Science (086) — AI-generated practice question

(a) Labelled Diagram of Human Excretory System:

```
Right Kidney — Left Kidney
| |
Right Ureter — Left Ureter
|
Urinary Bladder
|
Urethra
```

(Label: Kidneys — one on each side of backbone; Ureters — carry urine to bladder; Urinary Bladder — stores urine; Urethra — releases urine out of body)

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(b) Process of Urine Formation:

Blood entering the kidney is filtered in the nephrons — the basic filtration units. Each nephron has a cluster of thin-walled capillaries associated with a cup-shaped Bowman's capsule, which collects the filtrate.

The initial filtrate contains water, glucose, amino acids, salts, urea, and uric acid. As this filtrate passes through the nephron 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. What remains — concentrated with nitrogenous wastes — is urine. It passes through the ureter to the urinary bladder, and is released through the urethra.

Source: Life Processes, Section 5.5.1

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• Part (a): Draw a neat, labelled diagram. Even a simple schematic showing the four organs in correct anatomical relation earns full marks. Examiners check for all four labels.
• Part (b): Key terms examiners look for: nephron, Bowman's capsule, capillary cluster/glomerulus, selective reabsorption, nitrogenous waste (urea/uric acid). Mentioning that ~180 L is filtered daily but only 1–2 L is excreted (due to reabsorption) is a good bonus point if space allows.
• Do not confuse filtration (in Bowman's capsule) with reabsorption (in the tubule) — both steps must be mentioned for full marks.