Solved Examples on Transport in Plants

Question1: Two cells A and B are contiguous. Cell A has osmotic pressure 10 atm, turgor pressure 7 atm and diffusion pressure deficit 3 atm. Cell B has osmotic pressure 8 atm, turgor pressure 3 atm and diffusion pressure deficit 5 atm. The result will be [CBSE PMT’2007]

(a) no movement of water

(b) equilibrium between the two

(c) movement of water from cell A to B

(d) movement of water from cell B to A

Answer: c

Solution:

Movement of water will be from low DPD to high DPD i.e. from A to B.

Question2: Guard cells help in [CBSE PMT’2008]

(a) transpiration

(b) guttation

(c) fighting against infection

(d) protection against grazing

Answer: a

Solution:

Guard cells help in transpiration. Transpiration is the evaporation of water from the aerial parts of plants, especially leaves but also stems, flowers and roots. Stomatal opening allows the diffusion of carbon dioxide and oxygen during photosynthesis.

Question3: Guttation is the result of [CBSE PMT’2011 M]

(a) diffusion

(b) transpiration

(c) osmosis

(d) root pressure

Answer: d

Solution:

The main cause of guttation in plants is root pressure. During night when root pressure is high, sometimes due to this high pressure watery drops ooze out with the assistance of special structures  which help in guttation called hydathodes.

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