Question

6. Which of these conditions will lead to evolution by natural selection? a. Heavy metal pollution reduces reproductive success of all phenotypes of green algae in the pond. b. Variation among individuals is not genetic; instead it results from learned behavior or physiological environmental responses. c. Introduction of an exotic predator species results in one native prey phenotype evading predation while other phenotypes get eaten. d. Individuals of the population are clones (genetically identical). 7. Which one is used as strict evidence that microevolution has occurred? a. males competing for female attention c. change in allele frequencies from one generation to the next b. increase in the frequencies of rare phenotypes d. genotype frequencies gets altered immediately after a large fire 8. Which statement is NOT true when an allele for a given locus is said to be fixed in a population? a. All individuals are homozygous for that locus c. There is no genetic variation in that locus. b. There is only one allele for that locus in the population d. Allele frequency for that locus equals 0. 9. An isolated population's allele frequencies appear to be randomly fluctuating over generations, losing some eventually and allowing alleles coding for harmful traits to get fixed. Which mechanism of evolution must be acti most strongly in this population? a. selfing (or mating with own kind) b. genetic drift c. natural selection 10. In a large sexually reproducing population, the frequency of an allele was consistently being reduced drastica from one generation to the next. From this change, one may logically infer that a. random processes changed the allelic frequencies c. the allele frequently mutates b. there is no sexual selection in the population d. natural selection was acting against the allele

Answer 1

6) answer is c.

Becose Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations.

7) answer is c.

Microevolution is simply a change in gene frequency within a population. Evolution at this scale can be observed over short periods of time — for example, between one generation and the next, the frequency of a gene for pesticide resistance in a population of crop pests increases.

8) answer is d.

A fixed allele is homozygous for all members of the population.

Because loci are located on chromosomes, and inherit one chromosome from each of our parents, each locus has two alleles.

The frequency of the allele is 100%, i.e. being the only gene variant present in any member, it is said to be "fixed" in the population. Allele frequency zero means the particular variant is absent from the population.

9) answer is b.

Genetic drift is the change in the frequency of an existing gene variant (allele) in a population due to random sampling of organisms. Evolution within species is caused by the random fluctuation of neutral allele frequencies, so by genetic drift, rather than natural selection. Genetic drift may cause gene variants to disappear completely and thereby reduce genetic variation. It can also cause initially rare alleles to become much more frequent and even fixed.