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NDM Midsemester Exam 2004

1

Which one of the following statements relating to studies of Basal Metabolic Rate (BMR) in humans is CORRECT?


  The BMR typically varies by 40% a day depending on levels of activity.

  The BMR of a person with Body Mass Index (BMI) = 25 would typically be higher than that of a person with BMI = 20.

  The proportion of BMR attributable to the brain is around 20%.

  The proportion of BMR attributable to adipose tissue is gender dependent, but typically in the range 15 -30%.

  The BMR is routinely measured during sleep.

2

Choose the most CORRECT completion. A scientifically justifiable level of protein intake, appropriate to the adult Australian diet, to avoid complications of under and over consumption is:


  0.5 grams per kg

  1 gram per kg

  2.5 grams per kg

  5 grams per kg

  10 grams per kg

3

Which one of the following statements describing reactions of glycolysis is CORRECT?


  Fructose-1,6-bisphosphate is an aldol and is the substrate for the enzyme aldolase.

  Fructose-1,6-bisphosphate is hydrolytically cleaved to dihydroxyacetone phosphate and glyceraldehyde-3-phosphate.

  The interconversion of dihydroxyacetone phosphate and glyceraldehyde-3-phosphate, has a standard free energy close to zero and an equilibrium constant close to one.

  The interconversion of dihydroxyacetone phosphate and glyceraldehyde-3-phosphate is catalysed by glycerophosphate mutase.

  If glycolysis was inhibited at the production of glyceraldehyde-3-phosphate then no net ATP would be consumed or produced per mole of glucose converted to glyceraldehyde-3- phosphate.

4

Which one of the following statements describing events in oxidative phosphorylation is CORRECT?


  All electrons that pass through complex II originate from NADH.

  All electrons that pass through complex III have passed through cytochrome-c.

  The terminal respiratory complex (complex IV) does not pump protons across the inner mitochondrial membrane.

  No ATP is made as electrons flow through complexes I to IV.

  Ubiquinone and cytochrome-c are mobile electron carriers that transfer two electrons at a time between complexes of the respiratory chain.

5

Which one of the following alternative products from the transamination (amino transferase) reaction involving pyruvate as a substrate is CORRECT?


  The amino acid aspartate.

  The amino acid alanine

  The oxoacid oxaloacetate

  Lactate under anaerobic conditions

  Acetyl-CoA in mitochondria.

6

Which one of the following statements about waste nitrogen in animals is CORRECT?


  Ammonium ion is highly toxic and humans have no pathways leading to its production.

  Uric acid is produced selectively by animals with ready access to water e.g. fish.

  Urea can be produced without further energy (ATP) being needed after nitrogens have been incorporated into arginine in the urea cycle.

  Carbamoyl phosphate synthase uses glutamine as a substrate to produce carbamoyl phosphate, in a reaction needing 2ATP per mole of product.

  Ammonia can be secreted from human intestinal cells to neutralise stomach acid and remove waste nitrogen via faeces.

7

Select the one CORRECT completion to the following statement. The conversion of glucose-6- phosphate to ribose-5-phosphate in the pentose phosphate pathway is:


  The first phase called the non-oxidative phase.

  A sequence involving CO2 production.

  A sequence involving NADH production.

  A sequence involving ATP production.

  An oxidative process involving the incorporation of molecular oxygen.

8

Which one of the following statements with respect to ketone bodies is NOT CORRECT?


  Ketone bodies are not strictly bodies, but freely soluble molecules.

  Ketone bodies are produced in liver mitochondria under hormonal conditions of sustained fasting.

  Ketone bodies may reach high levels in uncontrolled insulin-dependent diabetics.

  Ketone bodies produce a metabolic alkalosis.

  The compound abbreviated HMG-CoA is an intermediate in ketone body synthesis.

9

Which one of the following statements, with respect to the properties and actions of the F1Fo complex of mitochondrial membranes, is NOT CORRECT?


  The F1Fo complex is an ATPase when isolated experimentally.

  ATP binds strongly to α−β subunits and requires approximately 30kJ of energy to drive the release of ATP.

  The subunits that rotate during ATP synthesis include the γ-subunit.

  The Fo complex is located within the mitochondrial membrane and the F1 complex is external.

  When working optimally, one complete rotation of the moving core of the complex can produce one ATP.

10

Which of the following statements, regarding the role of skeletal muscle protein in metabolism in non-fed states, is NOT CORRECT?


  Skeletal muscle protein is the main source of amino acids for gluconeogenesis.

  Amino groups from the breakdown of muscle protein are carried in the blood as alanine or other amino acids to the liver for excretion as urea.

  Protein from muscle replaces fat as the major supplier of energy after approximately seven days of starvation.

  The use of protein as energy represents a loss of functional protein to the body.

  Protein catabolism in muscle is stimulated by elevated glucagon levels.

11

Regarding changes in metabolism as a result of starvation, which one of the following statements is CORRECT?


  The conservation of glycogen stores in muscle and liver is a high priority.

  In the late stages of starvation, ketone bodies provide about 30% of the energy required by the brain.

  Net breakdown of skeletal muscle protein is replaced by net protein synthesis.

  Metabolic responses to a state of starvation are mostly complete after one day of starvation.

  The rate of degradation of skeletal muscle protein is lower at late stages of starvation than in the early stages.

12

Which of the following statements, regarding metabolic changes accompanying stresses such as injury, burns, surgery and infections, is NOT CORRECT?


  Negative nitrogen balance in injured or infected patients is mediated by cytokines produced by monocytes and lymphocytes.

  Conditions that lead to a lack of muscle contraction cause a net loss of skeletal muscle through increased degradation of protein.

  The stresses (burns, surgery and infections) are associated with insulin resistance.

  The cytokine TNF-alpha has several metabolic effects, including the inhibition of lipolysis in adipose tissue.

  The stresses (burns, surgery and infections) cause muscle protein synthesis to decrease and muscle protein degradation to increase

13

Which of the following statements about glucose transporters (GLUTs) is NOT CORRECT?


  A common feature of GLUT structure is the presence of 12 transmembrane domains.

  Glucose is taken up by hepatocytes only when blood glucose levels are elevated because GLUT2 has a high Km.

  Insulin causes an increase in the number of GLUT4 molecules at the plasma membrane of skeletal muscle cells.

  The rate of glucose transport by GLUT3 is directly proportional to circulating glucose concentration within the normal physiological range.

  GLUT 1 is one of the transporters that carries glucose across the blood brain barrier.

14

Which of the following statements, regarding the properties of plasma lipoproteins, is CORRECT?


  On a percentage weight basis, LDL contains more cholesteryl ester than HDL.

  The core of chylomicrons contains approximately equal amounts of triacylglycerols and cholesteryl esters.

  Newly formed, or nascent, HDL consists mainly of apoA-I and lecithin-cholesterol acyltransferase (LCAT).

  The level of plasma LDL is regulated by the total concentration of free plus esterified cholesterol in plasma.

  Apolipoprotein C-II present on the surface of VLDL and chylomicrons causes inhibition of lipoprotein lipase activity.

15

Which of the following does NOT stimulate feeding behaviour?


  Neuropeptide Y (NPY).

  Melanocyte Stimulating Hormone (MSH).

  Agouti Related Peptide (AGRP).

  Orexin.

  Melanin Concentrating Hormone (MCH).

16

Which of the following is NOT a feature of the metabolic syndrome?


  Obesity.

  Insulin resistance.

  Proteinuria.

  Hypertension.

  Dyslipidaemia.

17

Which of the following statements, regarding arachidonic acid metabolites, is NOT CORRECT?


  Thromboxane is a vasoconstrictor synthesised in platelets.

  Prostaglandin E2 synthesis in the hypothalamus causes an increase in body temperature.

  Impaired perfusion of the kidney increases synthesis of prostacyclin (PGI2) and PGE2 in the renal vasculature.

  Leukotriene C4 is a potent bronchoconstrictor.

  Leukotriene C4, D4 and E4 are inactive metabolites of leukotriene B4.

18

Which of the following, with regard to the evidence for type 1 diabetes mellitus (DM) as an autoimmune disease, is NOT CORRECT?


  Type 1 DM clusters with other forms of auto-immune disease such as thyroiditis and adrenalitis.

  A possible cause of the insulitis associated with type 1 DM is a shared amino acid sequence between glutamic acid decarboxylase (GAD) and Coxsackie B virus.

  Abnormal expression of type 2 HLA antigens may occur on beta cells.

  The insulitis associated with type 1 DM involves infiltration of the islets by neutrophils.

  Induction of T-cell anergy in animals has provided a model of type 1 DM.

19

In radiological imaging of the abdomen which of the following is CORRECT?


  Magnetic resonance can be used in patients with cardiac pacemakers because it does not use ionizing radiation.

  Intravascular contrast agents contain calcium atoms to increase absorption of X-rays.

  Ultrasound relies on absorption of the ultrasound beam to generate images.

  Radioisotope scanning relies on detection of electromagnetic radiation using a gamma camera.

  The Doppler effect is used to measure the density of tissue.

20

Which one of the following statements, regarding a penetrating injury through the midline at the umbilicus, is NOT CORRECT?


  A penetrating injury through the midline at the umbilicus endangers the jejunum.

  A penetrating injury through the midline at the umbilicus endangers the ileum.

  A penetrating injury through the midline at the umbilicus endangers the caecum.

  A penetrating injury through the midline at the umbilicus endangers the transverse colon.

  A penetrating injury through the midline at the umbilicus endangers the abdominal aorta.

21

Which one of the following statements, regarding the portal vein, is NOT CORRECT?


  The portal vein drains blood from the hindgut.

  The portal vein drains blood from the spleen.

  The portal vein drains blood from the lower end of the oesophagus.

  The portal vein drains blood from the vermiform appendix.

  The portal vein drains blood from the right kidney.

22

Which of the following statements relating to acid secretion by the gastric gland is (are) CORRECT? A) Acid is secreted by the peptic cell. B) Acid secretion is increased by protein digestion products in the duodenum. C) The effect on acid secretion of histamine and gastrin is additive. D) Acid secretion is increased by protein digestion products in the antrum.


  If only A, B and C are correct.

  If only A and C are correct.

  If only B and D are correct.

  If only D is correct.

  If all are correct.

23

Which of the following statements relating to peptic ulceration is (are) CORRECT? A) Histamine increases acid secretion by a direct effect on the peptic cell. B) Aspiration of gastric juice will lead to a metabolic acidosis. C) Most peptic ulcers can be cured by antacid therapy. D) Aspiration of gastric juice will lead to hypokalaemia.


  If only A, B and C are correct.

  If only A and C are correct.

  If only B and D are correct.

  If only D is correct.

  If all are correct.