What could Mendel do with his plants that we cannot do with people?

Correct Answer: D

Rationale: Certainly! Mendel could look at several traits in the same cross with his plants because they exhibit clear and distinct traits that are easy to observe and manipulate. This allowed him to study inheritance patterns of multiple traits simultaneously. In contrast, it is challenging to observe and manipulate multiple traits in people due to complex genetic interactions and environmental factors. This makes it difficult to isolate and study individual traits in humans compared to plants. Therefore, the ability to study several traits in the same cross is a unique advantage that Mendel had with his plants, making option D the correct answer.

Correct Answer: D

Rationale: The correct answer is D because all factors listed (A, B, and C) can influence the clinical effects of chromosome aberrations. A) Whether genetic material is lost or gained affects the function of genes. B) The amount of genetic material lost or gained can lead to more severe consequences. C) Euchromatic vs. heterochromatic material influences gene expression and function. Therefore, considering all these factors together provides a comprehensive understanding of the clinical effects of chromosome aberrations. Other choices are incorrect because they only focus on individual aspects and do not provide a holistic view.

Correct Answer: A

Rationale: Step 1: Amniocentesis and chorionic villus sampling are prenatal diagnostic tests. Step 2: These tests are performed to access fetal DNA for genetic analysis. Step 3: Amniocentesis involves extracting amniotic fluid, while chorionic villus sampling involves collecting cells from the placenta. Step 4: Both procedures allow for genetic testing of the fetus. Step 5: Choice A is correct as it accurately describes the purpose of these tests. Summary: Choices B, C, and D are incorrect because they do not accurately reflect the main purpose of amniocentesis and chorionic villus sampling, which is to access fetal DNA for genetic analysis, not to result in induced miscarriage, not just when non-invasive techniques are uninformative, and not necessarily to document a genetic defect.

Correct Answer: A

Rationale: Step 1: Unique DNA sequences are low copy number regions that are present in the genome in limited copies. Step 2: These sequences anneal slowly because of their low copy number, making them distinct from high copy number sequences. Step 3: Unique sequences can include functional genes as well as non-coding regions. Step 4: By combining steps 1-3, we can conclude that all of the above statements are true for unique DNA sequences, making option A correct. Summary: Option B is incorrect because the slow annealing is specific to unique sequences. Option C is incorrect as unique sequences can include non-functional regions too. Option D is incorrect because unique sequences can represent more than 1.5% of the human genome.

Correct Answer: D

Rationale: The correct answer is D (All of the above). Fetal cells in maternal blood include lymphocytes, nucleated erythroblasts, and extra villus cytotrophoblasts. Lymphocytes can cross the placental barrier, nucleated erythroblasts are fetal blood cells, and extra villus cytotrophoblasts are from the placenta. These fetal cells can be detected in maternal blood samples through various methods, making D the correct choice. Choices A, B, and C are incorrect as they only represent specific types of fetal cells found in maternal blood, while D encompasses all potential types.