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1. Introduction to Biology eLearn.Punjab

Figure 1.4: Amoeba, Paramecium and Euglena

In colonial type of cellular organization, many unicellular
organisms live together but do not have any division of
labour among them. Each unicellular organism in a colony
lives its own life and does not depend on other cells for its
vital requirements. Volvox is a green alga found in water
that shows colonial organization. Hundreds of Volvox cells
make a colony (Figure 1.5).

In multicellular organization, cells are organized in
the form of tissues, organs and organ systems. Frog
and mustard are the familiar examples of multicellular
organization.

Figure 1.5: Volvox colony

Mustard plant

Mustard plant (scientific name: Brassica campestris) is sown in winter and it produces seeds at the
end of winter. The plant body is used as vegetable and its seeds are used for extracting oil. The
organs of the body can be divided into two groups on the basis of their functions. Root, stem,
branches and leaves are the vegetative organs, which do not take part in the sexual reproduction
of the plant. Flowers are the reproductive parts of the plant because they take part in sexual
reproduction and produce fruits and seeds. (Figure 1.6)

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