formative

Question 1

remember with BMI

Answer 1

UNITS
kg/m squared

to 1 decimal place

Question 2

Give TWO reasons why the patient has gained so much weight.

Answer 2

Daily energy intake exceeds energy requirement (energy requirement sedentary male <12,000 kJ/day).

Extra energy stored as triacylglycerols in adipose tissue

Question 3

in which order are potentially fuel molecules mobilised and utilised

Answer 3

Glucose from glycogen (allow glucose 6-P in skeletal muscle) Glucose from gluconeogenesis
Fatty acids and glycerol from adipose tissue
Ketone bodies from fatty acids via acetyl Co-A
Glucogenic and ketogenic amino acids from muscle protein

Question 4

what impacts BMR

Answer 4

Body weight Body temperature
Gender Thyroid status Pregnancy/lactation

Question 5

Briefly explain how uncoupling proteins (UCPs) are involved in heat generation in the body.

Answer 5

UCPs allow a leak of protons across the membrane (1 mark), reducing the p.m.f, and the energy is dissipated as heat rather than ATP production. (1 mark)
UCP1 is expressed in brown adipose tissue and is involved in thermogenesis. (1 mark)

Question 6

TCA cycle provides precursors for:

Answer 6

• Amino acid synthesis
• Haem synthesis
• Fatty acid synthesis
• Glucose synthesis

Question 7

Explain where, how and why lactate is produced.

Answer 7

Where: Tissues carrying out anaerobic glycolysis. Exercising skeletal muscle, rbc, wbc, kidney medulla

How: Lactate dehydrogenase(LDH) converts pyruvate to lactate

Why: To enable NADH to be oxidised back to NAD+ so that glycolysis (when NAD+  NADH) can continue. Thus some energy produced for tissues without mitochondria/O2.

Question 8

how is lactate utilised by the body

Answer 8

Circulated in the blood
Taken up by:
Heart muscle & liver [allow kidney] (1 mark)
Lactatepyruvate (by LDH)
Pyruvatecatabolism (heart muscle) Pyruvategluconeogenesis (liver (mostly) + kidney)

Question 9

causes of metabolic acidosis

Answer 9

Ketone bodies, pyruvate, lactate, fatty acids, amino acids.

Question 10

State two tissues in which glycogen is stored and state what these stores are used for in each tissue?

Answer 10

Liver – Used to maintain blood glucose (1 mark)
Skeletal muscle – Used to provide glucose 6-phosphate to be catabolised (via glycolysis) to produce energy

Question 11

Glycogen degradation controlled by the regulation of

Answer 11

glycogen phosphorylase.

Question 12

which is triacylglycerol a good storage molecule

Answer 12

hydrophobic, stored in anhydrous form

Question 13

Outline the hormonal signal, enzyme and resulting products involved in the mobilization of triacylglycerol from fat stores.

Answer 13

Glucagon OR adrenaline (1 mark for either hormone) stimulate the enzyme hormone sensitive lipase (1 mark for enzyme) in adipose tissue to hydrolyse triacylglycerol yielding fatty acids and glycerol. (1 mark for fatty acids AND glycerol)

Question 14

A 30 year old man is admitted to hospital suffering from dinitrophenol (DNP) poisoning which ultimately results in his death due to its effect on oxidative phosphorylation.

Briefly outline the process of oxidative phosphorylation.

Answer 14

• Reduced coenzymes are re-oxidised.
• Electrons are passed along electron transport chain to O2
  releasing energy
• Energy drives H+ transport across membrane * H+ gradient produced
• H+ re-enter via ATP synthase (ATP synthesis)

Question 15

Briefly explain the effect of dinitrophenol (DNP) (a similar compound to dinitrocresol) on oxidative phosphorylation.

Answer 15

DNP increases the permeability of the mitochondrial membrane to H+ ions (1 mark)
This uncouples electron transport from ATP (1 mark)

Question 16

Briefly explain why the effect of an inhibitor of a key enzyme in the electron transport chain (such as cyanide) is different to that of dinitrophenol.

Answer 16

An enzyme inhibitor, such as cyanide, disrupts the electron transport chain (blocks passage of electron to O2), so that energy is not available to drive the pumping of protons to produce the p.m.f.
Without the p.m.f. ATP is not produced and heat is not produced.
Uncouplers, such as dinitrophenol, increase the permeability of the inner mitochondrial membrane to protons, which collapses the proton gradient (p.m.f.). ATP is not produced, but the potential energy of the p.m.f. is dissipated as heat.

Question 17

Give THREE differences between oxidative phosphorylation and substrate level phosphorylation.

Answer 17