Human Excretory System

20 Grade 7 Integrated Science questions on Human Excretory System, with worked marking schemes. 20 questions are available on this topic in full.

1. Question 1

   1 mark

   The main organ of excretion in the human body is the

   A. stomach

   B. kidney

   C. heart

   D. liver

   (1 mark)

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2. Question 2

   1 mark

   Which of the following practices helps maintain a healthy excretory system?

   A. Avoiding all fruits

   B. Drinking plenty of water

   C. Eating too much salt

   D. Reducing physical activity

   (1 mark)

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3. Question 3

   1 mark

   Excess water and salts are excreted through the skin as

   A. urine

   B. sweat

   C. saliva

   D. tears

   (1 mark)

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4. Question 4

   1 mark

   Which excretory organ removes the waste gas carbon dioxide from the body when we breathe out?

   A. The bladder

   B. The kidneys

   C. The lungs

   D. The skin

   (1 mark)

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5. Question 5

   4 marks

   (a) Name the main organ of the human excretory system that filters waste from the blood. (1 mark)

   (b) State the excretory product removed by each of the following organs:

   (i) the lungs; (ii) the skin. (2 marks)

   (c) Give one reason why excretion is important to the body. (1 mark)

   (4 marks)

   Marking scheme

   (a) The kidney. (1 mark) (b) (i) Lungs: carbon dioxide (and water vapour); (ii) skin: sweat (water, salts and a small amount of urea). (2 marks) (c) Any one: to remove harmful/poisonous waste products from the body; to prevent the build-up of toxic substances that could harm the body. (1 mark)

6. Question 6

   1 mark

   The waste product removed from the body by the kidneys is

   A. urea

   B. glucose

   C. carbon dioxide

   D. oxygen

   (1 mark)

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7. Question 7

   4 marks

   (a) Name the main organ of the human excretory system that filters waste from the blood to form urine. (1 mark)

   (b) Name the waste product removed by the kidneys in urine. (1 mark)

   (c) State two ways through which the human body loses water (excretes). (2 marks)

   (4 marks)

   Marking scheme

   (a) The kidney(s). (1 mark) (b) Urea (the main nitrogenous waste; the kidneys also remove water and excess salts). (1 mark) (c) Any two of: through urine (via the kidneys); through sweat (via the skin); through the breath/exhaled air as water vapour (via the lungs); through faeces. (2 marks)

8. Question 8

   4 marks

   Explain two ways to maintain a healthy excretory system.

   (4 marks)

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9. Question 9

   1 mark

   Which of the following is the MAIN organ of the human excretory system responsible for filtering waste from the blood to form urine?

   A. The lungs

   B. The kidney

   C. The stomach

   D. The liver

   (1 mark)

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10. Question 10

    1 mark

    When a person exercises vigorously on a hot day, they sweat a lot. Through which excretory organ is this waste (sweat) removed?

    A. The large intestine

    B. The skin

    C. The kidney

    D. The lungs

    (1 mark)

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11. Question 11

    1 mark

    Carbon dioxide is excreted from the body through the

    A. skin

    B. lungs

    C. kidneys

    D. liver

    (1 mark)

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12. Question 12

    1 mark

    The tube that carries urine from the kidney to the bladder is called the

    A. vein

    B. aorta

    C. ureter

    D. urethra

    (1 mark)

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13. Question 13

    1 mark

    Urine formed in the kidneys is carried to the urinary bladder for temporary storage through a tube called the:

    A. Trachea

    B. Oesophagus

    C. Ureter

    D. Urethra

    (1 mark)

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14. Question 14

    1 mark

    Sweat helps the body get rid of waste and also helps to:

    A. Store urine

    B. Produce red blood cells

    C. Digest fatty foods

    D. Cool the body / regulate body temperature

    (1 mark)

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15. Question 15

    3 marks

    The kidneys are important excretory organs in the human body.

    (a) State two substances that are removed from the body in urine.

    (b) State one way a person can keep their kidneys healthy.

    (3 marks)

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16. Question 16

    4 marks

    John notices that on a cold day he passes urine more often and sweats less, while on a hot day he sweats a lot and passes less urine. Explain the relationship between sweating and urine production that accounts for John's observation.

    (4 marks)

    Marking scheme

    On a hot day the body loses a lot of water through sweating (to cool the body), so less water is available and the kidneys produce a small amount of concentrated urine (2). On a cold day little water is lost as sweat, so more water remains in the body and the kidneys remove the excess water, producing more urine (2). Total 4 marks.

17. Question 17

    1 mark

    A doctor advises a patient to drink plenty of clean water each day to keep the kidneys healthy. The main function of the kidneys in the excretory system is to:

    A. Digest proteins into amino acids

    B. Produce bile for digestion

    C. Pump blood around the body

    D. Remove nitrogenous waste such as urea from the blood

    (1 mark)

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18. Question 18

    5 marks

    (a) Name the main organ of the human excretory system that filters waste from the blood. (1 mark)

    (b) State two excretory products removed from the body and the organ that removes each one. (4 marks)

    (5 marks)

    Marking scheme

    (a) The kidney. (1 mark) (b) Any two pairs: urine/urea is removed by the kidneys; carbon dioxide (and water vapour) is removed by the lungs; sweat (water, salts and urea) is removed by the skin. (2 marks for each correct product-organ pair = 4 marks)

19. Question 19

    4 marks

    The kidneys are important organs in the human excretory system.

    (a) State the main function of the kidneys. (1 mark)

    (b) Name one excretory product removed from the body in urine. (1 mark)

    (c) State two other organs of excretion in the human body and the waste each removes. (2 marks)

    (4 marks)

    Marking scheme

    (a) The kidneys filter the blood to remove waste products and excess water, forming urine (they help in excretion and regulating water/salt balance). (1 mark) (b) Any one of: urea / excess water / excess salts (mineral salts). (1 mark) (c) Any two organs with correct waste: Skin - removes sweat (water, salts, small amount of urea); Lungs - remove carbon dioxide (and water vapour). (1 mark each, organ + waste)

20. Question 20

    3 marks

    Name the excretory products and the organs that excrete them:

    (a) Carbon dioxide

    (b) Urea

    (c) Excess water and salts

    (3 marks)

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