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1.
Marine mammals have a series of physiological responses to diving. This enables them to stay
submerged for long periods in water colder than their body temperature. Collectively these
responses are termed the diving reflex.
To investigate the diving reflex in humans, heart rate changes in ten healthy subjects were
monitored during facial immersions in water ranging from 3°C to 37°C. The data for this
experiment is shown below.
–5
–10
–15
Percentage change in heart rate
–20
–25
–30
–35
0
5
10
15
20
25
30
Water temperature / ºC
35
40
[Source: N R York, Effect of Water Temperature on Diving Reflex Induced Bradycardia in Humans,
http://kesler.biology.rhodes.edu/sciJ/York.html]
(a)
(i)
State the effect of facial immersion on heart rate over the range of temperatures
shown on the graph.
...........................................................................................................................
...........................................................................................................................
(1)
(ii)
Suggest one reason for the relationship between facial immersion and heart rate.
...........................................................................................................................
...........................................................................................................................
(1)
(b)
Outline the effect of the water temperature on heart rate.
.....................................................................................................................................
.....................................................................................................................................
(1)
1
(c)
Calculate the heart rate of a person immersed in water at a temperature of 15°C, if their
heart rate before immersion was 70 beats per minute.
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.....................................................................................................................................
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(2)
(Total 5 marks)
2.
Cancer of the colon is the fourth most common cancer throughout the world. A number of
epidemiological studies have shown that dietary starch and fibre can influence the incidence of
colon cancer. The results of two of these studies are shown below. Each point on the graphs
represents the human population of one region.
400
300
Starch intake
/ g day –1
200
13.5
fibre intake / 13.0
g day –1
12.5
12.0
100
11.5
0
11.0
0
10
20
30
Incidence of colon cancer / %
16
17
18
19
20
Colon cancer mortality /
deaths per 1000 000 population
[Source: adapted from Food, Nutrition and the Prevention of Cancer: a Global Perspective, World Cancer Research Fund,
American Institute for Cancer Research, (1997), page 380]
(a)
Outline the relationship between fibre intake and colon cancer mortality.
.....................................................................................................................................
.....................................................................................................................................
(1)
2
(b)
(i)
Determine the predicted mortality due to colon cancer at a daily fibre intake of
12.5 g day–1
...........................................................................................................................
...........................................................................................................................
(1)
(ii)
Calculate how much more starch a person would have to consume per day to
reduce the cancer risk by 10%.
...........................................................................................................................
...........................................................................................................................
(1)
(c)
Compare the effect of fibre and starch on cancer of the colon.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(d)
Discuss the effect of daily fibre intake on lowering the mortality rates of cancer of the
colon.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(Total 7 marks)
3
Carotenoids are plant pigments which occur in different forms, such as lutein (from spinach),
-carotene (from carrots), and lycopene (from tomatoes). Researchers investigated the
processing of carotenoids from vegetables in the stomach and small intestine. Healthy men were
fed three test meals differing only in the vegetable added. The carotenoid content of each test
meal was the same. Although the meals were basically liquid, the spinach meal had been made
from chopped spinach leaves. The meals were ingested in random order with three-week
intervals between them. Prior to the first meal, tubes leading directly into the stomach and small
intestine were fitted to each man. Samples of stomach and small intestine contents were
collected from these tubes at regular intervals after each meal. Data from this study is shown
below.
Key:
60
Concentration of carotenoids
in the stomach / mol dm–3
Concentration of carotenoids
in the stomach / mol dm–3
3.
50
40
30
20
10
0
0
60
120
Time / mins
= lutein (spinach meal)
180
30
25
20
15
10
5
0
0
= -carotene (carrot meal)
60
120
Time / mins
180
= lycopene (tomato meal)
[Source: Tyssandier et al, American Journal of Physiology, 284, (2003), pages 913–922. Copyright 2003 by
Am Physiological Society. Reproduced with permission of Am Physiological Soc via Copyright Clearance Center]
(a)
(i)
Calculate the rate of decrease of lycopene concentration in the period 60 minutes to
120 minutes after ingestion in the stomach.
...........................................................................................................................
...........................................................................................................................
(1)
(ii)
Predict how many minutes from ingestion it will take lycopene to completely leave
the stomach.
...........................................................................................................................
(1)
4
(b)
Describe the changes in stomach content of lutein,  -carotene and lycopene during the
180 minutes following ingestion.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(c)
Suggest a reason why the concentration of lycopene stays relatively constant in the small
intestine.
.....................................................................................................................................
.....................................................................................................................................
(1)
(Total 5 marks)
4.
Atherosclerosis is a chronic disease caused by elevated serum cholesterol levels resulting in
deposition of lipids in arteries. Diet modification, weight reduction and exercise are initially
prescribed to alleviate high cholesterol levels. Due to health and possibly genetic reasons, these
attempts may be unsuccessful. Drugs may then be prescribed to lower cholesterol production.
One of the enzymes that can be competitively inhibited by these drugs is involved in the
pathway for the synthesis of bile and steroid hormones.
The safety and effectiveness of a new member of a family of drugs called statins was
investigated. The effect of the drug on the blood serum levels of cholesterol, low density
lipoproteins (high levels are unhealthy), high density lipoproteins (high levels are healthy) and
triglycerides (high levels are unhealthy) are shown below.
Serum blood level / % change from baseline
Dose of drug / mg
Cholesterol
Low density
lipoproteins
High density
lipoproteins
Triglycerides
0 (placebo)
4
4
–3
10
10
–29
–39
6
–19
20
–33
– 43
9
–26
40
–37
–50
6
–29
[Source: adapted from Parke-Davis, (2000), Lipitor (Atorvastatin Calcium) tablets, Spec #0155G247,
page 4, Parke-Davis, New York, www.216.86.213.73/2pdfs/0494lipitor.pdf]
5
(a)
State the dose that was most effective in raising the level of high density lipoproteins in
the treated groups.
....................................................................................................................................
....................................................................................................................................
(1)
(b)
State the relationship between dose and cholesterol levels.
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
(2)
(c)
Distinguish the effect of dose size on low density lipoproteins and high density
lipoproteins.
....................................................................................................................................
....................................................................................................................................
(1)
(d)
Explain the use of a placebo in these investigations.
....................................................................................................................................
....................................................................................................................................
(1)
(e)
Suggest one possible physiological side effect when taking statins for atherosclerosis.
....................................................................................................................................
....................................................................................................................................
(1)
(Total 6 marks)
6