How can chromosome “aberrations” arise?

Correct Answer: D

Rationale: The correct answer is D, "All of the above." Chromosome aberrations can arise through breakage, which may occur due to various factors such as errors during DNA replication or exposure to mutagens. Recombination can also lead to chromosome aberrations when there are errors in the exchange of genetic material between chromosomes. Additionally, radiation can cause chromosome aberrations by inducing DNA damage. Therefore, all the choices (A, B, and C) are valid mechanisms through which chromosome aberrations can arise.

Correct Answer: B

Rationale: The correct answer is B because noninvasive tests can provide accurate results without the need for invasive follow-up procedures like amniocentesis, reducing risks to the mother and fetus. Choice A is incorrect as noninvasive tests do not approach 100% detection for Down syndrome. Choice C is incorrect because noninvasive tests are typically done earlier in the pregnancy for better accuracy. Choice D is incorrect as noninvasive tests do not induce miscarriage, regardless of the baby's health status.

Correct Answer: C

Rationale: The correct answer is C because during Fluorescent In Situ Hybridization (FISH), the fluorescent probes specifically bind to target DNA sequences on chromosomes. When there is a rearrangement, the probes will separate or change color at the breakpoints, indicating the presence of a chromosomal rearrangement. This makes it easy to detect the location and extent of the rearrangement. Choice A is incorrect because FISH probes can bind to both normal and rearranged chromosomes. Choice B is incorrect because FISH probes do not cause chromosomes to change color; they simply show the presence of rearrangements through color separation. Choice D is incorrect because FISH probes are not full of rearranged chromosomes; they are used to detect rearrangements on chromosomes.

Correct Answer: D

Rationale: The correct answer is D, All of the above, because families with recurrent genetic problems have various options to consider. Decision not to have children can prevent passing on genetic issues. Adoption allows them to expand their family without genetic concerns. Sperm or egg donation provides the option of having biological children through a different genetic source. Therefore, all options - not having children, adoption, and donor options - are available to families dealing with recurrent genetic problems.

Correct Answer: D

Rationale: The correct answer is D, "All of the above." Unbalanced translocations, aneuploidy, and aneusomy can all be recurrent in a family due to genetic factors being passed down through generations. Unbalanced translocations involve an abnormal chromosomal arrangement, aneuploidy is the presence of an abnormal number of chromosomes, and aneusomy refers to an abnormal number of copies of a particular chromosome. These genetic abnormalities can be inherited and recur in families, making D the correct choice.