Competitive Exams: Botany MCQs (Practice-Test 43 of 104)

    • Assertion (A): The secondary phloem constitutes a less prominent part of the tree trunk than the secondary xylem.
    • Reason (R): The amount of phloem produced by the vascular cambium is smaller than that of secondary xylem.
    1. Both A and R are true and R is the correct explanation of A

    2. Both A and R ate true but R is not a correct explanation of A

    3. A is true but R is false

    4. A is false but R is true

    • Assertion (A): The foliose lichen fixes considerable amount of atmospheric nitrogen which is released as nitrate by talus decomposition.
    • Reason (R): Since lichens are efficient bioaccumulations, one would expect them to contribute to nutrient cycling in the forest ecosystem.
    1. Both A and R are true and R is the correct explanation of A

    2. Both A and R ate true but R is not a correct explanation of A

    3. A is true but R is false

    4. A is false but R is true

    • Assertion (A): If the protein-sheath of a virus is removed, it can infect many hosts.
    • Reason (R): By removing protein-sheath of a virus, genetic matter can be activated to enable it to infect any host.
    1. Both A and R are true and R is the correct explanation of A

    2. Both A and R ate true but R is not a correct explanation of A

    3. A is true but R is false

    4. A is false but R is true

    • Assertion (A): The allotter enzyme show a ‘Sigmoid’ curve when their activity is plotted against substrate concentration.
    • Reason (R): The allosteric enzymes deviate from Michaelis-Menten behavior.
    1. Both A and R are true and R is the correct explanation of A

    2. Both A and R ate true but R is not a correct explanation of A

    3. A is true but R is false

    4. A is false but R is true

    • Assertion (A): When an apical bud is removed, several auxiliary buds start growing.
    • Reason (R): Cytokines produced in roots move into the shoot system.
    1. Both A and R are true and R is the correct explanation of A

    2. Both A and R ate true but R is not a correct explanation of A

    3. A is true but R is false

    4. A is false but R is true

    • Assertion (A): Senescence is delayed by the application of cytokine in plants.
    • Reason (R): Cytokine prevents the breakdown of chlorophyll, protein and nucleic acids.
    1. Both A and R are true and R is the correct explanation of A

    2. Both A and R ate true but R is not a correct explanation of A

    3. A is true but R is false

    4. A is false but R is true

    • Assertion (A): A short day plant will flower if the long inductive dark period is interrupted with red light.
    • Reason (R): Photoperiodic flowering response of such a kind is under the control of phytochrome.
    1. Both A and R are true and R is the correct explanation of A

    2. Both A and R ate true but R is not a correct explanation of A

    3. A is true but R is false

    4. A is false but R is true

    • Assertion (A): Formation of two noncrossover and two crossover types from a pair of homologous chromosomes, is the result of a single chiasma.
    • Reason (R): Crossing over takes place between whole chromosomes.
    1. Both A and R are true and R is the correct explanation of A

    2. Both A and R ate true but R is not a correct explanation of A

    3. A is true but R is false

    4. A is false but R is true

    • Assertion (A): Eradication of alternative host barberry reduces opportunities for the development of new races of the rust fungus through genetic recombination of barberry.
    • Reason (R): Eradication of alternate host barberry does not contribute to the success of breeding resistant varieties.
    1. Both A and R are true and R is the correct explanation of A

    2. Both A and R ate true but R is not a correct explanation of A

    3. A is true but R is false

    4. A is false but R is true

    • Assertion (A): By using trap crops in a crop rotation programmee, the population of nematode in soil is reduced considerably.
    • Reason (R): Trap crops parasitize nematodes and kill them.
    1. Both A and R are true and R is the correct explanation of A

    2. Both A and R ate true but R is not a correct explanation of A

    3. A is true but R is false

    4. A is false but R is true

    • Assertion (A): The most characteristic property of Agro bacterium tumefactions is its ability to transform normal host cell to tumor cell.
    • Reason (R): The tumor cell is dependent on the bacterium and continues to grow only when the bacterium is present
    1. Both A and R are true and R is the correct explanation of A

    2. Both A and R ate true but R is not a correct explanation of A

    3. A is true but R is false

    4. A is false but R is true

    • Assertion (A): Jojoba hohoba (Simmondsia chine sis) is the only known flowering plant in which the food reserve is neither starch nor an oil, but a liquid wax.
    • Reason (R): Though the wax if formed by the combination of fatty acids with an alcohol, the alcohol is not the trihy dric alcohol is not the trihedral alcohol glycerol.
    1. Both A and R are true and R is the correct explanation of A

    2. Both A and R ate true but R is not a correct explanation of A

    3. A is true but R is false

    4. A is false but R is true

    • Assertion (A): Epiphytic orchids are adapted to grow on stems and branches of big trees.
    • Reason (R): This adaptation ensures them high light intensity as they remain in an elevated position form the ground surface.
    1. Both A and R are true and R is the correct explanation of A

    2. Both A and R ate true but R is not a correct explanation of A

    3. A is true but R is false

    4. A is false but R is true

    • Assertion (A): Biomass and energy are inters dependent.
    • Reason (R): Biomass and energy are inters dependent by suitable conversion technology.
    1. Both A and R are true and R is the correct explanation of A

    2. Both A and R ate true but R is not a correct explanation of A

    3. A is true but R is false

    4. A is false but R is true

    • Assertion (A): If sufficient water is available, deserts are highly productive.
    • Reason (R): Evaporation of water in deserts results in accumulation of salts at the surface.
    1. Both A and R are true and R is the correct explanation of A

    2. Both A and R ate true but R is not a correct explanation of A

    3. A is true but R is false

    4. A is false but R is true