General Science Quiz: Plant Kingdom: Algae to Angiosperms

Eichler divided the plant kingdom into two: the Cryptogamae, meaning plants with hidden reproductive organs and no seeds, which include the algae or thallophytes, the bryophytes and the pteridophytes; and the Phanerogamae, the seed bearing plants.

Bryophytes such as Marchantia, Riccia, Funaria and Sphagnum grow on soil, rocks and tree trunks, but their male gametes are flagellate and must swim through a film of water to reach the egg, so fertilisation cannot take place in dry conditions.

Ferns and their relatives, such as Selaginella, Lycopodium, Equisetum, Pteris, Adiantum and Marsilea, are the first plants with xylem to conduct water and minerals and phloem to conduct food, and the first with a true root, stem and leaf; for that reason they are also called the vascular cryptogams.

Agar is obtained chiefly from Gelidium and Gracilaria, members of the Rhodophyceae, and it is used to prepare the solid media on which microbes and plant tissues are grown, as well as in jellies and ice cream.

The green algae owe their colour to chlorophyll a and chlorophyll b, which are not masked by any other pigment; Chlamydomonas, Volvox, Spirogyra, Ulothrix and Chara belong here, and their stored food is starch.

Brown algae of the class Phaeophyceae contain chlorophyll a and c along with the xanthophyll pigment fucoxanthin, and because fucoxanthin masks the green chlorophyll the plant looks olive green to deep brown; Laminaria, Sargassum, Fucus, Ectocarpus and Dictyota are examples, and many of them bear air bladders that keep the…

Besides its normal roots, Cycas bears small branched roots that grow upward near the surface and look like coral; these coralloid roots hold cyanobacteria such as Anabaena and Nostoc, which fix atmospheric nitrogen and supply it to the plant.

It is the only surviving species of its order, has remained almost unchanged for many millions of years and is known from fossils of the age of the dinosaurs, which is why it is called a living fossil; it is a gymnosperm with fan-shaped leaves, grown widely as an ornamental…

The word itself means naked seed: the ovules are not enclosed in an ovary, so after fertilisation the seeds lie exposed on the surface of the scales of a cone and no fruit is formed.

An angiosperm shows double fertilisation: of the two male gametes brought by the pollen tube, one fuses with the egg to give a diploid zygote, and the other fuses with the two polar nuclei of the central cell.

Sphagnum is a bog moss, a bryophyte, whose dead cells hold many times their own weight of water; in waterlogged and acidic bogs its remains decay only partly and pile up as peat, which is cut, dried and burnt as fuel and is also used in nurseries to keep soil…