Nursing Elites

1. Choose the two bases that have two carbon rings:

• A. Adenine
• B. Cytosine
• C. Thymine
• D. Guanine

Correct answer: A

Rationale: Adenine and guanine have two carbon rings and are known as purines. These bases are found in nucleic acids such as DNA and RNA. Adenine (option A) and guanine (option D) are the correct choices as they both have two carbon rings in their molecular structure. Cytosine (option B) and thymine (option C) have a single carbon ring each, making them incorrect choices for bases with two carbon rings.

2. During which phase is the chromosome number reduced from diploid to haploid?

• A. S phase
• B. interphase
• C. mitosis
• D. meiosis I

Correct answer: D

Rationale: The correct answer is 'meiosis I.' During meiosis I, the chromosome number is reduced from diploid to haploid through two rounds of division. Choice A ('S phase') is incorrect as the S phase is part of the cell cycle where DNA is replicated. Choice B ('interphase') is also incorrect as interphase is the phase where the cell prepares for division. Choice C ('mitosis') is incorrect as mitosis is a process where a diploid cell divides to produce two identical diploid daughter cells, maintaining the chromosome number.

3. How does asexual reproduction differ from sexual reproduction?

• A. asexual reproduction results in all cells being identical to the original cell; sexual reproduction results in half of the cells being identical to the original cell
• B. asexual reproduction results in two cells that contribute genetic material to daughter cells, resulting in significantly greater variation
• C. sexual reproduction involves two cells that contribute genetic material to daughter cells, resulting in significantly greater variation
• D. sexual reproduction involves one cell that yields all cells produced to be identical

Correct answer: C

Rationale: Sexual reproduction involves two cells (gametes) that contribute genetic material to daughter cells, resulting in significantly greater genetic variation in the offspring. This genetic variation is essential for evolution and adaptation to environmental changes. In contrast, asexual reproduction involves one cell dividing to produce offspring that are genetically identical to the parent cell. Choice A is incorrect because sexual reproduction does not result in half of the cells being identical to the original cell; it involves two cells contributing genetic material. Choice B is incorrect because asexual reproduction does not result in significantly greater variation; it produces genetically identical offspring. Choice D is incorrect because sexual reproduction involves two cells contributing genetic material, not one cell yielding all identical cells.

4. As cattle graze, cattle egrets consume the insects they stir up. This is an example of ___________.

• A. Mutualism
• B. Parasitism
• C. Commensalism
• D. Competition

Correct answer: C

Rationale: Commensalism is a relationship between two species in which one benefits without affecting the other species. In this scenario, the cattle egrets benefit from the insects stirred up by cattle while the cattle are not significantly impacted by the presence of the egrets. The egrets obtain food easily, and the cattle are neither harmed nor helped by the egrets' presence, making it an example of commensalism. Mutualism involves both species benefiting, parasitism involves one species benefiting at the expense of the other, and competition involves both species being negatively affected by their interactions, none of which apply to the relationship between cattle and cattle egrets in this context.

5. Which is true of the term Phenotype?

• A. It is the genetic code
• B. Phenotype determines genotype
• C. Genotype determines phenotype
• D. Genotype, epigenetic factors, and environmental factors determine phenotype

Correct answer: D

Rationale: The term "phenotype" refers to the observable characteristics or traits of an organism, which are determined by a combination of genotype (genetic makeup), epigenetic factors (modifications to gene expression), and environmental factors (external influences and experiences). Genotype, epigenetic factors, and environmental factors all play a role in determining an individual's phenotype, making option D the correct statement. Options A, B, and C are incorrect because the phenotype is not the genetic code, the phenotype does not determine the genotype, and it is the genotype that influences the phenotype, not the other way around.

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