Question

Which of the following can be detected by amniocentesis but not by chorionic villus sampling?

Inborn errors of metabolism

Trisomy 21 (Down syndrome)

Chromosome number

Klinefelter syndrome (XXY syndrome)

Aneuploidy

Microevolution can occur as the result of all of the following processes except ______.

natural selection

random mating

mutation

genetic drift

migration

Although natural selection works to decrease the frequency of deleterious alleles in a population's gene pool, deleterious recessive alleles often remain in the gene pool. What maintains deleterious recessive alleles in a population?

Ability to be hidden in heterozygotes

Migration

Nonrandom mating

Natural selection

Evolution

Answer 1

Which of the following can be detected by amniocentesis but not by chorionic villus sampling?

The correct answer is: Inborn errors of metabolism.

Explanation: Amniocentesis is a technique by which a small amount of amniotic fluid is sucked out of the amniotic sac for the prenatal diagnosis of chromosome abnormalities, sex determination and also other fetal problems.

On the other hand, chorionic villus sampling is one type of technique by which genetic disorders or chromosomal disorders can be diagnosed. In this process, chorion is taken for the examination.

Both of these techniques can be used to detect Trisomy 21 (Down syndrome), chromosome number and Klinefelter syndrome (XXY syndrome), and aneuploidy. Amniocentesis can be used to detect inborn errors of metabolism but chorionic villus sampling cannot be used to detect that because it does not contain the amniotic fluid.

Microevolution can occur as the result of all of the following processes except ______.

The correct answer is: random mating.

Explanation: Microevolution reflects changes in DNA sequences and allele frequencies within a species over time. According to Hardy-Weinberg law, the allele frequency does not change in a population from one generation to the next if there is random mating taking place and there is no mutation, no natural selection, no migration within that population and the population should be large (so that genetic drift does not work and therefore the allele frequency remains constant). So, microevolution can occur as the result of all of the following processes except random mating.

Although natural selection works to decrease the frequency of deleterious alleles in a population's gene pool, deleterious recessive alleles often remain in the gene pool. What maintains deleterious recessive alleles in a population?

The correct answer is: Ability to be hidden in heterozygotes.

Explanation: Natural selection is a process by which the forms of organisms in a population that are the best adapted increase in frequency relative to the less adapted form over a number of generation. Genetic changes that decrease the organism's fitness tend to disappear. So the frequency of deleterious alleles decreases in the population because of the natural selection. But those deleterious alleles often remain in the gene pool because these alleles can hide in the form of heterozygous.