Nursing Elites

1. Antigenic variation, a common strategy used by some viruses, allows them to:

• A. Produce toxins
• B. Evade the immune system
• C. Survive outside a host
• D. Replicate rapidly

Correct answer: B

Rationale: Antigenic variation is a strategy used by some viruses to evade the host's immune response. By constantly changing their surface antigens, viruses can avoid recognition and destruction by the immune system. This allows the virus to persist in the host and continue replicating, leading to prolonged infection and potential transmission to other hosts. Antigenic variation does not directly involve the production of toxins, survival outside a host, or rapid replication, making options A, C, and D incorrect in this context.

2. Which of the following statements regarding macrophages is incorrect?

• A. They are found abundantly in the blood
• B. They are larger than neutrophils
• C. They are long-lived
• D. They are made in the bone marrow as monocytes, called macrophages once they reach organs

Correct answer: A

Rationale: The correct answer is A. Macrophages are not found abundantly in the blood; they are present in tissues and organs. Macrophages are tissue-resident immune cells that play a key role in immune responses and are derived from monocytes produced in the bone marrow. Choice B is correct as macrophages are larger than neutrophils. Choice C is correct as macrophages are long-lived cells. Choice D is correct as macrophages originate in the bone marrow as monocytes and differentiate into macrophages once they migrate to various tissues and organs.

3. What is the difference between a homozygous recessive genotype and a homozygous dominant genotype?

• A. Both have the same phenotype, but different genotypes.
• B. Both have the same genotype, but different phenotypes.
• C. Homozygous recessive has two dominant alleles, while homozygous dominant has two recessive alleles.
• D. Homozygous recessive has two identical recessive alleles, while homozygous dominant has two identical dominant alleles.

Correct answer: D

Rationale: - Homozygous recessive genotype refers to an individual having two identical recessive alleles for a particular gene (e.g., rr for a trait where r represents the recessive allele). - Homozygous dominant genotype refers to an individual having two identical dominant alleles for a particular gene (e.g., RR for a trait where R represents the dominant allele). - The difference between the two genotypes lies in the specific alleles present in each case, with homozygous recessive having two recessive alleles and homozygous dominant having two dominant alleles. - This genetic difference results in different phenotypes being expressed, as the dominant allele typically masks the expression of the recessive allele in heterozygous individuals.

4. Which bones are included in the axial skeleton?

• A. Head, neck, and trunk
• B. Arms and legs
• C. Hands and feet
• D. All of the above

Correct answer: A

Rationale: The correct answer is A: Head, neck, and trunk. The axial skeleton comprises bones located in the head, neck, and trunk region, such as the skull, vertebral column, and rib cage. These bones provide structural support and protect vital organs like the brain, spinal cord, and heart. Choices B and C are incorrect because arms, legs, hands, and feet are part of the appendicular skeleton, not the axial skeleton. The appendicular skeleton is responsible for movement, manipulation, and mobility, while the axial skeleton primarily provides central support and protection for essential organs.

5. Neurons, the functional units of the nervous system, belong to which tissue type?

• A. Epithelial tissue
• B. Connective tissue
• C. Muscle tissue
• D. Nervous tissue

Correct answer: D

Rationale: Neurons are the functional units of the nervous system and are specialized cells that transmit nerve impulses. They belong to nervous tissue, which is the primary tissue type of the nervous system. Nervous tissue is composed of neurons and supporting cells called neuroglia. Choices A, B, and C are incorrect because epithelial tissue functions mainly in covering and lining body surfaces, connective tissue provides support and structure, and muscle tissue is responsible for movement. Neurons, being the basic functional units of the nervous system, are specifically classified under nervous tissue.

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