Page 19 - Science Class 08
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parent cell. Each daughter cell is a clone of the We use vaccines and an bio cs, an sep cs,
parent cell. disinfectants and heat to kill harmful bacteria.
Fungi
Fungi are living organisms that are distantly
4
related to plants and more closely related to
1 2 3
animals, but rather different from either of
Binary Fussion those groups.
When condi ons are favourable such as the
right temperature and nutrients are available,
some bacteria like Escherichia coli can divide
every 20 minutes. This means that in just 7
hours one bacterium can generate 2,097,152
bacteria. A er one more hour the number of
bacteria will have risen to a colossal
16,777,216. That’s why we can quickly become
ill when pathogenic microbes invade our
bodies. Fungus
Helpful Bacteria : Bacteria are helpful as under:
Fungi can be recognised by the following five
v They help in diges on, destroy harmful characteris cs:
organisms from the body and produce v The cells of fungi contain nuclei with
useful vitamins needed by the body. chromosomes (like plants and animals, but
v They recycle carbon, nitrogen, sulphur and unlike bacteria).
other chemical elements used by humans. v Fungi cannot photosynthesise (they are
v They cause fermenta on used in making heterotrophic, like animals).
curd, cheese, vinegar, alcohol, etc. v Fungi absorb their food (they are osmotro-
v Bacteria are used in sewage treatment. phic).
v Bacteria are also used in making drugs and v They mostly develop very diffuse bodies
in tanning leather. made up of a spreading network of very
narrow, tubular, branching filaments called
v Bacteria break up dead organic ma er to
hyphae. These filaments exude enzymes,
produce nutrients that enrich the soil.
and absorb food, at their growing ps.
Harmful Bacteria : These are bacteria that Although these filaments are very narrow,
cause disease like cholera, leprosy, gonorrhea, they are collec vely very long and can
pneumonia, T.B., typhoid and whooping cough. explore and exploit food substrates very
Some other bacteria produce toxins (poisons) efficiently.
that lead to diseases like tetanus, botulism,
v They usually reproduce by means of
diphtheria, scarlet fever in humans, anthrax in
spores, which develop on and are released
animals and plant diseases like so -rot and
by a range of unique structures (such as
fire-blight.
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