Page 10 - Science Class 07

nutri on also offers vitamins, co-enzymes and
ions that are crucial for the plant’s chemical
processes.
The heterotrophic nutri on are commonly of
four types. They are:
v Saprophy c Nutri on
v Parasi c Nutri on
v Symbio c Nutri on
v Insec vorous Nutri on
SAPROPHYTIC NUTRITION
Some non-green plants live on dead bodies or
organic remains of plants and animals and ro en
food products. They obtain food from them.
These plants are called saprophytes. This mode
of nutri on is called saprophy c nutri on.
Here ‘sapro’ means decaying ma er and
‘phytos’ means plants.
These plants do not carry out photosynthesis
because they do not have chlorophyll in them.
They secrete some enzymes from their body
which break the complex organic ma er into
simpler substances. These simpler substances
are absorbed by their body and easily digested.
Some common examples of saprophytes are
mushroom, yeast, moulds and certain kinds of
bacteria.
Mushroom Moulds
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PARASITIC NUTRITION
Some organisms derive their food from the
body of another living organisms. This type of
nutri on is called parasi c nutri on and the
organisms that depend on such type of
nutri on are called parasites and the organisms
on or inside which a parasite lives is called the
host. The host and parasite live in close
associa on with each other. In the close
associa on, the parasites are always beneficial
while the host is harmed. Parasites obtain their
nourishment from the host and may damage or
even kill it in the process. For example, cuscuta
(Amarbel) is a common parasite that climbs on
the branches of other plants with the help of its
yellow coloured thread like stem. It also
develops parasi c roots at various places called
historian which pierce into the host plant to
obtain nutri on.
Cuscuta
Some other examples of parasites are
mistletoe, a few fungi and bacteria. Mistletoe is
an example of a par al parasite. It has green
leaves and can produce its own food, but get
water and minerals from the host plants.
SYMBIOTIC NUTRITION
Symbio c nutri on is a mode of nutri on in
which two different organisms depend on each
other for shelter and nourishment and both are
benefi ed. These organisms are called
symbio c organisms.
Science-7