Multiple Choice QuestionsAssertion: Movement of materials inside phloem is bidirectional i.e. it can be both upwards or downwards.
Reason: Movement of molecules inside xylem is unidirectional i.e. always upwards.
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.
Assertion: Light is one of the important factor in transpiration.
Reason: It induces stomatal opening and closing. Therefore, transpiration increases in light and
decreases in dark.
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.
Which of the following helps in ascent of sap?
Root pressure
Transpiration
Capillarity
All of these
Grafting is successful in dicots but not in monocots because the dicots have
vascular bundles arranged in a ring
cambium for secondary growth
vessels with elements arranged end to end
cork cambium
In the sieve elements, which one of the following is the most likely function of P-proteins
Deposition of callose on sieve plates
Providing energy for active translocation
Autolytic enzymes
Sealing mechanism on wounding
A scion is grafted to a stock. The quality of fruits produced will be determined by the genotype of
stock
scion
both stock and scion
neither stock nor scion.
Assertion: When the ambient temperature is high and soil contains excess of water, the plants tend to lose water in the form of droplets from lenticels.
Reason: Root pressure regulates the rate of loss of water form lenticels
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.
Assertion: 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
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