During pregnancy, the placenta __________.

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: The correct answer is the third month of pregnancy (choice B). During the third month of pregnancy, which is around 9-12 weeks, a fetal heartbeat can typically be heard using a stethoscope. This is an exciting milestone for expectant parents as it provides reassurance about the baby's well-being. Choices A, C, and D are incorrect because by the fourth week of pregnancy, the fetal heartbeat is not usually detectable with a stethoscope. The end of the second trimester and the beginning of the third trimester are too late in the pregnancy timeline for this milestone.

Correct Answer: B

Rationale: A baby born between the seventh and eighth months of pregnancy is considered premature. Premature babies are born before they are fully developed and may need assistance with breathing, including oxygen. They are at a higher risk for complications compared to full-term babies. Choice A is incorrect because premature babies are at a higher risk for health issues compared to full-term babies. Choice C is incorrect as modern medical advancements have significantly increased the survival rate of premature babies. Choice D is incorrect as being small-for-date does not solely depend on the gestational age at birth.

Correct Answer: D

Rationale: The harm done by teratogens depends on the age at the time of exposure. This means that the effects may vary depending on the developmental stage of the fetus when exposed to the teratogen. Teratogens can have different impacts at different stages of pregnancy, leading to a range of potential outcomes in terms of physical and/or cognitive development. Choices A, B, and C are incorrect because the harm caused by teratogens is not straightforward, may not be apparent at birth, and can go beyond physical damage, affecting cognitive development as well.

Correct Answer: B

Rationale: Mateo, being born prematurely to a cocaine-addicted mother, is at risk for several health issues. One common effect of prenatal drug exposure is a higher likelihood of sensory and regulatory problems, such as having abnormally shrill and piercing cries. This is a potential outcome that Mateo's caregivers can expect due to his circumstances. Choice A is incorrect as there is no direct correlation between being born prematurely to a cocaine-addicted mother and being very attentive to the environment. Choice C is incorrect as overcoming harmful effects of drug exposure by age 3 is overly optimistic and may not be the case for all children exposed to drugs prenatally. Choice D is incorrect as rapid motor development is not typically associated with prenatal drug exposure.