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 Multiple Choice QuestionsMultiple Choice Questions

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1.

Companion cell in plants are associated with

  • vessels

  • sieve elements

  • sperms

  • guard cells


B.

sieve elements

Companion cell A type of cell found within the phloem of flowering plants. Each companion cell is usually closely associated with a sieve element. Its function is uncertain, though it appears to regulate the activity of the adjacent sieve element and to take part in loading and unloading sugar into the sieve element. In gymnosperms a similar function is attributed to albuminous cells, which are found closely associated with gymnosperm sieve elements


2.

Assertion : A plant girdled upto bast will die.

Reason : Food transportation in such plant will cease followed by ceasation of water transport.

  • If both Assertion and Reason are true and Reason is the correct explantion of Assertion

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

  • If Assertion is true but Reason is false

  • If Assertion is false but Reason is true


A.

If both Assertion and Reason are true and Reason is the correct explantion of Assertion

A plant girdled upto bast will show below the girdled part, the non transportation of the food which occurs through phloem (bast). Water transport from roots to other plant parts via xylem will continue till root cells do not die due to starvation.


3.

The magnitude of root pressure ranges from

  • 2-5 atm

  • 0.1-0.2 atm

  • 1-5 atm

  • 4-6 atm


C.

1-5 atm

The term root pressure was coined by Stephen Hales (1727). The evidences that support the existence of this phenomenon are bleeding and guttation. The magnitude of root pressure is 1-2 atm and very rarely 5 atm.


4.

Assertion : Long distance flow of photoassimilates in plants occurs through sieve tubes.

Reason : Mature sieve tubes have parietal cytoplasm and perforated sieve plates.

  • 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


A.

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

The main function of sieve tube is the transport of food products from green and storage organs of the plant to other organs of the plant. The sieve clements are sieve tubes arranged one above the other and have sieve plates (obligue or transverse perforated septa) on their end walls. The cytoplasm occur in the form of a thin living layer along the inner side of cellulose wall. The nucleus disappears in mature sieve elements.


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5.

The real forces responsible for the movement of water from one cell to another cell is mainly

  • Osmotic Pressure (OP)

  • Turgor Pressure (TP)

  • Diffusion Pressure Deficit (DPD)

  • imbibition


C.

Diffusion Pressure Deficit (DPD)

The net force with which water is drawn into a cell is equal to difference of OP and TP, known as diffusion pressure deficit or suction pressure. DPD of pure water is maximum (= 1236 atm) solvent moves from cell of low DPD to high DPD. DPD, or SP= OP-TP.


6.

In plants, water moves from

  • less negative to more negative potentia

  • more negative to less negative potential

  • same potentials

  • none of the above


A.

less negative to more negative potentia

Water always moves from the area of high water potential to the area of low water potential i.e., from less negative potential to more negative potential.


7.

If turgor pressure becomes equal to the wall pressure, then

  • water leaves the cell

  • water enters the cell

  • no exchange of water takes place

  • solute goes from the cell into water


C.

no exchange of water takes place

Turgor pressure is the pressure that develops in a cell from time to time due to osmotic diffusion of water molecules into a cell resulting in the stretching of cell wall. Due to turgor pressure, rigid cell wall offers resistance. This resistance works in a direction opposite to turgor pressure. But it is equal to turgor pressure and is called wall pressure. In this condition, no exchange of water takes place.


8.

Good soil is :

  • which holds whole of the water that enters into it

  • which allows percolating the water slowly from it

  • which allows water to pass very quickly from it

  • which allows limited amount of water to retain into it


B.

which allows percolating the water slowly from it

Good soil is a soil which allows percolating the water slowly from it. Minerals, air, water and organic matter are essential for maintaining a good soil structure that enables adequate air exchange and water drainage. Eg, alluvial soil.


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9.

Which one of the following does'nt help in molecule transport?

  • Diffusion

  • Osmosis

  • Surface tension

  • Active transport


C.

Surface tension

Surface tension does not help in molecule transport. The process of diffusion and osmosis transport molecules is without using energy but in case of active transport energy (ATP) is used.


10.

Wooden doors swell up and get stuck during the rainy season. This is due to the phenomenon of

  • imbibition

  • endosmosis

  • capillarity

  • deplasmolysis


A.

imbibition

Jamming of wooden frames during rains is caused by swelling of wood due to imbibition. (The absorption of water by the solid particles of a substance without forming a solution is called imbibition).


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