Science 9 · Unit 4: Maintaining life · Cambridge Lower Secondary Science Stage 9

Questions

1. 1. What is excretion?

   • removing waste made by the body's chemical reactions
   • taking in food
   • making new cells
   • removing undigested food
   Check

2. 2. Is getting rid of faeces a kind of excretion?

   • No, faeces were never part of the body's cells or blood.
   • Yes, faeces are waste.
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3. 3. Carbon dioxide is a waste substance that humans excrete. How is it excreted from the body?

   • It diffuses from the blood into the lungs and is breathed out.
   • It is made into urea by the liver.
   • It is filtered out by the kidneys into the urine.
   • It leaves the body in faeces.
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4. 4. Which of these is NOT something humans excrete?

   • undigested food (faeces)
   • carbon dioxide
   • urea
   • excess water
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5. 5. Where in the body is urea made?

   • in the liver
   • in the kidneys
   • in the bladder
   • in the lungs
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6. 6. The liver makes urea. What does it make the urea from?

   • carbon dioxide from respiration
   • excess glucose
   • excess water
   • proteins that we have more of than we need
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7. 7. Why must urea be removed from the body?

   • It is needed in the bladder.
   • It is used to make urine for energy.
   • It is toxic if it builds up in the blood.
   • It makes blood too thick to flow.
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8. 8. Which organs filter waste out of the blood?

   • the lungs
   • the bladder
   • the kidneys
   • the heart
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9. 9. What is another name for the excretory system?

   • the circulatory system
   • the digestive system
   • the nervous system
   • the renal system
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10. 10. Which waste substance is filtered out of the blood by the kidneys?

    • urea
    • urine
    • glucose
    • oxygen
    Check

11. 11. Urea dissolves in water to form which liquid?

    • sweat
    • plasma
    • urine
    • blood
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12. 12. Which blood vessel brings blood to the kidney?

    • the renal vein
    • the renal artery
    • the urethra
    • the ureter
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13. 13. Which blood vessel takes blood away from the kidney?

    • the renal vein
    • the ureter
    • the bladder
    • the renal artery
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14. 14. What do the ureters do?

    • carry urine from the kidneys to the bladder
    • carry urine from the bladder out of the body
    • carry blood to the kidneys
    • store urine
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15. 15. What is the job of the bladder?

    • to make urea
    • to filter the blood
    • to store urine until it is released
    • to carry blood to the kidneys
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16. 16. What does the urethra do?

    • carries urine from the bladder out of the body
    • carries urine from the kidneys to the bladder
    • stores urine
    • filters blood
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17. 17. In which order does urine travel?

    • kidney → ureter → bladder → urethra
    • bladder → ureter → kidney → urethra
    • kidney → urethra → bladder → ureter
    • ureter → kidney → bladder → urethra
    Check