Plant Kingdom Test - 15

The pigments that give class-Rhodophyceae (red algae) its distinctive red colour is chlorophyll-a, d. These pigments are photosynthetic in nature and are located in the chromatophores. The other pigments present are β-carotene, xanthophylls, phycocyanin (blue in colour) and biliprotein (r-phycoerythrin-red in colour).

The dominant stage in Spirogyra is the gametophytic stage. The sporophyte is a single celled zygote.

Mosses and ferns belong to bryophytes and pteridophytes respectively. In bryophytes, the dominant phase in the life cycle is the gametophytic plant body. However, in pteridophytes, the main plant body is a sporophyte, which is differentiated into true root, stem, and leaves. These organs possess well-differentiated vascular tissues.

Ectocarpus, Dictyota, Laminaria, Sargassum, and Fucus belong to the class Phaeophyceae.

Sphagnum is used as fuel. It has the capacity to retain water for long periods and as such used to cover the plant roots during transportation.

Laminaria belong to the class Phaeophyceae. Plant body of Laminaria is generally attached to the substratum by a holdfast which has a stalk, the stipe, and frond which is the photosynthetic organ.

Peristome is a ring of teeth around the opening of the capsule in mosses (Funarid). It is involved in spore dispersal.

Fern plant is a diploid sporophyte.

In Cycas, seeds are naked because they are not covered by ovary.

Bryophytes have multicellular jacketed sex organs to protect gametes against drying effects of air and retention of zygote inside archegonium to provide nourishment to developing embryo.

Bryophytes are different from fungi in having sterile jacket layers.

(a) Batrachospermum is one of the fresh water forms of Rhodophyceae. This alga is found in slow running shallow streams and on the banks of lakes and ponds. It is more commonly found in well aerated waters.

(b) The plants are blue-green, olive-green, violet and reddish in colour. The variation in colour is as a result, of the differences in light intensity. The species which grow in deep water are reddish or violet in colour whereas the species growing in shallow water are olive-green in colour.

(c) The alga is also known as the frog spawn or the eggs of frog, because the plants are mucilaginous, moniliform or beaded in appearance to the naked eye.

(d) The thallus is filamentous, profusely branched and with a mucilaginous feel. Hence, looks like frog eggs.

The plants may reach a length of twenty centimetres and may easily be collected from well aerated water bodies.

The sporophyte of Riccia is total parasite.

• The endosperm froms a pad like tissue called coleorhiza which protects the tip of radicle.
• Since, a single Cycas ovule contains 2-8 archegonia; the same number of embryo develops.
• All degenerate except one embryo that reaches maturity.

Food is stored the form of luminarin, mannitol and oil in Fucus. Food is stored the form of starch and oil in Chara.

Food is stored the form of floridean starch and galactan polymers in Porphyra and Gracilaria.

The Prothallus is the fern gametophyte. It is a green, photosynthetic structure that is one cell thick, usually heart or kidney shaped, 3-10 mm long and 2-8 mm broad.

Prothallus of fern produces male and female gametes which after fertilization give rise to diploid sporophyte which produces spores.

The underside of the Prothallus is where the gametes are produced from the male and female sex organs.

The Prothallus has both male and female sex organs.

The coralloid root of Cycas is symbiotically associated with nitrogen fixing blue-green algae, Anabaena Cycadae and Nostoc punctiforme.

These blue-green algae (Cyanobacteria) are prokaryotic, photosynthetic and autotrophic.

(i) Arechegoniophre is a stalk of a prothallium on which archegonia grows. Marchantia is a genus of liverworts.

(ii) The thallus of Marchantia is dioecious in nature. It produces either female archegoniophores or male antheridiophores.

Pro means before which clearly explains it. Protostele is a primitive style of arrangement of conductive tissues in which a solid cylinder of xylem is present in the center and surrounded by a layer of phloem.

This pattern of arrangement is mainly seen in lower plants.

(a) The wood of gymnosperm is non-porous because it consists of lesser xylem fibres than angiosperms, the vessels are absent and it contains more tracheids than angiosperms.

(b) Due to the lesser number of vessels, and the high percentage of tracheids doesn't allow rapid conduction of water. The walls of the tracheids are thin so they are known as softwood.

(i) Such vessels form when cells join end to end in the xylem tissue and are common in flowering plants.

(ii) Most gnetophytes produce naked (exposed) seeds, like the other gymnosperms—ginkgo, cycads, and conifers.

(iii) Gnetum leyboldii, unlike most gymnosperms, produces seed enclosed in a juicy, fruit-mimicking layer.