Algae
Algae is a latin word (Algae - Sea
weeds). They are chlorophyll bearing, simple and primitive plants. These plants
are autotrophs. Algae belongs to thallophyta and the plant body of algae is
called thallus. i.e. the plant body is not differentiated into root, stem and
leaf.
Most of the algae are living in
aquatic region. It may be fresh water or marine water. Very few algae can
survive in wet soil. Some algae are very minute and float on the surface of the
water. These algae are called phytoplankton.
Some of the algae are symbionts (Algae living with fungi and they both are
mutually benefitted) . E.g. Lichen. A few species of algae are epiphytes. The
branch of study of algae is called phycology or algalogy. Algae reproduces by
three methods. They are:
* Vegetative reproduction takes
place by fragmentation. E.g. Spirogyra.
* Asexual reproduction takes place
by spore formation. E.g. Chlamydomonos.
* Sexual reproduction takes place by
means of fusion of gametes. E.g. Spirogyra,
Chara.
Algae are classified into different
classes based on the pigments. They are given in Table 17.1.
Food
Algae are consumed as food by people
in Japan, England and also in India. E.g. Ulva,
Spirulina, Chlorella etc. Some algae are used as food for domestic animals.
E.g. Laminaria, Ascophyllum.
Agriculture
Some of the blue green algae are
essential for the fixing of atmospheric nitrogen into the soil, which increases
the fertility of the soil. E.g. Nostoc,
Anabaena.
Agar
Agar
Agar agar is extracted from some red
algae, namely Gelidium and Gracillaria. It is used to prepare
growth medium in laboratories.
Iodine
Iodine is obtained from brown algae
like Laminaria.
Space
travel
Chlorella
pyrenoidosa is used
in space travel to get rid of CO2 and to decompose human wastes.
Single
Cell Protein (SCP)
Some of the single cell algae and
blue green algae are used to produce protein. E.g. Chlorella, Spirulina.
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