The basis of Mendelian genetics is

Correct Answer: B

Rationale: The correct answer is B: Both parents contribute a "haploid" gamete. In Mendelian genetics, offspring inherit one set of chromosomes from each parent, resulting in a combination of genetic material from both parents. This process involves the fusion of haploid gametes during fertilization, leading to genetic variation in the offspring. This fundamental principle of genetic inheritance is crucial in understanding Mendel's laws of segregation and independent assortment. A: Genes code for proteins - This statement is true but not the basis of Mendelian genetics. The relationship between genes and proteins is important but not specific to Mendelian genetics. C: One parent's genome is dominant - This statement is incorrect. Dominance is a concept related to gene expression, not the basis of Mendelian genetics. D: Genes can skip generations - This statement refers to non-Mendelian inheritance patterns, such as incomplete dominance or epistasis, which do not align with the basic principles of Mendelian genetics.

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: C

Rationale: The correct answer is C: It is a non-invasive technique. Ultrasound is safe and non-invasive, making it ideal for prenatal screening as it does not pose any risk to the mother or the fetus. Choices A and B are incorrect because ultrasound must be performed by a trained healthcare professional in a medical setting, not at home, and it requires specialized equipment and expertise, making it more expensive and reliant on advanced technology. Choice D is incorrect as choices A and B are not true, making it not all of the above.

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.