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CAIE IGCSE Biology 13.1 Human Excretion

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

  • match lungs and kidneys to carbon dioxide, urea, excess water and ion excretion
  • interpret kidney, ureter, bladder and nephron diagrams to trace urine formation
  • explain liver assimilation, deamination and urea formation from excess amino acids

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

13.1 Excretion in humans question 1

[Maximum number: 14]

The kidney is an organ in the excretory system.

Question (a)

(a)

Describe what is meant by the term excretion.

[ 2 ]

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

Fig. 4.1

[ 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

Fig. 4.2

[ 3 ]

Question (d)

(d)

Describe and explain the difference in the composition of the fluids in structures X, Y and Z in Fig. 4.2.

[ 6 ]

Question (e)

(e)

The liver is also involved in excretion.

Describe two ways that amino acids are processed in the liver.
1
2

[ 2 ]

13.1 Excretion in humans question 2

[Maximum number: 2]

Question (a)

(a)

The carbon dioxide produced during exercise is excreted. Urea is another substance that is excreted.

[ 2 ]

Question (i)

(i)

State the name of the organ that produces urea.

[ 1 ]

Question (ii)

(ii)

State the name of the organ that excretes urea.

[ 1 ]

13.1 Excretion in humans question 3

[Maximum number: 1]

The diagram shows the human excretory system.
Which labelled structure is the urethra?

Figure for Question 13.1 Excretion in humans question 3 — CAIE IGCSE Biology
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