How do biologists make a gross estimate of the total number of species on Earth?

How do biologists make a gross estimate of the total number of species on Earth?
  1. By comparing the species richness of exhaustively studied group of insects
  2. By extrapolating the ratio to other groups of animals and plants
  3. By using statistical methods
  4. All of the above

Solution

Biologists make a gross estimate of the total number of species on Earth by comparing the species richness of an exhaustively studied group of insects, extrapolating this ratio to other groups of animals and plants, and using statistical methods.

Asked in: NCERT

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