Q6 of 67 Page 48

What is transpiration pull? How is it caused?

Transpiration pull is defined as the force imposed by the process of transpiration of water on the absorption and ascent of water from the soil.

As the water is lost from the surface of the leaf by transpiration, more water molecules is pulled up due to the tendency of the water molecules to remain joined, known as cohesion. Thus, it produces a continuous column of water through the stem.


More from this chapter

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4

Explain how soaked seeds swell up and burst their seed coats.

 5

Leaves of the sensitive plant wilt and droop down on a slight touch. What mechanism brings about this change?

 1

The following diagram represents a plant cell after being placed in a strong sugar solution.


Guidelines 1 to 5 indicate the following:


(1) Cell Wall


(2) Strong Sugar Solution


(3) Protoplasm


(4) Large vacuole


(5) Nucleus


(a) What is the state of the cell shown in the diagram?


(b) Name the structure which acts as a selectively permeable membrane.


(c) If the cell had been placed in distilled water instead of strong sugar solution, which feature would not have been seen?


(d) Name any one feature of this plant cell which is not present in an animal cell.

 2

A leaf cell of a water plant was placed in a liquid other than pond water. After some time, it assumed a shape as shown below:


(a) Give the term for the state of the cell it has acquired.


(b) Comment on the nature (tonicity) of the liquid surrounding the cell.


(c) Redraw in the space provided, the diagram of the cell if it is soon placed in ordinary water for some time.