Lytic cycle of the bacteriophages differs from the lysogenic one by

Correct Answer: A

Rationale: The correct answer is A because in the lytic cycle, the bacteriophage destroys the host cell upon release, whereas in the lysogenic cycle, the phage integrates its DNA into the host genome without killing the host immediately. This integration may lead to the destruction of the host cell at a later stage. Choice B is incorrect as lytic phages do destroy the host cell. Choice C is incorrect as the two cycles have distinct mechanisms. Choice D is incorrect as there are clear differences between the lytic and lysogenic cycles.

Correct Answer: A

Rationale: The correct answer is A because in the lytic cycle, the bacteriophage destroys the host cell upon release, whereas in the lysogenic cycle, the phage integrates its DNA into the host genome without killing the host immediately. This integration may lead to the destruction of the host cell at a later stage. Choice B is incorrect as lytic phages do destroy the host cell. Choice C is incorrect as the two cycles have distinct mechanisms. Choice D is incorrect as there are clear differences between the lytic and lysogenic cycles.

Correct Answer: B

Rationale: The correct answer is B: Disinfection. Disinfection is not a method for food preservation but rather a process of destroying harmful microorganisms on surfaces. A: Pasteurization involves heating food to kill pathogens, preserving the food. C: Irradiation uses radiation to kill bacteria and parasites, extending shelf life. D: Ultrahigh-temperature pasteurization involves heating food at very high temperatures to extend shelf life. In summary, disinfection is not a method used to preserve food but rather to clean surfaces.

Correct Answer: A

Rationale: The correct answer is A: Bordetella pertussis. Bordetella pertussis is the bacterium responsible for causing whooping cough, also known as pertussis. It produces toxins that damage the respiratory tract, leading to severe coughing fits. Haemophilus influenzae, Streptococcus pneumoniae, and Mycobacterium tuberculosis are not associated with whooping cough. Haemophilus influenzae can cause respiratory infections but not whooping cough. Streptococcus pneumoniae is known for causing pneumonia, and Mycobacterium tuberculosis causes tuberculosis, both different from whooping cough. Therefore, the correct answer is A as it is the specific bacterium linked to the disease in question.

Correct Answer: D

Rationale: The correct answer is D: Positive strand RNA viruses. These viruses have RNA genomes that can be directly translated by host ribosomes without the need for transcription. In contrast, single-strand DNA and double-strand DNA viruses require transcription to generate mRNA for translation. Choice A is incorrect as there is a correct answer. Choice B and C are incorrect because both single-strand DNA and double-strand DNA viruses require transcription for mRNA synthesis.

Correct Answer: D

Rationale: The correct answer is D, "All of the above." Escherichia coli is the most common bacteria causing UTIs due to its ability to colonize the urinary tract. Salmonella enterica and Neisseria gonorrhoeae are not typically associated with UTIs. Therefore, by process of elimination, since A is correct, B and C are incorrect.

Correct Answer: D

Rationale: The correct answer is D: BCG vaccination. BCG vaccination is recommended for individuals with a negative Mantoux test result, especially in countries where tuberculosis is prevalent. This vaccination can help provide protection against tuberculosis. Choice A is incorrect because repeating the Mantoux test in a month is unnecessary since the boy already had a negative reaction. Choice B is incorrect as serodiagnosis of tuberculosis is not the first-line approach for diagnosis, especially in this scenario. Choice C is incorrect because urgent isolation is not necessary based solely on the Mantoux test result. Isolation is typically reserved for individuals with active tuberculosis.

Correct Answer: A

Rationale: The correct answer is A: Continuous infection with long incubation period. Fudrjant fern of injection is a term used to describe an infection that is continuously present in the body after being introduced through injection. The long incubation period refers to the time between the injection and when symptoms of the infection become apparent. This choice is correct as it accurately describes the characteristics of fudrjant fern of injection. Choice B is incorrect because chronic infections typically have a long duration, not a short incubation period. Choice C is incorrect as immediate infections would not have a long incubation period. Choice D is incorrect because a 'sleeping' infection implies a dormant state, not continuous presence in the body as seen in fudrjant fern of injection.

Correct Answer: C

Rationale: The correct answer is C: Acid-fast cell wall. Mycobacterium tuberculosis is characterized by its unique cell wall composition, containing high levels of mycolic acids which make it acid-fast. This property allows it to resist decolorization during acid-fast staining procedures. This distinguishes it from other bacteria. A: Producing spores is not a key feature of Mycobacterium tuberculosis. Spore formation is more commonly associated with bacterial species such as Bacillus and Clostridium. B: Mycobacterium tuberculosis is not Gram-negative. It is classified as acid-fast Gram-positive. D: Mycobacterium tuberculosis does not produce toxins as a key feature. Its pathogenicity is more closely related to its ability to evade host immune responses and persist in host tissues.