Which of the following best describes a sequential design?

Correct Answer: B

Rationale: A sequential design permits researchers to check if cohort effects are operating. This design involves combining cross-sectional and longitudinal research, allowing for the comparison of different cohorts at different ages. By using this approach, researchers can determine if developmental changes observed are due to age or generation-specific factors. Therefore, a sequential design is valuable in addressing the potential influence of cohort effects on developmental outcomes. Choices A, C, and D are incorrect because a sequential design does not neglect diversity in developmental outcomes, is not necessarily less efficient than a longitudinal design, and can make both cross-sectional and longitudinal comparisons.

Correct Answer: B

Rationale: The correct answer is B. The corpus luteum is a temporary endocrine structure in the ovary that forms after ovulation. It secretes hormones, particularly progesterone, which help prepare the uterine lining for possible implantation of a fertilized ovum. This process is crucial for maintaining a potential pregnancy. Choices A, C, and D are incorrect. Choice A is inaccurate as fertilization typically occurs in the fallopian tubes. Choice C describes the fallopian tubes, not the corpus luteum. Choice D refers to the ovaries, not specifically the corpus luteum.

Correct Answer: B

Rationale: During the first week of pregnancy, the zygote (fertilized egg) undergoes rapid cell divisions and forms a blastocyst. This is a crucial stage where the cells differentiate and specialize, setting the foundation for the development of the embryo. It is during this time that the zygote implants itself into the uterine wall, initiating the process of pregnancy. Choices A, C, and D are incorrect because during the first week of pregnancy, the focus is on the initial development and multiplication of the zygote, not on the development of heart muscles, a primitive brain and spinal cord, or the embryo's ability to move.

Correct Answer: D

Rationale: The placenta delivers food and oxygen to the developing organism during pregnancy. It is a temporary organ that forms in the first trimester of pregnancy. Choice A is incorrect as the placenta forms in the first trimester, not the second trimester. Choice B is incorrect as the amniotic sac, not the placenta, encloses the developing organism in amniotic fluid. Choice C is incorrect as the placenta contains blood vessels (arteries and veins) that deliver nutrients to the embryo, not just one large vein.

Correct Answer: C

Rationale: During the last half of the first month of pregnancy, the nervous system develops the fastest among the options provided. This rapid development of the nervous system is crucial for the overall growth and functioning of the fetus. The nervous system includes the brain and spinal cord, which are essential for various bodily functions and will continue to develop throughout the pregnancy. The circulatory system, although important, does not develop at the fastest rate during this stage. The endocrine system and skin also play significant roles in the development of the fetus but are not the systems that develop the fastest in the last half of the first month of pregnancy.