Multiple Choice Questions

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After doble fertilization, a mature ovule has

  • 1 diploid and 1 haploid cell

  • 1 diploid and 1 triploid cell

  • 2 haploid and 1 triploid cell

  • 1 haploid and 1 triploid cell


B.

1 diploid and 1 triploid cell

Double fertilization is the fusion of two male gametes with a female gametophyte. It is found only in Angiosperms.

In angiosperms, the pollen tube bursts open in one of the two synergids to release the two male gametes. One male gamete fuses with the egg to form a diploid zygote and is known as generative fertilization. The second male gamete descends down and fuses with the diploid secondary nucleus of the central cell to form a triploid primary endosperm cell and is known as vegetative fertilization.

After double fertilization, mature angiospermous ovule contains one diploid cell (zygote) and one triploid cell (endosperm).


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How many haploid nuclei are present in a mature pollen grain

  • One

  • Two

  • Three

  • Four


Sporopollenin is a constituent of pollen exine. It can be degraded by the action of

  • enzymes

  • high temperature

  • strong acids

  • cannot be degraded


The pollen grains of rice and wheat lose their viability inminutes of their release

  • 30

  • 10

  • 60

  • 90


Plants with inferior ovary usually bear

  • pseudocarps

  • berries

  • aggregate fruits

  • seedless fruits


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Which of the following is not true for inbreeding?

  • It causes inbreeding depression after a few generations

  • It always increases the productivity.

  • It is used to produce a pure line.

  • It leads to homozygosity


The given figure shows L.S of the seed of maize. What do A, B, C and D represent?

  • A : endosperm, B : scutellum, C : plumule, D : coleoptile

  • A : scutellum, B : pericarp, C : radicle, D : coleoptile

  • A : endosperm, B : scutellum, C : radicle, D : coleorrhiza

  • A : scutellum, B : pericarp, C : plumule, D : coleorrhiza


Assertion : Commelina shows cleistogamy.

Reason : This reduces chances of inbreeding.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


What is the characteristic of tapetum

  • It does not store food.

  • It is multi-nucleated.

  • It is multi-layered structure.

  • It nourishes the megaspore


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Cotton fibres mainly contains

  • cellulose

  • glycogen

  • protein

  • lipid


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