An enzyme process of producing two identical copies of DNA from one original DNA molecule is called:

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.

Correct Answer: D

Rationale: The correct answer is D (All of the above) because all three bacteria (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus) are known to cause urinary tract infections. E. coli is the most common causative agent of UTIs due to its ability to colonize the urethra. P. aeruginosa can cause UTIs in hospitalized patients with catheters. S. aureus is less common but can lead to UTIs, especially in individuals with underlying health conditions. Therefore, all three bacteria are potential pathogens for UTIs. Choices A, B, and C are incorrect because each of these bacteria can individually cause UTIs, making the correct answer D.

Correct Answer: C

Rationale: The correct answer is C: acetyl-CoA. Acetyl-CoA is the compound that combines with oxaloacetic acid at the beginning of the Krebs cycle to form citric acid. This step is essential for the cycle to proceed, making acetyl-CoA the correct choice. A: Citric acid is formed after acetyl-CoA combines with oxaloacetic acid, so it is a product of the reaction, not the compound that enters the cycle. B: Pyruvic acid is converted to acetyl-CoA in a separate process before entering the Krebs cycle. D: Phosphoglyceraldehyde is not involved in the Krebs cycle; it is a compound in glycolysis.

Correct Answer: A

Rationale: The correct answer is A: Streptococcus pneumoniae. The presence of Gram-positive diplococci with a capsule is characteristic of S. pneumoniae. This bacterium is a common cause of pneumonia, especially in patients with fever and cough. It is also known for causing infections such as otitis media and sinusitis. Staphylococcus aureus (B) is a Gram-positive cocci but does not typically form diplococci or have a capsule. Neisseria meningitidis (C) is a Gram-negative diplococcus commonly associated with meningitis, not pneumonia. Klebsiella pneumoniae (D) is a Gram-negative rod, not a diplococcus, and is more commonly associated with pneumonia in immunocompromised patients.

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.

Correct Answer: B

Rationale: The correct answer is B: prokaryotic. Bacteria are prokaryotic cells because they lack a true nucleus and membrane-bound organelles. They have a simple cell structure with genetic material floating freely in the cytoplasm. Choice A (eukaryotic) is incorrect because eukaryotic cells have a nucleus and membrane-bound organelles. Choice C (diploid) is incorrect as bacteria do not have a defined ploidy level like diploid organisms do. Choice D (haploid) is also incorrect as bacteria do not have a true haploid or diploid state due to their lack of a defined nucleus.

Correct Answer: B

Rationale: The correct answer is B because the complement fixation test is a serological test that detects the presence of specific antibodies or antigens in a patient's serum. It works by measuring the ability of antibodies to fix complement proteins. Choice A is incorrect because the complement fixation test typically involves several steps, not necessarily three. Choice C is incorrect as standardized complement proteins are commonly used in this test. Choice D is incorrect because sheep red blood cells are not essential for performing the complement fixation test.

Correct Answer: C

Rationale: The correct answer is C because disinfectants are non-selective and can harm a wide range of microbial cells. Disinfectants work by disrupting cell membranes, proteins, and nucleic acids, affecting both harmful and beneficial microorganisms. Choices A and B are incorrect because disinfectants are designed to be potent and non-selective. Choice D is incorrect because the effects of disinfectants are often permanent and irreversible on microbial cells.

Correct Answer: A

Rationale: The correct answer is A: Pseudomonas aeruginosa. Pseudomonas aeruginosa is known to produce a blue-green pigment called pyocyanin, which is characteristic of the organism. Additionally, it has a distinct fruity odor due to the production of certain volatile compounds. Escherichia coli (B) does not produce blue-green pigment or have a fruity odor. Klebsiella pneumoniae (C) and Proteus mirabilis (D) also do not exhibit these specific characteristics associated with Pseudomonas aeruginosa.