Amniocentesis and chorionic villus sampling

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: 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.

Correct Answer: A

Rationale: The correct answer is A because preimplantation diagnosis involves screening embryos for genetic abnormalities before they are transferred to the uterus, allowing for the exclusion of abnormal embryos. This ensures that only healthy embryos are selected for implantation, increasing the chances of a successful pregnancy. Choice B is incorrect because preimplantation diagnosis is not done for the creation of stem cells but rather to identify genetic abnormalities. Choice C is incorrect because the purpose of preimplantation diagnosis is not to make decisions about terminating pregnancies but to select healthy embryos for transfer. Choice D is incorrect because preimplantation diagnosis must be done before implantation to identify abnormal embryos and avoid transferring them.

Correct Answer: A

Rationale: Step-by-step rationale: 1. In vitro fertilization (IVF) is commonly used when a couple faces infertility issues. 2. IVF involves fertilizing an egg with sperm outside the body in a laboratory setting. 3. This method helps couples who struggle with conceiving naturally. 4. Choice A is correct as it aligns with the primary purpose of IVF for couples experiencing fertility problems. Summary: - Choice B is incorrect as preimplantation diagnosis is a separate procedure within IVF. - Choice C is incorrect as IVF is not primarily for observing early development but for assisting in conception. - Choice D is incorrect as the optimization of the fertilized egg is not the main goal of IVF, but rather achieving pregnancy for couples with fertility challenges.

Correct Answer: D

Rationale: Certainly! The correct answer is D because both ionizing and non-ionizing radiation originate from the sun (A), are part of the electromagnetic spectrum (C), and have the potential to cause cancer (B) depending on the dose and exposure. Ionizing radiation has higher energy and can directly damage DNA, leading to cancer. Non-ionizing radiation has lower energy but can still cause harm, such as skin burns or increasing cancer risk with prolonged exposure. Therefore, all of the above choices are correct as they accurately describe characteristics of both types of radiation.