Katie wonders when she will first be able to hear her fetus's heartbeat through a stethoscope. You tell her that this should happen by the __________.

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: 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: C

Rationale: Anoxia during labor and delivery can cause cerebral palsy. Cerebral palsy is a group of disorders that affect a person's ability to move and maintain balance and posture. It is caused by damage to the developing brain, often due to a lack of oxygen during labor and delivery. Spina bifida (Choice A) is a neural tube defect that occurs during embryonic development and is not directly caused by anoxia during labor. Anencephaly (Choice B) is a severe neural tube defect where the baby is born without parts of the brain and skull, not typically caused by anoxia during labor. Muscular dystrophy (Choice D) is a genetic disorder characterized by progressive muscle weakness and is not directly related to anoxia during labor and delivery.

Correct Answer: B

Rationale: A small-for-date baby, also known as a small-for-gestational-age (SGA) baby, is a baby who is born below their expected weight considering the length of the pregnancy. This can be due to various factors including issues with growth restriction in the womb. Being small-for-date is different from being preterm (born prematurely) and does not necessarily mean that the baby was born early. Choice A is incorrect because being small-for-date does not specifically indicate being born several weeks or more before the due date. Choice C is incorrect because being small-for-date does not guarantee fewer problems than a preterm infant, as each baby's health outcomes can vary. Choice D is incorrect because while small-for-date babies may have initial difficulties, it does not guarantee that these issues will be outgrown by the preschool years.

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: Unlike adults, newborn babies see nearby objects most clearly. This is due to the fact that newborns have a limited ability to focus their eyes on objects that are farther away. Their visual acuity is not fully developed at birth, leading to clearer vision of objects situated at a close distance. Choice A is incorrect because newborn babies have a well-developed sense of smell. Choice C is incorrect as newborns typically show a preference for familiar voices, such as their mother's voice. Choice D is incorrect as newborns do not see unclearly across a wide range of distances; rather, their vision is clearer for nearby objects.

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.

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: B

Rationale: Passive smoking, also known as secondhand smoke, can have harmful effects on pregnancies. Research has shown that exposure to smoke-filled environments during pregnancy is linked to low birth weight, infant death, and childhood respiratory illnesses. Pregnant women should avoid exposure to secondhand smoke to protect the health of their unborn babies. Choice A is incorrect because passive smoking affects both the mother and the unborn child, not just children born to heavy smokers. Choice C is incorrect as it underestimates the risks of smoke-filled environments on unborn children. Choice D is incorrect as research has already established the harmful effects of passive smoking on pregnancies.