A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait (aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants. 12. What is the most reasonable conclusion that can be drawn from the fact that the frequency of the recessive trait (aa) has not changed over time? A. The population is undergoing genetic drift B. The two phenotypes are about equally adaptive under laboratory conditions C. The genotype AA is lethal D. There has been a high rate of mutation of allele A to allele a E. There has been sexual selection favoring allele a 13. What is the estimated frequency of allele A in the gene pool? A. 0.25 B. 0.50 C. 0.75

B. 0.50

Explanation:

The estimated frequency of allele A in the gene pool is 0.50. Allele A is a variant form of gene which has different forms located at same position. Allele frequency determines common presence of genetic locus of an allele in the population. It is calculated by dividing the number of common allele that appears in the population by total number of copies of genes.

sulfur dioxide

explanation: acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. these substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.

primary succession occurs in essentially lifeless areas regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. secondary succession occurs