Nursing Elites

1. Which of the following statements is true of mutations?

• A. Mutations can only occur by chance.
• B. Mutations produce sperm and ova cells.
• C. Mutations occur through radiation or other environmental influences.
• D. Mutations help adenine combine with guanine to form the single spiral structure of DNA.

Correct answer: C

Rationale: The correct answer is C. Mutations can occur due to environmental influences such as radiation, chemicals, or other external factors, leading to changes in the DNA sequence. Choice A is incorrect because mutations can also occur due to errors in DNA replication, not solely by chance. Choice B is incorrect as mutations affect the DNA sequence itself, not the production of specific cells. Choice D is incorrect because mutations involve changes in the DNA sequence and do not specifically involve the formation of the DNA structure.

2. After mitosis, the genetic code is identical in new cells unless _________ occur through radiation or other environmental influences.

• A. reductions
• B. expulsions
• C. conceptions
• D. mutations

Correct answer: D

Rationale: After mitosis, the genetic code is typically preserved and remains identical in the new cells. However, mutations can occur due to radiation or environmental influences, leading to changes in the DNA sequence and potentially altering the genetic code. Therefore, the correct answer is 'mutations.' Choices A, B, and C are incorrect because reductions, expulsions, and conceptions do not accurately describe the changes in the genetic code that can result from external factors. Mutations are the only option that reflects the alteration in the genetic code caused by external influences, making it the correct choice in this context.

3. Females with Turner syndrome:

• A. possess more thymine than cytosine.
• B. are taller than average.
• C. produce little estrogen.
• D. are more likely to give birth to twins.

Correct answer: C

Rationale: Turner syndrome is a chromosomal disorder in females characterized by short stature and underdeveloped ovaries, resulting in low estrogen production. This leads to symptoms such as delayed puberty and infertility. Choice A is incorrect because the chromosomal abnormality in Turner syndrome does not affect the thymine-cytosine ratio. Choice B is incorrect as females with Turner syndrome are typically shorter than average. Choice D is incorrect as Turner syndrome does not increase the likelihood of giving birth to twins.

4. Most victims of _____ die of respiratory infections in their 20s.

• A. Tay-Sachs disease
• B. cystic fibrosis
• C. Turner syndrome
• D. Klinefelter syndrome

Correct answer: B

Rationale: Individuals with cystic fibrosis have a genetic disorder that causes mucus to be thick and sticky, leading to blockages in the lungs and digestive system. This mucus buildup makes them more susceptible to severe respiratory infections, which can ultimately result in premature death in their 20s. Tay-Sachs disease (Choice A) is a genetic disorder that affects the nervous system, not typically causing respiratory infections. Turner syndrome (Choice C) and Klinefelter syndrome (Choice D) are chromosomal disorders that do not directly lead to the respiratory issues observed in cystic fibrosis.

5. 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.

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