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SK299/F

Module Examination 2019

HUMAN BIOLOGY

PART ONE

This Part carries 25 marks of the 75 marks available for this paper and consists of a single question. You should attempt ALL parts of the question. Write your answers in the answer book provided. You are advised to spend no more than 1hour on this part of the paper, which carries 25 marks of the 75 marks available for this paper.

Question 1

Sunny Ascendant is a 32-year old teacher who is pregnant with her second child. Before she got pregnant, Sunny had a body mass index (BMI) in the healthy range. However, Sunny developed gestational diabetes during her first pregnancy and is therefore at risk of developing the condition again. To monitor Sunny’s diabetes status, she is given an oral glucose tolerance test (GTT) at her first antenatal appointment. Table 1 shows Sunny’s blood glucose concentrations baseline (after overnight fasting) and 1, 2, and 3 hours after drinking a glucose solution Also listed are the typical values for blood glucose concentrations in a healthy pregnant woman who took the same test.

Table 1 Oral glucose tolerance test results for Sunny and a healthy woman

a) Using the information in Table 1, use the graph paper provided to draw an X-Y (line) graph showing the change in Sunny’s blood glucose concentration during the test and the values for the non-diabetic woman. Make sure to choose appropriate scales for the axes, label both axes, and include an appropriate title for the graph.

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b) Based on the results of Sunny’s GTT, would you conclude that she does or does not have gestational diabetes.

Sunny is referred to a nutritionist who advises her that eating foods with a low glycemic index (GI) will help control her blood glucose. The GI is used to classify and rank carbohydrate-rich foods based on how quickly they affect blood glucose concentrations after a meal. Sunny is advised to avoid foods with a high GI because they are quickly broken down, while foods with a low GI take a longer time to be digested and thus raise blood glucose concentrations more slowly.

c) Which of the following class of carbohydrates could have a high GI: monosaccharides, disaccharides, or polysaccharides? Briefly explain your answer.

Once back home, Sunny does a bit more research into dietary control of gestational diabetes. She learns that in addition to the GI, the glycemic load of the food she eats is important. Glycemic load takes into consideration, not only the type of carbohydrate but also the quantity of carbohydrate in the food. Sunny finds a formula to calculate the glycemic load of food items:

d) Using the information in Table 2, calculate the glycemic load that Sunny is late for breakfast and dinner. Assume that Sunny has eaten 1 serving of each item Round the total values to the nearest whole number. Make sure to show your workings

Table 2 Carbohydrate content and glycemic index of foods eaten by Sunny

e) Based on your calculations, list the food items that have the lowest and highest GL per serving.

f) In addition to dietary control, Sunny learns that gestational diabetes can be treated with a drug called Metformin. Metformin works in part by increasing the sensitivity of tissues to insulin. Briefly describe how stimulation of the insulin receptor leads to decreased concentrations of blood glucose.

g) Research has shown that children born to women with gestational diabetes have a higher risk of developing diabetes themselves in adulthood. Briefly describe how gene-environment interactions influence the phenotype of an individual.

PART TWO

Answer ONE of the essay questions in this Part. Write your answer in the same answer book as you used for Part 1. You are advised to spend about 1 HOUR 20 MINUTES on this part of the paper. Your answer should include an essay plan and your essay, written in an appropriate essay style with proper sentences and paragraphs. You should include relevant drawings, tables, and diagrams if you think these will enhance your answer. You are not required to provide references.

The question from this Part carries 35 marks of the 75 marks available for this paper.

Question 2

This essay is based on the chosen topic of Stress.

Use your knowledge of SK299 to describe the effects of stress on body systems and health. In your answer, ensure that you distinguish between acute and chronic stress and describe the physiological mechanisms and anatomical structures that underlie them.

Question 3

This essay is based on the chosen topic Musculoskeletal system.

Use your knowledge of SK299 to describe the homeostatic mechanisms involved in the regulation of blood calcium levels. In your answer, ensure you discuss the cellular mechanisms involved in the maintenance of bone and how these are affected by lifestyle choices and age.

Question 4

This essay is based on the chosen topic Reproduction & fertility.

Use your knowledge of SK299 to describe how the following methods are used and act to avoid the establishment of pregnancy: combined oral contraceptive (COC), progestin-only pills (POP) and emergency contraceptive pill (ECP). In your answer, ensure that you describe how each of these methods differs from the other. (Details of steroid concentrations or examples of product trade are not required)

PART THREE

This Part contains one question and carries 15 marks of the 75 marks available for this paper. Answer ALL the parts of this question. Write your answers in the same answer book used for Part 1 and Part 2 (if you need another answer book, ask the invigilator). You should answer each part of this question in the style requested.

You are advised to spend no more than 40 MINUTES on this part of the paper, which carries 15 marks of the 75 marks available for this paper.

Question 5

Margaret Hack is a 55-year-old teacher who considers herself to be in good health. She is 1.65 m tall and weighs 58 kg.

(a) Use the following equation for Body Mass Index (BMI) to calculate her BMIto one decimal place. Show your work and indicate the weight classification that applies to Margaret.

BMI = weight/kg

(height/m²)

On a Friday afternoon, she goes out for tea with friends. While returning home, she starts feeling itchy has trouble breathing, and experiences abdominal pain. Luckily, one of her friends is with her and helps her enter the house. Unfortunately, Margaret’s symptoms deteriorate rapidly: her tongue is swollen, she vomits several times, and collapses. At this point, her friend calls an ambulance. At the hospital, the paramedics find that Margaret’s blood pressure is 95/65

mmHg, her heart rate is 112 beats per minute and her respiratory rate is lower than normal.

(b) Based on your study of SK299, indicate whether Margaret’s blood pressure and heart rate are within the normal range, lower or higher than normal.

The paramedics measure Margaret’s arterial blood pH and find it to be 7.51(higher than normal), a condition called “alkalosis”. The paramedics immediately administer a solution containing hydrochloric acid and an anti-emetic drug (which prevents vomiting).

(c) Based on your study of SK299, explain how these two interventions will help restore a normal blood pH.

Blood pH is mainly regulated by the kidneys, which can eliminate acids and bases, and also by the lungs, which eliminate CO2. This equation illustrates the relationship between arterial blood pH and the blood concentration of bicarbonate(HCO3-), a basic substance present in the blood. Equation 1 Bicarbonate/CO2 equilibrium in the blood.

CO2 + H2O ↔ H2CO3 ↔ HCO3^- + H⁺

(d) Based on Equation 1, briefly describe how an increased renal excretion of

bicarbonate affects the arterial blood pH.

(e) Equation 1 also shows that the blood pH depends on the levels of CO2 in the blood (PCO2). Briefly explain how Margaret’s hypoventilation (slow breathing) could have partially counteracted the effects of her alkalosis.

Margaret starts feeling better and the paramedics ask her some questions to understand the causes of her illness. Margaret recalls that she had similar symptoms a long time ago when she was a teenager. Her GP told her that she was allergic to hazelnuts and she has carefully avoided eating hazelnuts since then. At this point, her friend recalls that one of the pastries they had with tea had a label saying: “This product may contain traces of hazelnuts”. Margaret must have overlooked that label. Margaret’s blood test shows elevated levels of histamine, confirming the paramedics’ suspicion that Margaret has had an allergic reaction.

(f) Based on your study of SK299, briefly describe what histamine is, which cells produce this molecule, and what its main effects are.

(g) Allergies are caused by an excessive immune reaction. Based on your study of SK299, explain why an allergic reaction is the result of the interaction between genetic and environmental factors.

Last updated: Jan 11, 2022 12:53 PM