Nursing Elites

1. Which of the following pairs of bases is present in the rungs of the ladder-like structure of deoxyribonucleic acid (DNA)?

• A. Cytosine with guanine.
• B. Rhodamine with biotin.
• C. Diaminopurine with ribozyme.
• D. Serine with tyrosine.

Correct answer: A

Rationale: The correct answer is A: Cytosine with guanine. In the DNA double helix, cytosine always pairs with guanine forming a base pair, and adenine pairs with thymine. These complementary base pairs form the rungs of the ladder-like structure of DNA. Choice B, Rhodamine with biotin, is incorrect as they are not base pairs found in DNA. Choice D, Serine with tyrosine, is incorrect as they are amino acids, not DNA bases. Choice C, Diaminopurine with ribozyme, is also incorrect as ribozyme is an enzyme, not a base, and diaminopurine is not one of the standard bases found in DNA.

2. A woman at 26 weeks of gestation is being assessed to determine whether she is experiencing preterm labor. Which finding indicates that preterm labor is occurring?

• A. Estriol is not found in maternal saliva.
• B. Irregular, mild uterine contractions occur every 12 to 15 minutes.
• C. Fetal fibronectin is present in vaginal secretions.
• D. The cervix is effacing and dilated to 2 cm.

Correct answer: D

Rationale: The correct answer is D. Cervical changes such as effacement and dilation to 2 cm are strong indicators of imminent preterm labor. These changes, combined with regular contractions, can signify labor at any gestation. Estriol can be detected in maternal plasma as early as 9 weeks of gestation. Levels of salivary estriol have been linked to preterm birth. Irregular, mild contractions occurring every 12 to 15 minutes without cervical change are generally not concerning. While the presence of fetal fibronectin in vaginal secretions between 24 and 36 weeks of gestation may predict preterm labor, its predictive value is limited (20%-40%). Therefore, cervical changes provide more reliable information regarding the risk of preterm labor.

3. The _____ is the inner layer of the embryo from which the lungs and digestive system develop.

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

Correct answer: C

Rationale: The endoderm is the correct answer. It is the innermost layer of the embryo that gives rise to organs such as the lungs, digestive system, liver, and pancreas. The neural tube (Choice A) forms the brain and spinal cord, not the lungs or digestive system. Mesoderm (Choice B) develops into structures like muscles, bones, and circulatory system, not the lungs or digestive system. The umbilical cord (Choice D) serves as a connection between the embryo and the placenta, providing nutrients and oxygen, but it is not the layer from which lungs and digestive system develop.

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 processes happen during mitosis?

• A. Strands of deoxyribonucleic acid (DNA) break apart.
• B. Adenine combines with its appropriate partner, cytosine.
• C. Sperm and ova cells are created.
• D. Twenty-three chromosomes are created.

Correct answer: A

Rationale: The correct process that happens during mitosis is the breaking apart, replication, and division of DNA strands into two new cells, each with the same number of chromosomes as the original cell. Choice B is incorrect because it describes base pairing in DNA, not a process specific to mitosis. Choice C is incorrect as the creation of sperm and ova cells is related to meiosis, not mitosis. Choice D is incorrect because chromosomes are not created during mitosis; they are replicated and divided equally between the daughter cells.

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