Lesson 3 of 12 · 6 min
Why algae matter
NCERT §3.1
At lunch the club reads the labels in their packed food. The ice-cream lists a gelling agent, the jelly lists agar, and a classmate's protein powder lists Chlorella. All of it comes from algae.
The lesson in notes
In short
Algae carry out at least half of all carbon dioxide fixation on earth through photosynthesis.
Because they photosynthesise, they raise the dissolved oxygen in the water around them.
As primary producers of energy-rich compounds, they form the base of the food cycles of all aquatic animals.
About 70 species of marine algae are eaten as food, among them many species of Porphyra, Laminaria and Sargassum.
Some marine brown and red algae make large amounts of hydrocolloids, substances that hold water. Algin comes from brown algae and carrageen from red algae; both are used commercially.
Agar is obtained from Gelidium and Gracilaria. It is used to grow microbes in the laboratory and in making ice-creams and jellies.
Chlorella is a single-celled, protein-rich alga used as a food supplement, even by people travelling in space.
Algae fall into three main classes: Chlorophyceae, Phaeophyceae and Rhodophyceae.