Topic : Absorption and Movement of Water In Plants
In assertion / reason question the options given are:
Study the two statements labelled as Assertion (A) and Reason (R).
Point out if:(a) Both, A and R, are true and R is the correct explanation of A
(b) Both, A and R, are true but R is not the correct explanation of A
(c) If A is true but R is false
(d) If both assertion and reason are false.
(e) If A is false but R is true
1. Assertion : The layer of ground water is called water table.
Reason : No plants can use ground water.
2. Assertion : Plants growing in arid regions are mostly deep rooted.
Reason : Shallow rooted plants cannot survive dry periods.
Reason : Ultimate source of run off water is rain.
Answers With Explanation
1. Answer :- (c) Assertion is true but reason is false.
Ground water bearing previous stratum is known as aquifer. The upper layer of ground water is called water table. Very few plants can send their roots up to fringe of the water table due to deficiecy of air. The plants which do so, are called pheratophytes. e. g.Populus deltoides.
Populus deltoides ( Common Cottowood Plant)
2. Answer :- (a) Both assertion and reason are true and reason is the correct explanation of assertion.
Water is unavailable in the top layer of soil in arid conditions.. Therefor plants root go deep in the arid soils in order to absorb maximum water . e.g. Aerva persica ( 60 cm high plant with 6 m deep root), Welwitschia mirabilis (18m) ,Alfaalfa (38.7m). In arid region shallow rooted plants cannot survive dry periods due to deficiency of water in soil in upper layers.
Welwitschia mirabilis Plant in desert
3. Answer :- (e) Assertion is false but reason is true.
A part of rain water does not enter the soil but is drained away from soil surface along the slope. It is called run away water .It cannot be reabsorbed by plants.
(To be Discussed in Class when School reopens.)
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