Plant Kingdom Test - 6

 In Phaeophyceae, food is stored as complex carbohydrates which may be in the form of laminarin or mannitol.

Kelps are marine algae of class phaeophyceae or brown algae. The body of kelp may reach upto 100 meter long. They vary in colour from olive green to various shades of brown depending upon xanthophyll pigments , fucoxanthin present in  them.

The shape of a chloroplast varies from species to species. It may be cup-shaped (e.g., Chlamydomonas), (e.g., Vaucheria), Girdle (e.g., Ulothrix), Stellate or Star-shaped (e.g., Zygnema), Reticulate or net-like (e.g., Cladophora, Oedogonium), Spiral or ribbon or scalariform (e.g., Spirogyra), ovoid or disc or spheroid in higher plants

The common forms of Brown algae or Phaeophyceae are Ectocarpus, Dictyota, Laminaria, Sargassum and Fucus.

The plant body of phaeophyceae is usually attached to the substratum by a holdfast whereas the angiosperms attach to the substratum with the help of  roots.

Being photosynthetic, algae increase the level of dissolved oxygen in their immediate environment.

In Ulothrix/Spirogyra reduction division (meiosis) occurs at the time of zygospore germination. Plant body of Ulothrix and Spirogyra, is gametophytic (haploid), they produce zoogametes (n) which fuses to form zygosporic (2n) diploid, which is a resting spore. Onset of favourable condition zygospore undergoes reductional division, or meiosis to produce zoo- meiospores.

Green algae usually have a rigid cell wall made of an inner layer of cellulose and an outer layer of pectose.

Phaeophyceae possess chlorophyll a, c, carotenoids and xanthophylls. They vary in colour from olive green to various shades of brown depending upon the amount of the xanthophyll pigment, fucoxanthin present in them.

Fusion between one large, non-motile female gamete and a smaller, motile male gamete is termed as oogamous e.g., Volvox, Fucus.