Nokea
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.
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At the peak of a baseball's trajectory, which of the following forces is acting on the ball?
- A. Only gravitational force
- B. Only the force of air resistance
- C. Both gravitational force and the force of air resistance
- D. Neither gravitational force nor the force of air resistance
Correct Answer: A
Rationale: At the peak of a baseball's trajectory, the ball momentarily stops moving upwards before it starts to fall back down. During this moment of temporary rest, the only force acting on the ball is the gravitational force pulling it downward towards the Earth. The force of air resistance is negligible at this point because the ball is momentarily stationary, and air resistance requires motion to be significant. Therefore, the correct answer is that only the gravitational force is acting on the ball at the peak of its trajectory. Choices B, C, and D are incorrect because air resistance does not have a significant effect when the ball is at its peak and momentarily stationary.
Where is pseudostratified columnar epithelium primarily found?
- A. Skeletal muscle
- B. Bony skeleton
- C. External ears
- D. Bloodstream
Correct Answer: C
Rationale: Pseudostratified columnar epithelium is a type of epithelial tissue found in the respiratory tract, including the lining of the trachea and bronchi. It is also found in the male reproductive system and parts of the auditory tube and external ear canal. Among the options provided, the external ears (option C) are the most relevant location for pseudostratified columnar epithelium. Skeletal muscle (option A) is primarily composed of muscle fibers, not epithelial tissue. The bony skeleton (option B) is composed of bone tissue. The bloodstream (option D) consists of blood cells and plasma, not epithelial tissue.
Which of the following is a functional group commonly found in alcohols?
- A. Carbonyl
- B. Hydroxyl
- C. Amine
- D. Ester
Correct Answer: B
Rationale: The hydroxyl functional group (OH) is commonly found in alcohols, giving them their characteristic properties. Alcohols are organic compounds that contain a hydroxyl group bonded to a carbon atom. The other choices, carbonyl, amine, and ester, are associated with different functional groups commonly found in other types of organic compounds. Carbonyl groups consist of a carbon atom double-bonded to an oxygen atom. Amines contain a nitrogen atom bonded to hydrogen atoms. Esters consist of a carbonyl group bonded to an alkoxyl group. Therefore, the correct answer is 'Hydroxyl (B),' as it specifically relates to the functional group present in alcohols, distinguishing it from the other options.
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.
What is the mass number of an element?
- A. The number of protons in an atom's nucleus.
- B. The number of neutrons in an atom's nucleus.
- C. The number of electrons in an atom's valence shell.
- D. The number of isotopes of an element.
Correct Answer: B
Rationale: The mass number of an element represents the total number of protons and neutrons in an atom's nucleus. It specifically focuses on the number of neutrons in an atom's nucleus, which contributes to the overall mass of the atom. Therefore, the mass number is not solely determined by the number of protons, electrons, or isotopes. Choice A is incorrect because it refers to the atomic number, which is the number of protons in an atom's nucleus. Choice C is incorrect as the number of electrons in the valence shell is related to the atom's reactivity and bonding behavior, not the mass number. Choice D is incorrect because the mass number does not represent the number of isotopes of an element, but rather the sum of protons and neutrons in an atom's nucleus. Thus, option B, the number of neutrons in an atom's nucleus, is the correct choice.