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[A] : Synergids play an important role i...

[A] : Synergids play an important role in directing the pollen tube growth .
[R] : Because synergids secrete some chemotropically active substance .

A

If both A and R are true and R is the correct explanation of A

B

If both A and R are true but R is not the correct explanation of A

C

If A is true and R is false

D

If both A and R are false

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This section contains Assertion (A) and Reason (R) type questions. Each question has choices (1), (2), (3) and (4), out of which only one is correct. Assertion (A) Synergids of embryo sac help in fertilisation in angiosperms. Reason (R) Filiform apparatus of synergids secrete certain chemotropically active substance due to which pollen tube grows towards the embryo sac.

The structures which guide the pollen tube into synergid is

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Which structure of synergid attracts pollen tube towards itself by secreting chemotropic substance ?

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TRUEMAN BIOLOGY-Plant Morphology & Reproduction -ASSERTION AND REASON
  1. [A] : Anemophillous plants have to produce enormous quantities of poll...

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  2. Assertion. The time involved between pollination and fertilization var...

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  3. [A] : Synergids play an important role in directing the pollen tube gr...

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  4. Assertion. In apomixis , plants of new genetic sequence are produced. ...

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  5. [A]: Incompatibility is a gene physiological process. [R]: Moderate...

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  6. [A]: The pollen sterility has been attributed to the malfunctioning of...

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  7. [A]: The three cells of the egg apparatus are arranged in a triangular...

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  8. [A]: Pollen grains from male parent are mostly transferred to the stig...

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  9. [A]: The two sperms cells in a pollen tube often change their shape. ...

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  10. [A] : Synandrous condition is found in curcurbits. [R] : The male fl...

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  11. [A]: In certain plants the stem that twins around the support is hard ...

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  12. [A]: Leaf in Daucus carota is decompound. [R]: Saprophytic and paras...

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  13. [A]: The colour of flowers in Bougainvillia is due to the coloured bra...

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  14. [A]: The endosperm contains the triploid number of chromosomes. [R]:...

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  15. [A]: Spore mother cells within the anther pollen sacs form four haploi...

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  16. [A]: One diploid embryo sac mother cell develops within the nucellus o...

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  17. [A]: Triple fusion results in veg~tative fertiliza- tion of angiosperm...

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  18. [A]: Pollination is essential for fertilization. [R]: Abscission or...

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  19. [A]: The biennial plants live for two years. [R]: They flower in bo...

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  20. Assertion (A): Many visitors to the hills suffer from skin and respira...

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