Nokea
Superoxide dismutase is an enzyme that catalyzes the conversion of oxygen radicals to peroxides. Which groups of organisms do not have this enzyme?
- A. aerobes
- B. facultative anaerobes
- C. oxyduric anaerobes
- D. oxylabile anaerobes
Correct Answer: D
Rationale: The correct answer is D: oxylabile anaerobes. These organisms cannot survive in the presence of oxygen and are sensitive to oxygen radicals. Superoxide dismutase is essential for organisms that are exposed to oxygen, as it helps convert harmful oxygen radicals into less harmful peroxides. Therefore, organisms that lack this enzyme, like oxylabile anaerobes, would not be able to detoxify oxygen radicals and would not survive in aerobic environments.
A: Aerobes have superoxide dismutase to protect against oxygen radicals.
B: Facultative anaerobes can switch between aerobic and anaerobic metabolism and would benefit from having superoxide dismutase.
C: Oxyduric anaerobes are resistant to oxygen and can still benefit from superoxide dismutase for detoxification.
You may also like to solve these questions
Ferrets have recently been objects of an intense debate within the scientific community in the field of Flu research because
- A. Of a recent outbreak caused by a novel Influenza strain
- B. Of a recent outbreak caused by a highly virulent H1N1 strain
- C. Mutations have been introduced in H5N1 creating a strain transmissible among these mammals
- D. Two publications on this animal model for Flu were put on hold due to biosecurity reasons
Correct Answer: C
Rationale: The correct answer is C because it indicates a specific reason for the intense debate within the scientific community regarding ferrets in Flu research. Mutations in H5N1 creating a strain transmissible among ferrets is significant as it highlights a potential threat of cross-species transmission and the need for further study.
A is incorrect as it does not provide a specific reason related to ferrets and their role in Flu research. B is incorrect because it focuses on a specific strain (H1N1) rather than mutations in H5N1. D is incorrect as it mentions publications being put on hold but does not address the core issue of mutations and transmissibility among ferrets.
Which of the following statements is incorrect about celiac disease?
- A. There is a strong genetic association: more than 90% of celiac patients express the HLA allele DO2 or DO8
- B. It is technically an allergy but has some features of autoimmunity
- C. The disease is mainly caused by an abnormal innate response to gluten while adaptive cells are not involved
- D. The disease is entirely driven by gluten exposure. The gut lesions observed in these patients disappeared upon removal of gluten from the diet
Correct Answer: C
Rationale: The correct answer is C because celiac disease primarily involves an abnormal adaptive immune response to gluten, not an innate response. Here's the rationale: 1) Celiac disease is characterized by a T-cell mediated response to gluten peptides in genetically susceptible individuals. 2) The adaptive immune system, particularly T cells, plays a crucial role in the pathogenesis by recognizing gluten peptides presented by HLA-DQ2 or HLA-DQ8 molecules. 3) This adaptive immune response leads to inflammation and damage to the intestinal mucosa. 4) In contrast, the innate immune system may also be activated, but it is not the primary driver of the disease.
Summary:
A: Correct - There is a strong genetic association with HLA alleles.
B: Incorrect - Celiac disease is primarily driven by an adaptive immune response, not just features of autoimmunity.
D: Incorrect - While gluten exposure triggers the immune response, the disease is not solely driven by gluten intake.
What is the primary difference between healing by primary intention and healing by secondary intention?
- A. Secondary healing requires surgical debridement for healing to occur.
- B. Primary healing involves suturing two layers of granulation tissue together.
- C. Presence of more granulation tissue in secondary healing results in more scarring.
- D. Healing by secondary intention takes longer because more steps in the healing process are necessary.
Correct Answer: C
Rationale: Healing by secondary intention involves more granulation tissue formation compared to primary intention, leading to greater scarring. Secondary intention also requires additional time for wound closure.
What discovery is attributed to Elie Metchnikoff?
- A. Antitoxins
- B. Phagocytosis
- C. Germ theory of disease
- D. Smallpox eradication
Correct Answer: B
Rationale: The correct answer is B: Phagocytosis. Elie Metchnikoff is credited with discovering phagocytosis, the process in which certain cells engulf and digest foreign particles or microorganisms. He observed this phenomenon in starfish larvae, leading to a groundbreaking understanding of how immune cells defend the body against pathogens.
Choice A (Antitoxins) is incorrect because although Metchnikoff made contributions to immunology, his notable discovery was phagocytosis, not antitoxins. Choice C (Germ theory of disease) is incorrect as this theory was developed by Louis Pasteur and Robert Koch. Choice D (Smallpox eradication) is incorrect as this achievement is primarily attributed to the efforts of Edward Jenner and the World Health Organization.
Anemia
- A. cancer of white blood cells
- B. results in extra leukocytes that do not function properly
- C. is usually fatal unless treated
- D. Abnormally low amounts of hemoglobin or red blood cells
Correct Answer: D
Rationale: The correct answer is D because anemia is defined as having abnormally low amounts of hemoglobin or red blood cells, leading to reduced oxygen-carrying capacity. This results in symptoms such as fatigue and weakness. Choice A is incorrect because anemia is not related to cancer of white blood cells. Choice B is incorrect as anemia does not result in extra leukocytes; rather, it leads to a decrease in red blood cells. Choice C is incorrect as anemia is not usually fatal if treated promptly and effectively.