Algae form and size , types of gamete

ALGAE 

■ chlorophyll-bearing, simple, thalloid, autotrophic and largely aquatic

■habitats: moist stones, soils and wood

■occur in association with 
• fungi – lichen
• animals – sloth bear

︎ form and size- highly variable

︎Vegetative reproduction - fragmentation.

︎Asexual reproduction - different types of spores, common – zoospores

︎ Sexual reproduction - fusion of two gametes.

︎ half of the total carbon dioxide fixation on earth is carried by algae

︎increase the level of dissolved oxygen in their immediate environment

︎ paramount importance as primary producers of energy-rich compounds

FORM AND SIZE

★ unicellular - Chlamydomonas
★ colonial form – Volvox
★ filamentous - Ulothrix and Spirogyra.
★ massive plant bodies – kelps


TYPE OF GAMETE

● isogamous flagellated and similar in size 

●non-flagellated and similar in size – Spirogyra

■ anisogamous
gametes dissimilar in size 

■ oogamous – Volvox, Fucus


USEFUL TO MANKIND

● Porphyra, Laminaria and Sargassum and 70 species of marine algae are used as food.

● algin (brown algae) and carrageen (red algae) produce large amounts of hydrocolloids 

●Gelidium and Gracilaria are used to grow microbes and in preparations of ice-creams and jellies

● Chlorella rich in proteins is used as food supplement even by space travellers
By: via STUDY MATERIAL