Page 135 - Biology_F5

Biology for Advanced Level Secondary Schools

(d) Some members cause diseases parasitic or saprophytic. Fungi produce
to plants. A good example is extracellular enzymes which digest almost
Phytophthora infectans that infects everything including protein and starch. The
tomato and potato plants. end products of digestion are absorbed by
special structures called haustoria (plural)

3.5 Kingdom Fungi or haustorium (singular). Some fungi are
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parasites, as they obtain nutrients directly
Task 3.6 from other living organisms such as plants
Use internet sources and the library and animals. They have cell walls made up
to search for information on kingdom of chitin, unlike plant cell walls which are
Fungi. made up of cellulose. Organisms under this
kingdom store carbohydrate in the form of
Organisms belonging to this kingdom are glycogen similar to animals, but not starch,
those originally placed in kingdom Plantae as in chlorophytes and plants.
under the two kingdom classification
system. The early placement of fungi They have a variety of shapes and sizes
under kingdom Plantae was due to the extending from microscopic to macroscopic.
morphological appearance of some fungi, Sexual reproduction in fungi involves two
particularly the mushrooms which resemble haploid nuclei of compatible mating hyphae
plants. The microscopic fungi were not strains that unite to form a zygote, which
yet known by then, since the microscopes later grows into a new fungal body. Asexual
were not yet invented. It was discovered reproduction is accomplished by production
later that fungi differ from plants in several of asexual spore, which under favorable
ways, hence they were placed in their own conditions, germinates and grows to form
kingdom, and most of them had economic new haploid fungal hyphae. Examples
importance. Through mycology (a study of of organisms in this kingdom include
fungi), over 100,000 species of Fungi have mushrooms, yeasts, Penicillium, bread
been described. It is estimated that there are mould, and toadstool.
over 1million species of unidentified Fungi.
3.5.1 Position of kingdom Fungi
Fungi are eukaryotic, unicellular or As explained earlier, the position of fungi in
multicellular multinucleate organisms, classification was one of the controversial
made up of a mass of branching and delicate arguments. It was previously not clear
thread-like structures called hyphae, which whether fungi should be classified as an
collectively constitute fungal bodies called animal or as a plant, because they have
mycelium. Depending on the species, some some features in common to both plants
hyphae may have cross walls called septa, and animals.
dividing hyphae into many cells with one or
more nuclei. In some species, the cytoplasm Similarities between fungi and animals
is continuous without cross walls. Fungi Similar to animals, fungi have the
are thallophytes, lacking chlorophyll, following features:
hence nutrition in these organisms is either

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