Multiple Choice Questions

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In a dicotyledonous stem, the sequence of tissues from the outside to the inside is

  • phellem - pericycle - endodermis - phloem

  • phellem - phloem - endodermis - pericycle

  • phellem - endodermis - pericycle - phloem

  • pericycle - phellem - endodermis - phloem


C.

phellem - endodermis - pericycle - phloem

Phellem or cork is a tissue formed on the outer side of phellogen or cork cambium. It is protective in function.

Endodermis is the boundary between the cortex and the stele. It is a distinctly visible layer of cells immediately outside the vascular cylinder in roots and shoots.

Pericycle regulates the formation of lateral roots by rapidly dividing near the xylem elements of the root.

Phloem is the vascular tissue in plants which conducts sugars and other metabolic products downwards from the leaves.


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Assertion : Water and mineral uptake by root hairs from the soil occurs through apoplast until it reaches endodermis.

Reason : Casparian strips in endodermis are suberized

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

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

  • If Assertion is true statement but Reason is false

  • If both Assertion and Reason are false statements


Casparian strips are present in :

  • cortex

  • epidermis

  • endodermis


Assertion : In woody stems, the amount of heart wood continues to increase year after year.

Reason : The cambial activity continues uninterrupted.

  • 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


Assertion : Petroplants produce large amount of latex.

Reason : The latex contains long chain hydrocarbons.

  • 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


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Plasmodesmata connections help in

  • cytoplasmic streaming

  • synchronous mitotic divisions

  • locomotion of unicellular organism

  • movement of substances between cells


When does a plant wilt?

  • When phloem is blocked

  • When xylem is blocked

  • Pith is removed

  • A few leaves are removed


The quiescent centre in root meristem serves as a

  • site for storage of food which is utilized during maturation

  • reservoir of growth hormones

  • reserve for replenishment of damaged cells of the meristem

  • region for absorption of water


Assertion: In angiosperms, transport of food and water is more efficient than gymnosperms and pteridophytes.

Reason: In angiosperms longitudinally arranged sieve elements and vessels with perforated end walls are present.

  • 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.


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Which one of the following statements pertaining to plant structure is correct?

  • Cork lacks stomata, but lenticels carry out transpiration.

  • Passage cells help in transfer of food from cortex to phloem

  • Sieve tube elements possess cytoplasm but no nuclei.

  • The shoot apical meristem has a quiescent centre


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