Excretion in plants — KCSE Biology
KCSE Biology · 73 practice questions · 2 syllabus objectives
25 easy28 medium20 hard
What You'll Learn
Key learning outcomes for this topic, aligned to the KNEC KCSE syllabus.
List excretory products of plants and how they are eliminated
Excretion in plants
Sample Questions
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1
easySHORT ANSWER6 marks
State the economic importance of the following plant excretory product: colchicine.
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Part (a) — 6 marks
Papain — used as a meat tenderizer; also used in the pharmaceutical industry for wound treatment (1 mk)
Colchicine — used in genetics / plant breeding to induce polyploidy by preventing spindle fibre formation during cell division (1 mk)
Tannin — used in the leather tanning industry; also used to make dyes and inks (1 mk)
Quinine — used as an antimalarial drug (1 mk)
Rubber / latex — used to manufacture tyres, gloves, and other rubber products (1 mk)
Caffeine — used as a stimulant in beverages (tea, coffee) (1 mk)
2
easySHORT ANSWER4 marks
Outline three ways in which plants excrete nitrogenous wastes.
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Part (a) — 4 marks
Nitrogenous wastes are stored in cell vacuoles as alkaloids (e.g. caffeine, quinine, nicotine) (1 mk)
Some are deposited in leaves which are later shed / dropped (leaf fall / abscission) (1 mk)
Some are converted to amino acids and reused in protein synthesis / recycled (1 mk)
Some are excreted through the roots into the surrounding soil (1 mk)
3
easySHORT ANSWER2 marks
Explain the necessity for excretion in plants.
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Part (a) — 2 marks
To remove toxic metabolic waste products that would poison / damage cells if they accumulated (1 mk)
To maintain a suitable internal chemical environment for enzyme activity and cell functioning (1 mk)
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