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What is the difference between DNA and RNA?
- A. Both are double-stranded.
- B. DNA contains deoxyribose sugar, while RNA contains ribose sugar.
- C. RNA contains the nitrogenous base uracil, while DNA contains thymine.
- D. Both are identical molecules.
Correct Answer: B
Rationale: A) Incorrect. DNA is double-stranded, but RNA is typically single-stranded.
B) Correct. DNA contains deoxyribose sugar, which lacks an oxygen atom on the 2' carbon of the sugar ring, while RNA contains ribose sugar, which has an additional hydroxyl group on the 2' carbon.
C) Incorrect. RNA contains the nitrogenous base uracil, while DNA contains thymine.
D) Incorrect. DNA and RNA have distinct structures and functions, so they are not identical molecules.
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What happens when the diaphragm contracts?
- A. Air is expelled from the lungs.
- B. The lungs expand to allow air intake.
- C. The vocal cords vibrate to produce sound.
- D. The trachea narrows to control airflow.
Correct Answer: B
Rationale: When the diaphragm contracts, it moves downward, creating more space in the chest cavity. This expansion of the chest cavity causes the lungs to expand as well, allowing air to be drawn into the lungs during inhalation. Therefore, the correct answer is that the lungs expand to allow air intake when the diaphragm contracts. Choices A, C, and D are incorrect because when the diaphragm contracts, it does not expel air from the lungs, cause the vocal cords to vibrate, or narrow the trachea to control airflow.
Which term describes the resistance of a substance to flow?
- A. Density
- B. Viscosity
- C. Conductivity
- D. Malleability
Correct Answer: B
Rationale: Viscosity is the term used to describe the resistance of a substance to flow. It quantifies how thick or thin a fluid is and how easily it flows. Density (A) refers to the mass of a substance per unit volume and does not directly relate to resistance to flow. Conductivity (C) is the property of a material to conduct electricity or heat, not related to resistance to flow. Malleability (D) is the property of a material to be hammered or rolled into thin sheets, which is not related to resistance to flow.
What is the relationship between mass and weight on Earth's surface?
- A. Mass and weight are equal
- B. Mass is greater than weight
- C. Weight is greater than mass
- D. Mass and weight are not related
Correct Answer: C
Rationale: The correct answer is C: Weight is greater than mass. Mass is a measure of the amount of matter in an object, while weight is the force of gravity acting on that object. On Earth's surface, weight is greater than mass because gravity pulls objects towards the center of the Earth, resulting in a force that we perceive as weight. Choice A is incorrect because mass and weight are not equal; weight is a force, while mass is a measure of the amount of matter. Choice B is incorrect because mass is not greater than weight; weight is the force exerted due to gravity. Choice D is incorrect as mass and weight are related; weight is dependent on mass and the gravitational force acting on the object.
What type of energy does an object in motion possess?
- A. Potential energy
- B. Kinetic energy
- C. Thermal energy
- D. Chemical energy
Correct Answer: B
Rationale: The correct answer is B. Kinetic energy is the energy possessed by an object in motion. When an object is in motion, it has the ability to do work due to its motion, which is known as kinetic energy. Potential energy, choice A, refers to stored energy that has the potential to do work but is not related to motion. Thermal energy, choice C, is related to the temperature of an object, not its motion. Chemical energy, choice D, is energy stored in the bonds of chemical compounds and is not directly related to an object's motion.
What is the functional group present in aldehydes?
- A. Hydroxyl
- B. Carbonyl
- C. Ester
- D. Amine
Correct Answer: B
Rationale: The correct answer is B: Carbonyl. Aldehydes contain the functional group -CHO, which is a carbonyl group where a carbon atom is double-bonded to an oxygen atom and single-bonded to a hydrogen atom. This distinguishes aldehydes from other functional groups. Choice A, Hydroxyl (-OH), is not characteristic of aldehydes as it is found in alcohols. Choice C, Ester (-COOR), and choice D, Amine (-NH2), represent different functional groups not typically found in aldehydes. Therefore, the correct functional group present in aldehydes is the carbonyl group.