Which scientist found that plots with more species showed less year-to-year variation in total biomass?

Write whether the following statements are true or false . (i) Communties with more species tend to be more stable that those with less species. (ii) David Tilman found that plots with less species showed less year-to-year variation in total biomass. (iii) A stable community must be resistant to invasions by ecotic species. (iv) Effect of reduction in diversity has been explained by Alexander von Humboldt through rivet popper hypothesis.

Assertion: A community with more species is more stable than that with less species. Reason: More the number of species, lesser the variation in the total biomass production year after year.

Assertion: Communities that comprise of more species tend to be more stable. Reason: A higher number of species results in less animal variation in total biomass.

How do scientists extrapolate the total number of species on earth ?

Which of the following statement/is /are wrong? I. Communities with more species, generally, tend to de more stable than those with less species. II. A stable community should show too much variation in productivity from year to year. III. The colonisation of tropical pacific Islands by humans is said to have led to the extinction of more than 2,000 species of native birds. IV. The accelerated rates of species extinctions that the world is facing now have nothing to do with human activities. V. The biological wealth of our planet has been declining rapidly and the accusing finger is clearly pointing to human activities .

Figure shows the variation of force acting on a boby with time. Assume the body to start from rest, the variation of its momentum with time is best represented by which plot?

Study the given graph and answer the question that follows the number of workers whose age is 32 years or more but less than 44 years is: