Human Growth and Development Exam 1

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: B

Rationale: Low-level radiation, whether from industrial leakage or medical X-rays, can increase the risk of childhood cancer by potentially damaging the developing fetus's cells. Even though the risk is relatively low, it is still a significant concern that should be acknowledged and monitored closely, especially during prenatal development. Choice A is incorrect as low-level radiation can still be harmful on its own without the need to be combined with other teratogens. Choice C is incorrect because low-level radiation exposure can indeed cause lasting damage, especially in the context of childhood cancer risk. Choice D is incorrect because low-level radiation exposure, even during the last trimester, can pose risks to the developing fetus and is not considered entirely safe.

Correct Answer: D

Rationale: Charles Darwin's theory of evolution emphasized natural selection and survival of the fittest. Natural selection is the process by which organisms with traits that help them survive and reproduce in their environment are more likely to pass on these traits to their offspring. Survival of the fittest refers to the idea that the organisms best adapted to their environment are more likely to survive and reproduce, leading to the gradual evolution of species over time. Both concepts are central to Darwin's theory of evolution. Choices A, B, and C are incorrect as they do not accurately reflect the key principles highlighted by Darwin in his theory of evolution.

Correct Answer: C

Rationale: Tammy's father likely believes that athletic ability is mostly determined by nature because he believes she showed great promise at a young age, indicating a natural talent or genetic predisposition towards gymnastics. This suggests that he attributes Tammy's abilities to her inherent qualities rather than her upbringing or experiences (nurture). While stages and early experiences can play a role in skill development, in this context, the emphasis is on innate abilities, making 'nature' the most suitable choice.