Nokea
The growth phase in which bacteria adapt to the conditions of cultivation is called:
- A. Stationary phase
- B. Log phase
- C. Lag phase
- D. Death phase
Correct Answer: C
Rationale: The correct answer is C: Lag phase. During the lag phase, bacteria adapt to the new environment before starting to grow and divide. This phase is characterized by a period of low growth as bacteria adjust their metabolism to the available nutrients. The stationary phase (A) is when growth rate equals death rate, the log phase (B) is rapid exponential growth, and the death phase (D) is when cells start to die due to nutrient depletion or accumulation of waste products. Thus, the lag phase is the initial phase where bacteria prepare for growth, making it the correct answer.
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Which staining method is used for proving the formation of spores
- A. Klett and Gins
- B. Ziehl-Neelsen
- C. Gram and Loeffler's
- D. Moeller
Correct Answer: D
Rationale: The correct answer is D: Moeller. Moeller staining method is specifically designed to detect spores due to its ability to differentiate between the spore and the vegetative cell. It involves applying multiple stains such as malachite green, safranin, and heat to visualize the endospore structure. This method is essential for proving the formation of spores as it highlights the resistant spore structures within the bacterial cell.
A: Klett and Gins is not used for spore staining.
B: Ziehl-Neelsen is used for acid-fast staining, not spore staining.
C: Gram and Loeffler's are used for gram staining, not spore staining.
Enzymes used in ELISA are those except:
- A. Î’-lactamase
- B. Alkaline phosphatase
- C. Horseradish peroxidase
- D. Î’- galactosidase
Correct Answer: A
Rationale: The correct answer is A: Β-lactamase. In ELISA, enzymes like alkaline phosphatase, horseradish peroxidase, and Β-galactosidase are commonly used as labels to detect the presence of specific molecules. Β-lactamase is not typically used in ELISA as it is an enzyme used to hydrolyze β-lactam antibiotics. Therefore, it does not serve the purpose of detecting specific molecules in ELISA. Alkaline phosphatase, horseradish peroxidase, and Β-galactosidase are preferred enzymes in ELISA due to their ability to produce a detectable signal when bound to specific molecules.
Which of the following bacteria is associated with the disease known as whooping cough?
- A. Bordetella pertussis
- B. Clostridium tetani
- C. Haemophilus influenzae
- D. Staphylococcus aureus
Correct Answer: A
Rationale: 1. Bordetella pertussis causes whooping cough.
2. It secretes toxins that damage the respiratory tract.
3. Symptoms include severe coughing fits and the characteristic "whoop" sound.
4. Clostridium tetani causes tetanus, not whooping cough.
5. Haemophilus influenzae causes various infections, not whooping cough.
6. Staphylococcus aureus causes skin infections, not whooping cough.
A 35-year-old patient has been admitted to a hospital for pain in the left sternoclavicular and knee joints, lumbar area. The disease has an acute character and is accompanied by fever up to 38oC. Objectively: the left sternoclavicular and knee joints are swollen and painful. In blood: WBCs - 9, 5x109/l, ESR - 40 mm/h, CRP - 1,5 millimole/l, fibrinogen - 4,8 g/l, uric acid - 0,28 millimole/l. Examination of the urethra scrapings reveals chlamydia. What is the most likely diagnosis?
- A. Reiter's syndrome
- B. Rheumatic arthritis
- C. Gout
- D. Bechterew's disease
Correct Answer: A
Rationale: The most likely diagnosis is Reiter's syndrome. This is suggested by the presence of joint pain, fever, elevated ESR and CRP levels, and chlamydia infection. Reiter's syndrome is a reactive arthritis triggered by an infection elsewhere in the body, such as chlamydia. The patient's symptoms of joint pain and swelling, along with the positive chlamydia test, support this diagnosis. Rheumatic arthritis (Choice B) is not associated with chlamydia infection, making it less likely. Gout (Choice C) typically presents with elevated uric acid levels, which are normal in this case. Bechterew's disease (Choice D) primarily affects the spine and sacroiliac joints, not the sternoclavicular and knee joints as seen in this patient.
The one-way transfer of genetic material from a donor cell to a recipient cell by direct cell-to-cell contact is:
- A. transformation
- B. transduction
- C. replication
- D. conjugation
Correct Answer: D
Rationale: Conjugation involves direct cell-to-cell contact for the transfer of genetic material, typically through a pilus. This process is well-documented in bacterial genetics. Transformation (A) involves uptake of free DNA from the environment. Transduction (B) is genetic transfer by a viral vector. Replication (C) is the process of producing identical copies of DNA or RNA. Therefore, the correct answer is D (conjugation) as it specifically refers to the one-way transfer of genetic material through direct cell-to-cell contact.