NDM Midsemester Exam 2007

1

Select the one statement below that is CORRECT with respect to nutrition.


  Fat cells can shrink during sustained dieting, but the number of fat cells remains the same.

  Leptin is considered a major hormone in signalling the stable weight that most adults maintain.

  The Atkins diet is generally considered to be the most effective and scientifically supported of the popular diet programs.

  An obese person has higher basal metabolic rate relative to a non-obese person of the same weight.

  Male obesity featuring central adiposity is less of a risk to health than the lower adiposity generally exhibited by women.

2

Select the one statement below that is INCORRECT with respect to nutrition.


  Our hominid ancestors ate a mixed diet that is also generally considered to be a good diet for modern man.

  The food guide pyramid of 1992 was flawed and was replaced with 'My Pyramid' in 2005.

  Fibre has been highly regarded by nutritionists for 50 years, but is unlikely to have the cancer-protective role assigned to it by Burkitt and Trowel in the 1970s.

  Glycogen is our premium reserve fuel, central to surviving times of sustained starvation.

  Low glycaemic index diets avoid the high peak-glucose levels that can lead to insulin resistance.

3

Select the one statement below that is CORRECT with respect to nutrition.


  High dietary fibre slows gut transit times.

  The glucose tolerance test involves a pin-prick skin test that indicates an allergic reaction in susceptible subjects.

  High fibre diets tend to be high glycaemic index diets.

  Whole grain and white breads are close to equivalent in their nutritional value.

  Cellulose is a major contributor to dietary fibre.

4

Select the one statement below that is CORRECT with respect to nutrition.


  Macronutrients are organic compounds, not made by the body, that support essential biochemical functions.

  The water soluble vitamins include thiamin, riboflavin, niacin and vitamin B12.

  The fat soluble vitamins are C, D, E and K.

  The two minerals most relevant to health in Australia are magnesium and calcium.

  Folate is known to be a generally effective treatment for Wernicke's Encephalopathy.

5

Select the one statement below that is CORRECT with respect to nutrition.


  Vitamin D is destroyed when skin is exposed to high levels of sunlight.

  Vitamin E is also known as ?-tocopherol.

  Fat soluble vitamins are contained in dietary fat and deficiencies can result from either dietary lack or poor uptake of fats.

  Fat soluble vitamins are stored in the body for short periods of time relative to water soluble vitamins.

  Vitamin A has low toxicity so that large doses are well tolerated.

6

The immediate precursor of 3-phosphoglycerate in the glycolytic pathway is:


  2-phosphoglycerate.

  Dihydroxyacetone phosphate.

  Phosphoenolpyruvate.

  3-phosphoglyceraldehyde.

  1,3-bisphosphoglycerate.

7

Select the one CORRECT statement about metabolism.


  The pyruvate dehydrogenase complex is always active so entry of substrate to the Krebs Cycle is regulated by entry of pyruvate into mitochondria.

  Pyruvate is a precursor for gluconeogenesis in the fasting state.

  Ignoring charges, a reasonable summary of the Krebs Cycle that balances the input and output molecules is: pyruvate + 3NAD+ + FAD +3H2O ? 2CO2 + 3NADH + FADH2 + 3H+.

  The pyruvate dehydrogenase complex requires 5 different coenzymes (all vitamins): CoA, NAD+, FAD, biotin and pyridoxal phosphate.

  Succinate and acetyl-CoA condense to form citrate in the first reaction of the Krebs Cycle.

8

Select the one CORRECT statement about metabolism.


  Fatty acid synthesis can proceed from glucose, alcohol or amino acids by way of acetyl-CoA generated in mitochondria.

  Î²-oxidation is a repeated cycle in which the two carbons at a time are removed as acetate (CH3COO-)

  Metabolic water, essential to desert dwelling creatures and hibernating bears, is produced only by fat oxidation because there is no net gain of water when carbohydrate is oxidised.

  Ketone bodies are microscopic vesicles in plasma constituted of a mixture of acetoacetate, ß-hydroxybutyrate and acetone.

  When ketones are made by liver, fats are broken down to acetyl-CoA in the cytosol where the ketone synthesis pathway is located.

9

Select the one CORRECT summary of an event that occurs at respiratory complex I in the inner mitochondrial membrane (ignore chemical balance):


  FAD → FADH2.

  FADH2 → FAD.

  NAD+ → NADH.

  NADH → NAD+.

  ADP + Pi → ATP.

10

Which of the following statements about the body's metabolic response after three days of starvation is CORRECT?


  Gluconeogenesis occurs in muscle.

  The brain oxidises fatty acids for energy.

  The synthesis of triacylglycerols in liver increases.

  Ketone bodies are formed in the liver from acetyl-CoA

  The breakdown of skeletal muscle protein increases.

11

Which of the following statements about insulin and its antagonists is CORRECT?


  Insulin is secreted from cells as a single polypeptide.

  The binding of insulin to its receptor triggers autophosphorylation of the receptor.

  Adrenaline acts via a nuclear receptor.

  Insulin decreases the activity of glycogen synthase.

  Glycogen synthase is activated by phosphorylation in response to glucagon.

12

Wasting of skeletal muscle due to degradation of protein can occur under conditions such as prolonged inactivity, recovery from surgery and renal disease. Which one of the following statements about the catabolism of skeletal muscle protein is CORRECT?


  The lysosomal protein degradation pathway is quantitatively the most important.

  The (poly)ubiquitin tag on proteins destined for degradation is attached to an internal glycine residue.

  The core particle of the 26S proteasome contains several proteolytic enzymes.

  The first step in ubiquitination is the activation of ubiquitin by acetyl-CoA.

  Ubiquitin is a polysaccharide.

13

The liver occupies a central role in metabolism and interacts via the bloodstream with the metabolism of extrahepatic tissues. Which one of the following correctly describes such an interaction?


  Skeletal muscle exports amino groups to the liver mainly as glutamate

  The brain exports pyruvate to the liver.

  Glucose made in the liver during fasting supplies the brain.

  Fatty acids mobilized from adipose tissue during fasting are exported to the liver for gluconeogenesis.

  Liver exports glucose 6-phosphate to steroidogenic tissue.

14

Concerning the lipoproteins that transport lipids in the bloodstream, which one of the following statements is CORRECT?


  The core of LDL is enriched in cholesteryl ester compared to the core of chylomicrons.

  VLDL is synthesized in the small intestine.

  By weight, HDL has a higher proportion of lipid than LDL.

  Apolipoprotein-A1 (apo-A1) is a ligand for the LDL receptor.

  LDL is converted to HDL by the action of cholesteryl ester transfer protein (CETP).

15

Familial hypercholesterolaemia (FH) is a type of dyslipidaemia. Which one of the following statements about FH is correct?


  FH is associated with high levels of HDL-cholesterol in blood.

  FH is caused by a mutation in apolipoproteinB-100 (apoB-100).

  FH is associated with hypertriglyceridaemia.

  In homozygous FH, the plasma concentration of total cholesterol is typically between 5 and 8 mM.

  FH is caused by a mutation in the LDL receptor.

16

Select the one statement that is NOT CORRECT about muscle contraction.


  Contraction is due to transient, cyclical interactions (cross bridges) between actin and myosin.

  Movement involves thick (myosin containing) and thin (actin-containing) filaments passing one another.

  Filaments do not change length during contraction.

  In a relaxed muscle, regulatory systems prevent the formation of strongly bound cross bridges.

  Strong cross bridges form following the binding of magnesium to troponin-C.

17

Select the one statement that is NOT CORRECT about muscle contraction.


  The contraction cycle proceeds with creatine phosphate hydrolysis providing the immediate source of energy for contraction.

  Upon the release of hydrolysis products, the conformation of the myosin molecule changes to achieve the conformation that has the lowest free energy.

  A conformational change in the myosin molecule, while bound to actin provides the 'power stroke'.

  Fatigue is a loss in the development of force and/or velocity that results from recurrent muscle activity.

  Muscle weakness is a chronic condition distinct from the condition of fatigue.

18

A major metabolic adaptation to exercise for sustaining the same power output after a period of endurance exercise training is:


  Increased creatine phosphate degradation at the onset of exercise.

  Lower intramuscular triglyceride utilisation.

  Increased blood lactate levels.

  Lower muscle glycogenolysis.

  Reduced reliance on fat oxidation.

19

Skeletal muscle contributes significantly to whole body insulin resistance in type 2 diabetes. An important intramuscular characteristic related to this insulin resistance is:


  Lower muscle glycogen levels.

  Reduced mitochondrial oxidative capacity.

  Increased activity of β-oxidative enzymes.

  Reduced intramuscular triglyceride levels.

  Elevated carnitine palmitoyl transferase-1 activity.

20

The medial borders of the rectus abdominus muscles are separated by:


  Tendinous intersections.

  The inguinal ligament.

  The linea alba.

  The arcuate line.

  Fascia transversalis.

21

The floor of the inguinal canal is formed by the:


  Fascia transversalis.

  Conjoint tendon.

  Transversus abdominis muscle.

  Internal oblique muscle.

  Inguinal ligament.

22

The main pancreatic duct opens into:


  The 1st part of the duodenum.

  The 2nd part of the duodenum.

  The 3rd part of the duodenum

  The 4th part of the duodenum.

  The gall bladder.

23

Which one of the following statements regarding the Islets of Langerhans is NOT CORRECT?


  80% of cells of the islets are insulin-producing cells.

  Î² cells make glucagon and amylin.

  a, d and f cells are located on the periphery of the islet.

  a cells make up about 10% of the islet cell population.

  d cells make somatostatin.

24

Which one of the following statements is CORRECT about ghrelin?


  Ghrelin is made in the duodenum.

  Ghrelin is reduced by fasting and elevated by feeding.

  Ghrelin is made in the stomach and rises prior to meals.

  Ghrelin works by slowing gastric emptying.

  Ghrelin has been shown to stimulate energy expenditure.

25

Which one of the following statements about insulin resistance is NOT CORRECT?


  There are multiple causes of insulin resistance.

  Glucose toxicity is mediated by the hexosamine biosynthesis pathway.

  TNF-a has been shown to induce insulin resistance.

  Adiponectin is elevated in obesity and has been shown to cause insulin resistance.

  Free fatty acid oxidation impairs glucose oxidation.

26

Which of the conditions below does not correctly complete the following statement? Compared to the general population, patients with type 1 diabetes mellitus have an increased risk of developing:


  Peripheral neuropathy.

  Hypoglycaemia.

  Renal papillary necrosis.

  Islet cell tumours.

  Pulmonary tuberculosis.

27

Indicate the one statement below that is NOT CORRECT.


  The gastrointestinal tract has its own nervous system, the enteric nervous system

  The gastrointestinal tract has an endocrine system called the gastro-entero-pancreatic (GEP) system.

  Gastrointestinal neurons are arranged in intrinsic nerve circuits, consisting of intrinsic sensory neurons, interneurons and motor neurons.

  Gastrointestinal neurons control the mixing and propulsive movements of the gastrointestinal tract, local blood flow and water and electrolyte transport in the small and large intestines.

  Acid secretion in the stomach is primarily under the control of cranial innervation and endocrine factors external to the gastrointestinal tract.

28

Which of the following statements about obesity is (are) CORRECT? A) The prevalence of obesity in Australia has risen from 1980 to today. B) Twin studies suggest that 70% of the variance in body weight is genetically determined. C) Obesity in Prader-Willi syndrome is associated with hyperphagia and mental retardation. D) Leptin deficiency is more common that leptin resistance as a cause of obesity.


  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.

29

Which of the following statements related to gastrin is (are) CORRECT? A) Gastrin increases gastro-oesophageal sphincter tone. B) Gastrin stimulates histamine release. C) Gastrin increases pyloric tone. D) Gastrin decreases gastro-oesophageal sphincter tone.


  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.

30

Which of the following statements related to peptic ulceration is (are) CORRECT? A) Normal gastric mucosa is relatively impermeable to protons. B) Bicarbonate is secreted by gastric mucosal cells. C) Most peptic ulcers can be healed by inhibiting acid secretion. D) Mucus secretion helps protect the gastric mucosa from acid damage.5


  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.