Nokea
An enzyme process of producing two identical copies of DNA from one original DNA molecule is called:
- A. Translation
- B. Transcription
- C. Replication
- D. Cell division
Correct Answer: C
Rationale: The correct answer is C: Replication. In DNA replication, the original DNA molecule is unwound and each strand serves as a template to synthesize a new complementary strand. This results in two identical copies of the original DNA molecule. Translation (A) is the process of synthesizing proteins from mRNA. Transcription (B) is the process of synthesizing mRNA from DNA. Cell division (D) is the process of a cell dividing into two daughter cells, not specifically producing identical DNA copies. Therefore, replication is the correct answer as it specifically refers to the process of copying DNA to produce two identical copies.
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Which of the following bacteria is responsible for causing the disease known as whooping cough?
- A. Bordetella pertussis
- B. Clostridium tetani
- C. Haemophilus influenzae
- D. Staphylococcus aureus
Correct Answer: A
Rationale: Step 1: Bordetella pertussis is the causative agent of whooping cough, also known as pertussis.
Step 2: This bacterium produces toxins that damage the respiratory tract, leading to severe coughing fits.
Step 3: Clostridium tetani causes tetanus, Haemophilus influenzae causes respiratory infections, and Staphylococcus aureus causes skin infections.
Step 4: Therefore, A is the correct answer as it is the only bacterium directly associated with whooping cough.
The main function of siderophores in bacteria is:
- A. to enhance antibiotic resistance
- B. to sequester iron from the environment
- C. to form capsules
- D. to perform oxidative phosphorylation
Correct Answer: B
Rationale: The correct answer is B: to sequester iron from the environment. Siderophores are molecules produced by bacteria to chelate and acquire iron, an essential nutrient for their growth and survival. By sequestering iron, bacteria can compete with host cells and other microbes for this vital resource. This enhances their ability to thrive and establish infections. Choices A, C, and D are incorrect because siderophores do not directly enhance antibiotic resistance, form capsules, or perform oxidative phosphorylation. These functions are unrelated to the primary role of siderophores in iron acquisition.
In preparation for business trip abroad the doctor was prescribed a histoschizontocidal antimalarial drug as a personal means of disease prevention. What drug was given to the doctor?
- A. Chingamin
- B. Mefloquine
- C. Biseptol (Co-Trimoxazole)
- D. Quinine
Correct Answer: B
Rationale: The correct answer is B: Mefloquine. Mefloquine is a histoschizontocidal antimalarial drug commonly prescribed for prevention of malaria in travelers. It is effective against the liver stage of the malaria parasite, which is crucial for preventing the development of the disease. Chingamin (A) is not a commonly used antimalarial drug. Biseptol (C) is a combination antibiotic and is not effective against malaria parasites. Quinine (D) is primarily used for treating malaria, not preventing it, and it is not specifically histoschizontocidal.
How many types of herpes simplex virus are there?
- A. 1
- B. 2
- C. 3
- D. 4
Correct Answer: B
Rationale: The correct answer is B because there are two types of herpes simplex virus: HSV-1 and HSV-2. HSV-1 typically causes oral herpes, while HSV-2 usually causes genital herpes. Choice A is incorrect because there is more than one type. Choices C and D are also incorrect as there are only two types of herpes simplex virus known to infect humans.
Which statement about the epidemiology and specific prophylactic of Haemophilus influenzae is NOT CORRECT?
- A. Non-encapsulated strains can be isolated from healthy carriers
- B. There is an effective killed vaccine, protective against all capsular types of Haemophilus spp.
- C. The infection is airborne
- D. None of the above
Correct Answer: B
Rationale: The correct answer is B because there is no effective killed vaccine that is protective against all capsular types of Haemophilus spp. The Haemophilus influenzae vaccine primarily targets specific capsular types, not all of them. Choice A is incorrect because non-encapsulated strains can indeed be isolated from healthy carriers. Choice C is incorrect as Haemophilus influenzae is primarily transmitted through respiratory droplets, not through the air. Choice D is not correct because Choice B is indeed incorrect, making it the right answer.