Multiple Choice Questions

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Viruses that infect bacterial multiplication and cause their lysis, are called

  • Lysozymes

  • Lipolytic

  • Lytic

  • Lysogenic


C.

Lytic

When bacteriophage infects a bacterium, it entirely depends on the host for its multiplication. It utilises the host machinery for replication and produce a large number of progeny phage particles. The bacterium cell undergoes lysis and dies to liberate a large number of these phage particles, which are each ready to start another cycle by infecting new bacterial cell. This cycle is known as lytic cycle.


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The quiescent centre in root meristem serves as a

  • Site for storage of food, which is utilised during maturation

  • Reservoir of growth hormones

  • Reserve for replenishment of damaged cells of the meristem

  • Region for absorption of water


A plant requires magnesium (Mg) for

  • Holding cells together

  • Protein synthesis

  • Chlorophyll synthesis

  • Cell wall development


In prokaryotes, chromatophores are

  • Specialised granules responsible for the colouration of cells

  • Structures responsible for organising the shape of the organism

  • Inclusion bodies lying free inside the cells for carrying out various metabolic activities

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


In mammals, histamine is secreted by

  • Fibroblasts

  • Histocytes

  • Lymphocytes

  • Mast cells


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Which one of the following pairs, is not correctly matched?

  • Abscisic acid - Stomatal closure

  • Gibberellic acid - Leaf fall

  • Cytokinin -  Cell division

  • IAA - Cell wall elongation


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 off mechanism on wounding


An example of the competitive inhibition of an enzyme is the inhibition of

  • Succinic dehydrogenase by malonic acid

  • Cytochrome oxidase by cyanide

  • Hexokinase by glucose-6-phosphate

  • Carbonic anhydrase by carbon dioxide


Two cells A and B are contiguous. Cell A has osmotic pressure 10 atm, turgor pressure-7 atm and diffusion pressure deficit 3 atm. Cell B has osmotic pressure 8 atm, turgor pressure 3 atm and diffusion pressure deficit 5 atm. The result will be

  • Movement of water from cell B to A

  • No movement of water

  • The equilibrium between the two

  • Movement of water from cell A to B


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Which one of the following precedes re-formation of the nuclear envelope during M-phase of the cell Cycle?

  • Decondensation from chromosome and reassembly of the nuclear lamina

  • Transcription from chromosome and reassembly of the nuclear lamina

  • Formation of the contractile ring and formation of the phragmoplast

  • Formaltion of the contractile ring and transcription from chromosomes