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CLASS 11
CHAPTER 2
BIOLOGICAL CLASSIFICATION (Part 2)
I
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e) they are present everywhere
They grow in warm and humid places
White spots on mustard leaves are due to a parasitic fungus
Eg: Bread Mould, Orange Rots, Mushroom, Toadstools etc
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They are a source of antibiotics
and some unicellular fungi are used to make bread and beer products
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Eg: wheat rustcausing Puccinia
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Fungi bodies’ are made up of long, slender thread-like structures
called hyphae
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o Coenocytic Hyphae: They are continuous tubes filled with
multinucleated cytoplasm
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(Remember septum; the wall separating the chambers of the
heart)
Fungal cell wall is made up of chitin and polysaccahrides
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e) they absorb soluble
organic matter from dead and decaying matter
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e) they derive their nutrition from living
organisms by converting them into their host for nutrition
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Fungi adhering to symbiotic associations for
nutrition are symbionts
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Fragmentation

Vegetative
Propagation

Fission
Budding
Conidia

Asexual Reproduction (by
asexual spores)

Reproduction

Sporangiospores
zoospores

Sexual Reproduction (by
Sexual spores)

Oospores
Ascopsores
Basidiospores

i
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e) the mycelium breaks up into individual fragments, each
mycelial fragment capable of growing into a separate
mycelium, and later on fungi
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b)

Fission:

Process by which one cell undergoes nuclear division and splits
into two daughter cells
...

c)

Budding:

Process by which a bud develops on the parent fungi, with the
cytoplasm of the parent unifying with the bud and upon full
development, it separates from the fungi
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ASEXUAL REPRODUCTION:
a) Conidia:
It is a type of asexual reproductive spore usually produced at
the tip or side of hyphae or on special spore-producing
structures called conidiophores
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Large ones are called macroconidia and small ones are called
microconidia
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Sporangium can vary in shape from an
elliptical sphere or ellipsoidal or complete sphere or globose
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It is also seen in the
Oomycetes, which is a group of fungi that is phylogenetically
unrelated to the true fungi
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They are naked,
incapable of dividing, do not possess any walls and utilize their
endogenous food reserve for nourishment and energy
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iii
...

Ascospores
Found in clusters of
four or eight spores
within a single
mother cell called
the ascus
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Oospores
Result of sexual
reproduction in the
oomycote and
zygomycota
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Survival structures
in the soil
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Reproduced sexually
with the formation of
club-shaped and cells
knows as basidia
which usually carry
external meiospores
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of male and female
gamete
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It’s the first step
of sexual reproduction
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It’s
the second step of sexual reproduction
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In sexual reproduction, 2 haploid hyphae fuse together
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Dikaryophase: It is a phase in fungi that causes a momentary pause due to
the intervention of a dikaryon (a cell in which two nuclei from either parent
share a single cytoplasm for a certain period of time or up until conditions
are favourable) in between plasmogamy and karyogamy in fungi
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Fungi form fruiting bodies in which reduction division occurs, leading to
formation of haploid spores
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PHYCOMYCETES:
o Found in aquatic habitats, on decaying wood in moist and
damp places or as obligate parasites ( parasites that are
completely dependent on the host for its survival
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They are produced in the sporangium endogenously
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Isogamous: Fusion of two gametes that are same in
size
ii
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iii
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o Fusion of two gametes results in the formation of
zygospores
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ASCOMYCETES:
o Known as sac-fungi
o Some are unicellular like yeast while others are
multicellular
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o They have branched and septate mycelium
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o Each conidia on germination gives rise to mycelium
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o Ascospores are produced in sac-like structures called
asci
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o Eg: Aspergillus, Claviceps and Neurospora
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BASIDIOMYCETES:
o It grows in soil, on logs, tree stumps and in living plant
bodies as parasites as hosts
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o No asexual reproduction; vegetative propagation via
fragmentation is observed
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o Basidium produces four basidiospores exogenously after
meiosis
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4
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Only asexual or vegetative stages are known
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o Reproduce only via asexual spores called conidia
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o Most of them are decomposers of litter and help in mineral
cucling
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o Eg: Alternaria, Colleotrichum and Trichoderma
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KINGDOM PLANTAE:
 Plants are eukaryotic, autotrophic organisms containing a cellulosic
cell wall
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 Some are partial heterotrophs such as the insectivorous plants or
parasites
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 Plantae includes:
i
...
Bryophytes
iii
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Gymnosperms
v
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These phases alternate with each other
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III
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 They directly or indirectly are dependent on plants for food and
nutrition
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 They follow holozoic nutrition (by ingestion of food)
 Has a definite growth pattern (grow into adults with definite shape and
size), with higher forms showing sensory and neuromotor mechanism
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 They sexually reproduce followed by embryological development
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VIROIDS, VIRUSES, PRIONS AND LICHENS:
 Viroids, viruses, prions and lichens aren’t mentioned in the five
kingdom classification
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1
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o They are obligate parasites
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o They survive by using the cellular machinery and mechanisms
of the cell of the cell of the living host, slowly depriving the
host of nutrition and other essentials, and eventually killing the
host
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o D
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o M
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{This idea is in the direction
that viruses use host cellular machinery to live, but otherwise
are considered non-living}
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M Stanley (1935): He showed that the viruses could be
crystallized and crystals consist largely of proteins
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e) it has a protein coat (capsid) and
genetic material (RNA or DNA)
o No virus contains both RNA and DNA
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o Generally, viruses that infect plants have single stranded RNA
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o Bacteriophages (viruses infecting bacteria) have double
stranded DNA
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o Capsomeres are arranged in helical or polyhedral geometric
forms
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o In plants, the symptoms can be mosaic formation (appearance
of light and dark green patches in the leaves), leaf rolling and
curling, yellowing and vein cleaning, dwarfing and stunted
growth
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VIROIDS:
o Infectious agent with a low free molecular weight RNA and has
no protein coat
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o It was discovered by T
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o Viroids cause potato spindle tuber disease in plants
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PRIONS:
o Abnormally folded proteins that cause some infectious
neurological diseases
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o Causes bovine spongiform encephalopathy (BSE) or mad cow
disease in cattle
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4
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o They are very good pollution indicators as they do not grow in
polluted areas
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