12th Standard CBSE - Biology - Organisms and Populations

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Question - 1

Lichens are well known combination of an alga and a fungus where fungus has

  • A an epiphytic relationship with the alga
  • B a parasitic relationship with the alga
  • C a symbiotic relationship with the alga
  • D a saprophytic relationship with alga

Question - 2

Maximum growth rate occurs in 

  • A senescent phase
  • B lag phase
  • C exponential phase
  • D stationary phase

Question - 3

Zone of atmosphere near the earth surface is 

  • A Stratosphere
  • B Mesosphere
  • C Troposphere
  • D Thermosphere

Question - 4

In which one of the following habitats does the diurnal temperature of soil surface vary most?

  • A Forest
  • B Desert
  • C Grassland
  • D Shrub land

Question - 5

Photosynthetically active radiation (PAR) represents the following range of wavelength

  • A 450-950 nm
  • B 340-450 nm
  • C 400-700 nm
  • D 500-600 nm

Question - 6

A terrestrial animal must be able to

  • A Conserve water
  • B Actively pumps salts out through the skin
  • C Excrete large amounts of salt in urine
  • D Excrete large amounts of water in urine

Question - 7

What is a keystone species?

  • A A common species that has plenty of biomass, yet has a fairly low impact on the community's organization
  • B A race species that has minimal impact on the biomass and on other species in the community
  • C A dominant species that constitutes a larger proportion of the biomass and which affects many other species
  • D A species which makes up only a small proportion of the total biomass of community, yet has a huge impact on the community's organization and survival.

Question - 8

The term ecology was coined by

  • A Odum
  • B E. Munch
  • C Tansley
  • D Reiter

Question - 9

Animals have the innate ability to escape from predation. Examples for the same are given below. Select the incorrect example.

  • A colour change in chamaeleon
  • B enlargement of body size by swallowing air in puffer fish
  • C poison fangs in snakes
  • D melanism in months

Question - 10

The ability of the venus fly trap to capture insects is due to

  • A specialized 'muscle-like' cells
  • B chemical stimulation by the prey
  • C a passive process requiring no special ability on the part of the plant
  • D rapid turgor pressure changes
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