Nursing Elites

1. Duchenne muscular dystrophy is a recessive sex-linked trait carried on the X chromosome. In an example of an unaffected father and a female carrier who have two daughters and two sons, which is the predicted outcome?

• A. Both daughters will carry the disease.
• B. Both sons will carry the disease.
• C. One daughter may have the disease.
• D. One son may have the disease.

Correct answer: C

Rationale: Duchenne muscular dystrophy is a recessive sex-linked trait carried on the X chromosome. Since the father is unaffected and does not carry the disease, he must have a normal X chromosome. The mother is a carrier, which means she has one normal X chromosome and one X chromosome with the disease allele. The daughters will inherit one X chromosome from each parent; one would be normal, and the other has a chance of carrying the disease allele. So, there is a 50% chance that one daughter may have the disease, as she could inherit the X chromosome with the disease allele. The sons will inherit the Y chromosome from the father and the X chromosome from the mother, so they will not be affected by the disease. Therefore, the predicted outcome is that one daughter may have the disease, while the sons will not carry the disease. This rules out choices A, B, and D.

2. How does yeast reproduce?

• A. Binary fission
• B. Spore formation
• C. Budding
• D. Cloning

Correct answer: C

Rationale: Yeast typically reproduces through a process called budding. During budding, a small outgrowth forms on the parent yeast cell, gradually enlarging in size until it separates to become a new, genetically identical daughter cell. This method of reproduction allows yeast to rapidly multiply and grow in favorable conditions. It is different from binary fission, spore formation, and cloning. Binary fission involves the division of a single organism into two genetically identical organisms. Spore formation is a method seen in certain fungi where specialized cells develop into spores for reproduction. Cloning involves producing genetically identical copies of an organism. Therefore, budding is the correct answer for how yeast reproduces.

3. What are the two catabolic pathways that lead to cellular energy production?

• A. Fermentation and internal respiration
• B. Fermentation and external respiration
• C. Fermentation and cellular respiration
• D. Fermentation and anaerobic respiration

Correct answer: C

Rationale: The correct answer is 'Fermentation and cellular respiration.' Fermentation is an anaerobic catabolic process that occurs in the absence of oxygen, producing limited amounts of ATP. Cellular respiration, on the other hand, is the aerobic catabolic pathway that occurs in the presence of oxygen and is the most efficient way of producing ATP. Choices A, B, and D are incorrect because internal respiration, external respiration, and anaerobic respiration are not the correct pathways leading to cellular energy production.

4. When the genotype consists of a dominant and a recessive allele, the phenotype will be like the _ allele.

• A. Dominant
• B. Recessive
• C. Both
• D. Neither

Correct answer: A

Rationale: When the genotype consists of a dominant and a recessive allele, the phenotype will be like the dominant allele. This is because dominant alleles typically mask the expression of recessive alleles. Therefore, the dominant allele will be expressed in the phenotype in most basic cases. The recessive allele will only be expressed phenotypically if the individual is homozygous recessive. Choice B, 'Recessive,' is incorrect because the phenotype will not be like the recessive allele in this case. Choice C, 'Both,' is incorrect because in simple dominant-recessive inheritance, the dominant allele will overshadow the recessive allele. Choice D, 'Neither,' is incorrect as the phenotype will resemble the dominant allele.

5. What happens to glucose during glycolysis?

• A. Its energy is entirely lost.
• B. It splits into molecules of pyruvic acid.
• C. It is stored in NADH.
• D. It joins with molecules of citric acid.

Correct answer: B

Rationale: During glycolysis, glucose undergoes a series of enzymatic reactions in the cytoplasm of the cell, resulting in its breakdown into two molecules of pyruvic acid. This process also generates ATP and NADH as energy carriers. Choice A is incorrect because glucose is not entirely lost, but rather converted into other molecules. Choice C is incorrect because NADH is a product of glycolysis, not a storage form for glucose. Choice D is incorrect as glucose does not join with molecules of citric acid during glycolysis, but rather in subsequent stages of cellular respiration.

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