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HESI Focus on Maternity Exam
1. Humans begin life as a single cell that divides repeatedly. This cell is known as a(n):
- A. zygote.
- B. gonadotrope.
- C. embryo.
- D. chromaffin.
Correct answer: A
Rationale: A zygote is the correct answer. It is the initial cell formed when a sperm cell fertilizes an egg cell, marking the beginning of human development. Choice B, gonadotrope, is incorrect as it refers to a type of hormone-secreting cell in the pituitary gland. Choice C, embryo, is incorrect as it is the stage of development after the zygote has implanted into the uterine wall and undergone initial cell divisions. Choice D, chromaffin, is incorrect as it refers to cells found in the adrenal medulla that produce and store catecholamines.
2. The embryo and fetus develop within a protective _______ in the uterus.
- A. amniotic sac
- B. umbilical cord
- C. neural tube
- D. embryonic disk
Correct answer: A
Rationale: The correct answer is A, the amniotic sac. The amniotic sac is a fluid-filled structure that surrounds and protects the developing embryo and fetus in the uterus. It provides a cushion against external pressure, allows for movement and growth, and helps maintain a stable environment for the developing fetus. Choices B, C, and D are incorrect. The umbilical cord connects the fetus to the placenta and serves as a conduit for nutrients and waste; the neural tube is a structure that forms the central nervous system in early embryonic development; and the embryonic disk is a structure that forms during gastrulation, one of the early stages of embryonic development.
3. After meiosis, each new cell nucleus contains _____ chromosomes.
- A. 46
- B. 35
- C. 23
- D. 12
Correct answer: C
Rationale: After meiosis, each resulting cell contains 23 chromosomes. Meiosis is a process that involves two sequential divisions resulting in four daughter cells, each with half the number of chromosomes as the parent cell. In humans, the parent cell has 46 chromosomes (diploid), and after meiosis, the resulting cells (sperm or ova) have 23 chromosomes (haploid). Choice A (46 chromosomes) is incorrect because this is the number of chromosomes in a human diploid cell before meiosis. Choices B (35 chromosomes) and D (12 chromosomes) are incorrect as they do not represent the correct number of chromosomes after meiosis in human cells.
4. During which of the following periods does the development of arms and legs occur in a pregnancy?
- A. Development of the lungs
- B. Development of the heart
- C. Development of arms and legs
- D. Development of the stomach
Correct answer: C
Rationale: The correct answer is C. The development of arms and legs occurs during the critical period of the fourth to eighth weeks of pregnancy. This timeframe is crucial for the formation of limbs and other key body parts. Choices A, B, and D are incorrect because the development of the lungs, heart, and stomach respectively occurs at different stages of fetal development and is not primarily associated with the fourth to eighth weeks of pregnancy.
5. Do dizygotic (DZ) twins run in families?
- A. Yes
- B. No
- C. Rarely
- D. Never
Correct answer: A
Rationale: Yes, dizygotic (DZ) twins can run in families. This is due to genetic factors that influence hyperovulation, where a woman releases multiple eggs during her menstrual cycle. This genetic predisposition can be passed down through generations, increasing the likelihood of having dizygotic twins. Choices B, C, and D are incorrect because the statement that dizygotic twins run in families is true, as supported by scientific evidence. It is important to note that while the genetic predisposition for dizygotic twins can run in families, it does not guarantee that every generation will have twins, as other factors also play a role in twin pregnancies.
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