Science — AI-generated practice question

The nephron is the basic structural and functional unit of the kidney. Each kidney contains a large number of nephrons packed together.

Structure: Each nephron consists of a cup-shaped structure called the Bowman's capsule, which surrounds a cluster of thin-walled blood capillaries called a glomerulus. The Bowman's capsule leads into a long, coiled tubule.

Filtration: Blood entering the glomerulus is filtered under pressure. Water, glucose, amino acids, urea, salts, and other small molecules pass into the Bowman's capsule as the initial filtrate. Blood cells and large proteins remain in the blood.

Reabsorption: As the filtrate moves along the tubule, useful substances — glucose, amino acids, salts, and a large amount of water — are selectively reabsorbed back into the blood. The amount of water reabsorbed depends on the body's needs.

Urine formation: What remains after reabsorption — mainly urea and excess water — forms urine. Normally, about 180 L of filtrate is produced daily, but only 1–2 L is excreted as urine. Urine from each kidney passes into the ureter, then the urinary bladder, and is expelled through the urethra.

Source: Chapter 5, Section 5.5.1

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• Examiners expect: structure of nephron (Bowman's capsule + glomerulus + tubule), the process of filtration, selective reabsorption, and final urine formation — all four aspects for full marks.
• Quote the 180 L vs 1–2 L figure; it shows textbook accuracy and is often directly awarded a mark.
• Use bold/underline key terms like Bowman's capsule, glomerulus, selective reabsorption — examiners check for correct terminology.
• Do not pad with unrelated content (e.g., artificial kidney) unless specifically asked.