What type of molecules are enzymes?
- A. Water molecules
- B. Protein molecules
- C. Tripolar molecules
- D. Inorganic molecules
Correct Answer: B
Rationale: The correct answer is B: Protein molecules. Enzymes are biological catalysts made up of proteins. They function by facilitating and speeding up chemical reactions in living organisms. Therefore, enzymes are primarily composed of protein molecules, not water, tripolar, or inorganic molecules. Choice A (Water molecules), Choice C (Tripolar molecules), and Choice D (Inorganic molecules) are incorrect because enzymes are specifically classified as proteins due to their structure and function in biological systems.
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Where does gas exchange occur in the human body?
- A. Alveoli
- B. Bronchi
- C. Larynx
- D. Pharynx
Correct Answer: A
Rationale: The correct answer is A: Alveoli. Gas exchange occurs in the alveoli, which are tiny air sacs in the lungs. Oxygen from the air we breathe diffuses into the blood vessels surrounding the alveoli, while carbon dioxide from the blood diffuses into the alveoli to be exhaled. The bronchi, larynx, and pharynx are all part of the respiratory system but are not directly involved in gas exchange. The bronchi are airways that lead to the lungs, the larynx is the voice box, and the pharynx is the throat. These structures are important for breathing and vocalization but do not participate in the exchange of gases between the respiratory system and the circulatory system.
How do hydrogen bonds in water affect its characteristics?
- A. Hydrogen bonds are not polar enough to attract non-polar molecules.
- B. Hydrogen bonds cause water to be less dense when it is a solid than when it is a liquid.
- C. Hydrogen bonds cause water to have high surface tension, allowing some organisms to move across it.
- D. Hydrogen bonds cause water to be a good solvent.
Correct Answer: C
Rationale: Hydrogen bonds in water contribute to its high surface tension, enabling some organisms to move across the water's surface. This property is essential for certain insects and small animals that rely on surface tension to move or stay afloat on water. Choice A is incorrect because hydrogen bonds are polar and can attract polar and other charged molecules. Choice B is incorrect as hydrogen bonds make ice less dense than liquid water, which is a unique property. Choice D is incorrect as the ability of water to act as a good solvent is primarily due to its polarity, not just hydrogen bonding.
Fill in the blanks in the following sentence: Enzymes are ________ molecules that serve as _______ for certain biological reactions.
- A. complex; suppressors
- B. acidic; triggers
- C. small; targets
- D. large; catalysts
Correct Answer: D
Rationale: Enzymes are large molecules that act as catalysts, accelerating chemical reactions by lowering the activation energy required for the reactions to occur. In the context of biological reactions, enzymes function as catalysts, not suppressors, triggers, or targets. The use of 'large' and 'catalysts' accurately describes the nature and role of enzymes in facilitating biological processes.
Which of the following best describes a plane that divides the body into upper and lower portions?
- A. Coronal
- B. Transverse
- C. Oblique
- D. Median
Correct Answer: B
Rationale: The correct answer is B: Transverse. A transverse plane, also known as a horizontal plane, divides the body into upper and lower portions. This plane is perpendicular to the long axis of the body. Coronal planes divide the body into anterior and posterior portions. Oblique planes pass through the body at an angle, neither strictly horizontal nor vertical. The median plane passes longitudinally through the body, dividing it into equal left and right halves.
What units of measurement would a triple beam balance show?
- A. Liters
- B. Grams
- C. Meters
- D. Gallons
Correct Answer: B
Rationale: A triple beam balance is used to measure mass, typically in grams. Liters, meters, and gallons are units of volume, length, and capacity, respectively, not typically measured using a triple beam balance. Therefore, the correct answer is grams. Choice A, Liters, is a unit of volume. Choice C, Meters, is a unit of length. Choice D, Gallons, is a unit of capacity. These units are not typically measured using a triple beam balance.
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