Multiple Choice QuestionsAssertion: In angiosperms the conduction of water is more efficient because their xylem has vessels.
Reason: Conduction of water by vessel elements is an active process with energy supplied by xylem parenchyma rich in mitochondria
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.
C.
If assertion is true but reason is false
Xylem is the main conducting tissue in plants. It consists of 4 different components-tracheids, trachea or vessels, xylem fibre and xylem parenchyma.
Tracheids are elongated cells with tapering end. They arc generally present in ferns and gymnosperms for conduction of water. In angiosperms, vessels are composite structure as these are formed by dissolution of end walls of row of cells i.e., vessels elements. So angiosperms, have more efficient system of conduction due to presence of vessels. Conduction of water by vessel elements is also known as ascent of sap. Water absorbed by roots, goes upward to replace the water loss by transpiration. The most accepted theory for ascent of sap is transpiration pull theory i.e., when water is lost by transpiration from the leaves, a tension is created in the xylem and due to this water absorbed by roots hair is passed through vessels to the leaves. The xylem parenchyma are mainly for storage function but sometimes help in conduction.
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
The plant undergoes wilting when
xylem is blocked
cambium is blocked
phloem is blocked
some roots are reduced in number
Ectophloic siphonostele is found in
Osmunda and Equisetum
Marsilea and Botrychium
Adiantum and Cucurbitaceae
Dicksonia and Maiden hair fern
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