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A Handbook of Biology
Examples of Algae
BËÑËFÏTS ØF ÅLGÅË
Through photosynthesis, they fix nearly half of the total CO2 on earth and
increase the level of dissolved oxygen.
Many marine algae (70 species) are used as food. E.g. Porphyra,
Laminaria and Sargassum.
Some marine brown & red algae produce hydrocolloids (water holding
substances). E.g. Algin (brown algae) and carrageen (red algae). These
are used commercially.
They are primary producers and the basis of the food cycles of all
aquatic animals.
Agar (from Gelidium & Gracilaria) is used to grow microbes and in ice-
creams and jellies.
Chlorella and Spirulina are unicellular algae, rich in proteins and are
used as food supplements even by space travellers.
Algae include 3 classes: Chlorophyceae, Phaeophyceae and Rhodophyceae.
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They are usually grass green due to the pigments chlorophyll a and
b in chloroplasts.
The chloroplasts may be discoid, plate like, reticulate, cup shaped,
spiral or ribbon shaped in different species.
Most of them have one or more pyrenoids (storage bodies) located
in the chloroplasts Pyrenoids contain protein besides starch.
(AIPMT 2012)
Some algae store food in the form of oil droplets.
Have a rigid cell wall made of an inner layer of cellulose and outer
layer of pectose.
Some commonly from green algae are Chlamydomonas, Volvox,
Ulothrix, Spirogyra and Chara.