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Date May 2017 Marks available 2 Reference code 17M.3.SL.TZ2.3
Level Standard level Paper Paper 3 Time zone Time zone 2
Command term Discuss Question number 3 Adapted from N/A

Question

In an experiment to determine the effect of diet on response to leptin, mice were fed a control diet or a high fructose diet for six months and then either injected with a saline (salt) solution or injected with leptin. The food intake of both groups was then monitored over a 24 hour period.

Leptin is a hormone. Hormones are chemicals produced in one part of the body that have an effect in another part of the body.

Distinguish between the effect of leptin injection on 24 hour food intake in the mice fed the control diet and in the mice fed the high fructose diet.

[1]
a.

Discuss the implications of these results for recommending leptin injections as an appetite suppressant for humans.

[2]
b.

State the tissue that produces leptin in humans.

[1]
c.i.

State the target that leptin normally acts on.

[1]
c.ii.

Markscheme

no effect with fructose diet but «statistically significant» reduction in control

a.

a. effectiveness/effect of leptin depends on diet OWTTE

b. «if obese people/humans have a» high fructose diet, then it will not suppress appetite 

c. «for obese people/humans with a» control/low fructose diet, then it will suppress appetite

d. results for mice may not be the same for humans OWTTE

b.

adipose/fat tissue

c.i.

hypothalamus

c.ii.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.i.
[N/A]
c.ii.

Syllabus sections

Core » Topic 6: Human physiology » 6.6 Hormones, homeostasis and reproduction
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