51.

Which one of the following is a characteristic feature of cropland ecosystem?

• Least genetic diversity

• The absence of weeds

• Ecological succession

• Ecological succession

Which of the following is a restriction endonuclease?

• Protease

• DNase I

• RNase

• RNase

Which of the following would appear as the pioneer organisms on bare rocks?

• Liverworts

• Mosses

• Green algae

• Green algae

The term ecosystem was coined by

• AG Tansley

• E Haeckel

• E Warrning

• E Warrning

Which of the following is required as inducer(s0 for the expression of lac operon?

• galactose

• lactose

• lactose and galactose

• lactose and galactose

When does the growth rate of a population following the logistic model equal zero? The logistic model is given as dN/dt = rN(1-N/K)

• when N nears the carrying capacity of the habitat

• when N/K equals zero

• when death rate is greater than birth rate

• when death rate is greater than birth rate

Which one of the following statements is not true?

• Exine of pollen grains is made up of sporopollenin

• Pollen grains of many species cause severe allergies

• Stored pollen in liquid nitrogen can be used in the crop breeding programmes

• Stored pollen in liquid nitrogen can be used in the crop breeding programmes

In bryophytes and pteridophytes, transport of male gametes requires

• insects

• birds

• water

• water

Analogous structures are a result of

• convergent evolution

• shared ancestry

• stabilising selection

• stabilising selection

Proximal end of the filament of stamen is attached to the

• connective

• placenta

• thalamus

• thalamus