Multiple Choice QuestionsAssertion: Cytokinins increases shelf life of fruits and vegetables.
Reason : Cytokinins induce cell division.
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 one of the following methods is commonly used to maintain the genetic traits of a given plant
By propagating through seed germination
By propagating through vegetative multiplication
By generating hybrids through intergeneric pollination
By treating the seeds with gamma radiations
Phytohormones are
hormones regulating growth from seed to adulthood
growth regulators synthesised by plants and influencing physiological process
hormones regulating flowering
hormones regulating secondary growth.
The cells of the quiescent centre are characterised by
having dense cytoplasm and prominent nuclei
having light cytoplasm and small nuclei
dividing regularly to add to the corpus
dividing regularly to add to tunica
Assertion : Vernalization is acceleration of subsquent flowering by low temperature treatment.
Reason : Site of vernalization is apical meristem.
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
B.
If both assertion and reason are true but reason is not the correct explanation of assertion
Vernalization is coolong of seed during germination in order to accelerate flowering when it is planted.
In colder countries, there are cereals of 2 physiological types, i.e., winter cereals and spring
cereals. Winter cereals are sown in winter and flower in following summer whereas spring cereals are sown in spring and flower in summer.
If winter cereal are sown in spring, it shows vegetative growth but does not flower unless it receives low temperature of winter. However, they can be converted into spring cereal by providing artificial low temperature treatment, (i.e., springification.)
Some plants requiring low temperature requirement (vernalization) for flowering are Secale cereale (European rye), Triticum vulgare, Brassica oleracea, Beta vulgaris, Apium and Lolium perenne, etc.
Site of vernalization is apical meristem or all the meristematic cells. As a result of vernalization, a flowering hormone called "vernalin" is formed (reported by Melchers), but venalin has never been isolated. Once a plant is vernalized, it can be devernalized by exposing the plant to temperature of 30C or above. For establishing vernalization, plant should be kept at 20°Cfor 4-5 days.
Avena curvature test is a bioassay for examining the activity of
auxins
cytokinins
gibberellins
ethylene.
Gibberellins can promote seed germination because of their influence on
rate of cell division
production of hydrolyzing enzymes
synthesis of abscisic acid
absorption of water through hard seed coat
Pruning of plants promotes branching because the axillary buds get sensitized to
ethylene
gibberellin
cytokinin
indole acetic acid.
In a plant organ which is covered by periderm and in which the stomata are absent, some gaseous exchange still takes place through
aerenchyma
trichornes
pneumatophores
lenticels.
Cork cambium results in the formation of cork which becomes impermeable to water due to the accumulation of
resins
lignins
suberin
tannins.
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