In the sieve elements, which one of the following is the most lik

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 Multiple Choice QuestionsMultiple Choice Questions

51.

Assertion : Shrinkage of the protoplast of a cell occurs under the influence of hypertonic solution.

Reason : Hypertonic solution causes plasmolysis.

  • 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


52.

In active transport, carrier proteins are used, which use energy in the form of ATP, to

  • transport molecules against concentration gradient of cell wall.

  • transport molecules along concentration gradient of cell membrane.

  • transport molecules against concentration gradient of cell membrane.

  • transport molecules along concentration gradient of cell wall.


53.

Assertion: Water that enters into a plant cell through diffusion makes it turgid.

Reason: Entry of water into the cell through diffusion develops wall pressure inside the cell.

  • 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.


54.

Assertion: Movement of materials inside phloem is bidirectional i.e. it can be both upwards or downwards.

Reason: Movement of molecules inside xylem is unidirectional i.e. always upwards.

  • 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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55.

Assertion: Light is one of the important factor in transpiration.

Reason: It induces stomatal opening and closing. Therefore, transpiration increases in light and
decreases in dark.

  • 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.


56.

Which of the following helps in ascent of sap?

  • Root pressure

  • Transpiration

  • Capillarity

  • All of these


57.

Grafting is successful in dicots but not in monocots because the dicots have

  • vascular bundles arranged in a ring

  • cambium for secondary growth

  • vessels with elements arranged end to end

  • cork cambium


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58.

In the sieve elements, which one of the following is the most likely function of P-proteins

  • Deposition of callose on sieve plates

  • Providing energy for active translocation

  • Autolytic enzymes

  • Sealing mechanism on wounding


D.

Sealing mechanism on wounding

Sieve elements are a component of phloem tissue and are responsible for conduction of food in plants. A sieve tube element has peripheral layer of cytoplasm without any nucleus. The central part is occupied by a network of canals which contain fibrils of p-protein. The protein is vibratite and is believed to actively participate in the transport of nutrients. One general property of its ability to form a gel and it functions as a puncture repair substance forming a plug at any site of damage in sieve element, thus preventing loss of food materials being translocated by the phloem. Thus it is believed to have scaling function on wounding.


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59.

A scion is grafted to a stock. The quality of fruits produced will be determined by the genotype of

  • stock

  • scion

  • both stock and scion

  • neither stock nor scion.


60.

Assertion: When the ambient temperature is high and soil contains excess of water, the plants tend to lose water in the form of droplets from lenticels.

Reason: Root pressure regulates the rate of loss of water form lenticels

  • 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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