2 The diagram shows the arrangement of major blood vessels in the human circulatory system. Arrows show the direction that blood moves in each vessel. head and arms lungs liver small intestine kidneys lower body and legs G F E C D A B (a) Seven of the blood vessels have been labelled on the diagram using the letters A to G. Complete the table by writing one letter, A to G, for each name or description of a blood vessel. The first row has been completed for you. name or description blood vessel the aorta B carries blood containing the lowest concentration of urea one vessel that carries oxygenated blood carries blood at the highest pressure carries blood containing the highest concentration of glucose the hepatic vein an artery that carries deoxygenated blood [6] (b) Explain why the movement of blood through the circulatory system of a human is described as a double circulation. … … … … … … [3] [Total: 9]

1(a)(i) (type of tooth) (function) 1 canine ; 2 tearing / ripping / piercing ; 2 Ig chewing 1(b)(i) 4.75 ; 1 1(b)(ii) 1 15 ; 2 minutes / min ; 2 1(c)(i) 1 lower pH / more acidic / any pH between 3.5 and 4.74 ; 2 longer time / any time between 25 and 35 minutes ; 2 1(c)(ii) 1 brushing / cleaning / toothpaste ; 2 flossing / mouthwash ; 3 fluoride ; 4 avoid sugar AW / use artificial sweetener ; 5 use honey rather than sugar ; 2 Ig dental check-ups 1(c)(iii) 1 heart attack / angina AW / breathlessness ; 2 less ability AW of heart to + contract / pump ; 3 less blood to + body / tissues / organs or any named ; 4 less oxygen / less glucose to + body / tissues / organs or any named ; 5 anaerobic respiration / less aerobic respiration ; 6 lactic acid ; 7 less ability AW to carry out / fatigue + physical activity ; 4 2(a) name or description blood vessel the aorta carries blood containing the lowest concentration of urea E ; one vessel that carries oxygenated blood A / B / C ; carries blood at the highest pressure B ; carries blood containing the highest concentration of glucose D / F ; the hepatic F ; an artery that carries deoxygenated blood G ; 6 2(b) 1 blood through heart twice ; 2 heart / blood + to lungs / pulmonary ; 3 heart / blood + to body / systemic ; 3

3 A man is cooking in a hot kitchen and sweat is being released by sweat glands in his skin. (a) (i) Explain the term homeostasis with reference to sweating. … … … … [2] (ii) Explain how receptors and blood vessels in the man’s skin are also involved in homeostasis when he is in the hot kitchen. … … … … … … [4] (b) Sweat contains very small quantities of the waste product urea. State the name of the organ where most urea is made in the body. … [1] (c) The table shows the concentrations of some chemicals found in the sweat, urine and blood plasma of a healthy human. chemical concentration of chemical / mmol per dm3 sweat urine blood plasma urea 22 393 6 sodium 66 110 141 chloride 59 103 99 (i) Use the data in the table to compare the chemical composition of urine and blood plasma. … … … … … … [4] (ii) A patient has kidney disease and is about to start dialysis treatment. Suggest and explain the concentration of urea in the sweat of the patient compared to that of a person who does not have kidney disease. … … … … [3] [Total: 14]

3(a)(i) any two from: (homeostasis is) the maintenance of a constant ; internal environment / temperature ; return to norm / return to set-point / negative feedback ; evaporation of sweat removes heat / thermal energy / cools / decreases temperature ; 2 3(a)(ii) any four from: receptors + detection of temperature ; impulse to brain / CNS ; vasodilation ; arterioles / blood vessels widen ; increase in blood + near skin surface ; greater + loss of heat / thermal energy ; by radiation ; 4 3(b) liver ; 1 3(c)(i) any four from: less urea in blood plasma ; more sodium in blood plasma ; less chloride in blood plasma ; comparative data quote with units ; data manipulation, e.g. 50 × higher urea in urine than blood plasma ; 4 3(c)(ii) high(er) / over 22 (in patient) ; reduced filtration / reduced removal of urea (from kidney) ; reference to blood plasma ; 3

5 The graph shows how blood alcohol concentration changes after a person drinks alcohol. 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1 2 3 4 time after drinking alcohol / hours blood alcohol concentration / g per dm3 5 6 7 (a) Suggest how the shape of the graph can be explained by what happens in parts of the body after drinking alcohol. … … … … … … [4] (b) The graph shows that the highest blood alcohol concentration for this person after drinking alcohol is 0.75 g per dm3. Suggest two reasons why the highest blood alcohol concentration may be different for two people after drinking the same volume of alcohol. 1 … … 2 … … [2] (c) Describe the short-term effects of a high blood alcohol concentration. … … … [3] [Total: 9]

5(a) any four from: increases / in first hour + absorption / enters blood ; in stomach/small intestine / duodenum /ileum ; hepatic portal vein ; liver ; decrease in alcohol + break down / excretion / sweat / urine ; using an enzyme ; 4 5(b) any two differences: gender ; weight / mass / size ; how much eaten/different rate of absorption ; age ; different + ability to break down alcohol / health of liver / metabolism kidney efficiency ; 2 5(c) any three from: negative effect on reaction time / responses ; depressant ; blurred vision ; slurred speech ; reduced coordination / balance / dizziness ; description of cognitive ability impairment ; 3 e.g. loss of judgement, false courage, antisocial behaviour, increased aggression, drowsiness

7 (a) Excess amino acids are broken down in liver cells to form molecules of urea. Describe the pathway taken by a molecule of urea, from the liver of a mammal until it reaches the soil. … … … … … … … … … [7] (b) Urea is a molecule which contains nitrogen. Suggest why it is important that molecules that contain nitrogen are added to the soil. … … … … … [3] [Total: 10]

7(a) any seven from: transported in blood / plasma ; dissolved ; hepatic vein to vena cava / heart ; renal artery (to kidney) ; to kidney ; urea removed / filtered + from blood ; part of urine ; ureter (to bladder) ; bladder ; (bladder to) urethra ; 7 7(b) any three from: cycling / replenishing nitrogen ; used / converted by nitrifying bacteria / nitrogen fixing bacteria ; form + nitrates ; nitrates + taken up by plants ; production of proteins / amino acids ; increased soil fertility (for crops) / plants grow faster / bigger / AW ; animals / herbivores obtain protein / nitrogen from plants ; 3

Cambridge O Level Biology · 5090

O-Level Biology (5090) Excretion past paper questions

Revise O-Level Biology (5090) — Excretion with real Cambridge past-paper questions grouped by topic, each shown with its marking scheme. Working one topic at a time targets exactly the skill each question tests.

34 free questions from 2017–2021, each with its marking scheme. Open the full topical bank to filter by subtopic, paper, and year.

Excretion in O-Level Biology 5090 exams, 2020–2025

Across 2020–2025, Excretion accounted for 49 questions worth 227 marks in Cambridge O Level Biology (5090) papers.

By year
Year	Questions	Marks
2020	8	46
2021	11	58
2022	6	19
2023	7	36
2024	8	30
2025	9	38

Most-tested subtopics

13.1 Excretion153 marks
13.2 Urinary system127 marks

Appears in

Paper 1 · 30 qs
Paper 2 · 14 qs
Paper 3 · 3 qs
Paper 4 · 2 qs

All most-tested Biology topics

2021 May/Jun · Paper 2 · Q2 · 9 marks
Marking scheme
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2021 Oct/Nov · Paper 2 · Q3 · 14 marks
Marking scheme
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2021 Oct/Nov · Paper 2 · Q5 · 9 marks
Marking scheme
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2021 May/Jun · Paper 2 · Q7 · 10 marks
Marking scheme
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2021 May/Jun · Paper 1 · Q15 · 1 mark
Marking scheme
Mark scheme — 2021 Paper 1 Q15
Answer: B
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