23. Questions of exam

Question 1

 Glutamate (C5) is a glucogenic amino acid that can be converted to fatty acids. How many of the C-atoms from glutamate can show up at maximum in fatty acids? (A) all 5 (B) 4 (C) 3 (D) 2

Answer 1

(D) 2

Start from alfa-ketoglutarate (C5). All the way to pyruvate (C3) to acetyl-CoA (C2). Citrate is then shuttled out and fatty acids are synthetized. Thus, answer is C2.
You do not continue through the cycle to OAA and then citrate, as OAA needs to remain the carrier.

Question 2

 The body supports substrate cycling for the main energy bearing nutrients (Ch, protein, fat), because of heat regulation. What are the ATP costs for the substrate cycle: Tri-acylglyceorl <-> glycerol + 3 fatty acids? (A) 3 (B) 5 (C) 6 (D) 7

Answer 2

(D) 7

Tri-acylglycerol: break down into glycerol and 3x fatty acids. Then, fatty acids are needed again to synthesize triacylglycerol. Glycerol needs to be synthesized into glycerol-3-p before it can be converted to the triglyceride. Always look at the NET effect. So, invest and obtaining energy included.
See p.200

Question 3

Is it possible that chemical energy from muscle glycogen contributes to energy expenditure of other organs? (A) no (B) yes, by conversion of gl-6-p to glucose by glucose-6-phosphatase (C) Yes, via lactate exported from the muscle (D) No, inihibited by the pasteur effect

Answer 3

(C) Yes, via lactate exported from the muscle

Question 4

 A cyclist exercises during 1 hour at a level of 100 Watt (external power). How much heat is produced due to this level of cycling? (A) 360 kJ (B) 720 kJ (C) 1080 kJ (D) 1440 kJ
Make a scheme!

Answer 4

(C) 1080 kJ

100 Watt = 100 J/s * 60 = 6000 J/min * 60 = 360000 J/hour = 360 kJ/hr = 25%. 75% = 360*3 = 1080 kJ.

Question 5

During a daily training, a sportsman consumes 1.2 litre O2/min. He wants to eat bananas to conver his energy expenditure. The part of 1 banana that can be eaten (about 100 gr) contains 375 ME kj/100 gr. How many bananas should he eat for each hour of training to cover his energy expenditure? (A) 1 (B) 2 (C) 3 (D) 4

Answer 5

4 bananas
One hour = 1.2 L * 60 = 72 L O2. 1 L O2 = 20 kJ. 72 * 20 = 1440 kJ. = 4 bananas minimum.

Question 6

 Rank the thermogenic effect of a meal expressed as % of ingested ME (A) Ch < fat < protein (B) fat < protein < Ch (C) Fat < Ch < protein (D) Protein < fat < Ch

Answer 6

(C) Fat < Ch < protein

Question 7

 The theoretical heat diagram below shows the thermoneutral zones for two levels of heat production: 10 mJ/day (1xMaintenance) and 20 mJ/day (2xMaintenance). At which environmental temperature do you expect a spontaneous equilibrium between heat production for maintenance and the passive heat loss? (A) 12 (B) 18 (C) 22 (D) 32

p.201

Answer 7

(C) 22

Question 8

 What is the LCT at heat production of 1.4x maintenance? (A) 12 (B) 14 (C) 16 (D) 18

Answer 8

(D) 18

Question 9

 For which conditions can you assume the same level of heat production? (1) A+B (2) A + C (3) A+D (4) B+D

Answer 9

(1) A+B

Question 10

 For which conditions can you assume the same level of heat loss? (1) A+B (2) A + C (3) A+D (4) B+D

Answer 10

B+D = both upper critical temperature, therefore you make use of maximum evaporation capacity.

Question 11

 The pH optimum for salivary and pancreatic amylase can be different. True/false

Answer 11

true

Question 12

 Pepsin + trypsin are both endopeptidases. True/false

Answer 12

true
(not only at the end like exopept)

Question 13

 Pepsin + trypsin have same pH optimum. True/false

Answer 13

false

Pepsin = in stomach, trypsin = in small intestine.