Middle Tennessee State University - NFS 2220

Metabolism

Multiple Choice Questions

1)A typical cell contains "powerhouses," which is another name for            .

1. 1. DNA
   2. ribosomes
   3. mitochondria
   4. electron transport chains
   5. RNA

2. The site of lipid synthesis in the cell is the   .
   1. nucleus
   2. Golgi bodies
   3. mitochondria
   4. smooth endoplasmic reticulum
   5. exoplasm

3. Which reaction is characterized as anabolic?
   1. Pyruvate synthesis from glucose
   2. Acetyl CoA synthesis from cholesterol
   3. Carbon dioxide synthesis from citric acid
   4. Cholesterol synthesis from acetyl CoA molecules
   5. Hydrolysis of glycogen to glucose

4. Which statement defines a coenzyme?
   1. A unit consisting of an enzyme bound to reactants plus ATP
   2. An organic molecule required for the functioning of an enzyme
   3. The small, active part of an enzyme that binds to the organic reactants
   4. An inactive enzyme that becomes functional upon contact with specific cofactors
   5. An enzyme precursor

5. Glycolysis is the conversion of      .
   1. glycogen to fat
   2. glycogen to protein
   3. glucose to pyruvate
   4. glucose to glycogen
   5. glycogen to glucose

6. Which statement describes lactate production by muscle cells?
   1. It occurs only during intense exercise.
   2. When rapid, it causes muscle fatigue.
   3. It produces lactate that may eventually be used by the liver for glucose production.
   4. It lowers the pH of the muscle cell, thereby lowering muscle performance.
   5. It is an aerobic process.

7. What is a possible fate of acetyl CoA?
   1. Degradation to urea
   2. Synthesis to glycerol
   3. Synthesis to fatty acids
   4. Degradation to ammonia
   5. Storage in lipids

8. Fatty acid oxidation results in the direct production of .
   1. ketones
   2. Fructose
   3. pyruvate
   4. acetyl CoA
   5. Lactate

9. When energy-yielding nutrients are consumed in excess, which one(s) can lead to storage of fat?
   1. Fat only
   2. Carbohydrate only
   3. Fat and carbohydrate only
   4. Fat, carbohydrate, and protein
   5. Protein and fat only

10. If the carbohydrate content of the diet is insufficient to meet the body's needs for glucose, what can be converted to glucose?
    1. Fatty acids
    2. Acetyl CoA
    3. Amino acids
    4. Carbon dioxide
    5. Urea

11. When protein consumption is in excess of body needs and energy needs are met, the excess amino acids are metabolized and the energy in the molecules is    .
    1. stored as fat only
    2. excreted in the feces
    3. stored as amino acids only
    4. stored as glycogen and fat
    5. excreted in the urine

12. Which of the following is a feature of the electron transport chain?
    1. It captures energy in the high-energy bonds of ATP.
    2. It pumps carbon dioxide across the mitochondrial membrane.
    3. It is composed of a series of coenzymes that transfer electrons up a concentration gradient.
    4. It combines oxygen from carbon dioxide with hydrogen generated from the splitting of water.
    5. It facilitates the transport of sodium and calcium.

13. Which of the following can be synthesized from all three energy-yielding nutrients?
    1. Lactate
    2. Glycogen
    3. Acetyl CoA
    4. Oxaloacetate
    5. Glucose

14. What is the most likely explanation for the body's higher metabolic efficiency of converting a molecule of corn oil into stored fat compared with a molecule of sucrose?
    1. The enzymes specific for metabolizing absorbed fat have been found to have higher activities than those metabolizing sucrose.
    2. The absorbed corn oil is transported to fat cells at a faster rate than the absorbed sucrose, thereby favoring the uptake of corn oil fat.
    3. There are fewer metabolic reactions for disassembling the corn oil and re-assembling the parts into a triglyceride for uptake by the fat cells.
    4. Because corn oil has a greater energy content than sucrose, conversion of these nutrients into stored fat requires a smaller percentage of the energy from the corn oil.
    5. The metabolic reactions for disassembling the corn oil and re-assembling the parts into a triglyceride for uptake by the fat cells require less energy themselves.

15. How does excess carbohydrate intake contribute to obesity?
    1. It is efficiently converted to storage fat.
    2. It spares oxidation of body fat and dietary fat.
    3. It stimulates glucagon release, resulting in inhibition of fatty acid oxidation.
    4. It stimulates pancreatic lipase secretion, which results in higher dietary fat absorption.
    5. It results in large amounts of glycogen storage that is increased as carbohydrate consumption increases.

16. Of the total amount of glucose energy consumed by the body, approximately what percentage is used by the brain and nerve cells?

a.   10%

b.   30%

c.   50%

d.   70%

e.   90%

17. During the first few days of a fast, what energy source provides about 90% of the glucose needed to fuel the body?
    1. Protein
    2. Ketones
    3. Glycogen
    4. Triglycerides
    5. Glycerol

18. Which dietary nutrient would most rapidly reverse a state of ketosis in a starving person?
    1. Nonessential fatty acids
    2. Protein
    3. Amino acids
    4. Carbohydrate
    5. Essential fatty acids

19. How soon would death occur from starvation if the body was unable to shift to a state of ketosis?
    1. 3 to 5 days
    2. 7 to 10 days
    3. within 3 weeks
    4. 4 to 6 weeks
    5. 6 to 12 weeks