Total marks: 90 · Duration: 2 hours
Instructions to candidates
- This paper consists of SIX questions in TWO sections. Answer ALL questions.
- Section A has four structured questions. Section B has two essay questions.
- Write your answers in the spaces provided.
- Where appropriate, answers should be illustrated by diagrams.
- You may use a silent, non-programmable calculator.
- Where a question describes a graph or a structure in words, you may find it helpful to sketch it.
Information
- The total mark for this paper is 90. Each question carries 15 marks.
- The marks for each part question are shown in brackets.
- This paper covers the CSEC Human and Social Biology syllabus: living organisms and the environment; life processes and interdependence; heredity and variation; and disease and its impact on humans.
Paper
Section A — Structured Questions (60 marks)
Question 1 — Data analysis: blood glucose (15 marks)
Two people, X and Y, each drank a glucose solution after fasting overnight. Their blood glucose concentration was measured every 30 minutes.
| Time after drinking glucose (min) | 0 | 30 | 60 | 90 | 120 | 150 |
|---|---|---|---|---|---|---|
| Person X (mg per 100 cm³) | 90 | 150 | 130 | 110 | 95 | 90 |
| Person Y (mg per 100 cm³) | 160 | 250 | 280 | 270 | 250 | 230 |
(a) Plot both sets of results as line graphs on the same axes. [4 marks]
(b) (i) Which person is likely to have diabetes? [1 mark]
(ii) Give one piece of evidence from the data for your answer. [1 mark]
(c) Explain the changes in the blood glucose concentration of Person X between 30 and 150 minutes. [3 marks]
(d) Give two ways in which Type 2 diabetes can be managed. [2 marks]
(e) Calculate the percentage increase in Person X's blood glucose concentration between 0 and 30 minutes. [2 marks]
(f) Explain why glucose may be found in the urine of Person Y. [2 marks]
Question 2 — The heart and circulation (15 marks)
(a) Describe the path taken by blood from the vena cava to the aorta, naming the chambers and the blood vessels it passes through. [4 marks]
(b) A man's blood pressure is 150/95 mmHg. A normal reading is about 120/80 mmHg. What does his reading show, and why is it a risk to his health? [2 marks]
(c) Give three lifestyle factors that increase the risk of high blood pressure. [3 marks]
(d) State the function of red blood cells, white blood cells and platelets. [3 marks]
(e) Explain why veins have valves. [1 mark]
(f) Explain why the heart rate increases during exercise. [2 marks]
Question 3 — Excretion and temperature control (15 marks)
(a) Name the organ that excretes each of these waste products: carbon dioxide, urea, and excess water and salts in sweat. [3 marks]
(b) Describe how the skin helps to keep the body temperature constant on a hot day. [4 marks]
(c) Explain how ultrafiltration and selective reabsorption take place in a kidney nephron. [3 marks]
(d) Describe the principle of kidney dialysis. [3 marks]
(e) Explain why it is important to drink more water on a hot day. [2 marks]
Question 4 — Reproduction and heredity (15 marks)
(a) Describe the main events of the menstrual cycle, including the role of oestrogen and progesterone. [4 marks]
(b) Compare the condom and the contraceptive pill as methods of birth control. [3 marks]
(c) Sickle-cell anaemia is caused by a recessive allele (Hbˢ). The normal allele is Hbᴬ. Two parents are both carriers.
(i) Draw a genetic diagram to show the possible genotypes of their children. [3 marks]
(ii) State the probability that a child will have sickle-cell anaemia. [1 mark]
(d) Explain the cause of Down's syndrome. [2 marks]
(e) Explain why there is an equal chance of a baby being a boy or a girl. [2 marks]
Section B — Essays (30 marks)
Question 5 — Health and the environment (15 marks)
(a) Describe how a community should manage its solid waste, and explain how poor disposal of waste can spread disease. [8 marks]
(b) Describe the stages in treating water to make it safe to drink. [4 marks]
(c) Explain why rainwater storage tanks and drums should be kept covered. [3 marks]
Question 6 — Drugs, HIV and immunity (15 marks)
(a) Discuss the effects of the misuse of alcohol and of marijuana on the individual and on society. [6 marks]
(b) Describe how HIV is transmitted, and explain how its spread can be prevented. [5 marks]
(c) Distinguish between natural and artificial immunity, and between active and passive immunity. [4 marks]