Board Like Questions 1998 Dennis Livingston

1. Large amounts of ethanol completely overcome the inhibition by ethylene glycol on the enzyme alcohol dehydrogenase. This is most likely an example of:

a. allosteric regulation.

b. competitive inhibition.

c. suicide inhibition.

d. noncompetive inhibition.

e. transcriptional control.

2. Serum from the two parents of a child with Tay-Sachs disease (deficiency of Gm2 gangliosidase) is tested and each is found to have half the activity of normal person. To make this test:

a. the amount of the enzymes substrate should be considerably above the Km value.

b. the enzyme should be given a substrate concentration equal to the Km concentration.

c. there is no need to measure the protein concentration in the serum.

d. the enzyme should be allowed to catalyze the reaction until all the substrate is gone.

e. the enzyme must be tested at more than one pH value.

3. A diabetic patient hyperventilates to compensate for the acidosis caused by high levels of serum ketone bodies. Hyperventillation results in:

a. a higher partial CO2 pressure and a higher concentration of bicarbonate.

b. a lower partial CO2 pressure but a higher concentration of bicarbonate.

c. a higher partial CO2 pressure but a lower concentration of bicarbonate.

d. a lower partial CO2 pressure and a lower concentration of bicarbonate.

e. no change in either the partial CO2 pressure or in the bicarbonate concentration.

4. A patient is discovered to have cystathionuria. To cure this condition, which of the following vitamins should be given.

a. niacin

b. riboflavin

c. biotin

d. pyridoxine (B6)

e. folate

5. Pantothenate is a common supplement to food products. This vitamin is important for:

a. the conversion of glucose to pyruvate.

b. the conversion of lactate to glucose.

c. the conversion of glucose to ribose.

d. the conversion of glucose to palmitate.

e. the conversion of glucose to glycogen.

6. Exercising muscle produces lactic acid. This enhances oxygen release by hemoglobin because:

a. muscle cannot carry out anerobic glycolysis.

b. lactic acid is an allosteric regulator of hemoglobin.

c. oxygen binds less tightly to hemoglobin at lower pH.

d. bisphosphglycerate enhances oxygen binding.

e. the iron becomes oxidized.

7. A 3 month old child is brought in with a broken arm. After ruling out the likelihood of abuse, you begin to suspect a defect in:

a. the beta globin gene.

b. the actin gene.

c. the tubulin gene.

d. the calcitonin gene.

e. a collagen gene.

8. One copy of a beta globin gene from a thalassemic patient is subjected to DNA sequencing, and the entire primary sequence is found to be intact. A possible mutation is:

a. a frameshift mutation.

b. a deletion mutation.

c. a nonsense mutation.

d. a missense mutation.

e. a promoter mutation.

9. Alcoholics have a high serum concentrations of lactate because they:

a. cannot metabolize alcohol.

b. convert alcohol into lactate.

c. cannot convert lactate into pyruvate.

d. cannot convert alcohol into fatty acids.

e. convert alcohol into glucose.

10. The reason type 1 diabetics have high levels of serum chylomicrons is because insulin is needed to:

a. induce high levels of hormone sensitive lipase.

b. induce high levels of LDL receptors.

c. induce high levels apoCII.

d. induce high levels of lipoprotein lipase.

e. induce high levels of HDL.

11. After an overnight fast:

a. large amounts of ketone bodies circulate in the serum.

b. glucagon levels are relatively high.

c. serum glucose falls below 3 mM (54 mg/dl).

d. the liver is storing glycogen.

e. protein kinase A (cyclic A dependent protein kinase) is relatively inactive.

12. The insulin receptor:

a. phosphorylates proteins on serine and tyrosine residues.

b. makes seven passes throught the membrane.

c. is associated with a heterotrimeric G-protein.

d. is composed of two alpha and two beta chains.

e. binds to DNA.

13. Which of the following genes is induced under gluconeogenic conditions in the liver? The gene enoding:

a. phophoenolpyruvate carboxykinase

b. phosphofructokinase 1

c. glycogen synthase

d. pyruvate kinase

e. thiolase

14. Nitric oxide (NO) relaxes smooth muscle. Like hormones:

a. it binds to a membrane receptor.

b. it is made by an endocrine organ.

c. it is made from tyrosine.

d. it has a long half-life.

e. the target cells amplify its signal.

15. The ammonia used to make carbamoyl-phosphate for urea synthesis is mostly supplied by:

a. transamination of pyruvate by glutamate.

b. the action of glutamate dehydrogenase on glutamate.

c. glutamine synthetase acting on glutamate.

d. the action of arginase on arginine.

e. spontaneous deamination of cytosine.