Kidneys help to regulate the volume of fluid and various metabolites waste products in the body. Normally, kidney filter about 180 L of fluid daily but the volume actually excreted out is only a litre or two a day. Patients with kidney failures can be saved by dialysis and kidney transplant.
Generated by claude-sonnet-4-6 · 2026-06-11 09:53 · grounding stimulus
Model Answer
(a) Bowman's capsule is a cup-shaped structure surrounding the glomerulus in the nephron. It collects the filtrate (water, salts, glucose, urea) filtered from the blood under pressure.
(b) Because the remaining filtrate undergoes selective reabsorption in the tubular part of the nephron — useful substances like glucose, amino acids, salts, and most water are reabsorbed back into the blood. Only waste-laden fluid is excreted.
(c) Excretion is the process of removal of metabolic waste products from the body.
It is necessary because accumulated waste products like urea, CO₂, and excess salts are toxic and can disrupt normal cellular functions. Their removal keeps the internal environment (homeostasis) stable and ensures proper functioning of cells and organs.
Source: Life Processes, Excretion
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Explanation
- (a) Describe both structure (cup-shaped, surrounds glomerulus) and function (collects filtrate) — each earns half mark.
- (b) Key term is selective reabsorption; mention what is reabsorbed (glucose, water, salts) to make the answer complete.
- (c) Give the definition first, then explain why it is necessary — the 2 marks are split between definition and necessity. Use terms like "toxic waste", "homeostasis" or "proper functioning" to score full marks.