Chlorophyll a and chlorophyll b are the main pigments of which class of algae?
- A.Chlorophyceae
- B.Phaeophyceae
- C.Rhodophyceae
- D.Bacillariophyceae
Correct answer
Explanation
The correct answer is A, Chlorophyceae. 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. Option B, Phaeophyceae or brown algae, have chlorophyll a and c together with the brown pigment fucoxanthin, which gives the colour, and they store food as laminarin or mannitol. Option C, Rhodophyceae or red algae, have chlorophyll a and d with the red pigment r-phycoerythrin. Option D, Bacillariophyceae, is the group of diatoms, whose cell walls are of silica and whose remains form diatomaceous earth; in modern classification the diatoms are placed among the chrysophytes. A quick rule for the examination: name the pigment and the class follows, since each class is named after the colour its pigment gives.
Read the full article: Plant Kingdom: Algae to Angiosperms Exam Notes
Practice Questions
View allIn Eichler's classification, which group includes the plants that do not bear seeds?
- A.Cryptogamae
- B.Phanerogamae
- C.Gymnospermae
- D.Angiospermae
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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.
Read the full explanation →Bryophytes are called the amphibians of the plant kingdom because they:
- A.Grow both in water and in deserts
- B.Live on land but need water for fertilisation
- C.Have both roots and rhizoids
- D.Can photosynthesise as well as absorb food
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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.
Read the full explanation →Which group of plants is regarded as the first to develop vascular tissue?
- A.Algae
- B.Bryophytes
- C.Pteridophytes
- D.Gymnosperms
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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.
Read the full explanation →Agar, used in laboratory culture media and in ice cream, is obtained from:
- A.Green algae
- B.Brown algae
- C.Red algae
- D.Blue-green algae
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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.
Read the full explanation →The brown colour of Laminaria and Sargassum is due to which pigment?
- A.Phycoerythrin
- B.Fucoxanthin
- C.Phycocyanin
- D.Anthocyanin
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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…
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