The brown colour of Laminaria and Sargassum is due to which pigment?
- A.Phycoerythrin
- B.Fucoxanthin
- C.Phycocyanin
- D.Anthocyanin
Correct answer
Explanation
The correct answer is B, fucoxanthin. 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 thallus afloat. Option A, phycoerythrin, is the red pigment of the Rhodophyceae. Option C, phycocyanin, is the blue pigment of the cyanobacteria, the blue-green algae placed in the kingdom Monera. Option D, anthocyanin, is the water soluble pigment that colours the petals and fruits of flowering plants red, purple and blue, and it has no part in the colour of algae. Remember the pairing: fucoxanthin brown, phycoerythrin red, phycocyanin blue-green and chlorophyll b with the pure green algae.
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
Show answer
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
Show answer
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
Show answer
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
Show answer
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 →Chlorophyll a and chlorophyll b are the main pigments of which class of algae?
- A.Chlorophyceae
- B.Phaeophyceae
- C.Rhodophyceae
- D.Bacillariophyceae
Show answer
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.
Read the full explanation →