Nokea
Which of the following is an example of a nonpolar solvent?
- A. Water
- B. Ethanol
- C. Acetone
- D. Hydrochloric acid
Correct Answer: B
Rationale: - Water (option A) is a polar solvent due to its uneven distribution of charge, with the oxygen atom being partially negative and the hydrogen atoms being partially positive.
- Ethanol (option B) is a nonpolar solvent because it has a symmetrical molecular structure that does not result in significant charge separation.
- Acetone (option C) is a polar solvent as it contains a carbonyl group that results in a partial negative charge on the oxygen atom.
- Hydrochloric acid (option D) is a polar solvent due to the presence of the highly electronegative chlorine atom, which results in a partial negative charge.
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What is the term for a repetitive, involuntary muscle contraction that can cause pain and stiffness?
- A. Cramp
- B. Spasm
- C. Tic
- D. Fibrosis
Correct Answer: B
Rationale: A spasm is a repetitive, involuntary muscle contraction that can cause pain and stiffness. While cramps are a type of spasm, not all spasms are cramps. Tics are sudden, repetitive movements or sounds made involuntarily. Fibrosis refers to the formation of excess fibrous connective tissue in an organ or tissue as part of a reparative or reactive process. In this context, a spasm best fits the description provided, making it the correct answer. Cramp, although related to spasms, is more specific and not the general term being sought. Tic does not describe a muscle contraction but rather sudden movements or sounds. Fibrosis does not directly relate to muscle contractions but rather to the formation of excess fibrous tissue in organs or tissues.
The Minimum Inhibitory Concentration (MIC) of an antibiotic refers to:
- A. The lowest concentration that kills bacteria
- B. The dose required for 50% bacterial inhibition
- C. The time it takes for an antibiotic to work
- D. The spectrum of bacteria the antibiotic targets
Correct Answer: B
Rationale: A) The lowest concentration that kills bacteria is known as the Minimum Bactericidal Concentration (MBC), not the Minimum Inhibitory Concentration (MIC). MIC is the lowest concentration of an antibiotic that inhibits visible growth of bacteria.
B) The MIC of an antibiotic is the concentration at which bacterial growth is inhibited by 50%. This concentration is used to determine the effectiveness of an antibiotic against a specific bacterium.
C) The time it takes for an antibiotic to work is not described by the MIC. MIC is a measure of concentration, not time.
D) The spectrum of bacteria the antibiotic targets is not defined by the MIC. The MIC value is specific to a particular antibiotic and bacterium, regardless of the spectrum of activity of the antibiotic.
Which of the following is an example of a nosocomial infection?
- A. The common cold contracted from a family member
- B. A urinary tract infection (UTI) acquired during a catheterization
- C. A fungal skin infection from contaminated soil
- D. Food poisoning from undercooked chicken
Correct Answer: B
Rationale: A nosocomial infection, also known as a healthcare-associated infection (HAI), is an infection that is acquired in a healthcare setting. In this case, a UTI acquired during a catheterization procedure is a classic example of a nosocomial infection. Catheterization involves the insertion of a tube into the urinary tract, which can introduce bacteria into the urinary system and lead to an infection. Nosocomial infections are a significant concern in healthcare settings due to the potential for increased morbidity, mortality, and healthcare costs.
Let's review the other options:
A) The common cold contracted from a family member - This is not a nosocomial infection as it is acquired outside of a healthcare setting.
C) A fungal skin infection from contaminated soil - This is not a nosocomial infection as it is acquired from environmental exposure, not in a healthcare setting.
What information can be obtained from the mass number of an element?
- A. The number of protons in the nucleus
- B. The total number of protons and neutrons
- C. The number of electrons in the valence shell
- D. The element's chemical reactivity
Correct Answer: B
Rationale: The mass number of an element represents the total number of protons and neutrons in the nucleus. This information is crucial for determining the atomic mass of the element and understanding its stability and isotopes. The number of protons in the nucleus (option A) is represented by the atomic number, not the mass number. The number of electrons in the valence shell (option C) is related to the element's position in the periodic table and its chemical properties, but it is not directly determined by the mass number. The element's chemical reactivity (option D) is influenced by the number and arrangement of electrons in the atom's energy levels, not by the mass number.
Which of the following is NOT a primary producer in an ecosystem?
- A. Grass
- B. Deer
- C. Algae
- D. Mushroom
Correct Answer: B
Rationale: - A) Grass: Grass is a primary producer because it can photosynthesize and convert sunlight into energy, making it the base of the food chain.
- B) Deer: Deer are consumers that feed on primary producers like grass, so they are not primary producers themselves.
- C) Algae: Algae are primary producers that can photosynthesize and produce energy from sunlight.
- D) Mushroom: Mushrooms are decomposers that break down organic matter, so they are not primary producers.