Nokea
The net gain of ATP molecules after the breakdown of one glucose molecule in glycolysis is
- A. 1
- B. 2
- C. 3
- D. 4
Correct Answer: B
Rationale: The correct answer is B (2). During glycolysis, one glucose molecule is broken down into two molecules of pyruvate. In this process, a net gain of 2 ATP molecules is produced through substrate-level phosphorylation. Specifically, ATP is generated during the conversion of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate and during the conversion of phosphoenolpyruvate to pyruvate. The other choices are incorrect because the net gain of ATP molecules in glycolysis is not 1, 3, or 4; it is 2 based on the specific enzymatic reactions involved in the pathway.
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Psychrophiles are also referred to as:
- A. cryophiles
- B. thermophiles
- C. mesophiles
- D. psychrotrophs
Correct Answer: A
Rationale: The correct answer is A: cryophiles. Psychrophiles are microorganisms that thrive in cold temperatures. The prefix "cryo-" means cold, which accurately describes the environment in which these organisms grow. Choice B, thermophiles, are organisms that thrive in high temperatures. Choice C, mesophiles, grow best at moderate temperatures. Choice D, psychrotrophs, are organisms that can grow at refrigeration temperatures but have an optimal growth temperature range different from psychrophiles.
Which bacteria are capable of surviving in anoxic (oxygen-free) conditions?
- A. Obligate anaerobes
- B. Facultative anaerobes
- C. Obligate aerobes
- D. Microaerophiles
Correct Answer: A
Rationale: The correct answer is A: Obligate anaerobes. These bacteria can only survive in the absence of oxygen as they lack the enzymes needed for aerobic respiration. They typically use fermentation or anaerobic respiration for energy production.
Incorrect choices:
B: Facultative anaerobes can switch between aerobic and anaerobic metabolism based on oxygen availability.
C: Obligate aerobes require oxygen for survival and cannot survive in anoxic conditions.
D: Microaerophiles require low levels of oxygen for growth and are not capable of surviving in completely anoxic conditions.
A patient has symptoms of inflammation of urogenital tracts. Examination of a vaginal smear revealed big monocellular, pear-shaped organisms with the pointed spike at the posterior end of body, big nucleus and undulating membrane. What protozoa were found in the smear?
- A. Trichomonas vaginalis
- B. Trichomonas hominis
- C. Trichomonas buccalis
- D. Trypanosoma gambiense
Correct Answer: A
Rationale: Rationale: The correct answer is A: Trichomonas vaginalis.
1. Symptoms of urogenital inflammation match Trichomonas vaginalis infection.
2. Description matches Trichomonas vaginalis characteristics: pear-shaped, pointed spike, big nucleus, undulating membrane.
3. Trichomonas hominis and buccalis do not typically infect urogenital tracts.
4. Trypanosoma gambiense causes African trypanosomiasis, not urogenital infections.
According to their optimal growth temperatures, microorganisms are divided into:
- A. Thermophilic and thermophobic
- B. Psychophilic and psychophobic
- C. Psychophilic, mesophilic, thermophilic
- D. Thermophilic, thermophobic, mesophobic
Correct Answer: C
Rationale: Rationale:
1. Psychrophilic: Grow best in cold temperatures
2. Mesophilic: Grow best in moderate temperatures
3. Thermophilic: Grow best in high temperatures
- Choice A is incorrect as "thermophobic" is not a recognized term.
- Choice B is incorrect as "psychophobic" is not a recognized term.
- Choice D is incorrect as "mesophobic" is not a recognized term.
Which of the following is a phase I reaction in biotransformation?
- A. Oxidation
- B. Conjugation
- C. Acetylation
- D. Glucuronidation
Correct Answer: A
Rationale: The correct answer is A: Oxidation. Phase I reactions in biotransformation involve introducing or unmasking functional groups through oxidation, reduction, or hydrolysis. Oxidation reactions typically involve the addition of an oxygen atom or removal of hydrogen atoms, making them common phase I reactions. In this process, enzymes like cytochrome P450 play a crucial role in catalyzing the oxidation reactions.
Conjugation (B), acetylation (C), and glucuronidation (D) are all examples of phase II reactions, which involve the conjugation of the drug or metabolite with endogenous compounds to increase water solubility for excretion. These reactions typically follow phase I reactions and are not classified as phase I reactions in biotransformation.