The symptoms of asthma vary according to the time of year. A study was carried out in New York to determine if an increase in the amount of pollen in the air caused an increase in the number of asthma attacks. Over a period of 270 days, the number of people admitted to New York hospitals with asthma attacks was recorded. The graph below shows this data together with the pollen count.

1 8 0

1 6 0

1 4 0

1 2 0

1 0 0

8 0

6 0

4 0

2 0

0

2 5 0

2 0 0

1 5 0

1 0 0

5 0

0

P o llen / g ra in s m – 3 A d m iss io n sto h o sp ita l

A d m iss io n p e r d ayTo ta l p o llen p e r d ay

M arch A p ril M a y Ju n e Ju ly A u gu s t S ep tem b er O c to b er N o vem b er

[Source: Paul F Jamason et al., (1997) American Journal of Respiratory and Critical Care Medicine,156, pages 1781-1788]

(a) Identify the greatest number of hospital admissions in one day.

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(b) Describe how the numbers of hospital admissions changed over the period of study.

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(c) Evaluate whether the hypothesis that pollen in the air increases asthma attacks is supported by the data.

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(d) State one effect of asthma on the gaseous exchange system.

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(Total 7 marks)

(a) State where bile is synthesized.

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(b) Explain the role of bile in digestion.

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(Total 3 marks)

Explain the oxygen dissociation curve for adult hemoglobin and how it is affected by the Bohr shift.

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(a) Describe how the ileum uses active transport in the absorption of food.

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(b) Outline how the blood is routed to the liver, through the liver, and from the liver.

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(c) List two substances resulting from the breakdown of hemoglobin in the liver.

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(Total 7 marks)

Explain the events of the cardiac cycle.

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(a) State two components of saliva, other than water.

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(b) Outline the circulation of blood through the liver.

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(Total 4 marks)

Describe the mode of action of steroid hormones and peptide hormones.

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Explain the control of ADH secretion.

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Poor nutrition of a woman during pregnancy has been associated with a variety of metabolic disorders later in the life of her offspring.

During the second world war (WWII) the normally well-fed population of Holland suffered famine over a relatively short and precisely defined period. The data available from this period provided examples of fetuses that were affected by famine at specific periods during pregnancy.

Glucose tolerance was analysed in human adults 50–55 years of age who had suffered fetal famine during WWII (Figure 1). High glucose levels in blood plasma indicate poor glucose tolerance.

F ig u re 1 : G lu co se to le ra n ce

6 .46 .36 .26 .16 .05 .95 .85 .75 .65 .55 .4

P lasm a g lu co seco n cen tra tio n /

m m o l 1

B o rnb e fo refa m in e

L a tep reg n an cy

M idp reg n an cy

E a rlyp reg n an cy

C o n ce iv eda fte r

fam in e

P erio d o f ex p o su re to fam in e

– 1

[Source: N Metcalfe and P Monaghan, (2001), Trends in Ecology and Evolution, 16, pages 254-260]

(a) (i) Identify the period of exposure to famine that produces the greatest decrease in glucose tolerance.

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(ii) Calculate the percentage change in plasma glucose concentration after exposure to famine from early to late pregnancy.

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(iii) Suggest a reason why glucose tolerance did not return to normal in people conceived after the famine.

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(b) Outline a possible cause of poor glucose tolerance.

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(c) Suggest how poor glucose tolerance could be related to the occurrence of coronary heart disease.

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(Total 6 marks)

Describe the mechanisms that control the heartbeat.

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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

– 1 0

– 1 5

– 2 0

– 2 5

– 3 0

– 3 5

P e rcen ta g e c h a n g e in h e a r t ra te

0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0W ate r tem p era tu re / ºC

[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.

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(ii) Suggest one reason for the relationship between facial immersion and heart rate.

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(b) Outline the effect of the water temperature on heart rate.

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(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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(Total 5 marks)

Discuss factors which affect the occurrence of coronary heart disease.

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Explain the way the body acclimatizes to gas exchange at high altitudes.

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(a) Outline the role of the liver in the storage of nutrients.

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(b) Explain how the body overcomes the problem of lipid digestion in the alimentary canal.

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(Total 4 marks)

The diagram below shows a transverse section of the ileum.

[Source: P H Raven and G B Johnson, Biology, (2002), 6th edition, McGraw-Hill, page 1024]

(a) (i) State the name and function of the structures labelled 1 and 2.

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(ii) Distinguish between the muscles labelled 3 and 4.

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(Total 3 marks)

Describe how carbon dioxide is carried by the blood.

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(a) State two components of bile.

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(b) Outline the process of erythrocyte breakdown in the liver.

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(Total 4 marks)