In an area where DDT had been used extensively, the population of birds declined significantly because
birds stopped laying eggs
earthworms in the area got eradicated
cobras were feeding exclusively on birds
cobras were feeding exclusively on birds
D.
cobras were feeding exclusively on birds
DDT, its breakdown products and other chlorinated hydrocarbon pesticides posed an insidious threat to birds. These persistent poisons enter the food chain and they accumulate in the fatty tissues of organisms at lower trophic level and then tend to concentrate as they move through the food chain. This is called biomagnification or bioconcentration. The insidious aspect of this phenomenon is that large concentrations of chlorinated hydrocarbons do not usually kill the bird out right. Rather, DDT and its relatives alter the bird's calcium metabolism in a way that results in thing egg shells which are unable to support the weight of incubating bird. So, many of the birds eggs laid are not hatched. This causes a significant decline in the population of birds.
The figure below is the diagrammatic representation o the E.Coli vector pBR 322. Which one of the given options correctly identifies its certain components(s)?
Ori- original restriction enzyme
rop-reduced osmotic pressure
Hind III, Eco RI-selectable markers
Hind III, Eco RI-selectable markers
Removal of RNA polymerase -III from nucleoplasm will affect the synthesis of
tRNA
rRNA
mRNA
mRNA
Which part would be most suitable for raising virus-free plants for micropropagation?
Bark
Vascular tissue
Meristem
Meristem
Common cold differs from pneumonia in that
pneumonia is a communicable disease whereas the common cold is a nutritional deficiency disease
Pneumonia can be prevented by a live attenuated bacterial vaccine whereas the common cold has no effective vaccine
Pneumonia is caused by a virus while the common cold is caused by the bacterium haemophilus influenzae
Pneumonia is caused by a virus while the common cold is caused by the bacterium haemophilus influenzae
What is the figure given below showing in particular?
Ovarian cancer
Uterine cancer
Tubectomy
Tubectomy
Which one of the following is a wrong statement
Most of the forests have been lost in tropical areas
Ozone in upper part of atmosphere is harmful to animals
Greenhouse effect is a natural Phenomenon
Greenhouse effect is a natural Phenomenon
Evolution of different species in a given area starting from a point and spreading to other geographical areas is known as
Adaptive radiation
Natural selection
Migration
Migration
