Science — AI-generated practice question

Excretion in Human Beings:
Humans produce nitrogenous wastes (urea, uric acid) from metabolism. The excretory system consists of kidneys, ureters, urinary bladder and urethra. Inside each kidney, filtration units called nephrons filter blood through thin-walled capillaries enclosed in the Bowman's capsule. Useful substances like glucose, amino acids and water are selectively reabsorbed. The remaining urine passes through ureters → urinary bladder → urethra for elimination.

Excretion in Plants:
Plants lack specialised excretory organs. They use multiple strategies:

• Oxygen (waste from photosynthesis) and CO₂ are released through stomata.
• Excess water is removed by transpiration.
• Solid wastes are stored in cellular vacuoles, as resins and gums in old xylem, or in leaves that fall off.
• Some waste substances are excreted directly into the surrounding soil.

Key Contrast: Humans rely on a specialised organ system (kidneys/nephrons) producing liquid urine; plants have no such organ and instead store, convert, or passively release wastes using existing structures.

Source: Life Processes, Chapter 5 — Section 5.5.1 and 5.5.2

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• Examiners expect you to cover both organisms with equal weight for a compare-contrast question.
• Name specific structures: nephron, Bowman's capsule, ureters for humans; vacuoles, stomata, old xylem for plants.
• The contrast sentence at the end earns the synthesis mark — always include it.
• Avoid writing a long paragraph on only one side; balance is key.
• "Transpiration" is credited as a plant excretory mechanism (excess water removal).