Nursing Elites

1. How many pairs of autosomes does a human zygote contain?

• A. 46
• B. 44
• C. 23
• D. 22

Correct answer: D

Rationale: A human zygote contains 22 pairs of autosomes and one pair of sex chromosomes, totaling 46 chromosomes. Therefore, the correct answer is 22. Choices A, B, and C are incorrect because they do not accurately represent the number of autosomes in a human zygote. Option A (46) represents the total number of chromosomes in a human zygote, not the number of autosomes. Option B (44) is incorrect as it does not account for the correct number of autosomes. Option C (23) is inaccurate since it represents the total number of chromosomes in a human gamete, not the number of autosomes in a zygote.

2. What is the central layer of the embryo from which the bones and muscles develop?

• A. neural tube
• B. mesoderm
• C. ectoderm
• D. umbilical cord

Correct answer: B

Rationale: The correct answer is mesoderm. The mesoderm is the middle layer of the embryo that gives rise to the bones, muscles, and other connective tissues. The neural tube (choice A) develops into the nervous system, not bones and muscles. The ectoderm (choice C) forms the skin and nervous system, not bones and muscles. The umbilical cord (choice D) is a structure that connects the developing fetus to the placenta; it is not a layer of the embryo that gives rise to bones and muscles.

3. According to a study in the year 2013 by Fellman, if a woman is a twin, if her mother was a twin, or if she has previously borne twins, then:

• A. she will bear only monozygotic (MZ) twins.
• B. the chances of her becoming pregnant decrease.
• C. she is likely to be a healthy mother.
• D. the chances rise that she will bear twins.

Correct answer: D

Rationale: According to the study, the chances of a woman bearing twins increase if she is a twin herself, if her mother was a twin, or if she has previously borne twins. Therefore, the correct answer is D. Choice A is incorrect because the study does not specify that she will bear only monozygotic twins. Choice B is incorrect as the study does not mention any decrease in the chances of becoming pregnant. Choice C is incorrect because the study does not provide information about the woman's health status, focusing instead on the likelihood of bearing twins.

4. Individuals with Klinefelter syndrome produce:

• A. less estrogen than normal males.
• B. less testosterone than normal males.
• C. less adenine than normal males.
• D. less thymine than normal males.

Correct answer: B

Rationale: Individuals with Klinefelter syndrome have an extra X chromosome (XXY), leading to reduced production of testosterone, the primary male sex hormone. This deficiency can result in various physical and developmental characteristics associated with the syndrome. Estrogen levels may actually be relatively elevated due to the imbalance between testosterone and estrogen. Choices C and D are incorrect as adenine and thymine are nucleotide bases found in DNA and are not related to hormone production.

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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