Nokea
Which structure is used by bacteria for movement?
- A. Pili
- B. Flagella
- C. Capsule
- D. Fimbriae
Correct Answer: B
Rationale: The correct answer is B: Flagella. Flagella are whip-like appendages used by bacteria for movement. They rotate in a corkscrew motion to propel the bacteria through their environment. Pili (choice A) are hair-like structures used for attachment, not movement. Capsules (choice C) are protective layers around bacteria, not involved in movement. Fimbriae (choice D) are also used for attachment and biofilm formation, not for movement. Therefore, the correct choice is B as flagella are specifically adapted for bacterial motility.
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A patient working at a pig farm complains about paroxysmal abdominal pain, liquid feces with admixtures of mucus and blood, headache, weakness, fever. Examination of large intestine revealed ulcers from 1 mm up to several cm large, feces contained oval unicellular organisms with cilia. What disease should be suspected?
- A. Balantidiasis
- B. Amebiasis
- C. Toxoplasmosis
- D. Lambliasis
Correct Answer: A
Rationale: Rationale: The symptoms described are consistent with Balantidiasis, caused by the parasite Balantidium coli. The presence of ciliated oval organisms in the feces is characteristic of this disease. Ulcers in the large intestine are common in Balantidiasis due to tissue invasion by the parasite. Headache, fever, and abdominal pain are typical symptoms. Other choices can be ruled out: B) Amebiasis presents with similar symptoms but usually involves the liver. C) Toxoplasmosis typically presents with lymphadenopathy and flu-like symptoms. D) Lambliasis usually causes watery diarrhea without blood or mucus. Therefore, the correct answer is A: Balantidiasis.
Streptococci are:
- A. Gram-positive, short rod shaped bacteria and size 4-6 µm
- B. Gram-negative, rounded or lanceolate shape and size 0,5-1 µm
- C. Gram-negative, short rod shaped bacteria and size 4-6 µm
- D. Gram-positive, spherical or lanceolate shape and size 0,5-1 µm
Correct Answer: D
Rationale: The correct answer is D because Streptococci are Gram-positive bacteria, typically spherical in shape, and range from 0.5-1 µm in size.
A is incorrect as streptococci are not rod-shaped and are usually smaller in size. B is incorrect as they are not Gram-negative and are not typically of such small size.
C is incorrect as streptococci are not Gram-negative and are not usually rod-shaped. Thus, based on their characteristics, the correct answer is D.
A specific sequence of three consecutive nucleotides that is part of the genetic code and that specifies a particular amino acid in a protein or starts or stops protein synthesis is called:
- A. Codon
- B. Primer
- C. Nucleosome
- D. Polypeptide
Correct Answer: A
Rationale: Step 1: Definition - A codon is a sequence of three nucleotides that code for a specific amino acid or signal the start/stop of protein synthesis.
Step 2: Function - Codons are essential for translating genetic information into proteins.
Step 3: Specificity - Codons are specific in their role of encoding amino acids.
Step 4: Examples - Examples like AUG for methionine and UAA, UAG, UGA for stop codons illustrate codon functionality.
Step 5: Summary - The correct answer is A (Codon) because it accurately describes the function and specificity of a three-nucleotide sequence in genetic coding. Choices B, C, and D are incorrect as they do not align with the definition and function of a codon.
A patient suffering form tuberculosis was treated with rifampicin, which caused drug resistance of tuberculosis mycobacteria. In order to reduce mycobacteria resistance, rifampicin should be combined with the following drug:
- A. Isoniazid
- B. Acyclovir
- C. Intraconazole
- D. Metronidazole
Correct Answer: A
Rationale: The correct answer is A: Isoniazid. When rifampicin is used alone, there is a risk of developing resistance. Isoniazid is commonly used in combination with rifampicin to prevent resistance by targeting different mechanisms in the bacteria. Isoniazid works by inhibiting mycolic acid synthesis, while rifampicin targets RNA polymerase. This combination therapy is known as the first-line treatment for tuberculosis. Choices B, C, and D are incorrect because they do not have the same mechanism of action as isoniazid and would not be effective in preventing rifampicin resistance.
Which fact is correct about the nucleoids in bacteria:
- A. Contain a haploid bacterial chromosomes in each nucleus
- B. Are reabsorbed well by the method of Neisser
- C. Are 1 to 4 in each bacterial cell depending on the nature of the cell and the phases of growth and replication
- D. None of the above
Correct Answer: C
Rationale: The correct answer is C because nucleoids in bacteria can vary in number from 1 to 4 depending on the specific bacterial cell and its growth and replication phases. This is due to the dynamic nature of bacterial cells and their genetic material organization.
Choice A is incorrect because nucleoids do not contain nuclear membranes or multiple haploid chromosomes like eukaryotic nuclei. Choice B is incorrect as there is no known method of reabsorbing nucleoids by Neisser. Choice D is incorrect as option C is indeed the correct statement regarding the number of nucleoids in bacterial cells.