After double fertilisation, a mature ovule has from Biology Sexu

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 Multiple Choice QuestionsMultiple Choice Questions

211.

Which one of the following represents an ovule, where the embryo sac becomes horse-shoe shaped and the funiculus and micropyle are close to each other?

  • Circinotropous

  • Anatropous

  • Amphitropous

  • Atropous


212.

Double fertilisation was discovered by

  • Nawaschin

  • Starsburger

  • Emerson

  • None of the above


213.

Among plants "pheromones" are secreted by the cells of the following plants for given function

  • all plants for growth and development

  • Yeast for facilitating mating

  • all fungi for sexual reproduction

  • Rhizopus for formation of zygospore


214.

If the pollen tube enters the ovule through funiculus, the phenomenon is known as

  • porogamy

  • chalazogamy

  • mesogamy

  • heterogamy


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215.

Which of the following is the most resistant material in pollen grain

  • Sporopollenin

  • Intine

  • Exine

  • Certicle


216.

For the formation of tetrasporic embryosac, how many megaspore mother cells are required?

  • 1

  • 2

  • 3

  • 4


217.

Double fertilization means

  • fusion of nucleus of male gamete with the egg nucleus

  • fusion of two polar nuclei

  • fusion of sperm nucleus with secondary nucleus

  • fusion of one sperm nucleus with nucleus and fusion of other sperm nucleus with secondary nucleus


218.

If there are 4 microspore mother cells in an anther, what will be the number of pollen grains?

  • 4

  • 8

  • 12

  • 16


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219.

After double fertilisation, a mature ovule has

  • I diploid and I haploid cell

  • 1 diploid and I triploid cell

  • 2 haploid and I triploid cell

  • 1 haploid and I triploid cell


B.

1 diploid and I triploid cell

Double fertilisation is found only in angiosperms. In this group of plants, the pollen tube on entering the embryo sac bursts open in one of the two synergids to release the two male gametes.

One male gamete fuses with the egg or oosphere to form a diploid zygote or oospore. It is called generative fertilisation.

The second male gamete descends down and fuses with the diploid secondary nucleus of the central cell to form a triploid primary endosperm cell. It is known as vegetative fertilisation.

Thus, after double fertilisation, a mature angiospermous ovule contains one diploid cell (zygote) and one triploid cell (primary endosperm cell). The haploid cells of the ovule such as antipodals and synergids degenerate after fertilisation


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220.

Identify the parts labelled A, B, C and D in the given figure and select the correct option.

  • A- Scutellum, B- Epiblast, C- Coleoptile, D- Coleorhiza

  • A- Scutellum, B- Coleorhiza, C- Coleoptile, D- Epiblast

  • A- Scutellum, B- Coleoptile, C- Coleorhiza, D- Epiblast

  • A- Epiblast, B- Coleoptile, C- Coleorhiza, D- Scutellum


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