CAIE IGCSE Biology 13.1 Excretion in Humans Questions
Practise human-excretion questions on excretory organs, kidney and nephron diagrams, urine formation, deamination and urea removal.
- Syllabus
- 2026–2028
- Course
- Biology 0610
Exam points
- identify carbon dioxide as a lung excretory product and urea, excess water and ions as kidney excretory products
- label kidneys, ureters, bladder and urethra and trace urine flow in excretory-system diagrams
- compare renal artery and renal vein data to identify urea removal by kidneys
- predict urine-volume changes after water loss, water intake or salt intake
- identify cortex and medulla on longitudinal kidney sections and label the ureter
- interpret glomerulus filtration data for glucose, urea, ions and water while retaining proteins and cells
- explain nephron reabsorption: all glucose but only some water and ions return to blood
- explain active transport adaptations in tubule cells using mitochondria and microvilli
- distinguish liver assimilation of amino acids into protein from deamination to urea
- trace urea from excess amino acids in the liver through blood to kidney excretion
- explain why urea must be excreted as a toxic metabolic waste
Covered syllabus points
13.1.1—Carbon dioxide is excreted through13.1.2—Kidneys excrete urea and excess water13.1.3—Kidneys, ureters, bladder and urethra13.1.4—Structure of the kidney13.1.5—Structure and function of a nephron13.1.6—Role of the liver in the assimilation13.1.7—Urea is formed in the liver13.1.8—Deamination as the removal13.1.9—Importance of excretion
Question 1
The kidney is an organ in the excretory system.
Question (a)
(a)
Describe what is meant by the term excretion.
Question (b)
(b)
State the name of the substance excreted by the lungs.
(c) Fig. 4.1 shows a simplified diagram of a cross-section of a kidney.
Fig. 4.1
Question (c)
(c)
State the names of the parts labelled P, Q and R in Fig. 4.1.
P
Q
R
(d) Fig. 4.2 shows the structure of a kidney nephron.
Fig. 4.2
Question (d)
(d)
Describe and explain the difference in the composition of the fluids in structures X, Y and Z in Fig. 4.2.
Question (e)
(e)
The liver is also involved in excretion.
Describe two ways that amino acids are processed in the liver.
1
2
Question 2
Question (a)
(a)
The carbon dioxide produced during exercise is excreted. Urea is another substance that is excreted.
Question (i)
(i)
State the name of the organ that produces urea.
Question (ii)
(ii)
State the name of the organ that excretes urea.
Question 3
The diagram shows the human excretory system.
Which labelled structure is the urethra?
Question 4
The carbon dioxide produced during exercise is excreted. Urea is another substance that is excreted.
State the name of the organ that excretes urea.
Question 5
All living organisms excrete waste products.
Fig. 3.2 shows part of the human excretory system and associated blood vessels.
The arrows indicate the direction of blood flow.
not to scale
Draw a label line and the letter X on Fig. 3.2 to show the location of the cortex in one of the kidneys.
Question 6
Substances move between blood and tissues at various sites in the circulatory system of mammals.
State the site of filtration of blood in the kidneys.
Question 7
Which labelled organ has a major role in the assimilation of amino acids by converting them to proteins?
Question 8
The carbon dioxide produced during exercise is excreted. Urea is another substance that is excreted.
State the name of the organ that produces urea.
Question 9
Substances move between blood and tissues at various sites in the circulatory system of mammals.
State the name of the process in which excess amino acids are broken down in liver cells to produce ammonia.
Question 10
Urea is a waste product.
State why urea must be excreted.
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