Biology
Kingdom Fungi
4,697 words, 9 sections
Fungi are the decomposers, the pathogens and the fermentation industry of the living world, and this chapter is where a student meets the body plan, the four divisions the whole syllabus turns on, and the spore cycles that produce a mushroom. It carries 72 distinct questions across 49 official papers between 2000 and 2024, set by all six boards that examine Biology, with 472 more in the practice bank at a mean difficulty of 1.63. The PMDC syllabus table names no Fungi chapter and the papers do not agree with that omission, so what follows rests on measured examination evidence rather than on a learning outcome that does not exist. In the textbooks the material runs as one section headed PROTISTS AND FUNGI, beginning with the protists and continuing into the fungi, where the four-division table sits at the end. One warning belongs with the cross-reference: the algae and slime moulds are filed with the protists, and the water moulds, or oomycotes, are filed there too even though they are fungus-like rather than fungi proper. A student who has mastered this chapter can put any named fungus into its division, name the spore it makes, and say whether it earns money, costs money, or does both.
A fungus is a heterotroph that absorbs. It has no chlorophyll, so it takes its carbon and its energy from organic matter already made, and it does not swallow that matter as a protozoan does but secretes enzymes outward, digests the substrate outside the cell, and absorbs the soluble products. Every fungal cell has a wall, and the wall is chitin, not the cellulose of a plant and not the peptidoglycan of a bacterium, which is why chitin is the most reliable answer to "which of these is a fungus". Surplus food is stored as glycogen, the animal-like polysaccharide, and not as plant starch. All fungal nuclei are haploid except the transient diploid zygote, and division of the nucleus happens by nuclear mitosis, the nuclear envelope staying intact throughout, which is what separates fungi from plants, animals and protists in that question. Size runs from the unicellular yeast, a few micrometres across, to fruiting bodies of several centimetres, and the sindh text puts the group at more than a hundred thousand species, a figure a federal or punjab reader will not meet.
The adaptations for land show in what fungi have lost and what they tolerate. They have no flagellated cells at all, so nothing of theirs needs water to swim, their spores are non-motile and travel by wind, and a thick-walled zygote carries them through a bad season. They tolerate osmotic pressure that would destroy most bacteria, which is why a mould grows on jelly and on a discarded orange in a refrigerator while bacteria generally do not, and they endure temperatures from about below freezing to or more, across a range of 2 to 9. Almost all are sessile.
7 more sections in this chapter
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