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Organisms and Populations

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Biology

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Biology

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CBSE Gujarat Board Haryana Board

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Class 10 Class 12

Which one of the following is categorised as a parasite in the true sense?

  • Human foetus developing inside the uterus draws nourishment from the mother

  • Head louse living on the human scalp as well as laying eggs on human hair

  • The cuckoo (koel) lays its eggs in crow's nest

  • The female Anopheles bites and sucks blood from humans


B.

Head louse living on the human scalp as well as laying eggs on human hair

Human louse (pediculus) lives among hair and surface of human body feeding on blood. It spreads diseases like typhus.

Human louse (pediculus) lives among hair and surface of human body feeding on blood. It spreads diseases like typhus.


Ants give information to their companions :
  • by dancing
  • by secretion of pheromones
  • by making sound
  • by defecating

B.

by secretion of pheromones

Population density is denoted by the symbol
  • N
  • D
  • M
  • D

A.

N

To live in groups is beneficial because :
  • feeling of security
  • can obtain food easily
  • Partner is available for mating
  • All the above

D.

All the above

The departure of a individual from a population is called :
  • Natality 
  • Mortality
  • Immigration 
  • Emigration

D.

Emigration

The number of births during a given period in the
population that are added to the initial density is 

 :
  • Natality
  • Mortality
  • Migration
  • Immigration

A.

Natality