Excretion
Every cell makes waste as it works, and much of that waste is poisonous. Excretion removes the waste products of the chemical reactions in cells. It is not the same as getting rid of faeces, and examiners test that difference.
By the end of this page you can
- Describe how plants get rid of their wastes
- Name the human excretory organs and what each removes
- Follow urea from where it is made to where it leaves the body
- Tell excretion from egestion
- Answer exam questions on excretion
Goals tick themselves off as you try the activities below.
Photo: Forest and Kim Starr, CC BY 3.0, via Wikimedia Commons. Cropped.
Sea almond (Indian almond) trees, common on Caribbean beaches. Their leaves turn red before they fall, taking stored wastes with them.
How often it shows up in past papers
Paper 1 counts come from our past-paper bank of CSEC Biology Paper 1s. Paper 2 is not included yet.
Plants store their wastes, then shed them
Plants make less waste than animals and have no kidneys. They store wastes out of harm’s way and lose them later. Tap each card.
Four organs remove the wastes
Each excretory organ removes particular waste products of metabolism, the chemical reactions in your cells. Tap each organ.
Which organ removes what?
Tap an organ on the list to see the wastes it removes.
Bile pigments leave in faeces, but they are excretion: they came from broken-down cells. The undigested food in faeces is egestion.
Follow urea out of the body
Urea is made from amino acids your body does not need. Drag or tap each stop into its slot.
Where is urea made?
Seven terms to know cold
Say what each term means before you flip the card. The first two are the pair examiners love to test.
Six quick questions, then a real one
Pick an answer to see why it’s right or wrong.
Which BEST describes excretion?
Which is NOT an excretory product in humans?
A person whose kidneys have failed needs dialysis because their blood wastes would otherwise
Dyes in heartwood and tannins in the bark of trees are MOST likely products of
Which of these is an excretory product that plants store as crystals?
Which is NOT a form of excretion in plants?
exam style · 2 marks
Distinguish between excretion and egestion.
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Practice questions are written by My V.I.P. Academy. They are not official CXC papers.