in the structure of deoxyribonucleic acid dna which of the following bases combines with thymine
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1. In the structure of deoxyribonucleic acid (DNA), which of the following bases combines with thymine?

Correct answer: B

Rationale: The correct answer is B: Adenine. In the structure of DNA, adenine pairs with thymine through hydrogen bonding, forming one of the complementary base pairs that make up the double helix structure of DNA. Cytosine pairs with guanine, not thymine. Rhodamine and serine are not DNA bases and do not participate in DNA base pairing. Therefore, choices A, C, and D are incorrect.

2. The healthcare provider is planning care for a client at 30 weeks gestation who is experiencing preterm labor. Which medication is most important in preventing this fetus from developing respiratory distress syndrome?

Correct answer: B

Rationale: Betamethasone is a corticosteroid given to stimulate fetal lung maturity and reduce the risk of respiratory distress syndrome in preterm infants. Ampicillin (Choice A) is an antibiotic and does not prevent respiratory distress syndrome. Terbutaline (Choice C) is a tocolytic used to inhibit contractions and does not directly prevent respiratory distress syndrome. Butorphanol tartrate (Choice D) is an opioid analgesic and does not have a role in preventing respiratory distress syndrome in preterm infants.

3. Before meiosis, a sperm cell:

Correct answer: A

Rationale: Before meiosis, a sperm cell contains 46 chromosomes. This is because sperm cells, like other somatic cells, have a diploid number of chromosomes. During meiosis, the number of chromosomes is halved to 23 to combine with an egg cell during fertilization. Choice B is incorrect because a sperm cell carries either an X or a Y chromosome, not both (Choice D). Choice C is incorrect as sperm cells are generally smaller than egg cells, which is an adaptation that aids in motility and penetration of the egg during fertilization.

4. What is the structure of deoxyribonucleic acid (DNA)?

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.

5. Which of the following processes happen during mitosis?

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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