Ch. 14

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Quiz by super_birdie, updated more than 1 year ago
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Created by super_birdie over 6 years ago
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Description

Quiz on Ch. 14, created by super_birdie on 08/21/2014.

Resource summary

Question 1

Question
Glycolysis is the name given to a metabolic pathway occurring in many different cell types. It consists of 11 enzymatic steps that convert glucose to lactic acid. Glycolysis is an example of:
Answer
  • aerobic metabolism.
  • anabolic metabolism.
  • a net reductive process.
  • fermentation.
  • oxidative phosphorylation

Question 2

Question
The anaerobic conversion of 1 mol of glucose to 2 mol of lactate by fermentation is accompanied by a net gain of:
Answer
  • 1 mol of ATP.
  • 1 mol of NADH.
  • 2 mol of ATP.
  • 2 mol of NADH.
  • none of the above.

Question 3

Question
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:
Answer
  • A) dihydroxyacetone phosphate → glycerol 3-phosphate B) glucose 6-phosphate → fructose 6-phosphate C) isocitrate → α-ketoglutarate D) oxaloacetate → malate E) pyruvate → lactate
  • dihydroxyacetone phosphate → glycerol 3-phosphate
  • glucose 6-phosphate → fructose 6-phosphate
  • isocitrate → α-ketoglutarate
  • oxaloacetate → malate
  • pyruvate → lactate

Question 4

Question
If glucose labeled with 14C in C-1 were fed to yeast carrying out the ethanol fermentation, where would the 14C label be in the products?
Answer
  • In C-1 of ethanol and CO2
  • In C-1 of ethanol only
  • In C-2 (methyl group) of ethanol only
  • In C-2 of ethanol and CO2
  • In CO2 only

Question 5

Question
The conversion of 1 mol of fructose 1,6-bisphosphate to 2 mol of pyruvate by the glycolytic pathway results in a net formation of:
Answer
  • 1 mol of NAD+ and 2 mol of ATP.
  • 1 mol of NADH and 1 mol of ATP.
  • 2 mol of NAD+ and 4 mol of ATP.
  • 2 mol of NADH and 2 mol of ATP.
  • 2 mol of NADH and 4 mol of ATP.

Question 6

Question
In an anaerobic muscle preparation, lactate formed from glucose labeled in C-3 and C-4 would be labeled in:
Answer
  • all three carbon atoms.
  • only the carbon atom carrying the OH.
  • only the carboxyl carbon atom.
  • only the methyl carbon atom.
  • the methyl and carboxyl carbon atoms.

Question 7

Question
Which of the following statements is not true concerning glycolysis in anaerobic muscle?
Answer
  • Fructose 1,6-bisphosphatase is one of the enzymes of the pathway.
  • It is an endergonic process.
  • It results in net synthesis of ATP.
  • It results in synthesis of NADH.
  • Its rate is slowed by a high [ATP]/[ADP] ratio.

Question 8

Question
When a muscle is stimulated to contract aerobically, less lactic acid is formed than when it contracts anaerobically because:
Answer
  • glycolysis does not occur to significant extent under aerobic conditions.
  • muscle is metabolically less active under aerobic than anaerobic conditions.
  • the lactic acid generated is rapidly incorporated into lipids under aerobic conditions.
  • under aerobic conditions in muscle, the major energy-yielding pathway is the pentose phosphate pathway, which does not produce lactate.
  • under aerobic conditions most of the pyruvate generated as a result of glycolysis is oxidized by the citric acid cycle rather than reduced to lactate.

Question 9

Question
Glycolysis in the erythrocyte produces pyruvate that is further metabolized to:
Answer
  • CO2.
  • ethanol.
  • glucose.
  • hemoglobin.
  • lactate.

Question 10

Question
When a mixture of glucose 6-phosphate and fructose 6-phosphate is incubated with the enzyme phosphohexose isomerase, the final mixture contains twice as much glucose 6-phosphate as fructose 6-phosphate. Which one of the following statements is most nearly correct, when applied to the reaction below (R = 8.315 J/mol·K and T = 298 K)? Glucose 6-phosphate ↔ fructose 6-phosphate
Answer
  • ΔG'° is +1.7 kJ/mol.
  • ΔG'° is –1.7 kJ/mol.
  • ΔG'° is incalculably large and negative.
  • ΔG'° is incalculably large and positive.
  • ΔG'° is zero.

Question 11

Question
In glycolysis, fructose 1,6-bisphosphate is converted to two products with a standard free-energy change (ΔG'°) of 23.8 kJ/mol. Under what conditions (encountered in a normal cell) will the free-energy change (ΔG) be negative, enabling the reaction to proceed to the right?
Answer
  • If the concentrations of the two products are high relative to that of fructose 1,6-bisphosphate.
  • The reaction will not go to the right spontaneously under any conditions because the ΔG'° is positive.
  • Under standard conditions, enough energy is released to drive the reaction to the right.
  • When there is a high concentration of fructose 1,6-bisphosphate relative to the concentration of products.
  • When there is a high concentration of products relative to the concentration of fructose 1,6-bisphosphate.

Question 12

Question
Glucose labeled with 14C in C-1 and C-6 gives rise in glycolysis to pyruvate labeled in:
Answer
  • A and C.
  • all three carbons.
  • its carbonyl carbon.
  • its carboxyl carbon.
  • its methyl carbon.

Question 13

Question
If glucose labeled with 14C at C-1 (the aldehyde carbon) were metabolized in the liver, the first radioactive pyruvate formed would be labeled in:
Answer
  • all three carbons.
  • both A and C.
  • its carbonyl carbon.
  • its carboxyl carbon.
  • its methyl carbon.

Question 14

Question
In an anaerobic muscle preparation, lactate formed from glucose labeled in C-2 would be labeled in:
Answer
  • all three carbon atoms.
  • only the carbon atom carrying the OH.
  • only the carboxyl carbon atom.
  • only the methyl carbon atom.
  • the methyl and carboxyl carbon atoms.

Question 15

Question
If glucose labeled with 14C in C-3 is metabolized to lactate via fermentation, the lactate will contain 14C in:
Answer
  • all three carbon atoms.
  • only the carbon atom carrying the OH.
  • only the carboxyl carbon atom.
  • only the methyl carbon atom.
  • the methyl and carboxyl carbon atoms.

Question 16

Question
Which of these cofactors participates directly in most of the oxidation-reduction reactions in the fermentation of glucose to lactate?
Answer
  • ADP
  • ATP
  • FAD/FADH2
  • Glyceraldehyde 3-phosphate
  • NAD+/NADH

Question 17

Question
In comparison with the resting state, actively contracting human muscle tissue has a:
Answer
  • higher concentration of ATP.
  • higher rate of lactate formation.
  • lower consumption of glucose.
  • lower rate of consumption of oxygen
  • lower ratio of NADH to NAD+.

Question 18

Question
The steps of glycolysis between glyceraldehyde 3-phosphate and 3-phosphoglycerate involve all of the following except:
Answer
  • ATP synthesis.
  • catalysis by phosphoglycerate kinase.
  • oxidation of NADH to NAD+.
  • the formation of 1,3-bisphosphoglycerate.
  • utilization of Pi.

Question 19

Question
The first reaction in glycolysis that results in the formation of an energy-rich compound (i.e., a compound whose hydrolysis has a highly negative ΔG'°) is catalyzed by:
Answer
  • glyceraldehyde 3-phosphate dehydrogenase.
  • hexokinase.
  • phosphofructokinase-1.
  • phosphoglycerate kinase.
  • triose phosphate isomerase.

Question 20

Question
Which of the following is a cofactor in the reaction catalyzed by glyceraldehyde 3-phosphate dehydrogenase?
Answer
  • ATP
  • Cu2+
  • heme
  • NAD+
  • NADP+

Question 21

Question
In the phosphoglycerate mutase reaction, the side chain of which amino acid in the enzyme is transiently phosphorylated as part of the reaction?
Answer
  • serine
  • threonine
  • tyrosine
  • histidine
  • arginine

Question 22

Question
Inorganic fluoride inhibits enolase. In an anaerobic system that is metabolizing glucose as a substrate, which of the following compounds would you expect to increase in concentration following the addition of fluoride?
Answer
  • 2-phosphoglycerate
  • Glucose
  • Glyoxylate
  • Phosphoenolpyruvate
  • Pyruvate

Question 23

Question
Glycogen is converted to monosaccharide units by:
Answer
  • glucokinase.
  • glucose-6-phosphatase
  • glycogen phosphorylase.
  • glycogen synthase.
  • glycogenase.
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