Question

there are four mechanisms that can cause changes in the frequencies of genes in populations: mutation, migration, genetic drift, and natural selection. all four are mechanisms of evolutionary change. what is genetic drift?
in a population, it is the changes in allelic frequencies of a gene that are due to chance.
there is variation in any population; differential reproduction occurs and over time a more advantageous trait exists in the population.
a random error/change in the dna sequence. these may be inherited or occur in cells during the lifetime of the organism.
also known as gene flow. it is any movement of individuals and/or the genetic material they carry, from one population to another.
dichlorodiphenyltrichloroethane, commonly known as ddt, is a chemical compound developed as an insecticide. examine the data (from 1959) displaying the percentage of ddt resistance in insect populations. what statement best explains the trend seen in the data in terms of evolution?
ddt resistant mosquitoes existed in the population. the presence of ddt selected for mosquitoes that survived the application. those resistant mosquitoes reproduced with more success.
ddt resistant mosquitoes were present in the population. those mosquitoes were able to be tracked with more success than ddt susceptible mosquitoes, which were better camouflaged in the environment and more difficult to collect data on.
ddt caused phenotypic changes to occur in populations of mosquitoes as the chemical alters the diet of the insects. mosquitoes with altered diets were able to survive with greater success than non - resistant mosquitoes.
the presence of ddt induced mutations in the insect populations. mosquitoes that needed mutations survived and reproduced with greater success.

Explanation:

• Question 9:
• Genetic drift is defined as changes in allelic frequencies of a gene in a population due to chance.
• The second option describes natural selection (differential reproduction of advantageous traits).
• The third option is about mutation (random DNA sequence change).
• The fourth option is gene flow (movement of individuals/genetic material between populations).
• Question 10:
• Natural selection explains the trend. DDT - resistant mosquitoes already existed. DDT selected for them (they survived and reproduced more).
• The second option about tracking is not relevant to the evolutionary trend of resistance.
• The third option about diet alteration is incorrect; DDT acts as a selective pressure, not by changing diet.
• The fourth option is wrong because mutations are random and not induced by the presence of DDT.

Answer:

• Question 9: In a population, it is the changes in allelic frequencies of a gene that are due to chance.
• Question 10: DDT resistant mosquitoes existed in the population. The presence of DDT selected for mosquitoes that survived the application. Those resistant mosquitoes reproduced with more success.