41.

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

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

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 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

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

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

• Lysozymes

• Lipolytic

• Lytic

• Lysogenic

A plant requires magnesium (Mg) for

• Holding cells together

• Protein synthesis

• Chlorophyll synthesis

• Cell wall development

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

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

In mammals, histamine is secreted by

• Fibroblasts

• Histocytes

• Lymphocytes

• Mast cells