Nokea
Identify the incorrect statement
- A. There are ten times as many bacteria residing in the gut than human cells in the entire body
- B. Human babies, before birth, do not have commensal flora
- C. Studies on germ-free mice indicate that the microbiota is important for the development of the immune system
- D. A lower number of gut bacteria has been associated with obesity
Correct Answer: D
Rationale: The correct answer is D because a lower number of gut bacteria is not associated with obesity. In fact, research shows that an imbalance in gut bacteria, not a lower number, can contribute to obesity. Choice A is correct as there are indeed more bacteria in the gut than human cells in the body. Choice B is also correct as babies develop their commensal flora after birth. Choice C is correct, as studies on germ-free mice have shown the importance of microbiota in immune system development.
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Mucins are
- A. Produced by all epithelial cells
- B. Heavily glycosylated proteins that form a gel-like physical barrier on mucosal surfaces
- C. Natural antibiotics produced by specialized epithelial cells
- D. Found exclusively in the respiratory tract
Correct Answer: B
Rationale: Step-by-step rationale:
1. Mucins are heavily glycosylated proteins that form a gel-like barrier on mucosal surfaces.
2. This barrier helps protect the underlying tissues from pathogens and physical damage.
3. Mucins are primarily produced by goblet cells in epithelial tissues.
4. Choice B correctly describes the function and structure of mucins.
Summary:
- Choice A is incorrect because not all epithelial cells produce mucins.
- Choice C is incorrect as mucins are not natural antibiotics.
- Choice D is incorrect as mucins are present in various mucosal surfaces, not exclusively in the respiratory tract.
Avian Influenza has not so far caused a human pandemic because
- A. Avian flu causes only mild infection in humans compared to birds
- B. Avian flu recognize a variant of sialic acid found only on avian cells
- C. Avian flu recognizes a variant of sialic acid only found in deep tissues of humans
- D. Of cross-protection obtained from the annual vaccine
Correct Answer: C
Rationale: The correct answer is C because avian influenza has not caused a human pandemic due to the fact that it recognizes a variant of sialic acid only found in deep tissues of humans. This unique binding preference prevents efficient human-to-human transmission, which is crucial for a pandemic to occur. Choice A is incorrect as avian flu can cause severe illness in humans. Choice B is incorrect because avian flu recognizing a variant of sialic acid found only on avian cells would not prevent a pandemic in humans. Choice D is incorrect as there is no specific annual vaccine for avian influenza.
The industrial nurse examines an employee who complains of right shoulder pain on abduction. He points with one finger to the exact location of the pain and mentions that he won a racquetball tournament yesterday. The nurse suspects the employee is suffering from which problem?
- A. Rotator cuff tear
- B. Bursitis
- C. Dislocation
- D. Subluxation
Correct Answer: B
Rationale: The correct answer is B: Bursitis. The employee's complaint of shoulder pain on abduction, localized pain with a specific trigger (racquetball tournament), and no mention of trauma or instability suggest an inflammatory condition like bursitis. The other choices are incorrect because a rotator cuff tear typically presents with weakness, dislocation with a history of trauma and visible deformity, and subluxation with recurrent episodes of partial dislocation.
Which of the following DNA polymerases cleaves a DNA sequence at the direction of 5' → 3'?
- A. DNA polymerase I
- B. DNA polymerase II
- C. DNA polymerase III
- D. DNA polymerase IV
Correct Answer: A
Rationale: The correct answer is A: DNA polymerase I. DNA polymerase I has both 5' to 3' polymerase activity and 5' to 3' exonuclease activity, allowing it to cleave DNA in the 5' to 3' direction. This enzyme can remove RNA primers during DNA replication by cleaving them in the 5' to 3' direction and replace them with DNA nucleotides. DNA polymerase II, III, and IV do not have the same exonuclease activity as DNA polymerase I, so they are not capable of cleaving DNA sequences in the 5' to 3' direction like DNA polymerase I.
What was Edward Jenner's major contribution to immunology?
- A. Discovering antibodies
- B. Proposing innate immunity theory
- C. Developing the smallpox vaccine
- D. Discovering the germ theory of disease
Correct Answer: C
Rationale: Edward Jenner's major contribution to immunology was developing the smallpox vaccine. He introduced the concept of vaccination by using cowpox to protect against smallpox. This marked the beginning of modern immunization. Discovering antibodies (A) and proposing innate immunity theory (B) were not directly attributed to Jenner. Discovering the germ theory of disease (D) was later proposed by Louis Pasteur and Robert Koch, not Jenner. Overall, choice C is correct as it aligns with Jenner's groundbreaking work in immunization.