We cannot remove deleterious alleles from the human population by selection (culling, assigned parentage, sterilization) because

Correct Answer: B

Rationale: Correct Answer: B Rationale: 1. Mutations are random and constantly occurring in populations. 2. Deleterious alleles can arise from new mutations. 3. Selectively removing carriers won't prevent new mutations. 4. Thus, even if carriers are eliminated, new carriers will emerge, making it impossible to completely eradicate deleterious alleles. 5. This perpetual nature of mutations undermines any effort to eliminate deleterious alleles effectively.

Correct Answer: C

Rationale: The correct answer is C because small chromosome deletions involving a number of linked genes can lead to contiguous gene syndromes due to the deletion affecting multiple genes in close proximity. This can result in a cluster of related symptoms or phenotypes. Choices A and B are incorrect because the presence or absence of centromere or telomere in the deletion does not directly lead to contiguous gene syndromes. Choice D is incorrect as the deletion affecting genes at the breakpoints may not necessarily cause contiguous gene syndromes unless multiple genes in close proximity are involved.

Correct Answer: B

Rationale: The correct answer is B because maternal serum testing is complicated due to the fact that none of the available tests are individually definitive for fetal abnormalities. This means that a single test cannot conclusively determine the presence or absence of abnormalities, requiring a combination of tests for a more accurate assessment. Other choices are incorrect because A focuses on the quality of tests rather than their definitive nature, C mentions the involvement of health care professionals which is not the main reason for complexity, and D refers to the contents of maternal serum rather than the limitations of individual tests.

Correct Answer: B

Rationale: The correct answer is B because FISH (Fluorescence In Situ Hybridization) uses specific DNA probes that target a particular chromosome or chromosomal region. This allows for the visualization and analysis of specific genetic information without the need for spreads of mitotic chromosomes. Choice A is incorrect because FISH does not necessarily use DNA from whole chromosomes. Choice C is incorrect as chromosomes play a crucial role in genetic information. Choice D is incorrect because while chromosomes contain both DNA and protein, this is not the reason why FISH can provide genetic information without spreads of mitotic chromosomes.

Correct Answer: B

Rationale: The correct answer is B because karyotypes are generated by comparing the binding of probes from the experimental sample to a normal sample. This comparison allows for the visualization of chromosomal abnormalities. By analyzing the differences in probe binding patterns between the two samples, one can identify any genetic variations or mutations present. This method helps in identifying structural abnormalities in chromosomes. Choice A is incorrect because the number of probes used does not determine the generation of karyotypes. Choice C is incorrect as maternal DNA signal versus fetal DNA signal is not relevant to generating karyotypes. Choice D is also incorrect because comparing lymphocytes versus fetal nucleated erythroblasts does not directly lead to the generation of karyotypes.