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Which of the following properties does soap, an emulsifier, have that make it useful for washing dirt off one's hands with water?
- A. Soap's dual polar and nonpolar nature helps bond oil and water.
- B. Soap's acidity causes grime to precipitate into the water.
- C. Soap's rough texture physically scours grime off surfaces.
- D. Soap's enzymatic action helps to dissolve grime into smaller particles.
Correct Answer: A
Rationale: Soap acts as an emulsifier due to its dual polar (hydrophilic) and nonpolar (hydrophobic) nature, allowing it to effectively bond oil and water, making option A the correct choic
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A student makes a solution that simulates stomach acid. Which of the following would be true of this solution, compared to distilled water?
- A. It has a higher pH.
- B. It has more hydrogen ions.
- C. It contains more hydroxyl ions.
- D. It has more hydroxyl ions.
Correct Answer: B
Rationale: The correct answer is B. A solution that simulates stomach acid is acidic, which means it has a higher concentration of hydrogen ions compared to distilled water, which is neutral. Stomach acid is characterized by its high hydrogen ion concentration, which is responsible for its acidic nature. Hydroxyl ions are associated with bases, not acids, so options C and D are incorrect. Option A is incorrect as well because stomach acid would have a lower pH compared to distilled water due to its high acidity.
A patient goes to the doctor with a cold and sore throat and asks for antibiotics. The doctor refuses to prescribe antibiotics because the illness is caused by which of the following pathogens?
- A. Protist
- B. Fungus
- C. Virus
- D. Bacteria
Correct Answer: C
Rationale: The correct answer is C: Virus. Antibiotics are ineffective against viral infections, such as colds and sore throats caused by viruses. They are only effective against bacterial infections. In this case, the doctor refuses to prescribe antibiotics because the patient's illness is viral, not bacterial. It is important to differentiate between viral and bacterial infections to ensure appropriate treatment and avoid unnecessary use of antibiotics, which can contribute to antibiotic resistance.
Which of the following is used to determine a person's DNA sequence?
- A. hormones
- B. enzymes
- C. blood types
- D. genes
Correct Answer: D
Rationale: Genes are the correct choice for determining a person's DNA sequence. Genes carry genetic information that dictates various traits and characteristics in individuals. A person's unique DNA sequence is determined by the specific arrangement of nucleotides within their genes. Scientists can analyze genes to decode the DNA sequence that represents an individual's genetic composition.
The triple point of a substance is the temperature and pressure at which the substance exists as which of the following?
- A. As a gel with solid and liquid trapped in gas
- B. Simultaneously in sol, gel, and plasma phases
- C. Simultaneously in solid, liquid, and gas phases
- D. As a sol with gas and solid trapped in liquid
Correct Answer: C
Rationale: The triple point is a specific condition where a substance can exist simultaneously in all three phases: solid, liquid, and gas. The other options do not accurately describe this state.
Which of the following structures is an exocrine gland?
- A. Parotid gland
- B. Pituitary gland
- C. Parathyroid gland
- D. Pineal gland
Correct Answer: A
Rationale: An exocrine gland secretes substances into ducts that lead to other organs or out of the body. The parotid gland is a salivary gland that secretes saliva into the mouth through ducts, making it an exocrine gland. The pituitary gland, parathyroid gland, and pineal gland are endocrine glands, which release hormones directly into the bloodstream. Therefore, the correct answer is the Parotid gland, as it fits the definition of an exocrine gland by secreting substances through ducts.