UPSC Prelims 2023 Q16: Properties of Mushrooms — Explained
Consider the following statements:
1. Some mushrooms have medicinal properties.
2. Some mushrooms have psycho-active properties.
3. Some mushrooms have insecticidal properties.
4. Some mushrooms have bioluminescent properties.
How many of the above statements are correct?
- Only one
- Only two
- Only three
- All four
Answer: (d) All four
Statement-wise explanation
- 1: correct — Several mushrooms are used as medicine. Ganoderma lucidum (reishi) and Cordyceps militaris are long-standing remedies in East Asian traditional medicine. Cordycepin, first isolated from C. militaris, is being studied for anti-inflammatory, anti-cancer and immunomodulatory effects. The Himalayan caterpillar fungus Ophiocordyceps sinensis ('keeda jadi') is collected and traded at high prices for the same reason.
- 2: correct — 'Magic mushrooms' contain psilocybin and psilocin. These act on the brain's serotonin receptors and change perception and mood for up to about eight hours. Most of the 100-plus such species belong to the genus Psilocybe. The fly agaric (Amanita muscaria) is also psychoactive, through ibotenic acid and muscimol.
- 3: correct — The fly agaric (Amanita muscaria) gets its name from an old European practice: pieces of the mushroom were left in a dish of milk to stun or kill flies. Its ibotenic acid is toxic to insects. Insect-killing (entomopathogenic) fungi such as Cordyceps militaris infect and kill caterpillars, and its compound cordycepin is thought to cause the host insect's death.
- 4: correct — About 132 fungal species are known to glow (2024 count, up from 64 in 2008). Most are in the family Mycenaceae. The light comes from a luciferin, 3-hydroxyhispidin, reacting with oxygen with the help of a luciferase enzyme. In India, Roridomyces phyllostachydis, a glowing mushroom that grows on dead bamboo, was described in 2020 from Meghalaya. Mycena chlorophos has been recorded in the Western Ghats and Konkan.
How to eliminate
Every statement starts with 'Some mushrooms', which is a mild claim. It is true if even one species has the property. Questions of this kind ('some X have property Y') usually lean towards 'correct', because a single example is enough. Most candidates can confirm three statements from general knowledge: medicinal mushrooms (reishi, cordyceps), 'magic mushrooms' (psychoactive), and glowing fungi (foxfire, glowing mushrooms in the Western Ghats and the Northeast). The insecticidal statement is the one people hesitate over. Two facts settle it. The fly agaric is named for its use as a fly-killer, and Cordyceps fungi kill insects. Once you accept 'some', none of the four claims is far-fetched. Fact to remember: the fly agaric was used to kill flies.
Know more
Mushrooms are the spore-bearing fruiting bodies of certain fungi, mostly Basidiomycetes such as Agaricus, Pleurotus, Ganoderma and Amanita. Some are Ascomycetes, such as Cordyceps and morels. Fungi are heterotrophs. Their cell walls contain chitin, and they feed by absorption as saprophytes, parasites or symbionts.
| Property | Example | Active agent / basis |
|---|---|---|
| Edible / nutritional | Agaricus bisporus (button), Pleurotus (oyster), Gucchi (morel, Himalaya) | Protein, fibre, B vitamins; vitamin D when exposed to UV |
| Medicinal | Ganoderma lucidum (reishi), Cordyceps militaris, Ophiocordyceps sinensis | Beta-glucans, triterpenes, cordycepin |
| Psychoactive | Psilocybe spp., Amanita muscaria | Psilocybin/psilocin; ibotenic acid/muscimol |
| Insecticidal | Amanita muscaria (fly agaric), Cordyceps spp. | Ibotenic acid; parasitic infection of insect larvae |
| Bioluminescent | Mycena chlorophos, Roridomyces phyllostachydis, Omphalotus | Luciferin (3-hydroxyhispidin) + luciferase + O2 |
| Deadly poisonous | Amanita phalloides (death cap) | Amatoxins (liver failure) |
Bioluminescence in fungi is called 'foxfire'. It is a cold light, usually green (around 520–530 nm). It peaks at night and helps some species attract insects that spread their spores. Bioluminescent fungi are found in five lineages of the order Agaricales. Most are in humid subtropical and tropical forests, such as India's Western Ghats and the Northeast.
Common traps:
- Penicillin comes from a mould (Penicillium), not a mushroom.
- Yeast is a single-celled fungus.
- Bioluminescence (the organism makes its own light) is different from fluorescence (light is absorbed and given out again).