Some of the basic requirements for the antibacterial chemotherapeutics are:
- A. To be maximally toxic to bacteria, as a result of their accumulation in the body
- B. To disintegrate rapidly and not be water soluble
- C. To be maximally toxic to microorganisms, not to lead to allergic reactions, to be stable, to have a wide spectrum of activity
- D. None of the above
Correct Answer: C
Rationale: The correct answer is C because antibacterial chemotherapeutics need to be maximally toxic to microorganisms, not lead to allergic reactions, be stable, and have a wide spectrum of activity to effectively treat bacterial infections.
A is incorrect because maximum toxicity to bacteria can lead to harmful side effects in the body. B is incorrect because rapid disintegration and insolubility in water would hinder the drug's effectiveness. D is incorrect because the basic requirements for antibacterial chemotherapeutics are outlined in option C.
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Which of the following is a major characteristic of Gram-negative bacteria?
- A. Thick peptidoglycan layer
- B. Outer membrane with lipopolysaccharides
- C. Absence of a cell wall
- D. Presence of teichoic acids
Correct Answer: B
Rationale: The correct answer is B: Outer membrane with lipopolysaccharides. Gram-negative bacteria have an outer membrane that contains lipopolysaccharides, which play a role in pathogenicity and resistance to certain antibiotics. This outer membrane is a distinguishing feature of Gram-negative bacteria, as opposed to Gram-positive bacteria that have a thick peptidoglycan layer. Choices A, C, and D are incorrect because Gram-negative bacteria have a thin peptidoglycan layer, do have a cell wall (although it is different from Gram-positive bacteria), and do not contain teichoic acids.
Which bacteria are known for producing toxins that can cause severe gastrointestinal illness?
- A. Clostridium botulinum
- B. Vibrio cholerae
- C. Escherichia coli
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D, "All of the above." Clostridium botulinum produces botulinum toxin causing botulism, Vibrio cholerae produces cholera toxin leading to severe diarrhea, and certain strains of Escherichia coli produce toxins causing gastrointestinal illness. Therefore, all three bacteria are known for producing toxins that can cause severe gastrointestinal illness. Choices A, B, and C individually represent bacteria known for producing toxins that can cause severe gastrointestinal illness, making them incorrect individual choices.
Matrix formed outside the plasma membrane is referred to as:
- A. cytoplasm
- B. glycocalyx
- C. exoplasm
- D. cell wall
Correct Answer: B
Rationale: The correct answer is B: glycocalyx. The glycocalyx is a matrix formed outside the plasma membrane that consists of glycoproteins and glycolipids. It plays crucial roles in cell-cell recognition, protection, and immune response. Cytoplasm (A) is the gel-like substance inside the cell, not outside. Exoplasm (C) is not a recognized term in biology. Cell wall (D) is a rigid structure found in plant cells, not outside the plasma membrane in all cells.
Which of the following diseases can be transmitted by a tick?
- A. Botulism
- B. Anthrax
- C. Tularemia
- D. MRSA
Correct Answer: C
Rationale: The correct answer is C: Tularemia. Ticks can transmit tularemia, a bacterial infection caused by Francisella tularensis. Ticks pick up the bacteria when feeding on infected animals and can then transmit it to humans through their bites. Botulism (A) is caused by toxins produced by Clostridium botulinum bacteria, not transmitted by ticks. Anthrax (B) is a bacterial infection caused by Bacillus anthracis, typically transmitted through contact with contaminated animal products. MRSA (D) is a bacterial infection caused by Staphylococcus aureus, commonly transmitted through direct contact with infected individuals or contaminated surfaces, not by ticks.
The enzyme that breaks down the peptidoglycan in bacterial cell walls is:
- A. Lysozyme
- B. Amylase
- C. Protease
- D. Lipase
Correct Answer: A
Rationale: The correct answer is A: Lysozyme. Lysozyme is an enzyme that targets and breaks down the peptidoglycan in bacterial cell walls by cleaving the glycosidic bonds between the sugar components. This action weakens the cell wall, leading to bacterial cell lysis. Amylase (B) breaks down starch, not peptidoglycan. Protease (C) breaks down proteins, not peptidoglycan. Lipase (D) breaks down lipids, not peptidoglycan. Therefore, Lysozyme is the correct enzyme for breaking down peptidoglycan in bacterial cell walls.