A population of 100 butterflies living on an acre of land loses three-quarters of its members when a sudden freeze in the spring occurs just after they emerge as caterpillars. This population has undergone a reduction in population size due to

The correct answer is - a density independent factor.

Explanation:

Any external cause or change that leads to the change in the size of a population regardless of the density of the particular population known as a density independent factor in ecology.

Density independent factors are the factors that are not affected by the size of the population size of the species such as weather, climate and natural disasters.

Thus, the correct answer is -  a density independent factor.

ans.

dna fingerprinting is defined as a process that determines the dna characteristics of an individual. these dna characteristics are unique among individuals as their fingerprints, so it is known as dna fingerprinting.

steps of dna fingerprinting includes extraction of dna from sample, amplification of dna, restriction digestion of amplified dna, and then analysis of dna by gel electrophoresis, respectively.

thus, the next step performed by the scientist is 'to cut the amplified dna (obtained by polymerase chain reaction) by restriction enzymes that cleave the dna into fragments and their analysis.'

protistas excret ethanol used in the manufacture of vinegar