NDM Midsemester Exam 2009

1

Select the CORRECT statement about basal metabolic rate in humans.


  Basal metabolic rate can be deduced from total daily energy intake, but not measured directly.

  Children have higher basal metabolic rates than adults, relative to body mass.

  Obese adults have higher basal metabolic rates than lean adults, relative to body mass.

  Adult females will usually have higher basal metabolic rates than adult males, relative to body mass.

  Adult basal metabolic rate increases by around 2% for every ten years after age 20.

2

Select the CORRECT statement.


  Neighbourhoods of lower socio‐economic standing are observed to have lower obesity rates.

  Obesity is generally defined as having a body mass index equal or greater than 30.

  Body mass index is calculated as (height in metres)2/ weight in kg.

  Obesity provides a paradoxical protection against cancers.

  Obesity is likely to reoccur after a long‐term diet because fat cells never die.

3

Select the CORRECT statement about lipid digestion.


  Triacyl glycerols are partially digested by peptic lipases in the stomach.

  Triacyl glycerols are only absorbed in the intestine after complete hydrolysis to free fatty acids and glycerol.

  The intestinal mucosal cells synthesise chylomicrons that have a core of free fatty acids and a surface of phospholipids.

  Chylomicrons released by intestinal mucosa cells enter the hepatic portal vein.

  Chylomicrons release fatty acids when lipoprotein lipase is activated by recognition of apolipoprotein CII.

4

Select the CORRECT organ, system or tissue. If a fed 70kg male makes and breaks down 300 g of protein each day the highest amount of turnover (around 100g) would be in:


  Liver.

  Muscle.

  The central nervous system.

  Lymphocytes.

  The gut.

5

Select the CORRECT statement about vitamins.


  The major chemical form of dietary niacin is nicotinic acid.

  Thiamin is also known as vitamin B3.

  Vitamin B12 is also known as cobalamin.

  Pantothenic acid (the vitamin) is known as Coenzyme‐A in metabolism.

  Folic acid deficiency is usually only observed when raw eggs are eaten.

6

Select the CORRECT statement relating to the structure shown below. [PICTURE HERE]


  The compound is one of the products formed by the aldolase splitting of fructose‐1,6‐bisphosphate.

  The compound is 2‐phosphoglycerate.

  This compound is generated during gluconeogenesis by the enzyme pyruvate kinase.

  This compound has sufficient free energy of hydrolysis to react with ADP to create ATP in one of the reactions of glycolysis.

  This compound is phosphorylpyruvate.

7

With respect to the Krebs Cycle which of the following statements is CORRECT?


  The two carbons in acetyl‐CoA are fully oxidized to CO2 by combination with molecular O2.

  Hydrogen generated by one acetyl‐CoA entering the Krebs Cycle is preserved as five NADH and one FADH2.

  A decarboxylation of iso‐citrate produces α‐ketoglutarate. α‐Ketoglutarate then decarboxylates to the 4‐carbon‐compound succinyl‐CoA.

  The Krebs Cycle begins when acetyl‐CoA condenses with the 4‐carboncompound malic acid to create the‐six‐carbon‐compound citric acid.

  The enzymes of the Kreb’s cycle are all soluble enzymes of the mitochondrial matrix.

8

[PICTURE HERE] Indicate the CORRECT association of a letter in the diagram above, with a component or event in mitochondrial oxidative phosphorylation.


  The letter P represents the ATP synthase component called Fo.

  The letter D represents electron carrier ubiquinone (cytochrome Q).

  The letter A represents the contribution by NADH of 1 electron to the electron transport chain

  The letter H represents ATP.

  The letter Q represents osmotic force.

9

Select the CORRECT statement about incretins.


  Incretins are synthesised only by the mucosal cells of the stomach.

  Incretins are secreted as a specific response to dietary sugars, notably glucose.

  One of the incretins is glucose‐induced insulinotropic polypeptide (GIP).

  The incretins typically elevate the release of glucagon‐like peptide 1 (GLP‐1) from liver.

  Incretin enhancers (DPP‐4 inhibitors) include the clinically useful peptide called exenetide.

10

Select the CORRECT statement about endocrine functions associated with digestion.


  Somatostatin is a 51 amino acid polypeptide that enhances release of pancreatic digestive enzymes.

  The pancreatic Islets of Langerhans contain 2 cell types of which α‐cells are most abundant.

  Pancreatic polypeptide stimulates contraction of the gall bladder.

  Secretion of insulin requires the admission of K+ to pancreatic β‐cells via a voltage‐gated potassium ion transporter.

  Insulin, amylin, glucagon, and somatostatin are all hormones secreted in response to nutrient levels in the gut or in the circulation.

11

Select the CORRECT statement about central regulation of food intake.


  The ventromedial hypothlamus stimulates food intake.

  Pleasure pathways stimulated by eating include neurotransmission effects by Opioids, endorphins, Enkephalins, Dopamine and Endo‐cannabinoids.

  Inhibitors of food intake include Neuropeptide Y (NPY) and Agouti‐related peptide (AGRP).

  Inhibitors of food intake include Orexin and Melanin Concentrating Hormone (MCH).

  Stimulators of food intake include Cocaine and Amphetamine Regulated Transcript (CART).

12

Select the CORRECT statement about Insulin Resistance.


  Insulin resistance is said to be present when a normal concentration of insulin elicits no measurable biological response.

  Insulin Resistance is most clinically significant in its effect on the brain.

  Insulin Resistance is linked to nutrient excess of both fat and glucose.

  Insulin resistance is widely considered enough on its own to cause diabetes.

  Insulin resistant women may become insulin responsive during pregnancy.

13

The inguinal ligament is the free inferior edge of which of the following structures?


  External Oblique.

  Internal Oblique.

  Transversus Abdominus.

  Facsia Transversalis.

  Rectus Abdominus.

14

The common bile duct and pancreatic duct drain into which of the following structures?


  The 1st part of the duodenum.

  The jejeunum.

  The ileum.

  The caecum.

  None of the above.

15

The most posterior structure at the hilum of the kidney is:


  the renal artery.

  the renal vein.

  the ureteric pelvis.

  the adrenal gland.

  None of the above.

16

The conjoint tendon is comprised of fibres from which of the following structures?


  External Oblique and Internal Oblique.

  Internal Oblique and Transversus Abdominus.

  External Oblique only.

  Internal Oblique only.

  Transversus Abdominus only.

17

One of the major metabolic adaptations to endurance exercise training is:


  lower muscle glycogenolysis.

  lower intramuscular triglyceride stores.

  increased blood lactate levels.

  increased creatine phosphate degradation at the onset of exercise.

  reduced reliance on fat oxidation.

18

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


  lower muscle glycogen levels.

  elevated CPT1 activity.

  increased activity of β‐oxidative enzymes.

  reduced intramuscular triglyceride levels.

  reduced mitochondrial oxidative capacity.

19

With regard to type 1 diabetes mellitus (T1DM), which one of the following statements is CORRECT?


  The incidence of T1DM shows geographic variations that are the result of genetic differences in the populations involved.

  T1DM may be caused by mutations in the insulin gene.

  T1DM is associated with low plasma levels of C peptide.

  T1DM arises as a result of an insulitis initiated by autoantibodies directed against beta cell components such as GAD (glutamic acid decarboxylase).

  Most patients with T1DM are of the HLA DR3 and/or DR4 genotypes, which encode for class 1 MHC antigens.

20

Which of the following statements about metabolic responses to starvation is CORRECT?


  The blood level of chylomicrons increases.

  Insulin secretion increases.

  Glycogen phosphorylase is inhibited.

  Hepatic synthesis of ketone bodies increases.

  Citrate lyase is activated.

21

Which of the following statements about the hormones glucagon, adrenaline (epinephrine) and cortisol is CORRECT?


  The actions of cortisol are mediated by a cell surface receptor.

  Glucagon activates a signalling cascade that leads to inhibition of glycogen synthase by phosphorylation.

  Adrenaline release leads to increased synthesis of triacylglycerols in adipose tissue.

  Glucagon is synthesised in the adrenal gland.

  The action of adrenaline in the liver causes increased conversion of AMP to cAMP.

22

Which of the following statements about protein turnover and related metabolism is CORRECT?


  Most protein turnover occurs in the plasma.

  Amino groups from protein degradation in skeletal muscle are transferred to alpha‐ketoglutarate.

  The main transporter of amino groups from skeletal muscle to the liver is glutamine.

  Proteolysis by the 26S proteasome is a function of the 19S regulatory particle.

  Glutamate in the cytosol of hepatocytes donates the second amino group in the urea cycle.

23

Which of the following statements about metabolic specialisation between tissues is CORRECT?


  Under fasting conditions, skeletal muscle performs gluconeogenesis from glutamine.

  Hexokinase IV of liver is highly active at low concentrations of blood glucose.

  Glutamate synthase in liver and kidney catalyses the reaction: Glutamine + H2O → glutamate + NH4 +.

  Lactate levels in blood increase during light activity of skeletal muscle.

  High levels of alanine in skeletal muscle are due to amino transfer from glutamate to pyruvate.

24

Which of the following statements about the metabolism of lipoproteins is CORRECT?


  LDL is converted to HDL in the circulation.

  The main role of VLDL is to carry cholesterol ester to steroidogenic tissue.

  Nascent HDL interacts with ABCA1 on foam cells to initiate reverse cholesterol transport.

  VLDL is made by enterocytes.

  Lipoprotein lipase (LPL) is activated by apoA‐I.

25

A male patient of normal BMI is found to have elevated plasma total cholesterol (8.5 mM) and triglycerides in the normal range. Which of the following statements is consistent with this presentation?


  The patient consumes a high‐fibre diet.

  The patient has a deficiency of hepatic lipase.

  The patient has heterozygous familial hypercholesterolaemia.

  The patient has a mutation in the apoC‐II gene.

  The patient undertakes aerobic exercise daily.

26

Which one of the following statements regarding ATP usage in skeletal muscle is not CORRECT?


  ATP is required to allow dissociation of actin‐myosin crossbridges.

  ATP levels generally remain constant even during intense muscular activity.

  ATP is essential for Ca2+ release through Ca2+ channels (ryanodine receptors) of the sarcoplasmic reticulum.

  ATP cleavage provides energy for crossbridge cycling during contraction.

  ATP fuels pumps of the sarcoplasmic reticulum that remove Ca2+ from the muscle cytoplasm.

27

Which one of the following statements comparing contraction in skeletal and smooth muscle is NOT CORRECT?


  Smooth muscle generates the same force per cross‐sectional area as skeletal muscle.

  "Cost" (in ATP consumed) of contraction is lower for smooth muscle.

  Smooth muscle cells may contract to a smaller percentage of initial length than skeletal muscle fibres.

  Contraction in both muscle types is dependent on Ca2+ levels and regulated (triggered) in a similar manner.

  Contraction of smooth muscle is slower (lower velocity) than that of skeletal muscle.

28

Which one of the following statements is CORRECT with regard to acclimatisation to a hot climate?


  Primary secretion decreases.

  Sweat glands hypertrophy.

  Production of up to 5 litres/h of sweat at skin.

  Aldosterone decreases.

  Na+ loss may increase from 30 mmol/day to200 mmol/day.

29

Which one of the following statements is CORRECT for the Vagus nerve?


  It is also designated as the 8th cranial nerve.

  The nerve connections include the stomach, gall bladder spleen and kidney.

  The bundle contains only afferent nerves.

  It uses acetylcholine as the main transmitter.

  It inhibits gastric secretions initiated by cholecystokinin.

30

Which of the following statements regarding arachidonic acid and its metabolites is CORRECT?


  Phospholipase A2 (PLA2) liberates arachidonic acid from membrane phospholipid.

  Cyclooxygenase (COX) converts arachidonic acid into leukotrienes.

  Prostaglandin I2 (PGI2/prostacyclin)) stimulates platelet aggregation.

  Prostaglandin E2 (PGE2) enhances stomach acid production.

  Prostaglandin E2 has hypoalgesic activity.