Green algae are grouped as Chlorophyceae in the chapter. Chlorophylls a and b contribute to their characteristic colour. Their chloroplasts vary in shape, including cup-like, spiral and ribbon-like forms. Many possess pyrenoids associated with protein and starch; reserve food is commonly starch. Some also store oils, so a typical feature should not be converted into an absolute exclusion rule.

The usual wall has cellulose internally and pectose externally. Unicellular, colonial and filamentous bodies occur. Examples include Chlamydomonas, Volvox, Ulothrix, Spirogyra and Chara. Green algae can reproduce by fragmentation, asexual spores and several sexual patterns. The group is not defined by a single gamete-fusion category.

Where flagellated reproductive cells occur, the standard comparison lists equal, apically inserted flagella, commonly two to eight. This describes such motile stages; it does not mean every cell of every green alga has flagella. Spirogyra provides an important reminder that similar-sized gametes need not be motile. A combined pigment–reserve–structure description is stronger evidence than green appearance alone.

Worked example: An unknown alga with chlorophyll a and b, starch and equal apical flagella fits the green-algal comparison better than a specimen with fucoxanthin and laminarin.

Chlorophyll a+b; starch; equal apical flagella in motile stages.

NCERT Trap: Pyrenoids are not viral capsids, and the flagellar comparison is not a claim that every vegetative cell is motile.

Algal comparison:

Flagella refer to flagellated stages, where present.

Green algae

Pigments	Chlorophyll a and b
Reserves	Starch; pyrenoids contain protein
Wall	Inner cellulose, outer pectose
Flagellated stages	2–8 equal apical flagella
Examples	Chlamydomonas, Volvox, Ulothrix, Spirogyra, Chara

Brown algae

Pigments	Chlorophyll a and c; fucoxanthin
Reserves	Laminarin and mannitol
Wall	Cellulose with algin coating
Flagellated stages	Two unequal lateral flagella
Examples	Ectocarpus, Dictyota, Laminaria, Sargassum, Fucus

Red algae

Pigments	Chlorophyll a and d; phycoerythrin
Reserves	Floridean starch
Wall	Cellulose, pectin and polysulphate esters
Flagellated stages	Absent
Examples	Porphyra, Polysiphonia, Gelidium, Gracilaria

NEET Method: Link a+b with starch and the green-algal examples; then check the reproductive stage before applying a flagellar statement.

Plant Kingdom

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