CAPF AC 2023 Q21: Science & Technology – Biology
- (a) Spleen
- (b) Intestine
- (c) Kidney
- (d) Liver
Answer: (d) Liver
Explanation
Detoxification in the liver
How to think: the body's main chemical cleaning station is the liver.
Blood from the gut reaches it first, bringing drugs, alcohol and poisons.
Inside liver cells, the smooth endoplasmic reticulum (SER) changes these into harmless, water-soluble forms.
| Function of the SER | Where it is important |
|---|---|
| Detoxification of drugs and poisons | Liver cells of vertebrates |
| Making lipids and steroid hormones | Adrenal glands, testes, ovaries |
| Storing calcium ions | Muscle cells (sarcoplasmic reticulum) |
Other work of the liver: it makes bile, stores glycogen and converts ammonia into urea.
Answer: (d) Liver.
Why each option is right or wrong
- (a) Incorrect. The spleen filters blood and removes old red blood cells.
- (b) Incorrect. The intestine digests and absorbs food.
- (c) Incorrect. The kidney filters wastes from blood into urine but does not detoxify by SER.
- (d) CORRECT. SER in liver cells detoxifies many poisons and drugs.
Key point
NCERT Class IX: in the liver cells of vertebrates, SER plays a crucial role in detoxifying many poisons and drugs. RER: protein synthesis. SER: lipid synthesis and detoxification. Liver: largest gland; bile, glycogen, urea.
Remember
Liver SER detoxifies drugs and poisons.
Common mistakes
- Marking the kidney because it removes wastes from the body.
- Mixing up smooth ER (detoxification) with rough ER (proteins).
- Confusing excretion (removal) with detoxification (chemical change).
Exam tip
Educated guess: think of alcohol: heavy drinking damages the liver because that is where it is broken down.
Sources
- NCERT Class IX Science — The Fundamental Unit of Life (endoplasmic reticulum)
- NCERT Class XI Biology — Cell: The Unit of Life; Digestion and Absorption