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Homeostasis · Paper 2 — Free Biology HL Practice Questions

1MasterySAQ-SRegulation of blood glucose levels5 marksPaper 2~8 min

A marathon runner consumes a high-carbohydrate meal 2 hours before a race. During the race, her blood glucose concentration is monitored. Time (min) — Blood glucose

(\text{mmol}\,\text{L}^{-1})

0 — 5.2 30 — 4.8 60 — 4.5 90 — 4.3 120 — 4.0

(a)

State the hormone primarily responsible for raising blood glucose concentration during prolonged exercise. [1 mark]

(b)

Calculate the percentage decrease in blood glucose concentration from

t = 0

t = 120\,\text{min}

. Show your working. [2 marks]

(c)

Using the data and your knowledge of homeostasis, evaluate whether the negative feedback mechanism controlling blood glucose is fully effective during this race. [2 marks]

Solutions

2MasterySAQ-SRegulation of blood glucose levels5 marksPaper 2~8 min

A patient with Type 2 diabetes mellitus has a fasting blood glucose concentration of

9.8\,\text{mmol}\,\text{dm}^{-3}

(normal range:

3.9\text{–}5.6\,\text{mmol}\,\text{dm}^{-3}

). The patient's pancreatic beta cells still produce insulin, but body cells show reduced responsiveness to the hormone. A doctor prescribes Metformin, a drug that increases the sensitivity of liver and muscle cells to insulin.

(a)

Describe the mechanism by which insulin normally causes cells to absorb glucose from the blood. [2 marks]

(b)

Explain why the patient's blood glucose concentration remains elevated despite normal or raised insulin levels. [2 marks]

(c)

Deduce how Metformin could restore normal blood glucose concentration in this patient. [1 mark]

Solutions

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