The endosperm of an angiosperm seed is triploid because it is formed by:
- A.Fusion of two male gametes
- B.Triple fusion of a male gamete with two polar nuclei
- C.Division of the zygote
- D.Fusion of the egg with a synergid
Correct answer
Explanation
The correct answer is B. 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. That second event joins three haploid nuclei and is called triple fusion, so the primary endosperm nucleus and the endosperm tissue formed from it are triploid, and the endosperm nourishes the growing embryo. Option A is wrong because the two male gametes never fuse with each other. Option C is wrong because the zygote divides to form the embryo and not the endosperm. Option D is wrong because the synergids only guide the pollen tube to the egg and take no part in fertilisation.
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 →Chlorophyll a and chlorophyll b are the main pigments of which class of algae?
- A.Chlorophyceae
- B.Phaeophyceae
- C.Rhodophyceae
- D.Bacillariophyceae
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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.
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