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HESI Focus on Maternity Exam
1. Which of the following statements is true of a sperm cell?
- A. A sperm cell is significantly larger than an egg cell.
- B. A sperm cell contains two Y chromosomes.
- C. A sperm cell travels randomly inside a woman’s reproductive tract.
- D. A sperm cell is one of the smallest types of cells in the body.
Correct answer: D
Rationale: The correct answer is D. A sperm cell is indeed one of the smallest cells in the human body, much smaller than an egg cell. Choice A is incorrect as sperm cells are much smaller than egg cells. Choice B is incorrect because a sperm cell carries either an X or a Y chromosome, not two Y chromosomes. Choice C is incorrect since sperm cells move in a purposeful manner guided by various factors within a woman's reproductive tract, not randomly.
2. What is the structure of deoxyribonucleic acid (DNA)?
- A. single spiral
- B. double helix
- C. sphere
- D. cube
Correct answer: B
Rationale: The correct answer is B: double helix. DNA is structured as a double helix, resembling a twisted ladder made up of two strands of nucleotides. Choice A, single spiral, is incorrect as DNA is not a single spiral structure. Choice C, sphere, is incorrect as DNA does not form a spherical shape. Choice D, cube, is incorrect as DNA does not have a cubic structure. Understanding the double helix structure of DNA is essential as it allows for the storage and transmission of genetic information in living organisms.
3. Which of the following is a fatal genetic neurologic disorder whose onset is in middle age?
- A. Tay-Sachs disease
- B. Duchenne muscular dystrophy
- C. Hemophilia
- D. Huntington’s disease
Correct answer: D
Rationale: Huntington's disease is a fatal genetic neurologic disorder characterized by progressive nerve cell degeneration in the brain. It typically manifests in middle age with symptoms such as involuntary movements, cognitive decline, and psychiatric disturbances. Tay-Sachs disease (Choice A) is a genetic disorder that primarily affects the nervous system in early childhood, not middle age. Duchenne muscular dystrophy (Choice B) is a genetic disorder that primarily affects muscle function and usually presents in early childhood. Hemophilia (Choice C) is a genetic disorder related to blood clotting, and its onset is not typically in middle age.
4. What determines a child’s sex?
- A. Presence of teratogens at the time of conception.
- B. Sex chromosome received from the mother.
- C. Presence of teratogens at the time of ovulation.
- D. Sex chromosome received from the father.
Correct answer: D
Rationale: The correct answer is the sex chromosome received from the father. The father contributes either an X or Y chromosome, which determines the child's sex. This occurs at the moment of fertilization when the sperm carrying either an X (resulting in a female) or Y (resulting in a male) chromosome fertilizes the egg. Choices A, B, and C are incorrect because the presence of teratogens at the time of conception or ovulation does not determine the child's sex. While the sex chromosome received from the mother is important, it is the father's contribution that ultimately determines the child's sex.
5. Which of the following statements is true about Tay-Sachs disease?
- A. It is most commonly found among children in Jewish families of Eastern European background.
- B. Children who have this disease suffer from excessive production of mucus in the lungs and pancreas.
- C. It is most commonly found among children in Asian American families.
- D. Children who have this disease suffer from muscular dystrophy characterized by a weakening of the muscles.
Correct answer: A
Rationale: The correct answer is A. Tay-Sachs disease is most commonly found among Jewish families of Eastern European descent. It is a fatal genetic disorder that affects the nervous system. Choice B is incorrect because Tay-Sachs disease does not involve excessive mucus production in the lungs and pancreas. Choice C is incorrect as it states that Tay-Sachs disease is most commonly found among Asian American families, which is inaccurate. Choice D is also incorrect because Tay-Sachs disease does not cause muscular dystrophy characterized by weakening of the muscles.
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