Question 1

Which compound(s) is/are a high-energy intermediate(s) in glycolysis?

Accepted Answer

A)  fructose 1,6-bisphosphate 
B)  NADH 
C)  1,3-bisphosphoglycerate and phosphoenol pyruvate 
D)  fructose 1,6-bisphosphate, 1,3-bisphosphoglycerate, and phosphoenol pyruvate 
E)  NADH, 1,3-bisphosphoglycerate, and phosphoenol pyruvate

Question 2

The ultimate electron acceptor in the fermentation of glucose to ethanol is:

Accepted Answer

A)  acetaldehyde. 
B)  acetate. 
C)  ethanol. 
D)  NAD+. 
E)  pyruvate.

Question 3

When glucose is oxidized via glycolysis, the carbon atom that bears the phosphate in the 3-phosphoglycerate formed may have originally been either C-1 or C-6 of the original glucose. Describe this pathway in just enough detail to explain this fact.

Accepted Answer

The answer of When glucose is oxidized via glycolysis, the...

Question 4

Which statement does NOT describe a general function of the pentose phosphate pathway?

Accepted Answer

A)  The pentose phosphate pathway is used to produce NADPH for reductive biosynthesis in adipocytes. 
B)  The pentose phosphate pathway is used to facilitate the elimination of dangerous peroxides in erythrocytes. 
C)  The pentose phosphate pathway allows for the entry of dietary pentose intermediates into the glycolytic pathway. 
D)  The pentose phosphate pathway allows for the conversion of hexoses into pentoses that may be used as precursors in the synthesis of nucleosides. 
E)  The pentose phosphate pathway produces reduced molecules whose electrons may be shuttled to the mitochondria for oxidative phosphorylation.

Question 5

In humans, the Cori cycle shifts part of the metabolic burden of active muscle to the liver. Which two metabolic pathways are involved in this cycle?

Accepted Answer

A)  glycolysis and gluconeogenesis 
B)  pentose phosphate pathway and gluconeogenesis 
C)  glycolysis and the pentose phosphate pathway 
D)  gluconeogenesis and the Calvin cycle 
E)  None of the answers is correct.

Question 6

In some tissues, an increase in insulin will substantially increase the glucose transporters in the cell membrane and the transport of glucose into cells. Which tissues react in this manner?

Accepted Answer

A)  red blood cells and the brain 
B)  the brain and the liver 
C)  the liver and muscle 
D)  muscle and adipose tissue 
E)  adipose tissue and red blood cells

Question 7

During strenuous exercise, the NADH formed in the glyceraldehyde 3-phosphate dehydrogenase reaction in skeletal muscle must be reoxidized to NAD+ if glycolysis is to continue. The most important reaction involved in the reoxidation of NADH is:

Accepted Answer

A)  dihydroxyacetone phosphate $\rightarrow$  glycerol 3-phosphate. 
B)  glucose 6-phosphate $\rightarrow$  fructose 6-phosphate. 
C)  isocitrate $\rightarrow$ $\alpha$-ketoglutarate. 
D)  oxaloacetate $\rightarrow$  malate. 
E)  pyruvate $\rightarrow$  lactate.

Question 8

Which reaction does NOT convert gluconeogenic precursors to the next step in gluconeogenesis?

Accepted Answer

A)  Glycerol is converted to dihydroxyacetone phosphate using the enzymes glycerol kinase and glycerol-3-phosphate dehydrogenase. 
B)  Lactate is converted to alanine using lactate dehydrogenase. 
C)  Alanine is converted to pyruvate using alanine aminotransferase. 
D)  Glutamate is converted to $\alpha$-ketoglutarate using either glutamate dehydrogenase or an aminotransferase. 
E)  Pyruvate is carboxylated using bicarbonate and pyruvate carboxylase.

Question 9

Which reaction in glycolysis utilizes a covalent enzyme intermediate?

Accepted Answer

A)  phosphofructokinase-1 
B)  glyceraldehyde-3-phosphate dehydrogenase 
C)  phosphohexose isomerase 
D)  enolase 
E)  triose phosphate isomerase

Question 10

Which statement about the pentose phosphate pathway is INCORRECT?

Accepted Answer

A)  It generates CO2 from C-1 of glucose. 
B)  It involves the conversion of an aldohexose to an aldopentose. 
C)  It is prominant in lactating mammary gland. 
D)  It is principally directed toward the generation of NADPH. 
E)  It requires the participation of molecular oxygen.

Question 11

In the Cori Cycle, actively contracting muscle cells convert pyruvate to lactate. The lactate is transported in the blood to the liver, where it is "recycled" by gluconeogenesis to glucose, which is transported back to the muscle for additional ATP production. Why do active muscle cells simply not export pyruvate, which can also be converted in the liver to glucose?

Accepted Answer

The answer of In the Cori Cycle, actively contracting muscle...

Question 12

Which compound CANNOT serve as the starting material for the synthesis of glucose via gluconeogenesis?

Accepted Answer

A)  acetate 
B)  glycerol 
C)  lactate 
D)  oxaloacetate 
E)  $\alpha$-ketoglutarate

Exam 14: Glycolysis, Gluconeogenesis, and the Pentose Phosphate Pathway