The fruit fly drosophila melanogaster has an allele that confers resistance to ddt and similar insecticides, laboratory strains of d. melanogaster have been established from flies collected in the wild in the 1930s (before the widespread use of insecticides) and the 1960s (after 20 years of ddt use) lab strains established in the 1930s have no alleles for ddt resistance. in lab strains established in the 1960s, the frequency of the ddt-resistance allele is 37%. which statement is correct? a. resistance to ddt evolved in some fruit flies in order to allow them to survive. b. alloles for ddt resistance arose by mutation during the period of ddt use because of selection for pesticide resistance. c. the evolutionary fitness associated with the heritable trait of ddt resistance changed once ddt use became widespread.

The statement which is correct is

The evolutionary fitness associated with the heritable trait of DDT resistance changed once DDT use became widespread.

Explanation:

In the 1930's,  the usage if insecticides was minimal. Hence, the genes for DDT resistance were absent or silent in the fruit flies at that time.

In the 1960's, the DDT resistant forms of fruit fly began occurring at this rate because they were better adapted to survive. According to Darwin, the species which are better able to adapt to the environment survive and are able to reproduce. Hence, with the passage of time the resistant forms of fruit fly will keep reproducing and increase in number.

what is shown in the image?

eukaryote

chloroplast

mitochondrion

submitted

answer: ice crystals in air

the water from the water body or another source of water gets evaporated as water vapor as an effect of heat on water. these water vapor rises in the upper layers of the earth atmosphere under high atmospheric pressure. the atmospheric pressure of these water molecules starts to decrease due to the effect of cold air. the invisible water vapor condenses into visible water droplets and ice crystals.these ice crystals and water droplets being less denser than the surrounding air floats on air as clouds.