Multiple Choice Questions

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Avena curvature test is a bioassay for examining the activity of

  • auxins

  • cytokinins

  • gibberellins

  • ethylene.


A.

auxins

Bioassay is a testing of biological activity like growth response of a substance by employing plant part. Avena curvature test is a bioassay for examining the activity of auxins. It is based upon experiments of Went. 10° curvature is produced by auxin concentration of150 g/lit at 250C and 90% relative humidity. It can measure auxin upto 300g/litre. Auxin from shoot tip or any other plant organ is allowed to diffuse in a standard size agar block. 15- 30 mm long oat coleoptile grown in dark is held vertically over water. 1 mm tip of colcoptile is removed without injuring the primary leaf. After 3 hours a second decapitation is carried out for 4mm distance. Primary leaf is now pulled loose and agar block supported against it at the tip of decapitated coleoptile. After 90- 100 mm the coleoptile is found to have bent. The curvature is measured


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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


The given figure shows an angiogram of the coronary blood vessel. Which one of the following statements correctly describes, what is being done

  • It is coronary artery which has a cancerous growth that is being removed.

  • It is coronary artery which is blocked by a plaque and the same is being cracked.

  • It is coronary vein in which the defective valves are being opened.

  • It is coronary vein blocked by a parasite (blood fluke) that is being removed.


In prokaryotes, chromatophores are

  • specialized granules responsible for colouration of cells

  • structures responsbile for organizing the shape of the organism

  • inclusion bodies lying free inside the cells for canying out various metabolic activities

  • internal membrane systems that may become extensive and complex in photosynthetic bacteria


Myxomycetes are

  • saprobes or parasites, having mycelia, asexual reproduction by fragmentation, sexual reproduction by fusion of gametes

  • slimy mass of multinucleate protoplasm, having pseudopodia-like structures for engulfing food, reproduction through fragmentation or zoospores

  • prokaryotic organisms, cellular or acellular, saprobes or autotrophic, reproduce by binary fission

  • eukaryotic, single-celled or filamentous, saprobes or autotrophic, asexual reproduction by fusion of two cells or their nuclei.


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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


'Ordines Anomali' of Bentham and Hooker includes
  • seed plants showing abnormal forms of growth and development

  • plants described only in fossil state

  • plants described in the literature but which Bentham and Hooker did not see in original

  • a few orders which could not be placed satisfactorily in the classification.


Tadpoles of frog can be made to grow as giant sized tadpoles, if they are

  • administered antithyroid substance like thiourea

  • administered large amounts of thyroxine

  • reared on a diet rich in egg yolk

  • reared on a diet rich in both egg yolk and glucose.


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.


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The function of leghaemoglobin during biological nitrogen fixation in root nodules of legumes is to

  • convert atmospheric N2 to NH3

  • convert ammonia to nitrite

  • transport oxygen for activity of nitrogenase

  • protect nitrogenase from oxygen