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NEET biology

Question 1
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Which of the following pair of characters distinguish Gnetum from Cycas and Pinus?

  • Abscence of resin duct and leaf venation

  • Prasence of vessel elements and absence of archegonia

  • Perianth and two integuments

  • Embryo development and apical meristem

Solution

B.

Prasence of vessel elements and absence of archegonia

Gnetum is a genus of gymonosperms, the sole genus in the family-Gnetaceae. They are tropical evergreen trees, shrubs and lianas. Unlike other gymnosperms like Cycas and Pinus, they possess vessel elements in the xylem and absence of archegonia. Some species are found to be insect pollinated also. Thus, show affinities with angiosperms.

Question 2
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Fruit ripening is promoted by the hormone that also

  • promotes thinning of fruits in cherry and walnut

  • induce parthenocarpy in tomato

  • promote flowering in lemma

  • induce dormancy

Solution

A.

promotes thinning of fruits in cherry and walnut

Ethylene is the hormone that promotes fruit ripening. It also promoted thinning of fruits in cherry, cotton and walnut. It is a gaseous hormones, i.e. a gas that forms through the breakdown of methionine, which is in all cells. It is produced at a faster rate in rapidly growing and dividing cells, especially in darkness.

Question 3
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A plant cell is placed in a solution whose solute concentration is twice as great as the concentration of the cell cytoplasm. The plasma membrance is selectively permeable, allowing water but not solutes to pass through. What will happen to the cell?

  • The cell will swell because of endosmosis

  • The cell will shrivel because of exosmosis

  • The cell will shrivel because of active transport of water

  • No change will occur because of hard impervious cell wall present

Solution

B.

The cell will shrivel because of exosmosis

The cell will shrivel because of exosmosis. Exosmosis will occur as the concentration inside the cell is half than outside, hence, water will move from the cytoplasm to the surrounding medium causing the cell to shrivel.

Question 4
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Statement I:- α-ketoglutarate dehydrogenase catalyses the conversion of oxalosuccinic acid to α-ketoglutarate.

Statement II:- This reaction is accompained with release of CO2.

Choose the correct option.

  • Statement I is correct and statement II is incorrect

  • Statement II is correct and statement I is incorrect

  • Both statements correct

  • Both statements incorrect

Solution

B.

Statement II is correct and statement I is incorrect

α- ketoglutarate dehydrogenase catalyses conversion of α-ketoglutarate acid, i.e. a 5C compound to 4C Succinyl Co-A. The reaction is as follows

Question 5
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As compared to sun plants, the plants, which are adopted to low light intensity possess

  • more extended root system

  • very high rate of CO2 fixation

  • larger photosynthetic units

  • more extended shoot system

Solution

C.

larger photosynthetic units

As compare to sun plants the plants, which are adapted to low light intensity possess larger photosynthetic units.