  biotin 
B)  tetrahydrofolate 
C)  FAD 
D)  pyridoxal phosphate 
E)  thiamine pyrophosphate 
A)  biotin 
B)  tetrahydrofolate 
C)  FAD 
D)  pyridoxal phosphate 
E)  thiamine pyrophosphate

Question 5

What is the net reaction of the transketolase and transaldolase steps?

Accepted Answer

A)  3C5   2C6 + C3  
B)  2C5   C6 + C4  
C)  3C5   C6 + 3C3  
D)  2C5   2C4 + C2  
E)  None of the answers is correct. 
A)  3C5   2C6 + C3  
B)  2C5   C6 + C4  
C)  3C5   C6 + 3C3  
D)  2C5   2C4 + C2  
E)  None of the answers is correct.

Question 6

Describe the role of thioredoxin in regulating the Calvin cycle.

Accepted Answer

The light reactions of photosynthesis re

Question 7

The C4 pathway is necessary in tropical plants because

Accepted Answer

A)  at high temperatures, the plants cannot maintain sufficient water levels within the cells. 
B)  tropical plants do not have proper day/light cycles to maintain the balance of CO2 necessary for carbohydrate storage. 
C)  at high temperatures, the oxygenase activity of rubisco is high. 
D)  All of the answers are correct. 
E)  None of the answers is correct. 
A)  at high temperatures, the plants cannot maintain sufficient water levels within the cells. 
B)  tropical plants do not have proper day/light cycles to maintain the balance of CO2 necessary for carbohydrate storage. 
C)  at high temperatures, the oxygenase activity of rubisco is high. 
D)  All of the answers are correct. 
E)  None of the answers is correct.

Question 8

The purpose of the pentose phosphate pathway is to

Accepted Answer

A)  generate ATP. 
B)  generate NADPH. 
C)  metabolize 5-carbon sugars. 
D)  A and B. 
E)  B and C. 
A)  generate ATP. 
B)  generate NADPH. 
C)  metabolize 5-carbon sugars. 
D)  A and B. 
E)  B and C.

Question 9

What is photorespiration? Why is it wasteful?

Accepted Answer

Normal photosynthesis produces O₂ and fix

Question 10

Which cofactor supplies the reducing power for reduction of glutathione by glutathione reductase?

Accepted Answer

A)  FMN 
B)  TPP 
C)  FAD 
D)  NADPH 
E)  NADH 
A)  FMN 
B)  TPP 
C)  FAD 
D)  NADPH 
E)  NADH

Question 11

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

Accepted Answer

ribulose 1

Question 12

The KM of glucose-6-phosphate dehydrogenase for NADP+ is _____________ the KM for NAD+.

Accepted Answer

A)  a thousand times greater than 
B)  ten times greater than 
C)  equivalent to 
D)  ten times lower than 
E)  a thousand times lower than 
A)  a thousand times greater than 
B)  ten times greater than 
C)  equivalent to 
D)  ten times lower than 
E)  a thousand times lower than

Question 13

How is the pentose phosphate pathway regulated?

Accepted Answer

The level of NADP⁺ is very important in r

Question 14

How can a deficiency of glucose 6-phosphate confer a physiological advantage?

Accepted Answer

The deficiency appears to be protective

Question 15

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

Question 16

Which of the following tissues have the least active pentose-phosphate pathway?

Accepted Answer

A)  adrenal gland 
B)  liver 
C)  adipose tissue 
D)  ovary 
E)  skeletal muscle 
A)  adrenal gland 
B)  liver 
C)  adipose tissue 
D)  ovary 
E)  skeletal muscle

Question 17

Why is the chemistry of the "dark reactions" referred to as a cycle and not a pathway?

Accepted Answer

The Calvin cycle begins with the additio

Question 18

What is the energy requirement for the formation of hexose from CO2 in terms of ATP equivalents and NADPH?

Accepted Answer

It requires six molecules of CO₂ to make

Question 19

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

Accepted Answer

A)  NADPH 
B)  folate 
C)  vitamin E 
D)  vitamin C 
E)  glutathione 
A)  NADPH 
B)  folate 
C)  vitamin E 
D)  vitamin C 
E)  glutathione

Question 20

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

Accepted Answer

A)  glyoxylate 
B)  hydroxypyruvate 
C)  glycerate 
D)  phosphoglycolate 
E)  malate 
A)  glyoxylate 
B)  hydroxypyruvate 
C)  glycerate 
D)  phosphoglycolate 
E)  malate

Exam 20: The Calvin Cycle and the Pentose Phosphate Pathway

Using structures draw out the reactions of the oxidative phase of the pentose phosphate pathway.

Which sugar(s) is (are) converted into ribulose 5-phosphate by a single enzymatic step?

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

What prosthetic group is tightly bound to the enzyme transketolase?

What is the net reaction of the transketolase and transaldolase steps?

Describe the role of thioredoxin in regulating the Calvin cycle.

The C4 pathway is necessary in tropical plants because

The purpose of the pentose phosphate pathway is to

What is photorespiration? Why is it wasteful?

Which cofactor supplies the reducing power for reduction of glutathione by glutathione reductase?

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

The KM of glucose-6-phosphate dehydrogenase for NADP+ is _____________ the KM for NAD+.

How is the pentose phosphate pathway regulated?

How can a deficiency of glucose 6-phosphate confer a physiological advantage?

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

Which of the following tissues have the least active pentose-phosphate pathway?

Why is the chemistry of the "dark reactions" referred to as a cycle and not a pathway?

What is the energy requirement for the formation of hexose from CO2 in terms of ATP equivalents and NADPH?

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

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

Biochemistry: an Evolving Science

Protein Composition and Structure

Exploring Proteins and Proteomes

DNA, RNA, and the Flow of Genetic Information

Exploring Genes and Genomes

Exploring Evolution and Bioinformatics

Hemoglobin: a Portrait of a Protein in Action

Enzymes: Basic Concepts and Kinetics

Oxidative Phosphorylation

Catalytic Strategies

Regulatory Strategies

Carbohydrates

Lipids and Cell Membranes

Membrane Channels and Pumps

Signal-Transduction Pathways

Metabolism: Basic Concepts and Design

Glycolysis and Gluconeogenesis

The Citric Acid Cycle

The Light Reactions of Photosynthesis

Glycogen Metabolism

Fatty Acid Metabolism

Protein Turnover and Amino Acid Catabolism

The Biosynthesis of Amino Acids

Nucleotide Biosynthesis

Biosynthesis of Membrane Lipids and Steroids

The Integration of Metabolism

DNA Replication, Repair, and Recombination

Rna Synthesis and Processing

Protein Synthesis

The Control of Gene Expression in Prokaryotes

The Control of Gene Expression in Eukaryotes

Sensory Systems

The Immune System

Molecular Motors

Drug Development

Filters

The C₄ pathway is necessary in tropical plants because

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

The K_M of glucose-6-phosphate dehydrogenase for NADP⁺ is _____________ the K_M for NAD⁺.

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

What is the energy requirement for the formation of hexose from CO₂ in terms of ATP equivalents and NADPH?