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Which of the following is a weak acid commonly found in citrus fruits?
- A. Sulfuric acid (Hâ‚‚SOâ‚„)
- B. Hydrochloric acid (HCl)
- C. Citric acid
- D. Nitric acid (HNO₃)
Correct Answer: C
Rationale: Citric acid is a weak acid commonly found in citrus fruits like lemons, oranges, and limes. It is responsible for the sour taste in these fruits. Sulfuric acid (option A), hydrochloric acid (option B), and nitric acid (option D) are all strong acids that are typically used in laboratory settings and industrial processes, not naturally found in citrus fruits. Therefore, the correct answer is option C.
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Which enzyme plays a crucial role in DNA replication during the S phase of interphase?
- A. Helicase
- B. DNA polymerase
- C. Ligase
- D. Topoisomerase
Correct Answer: B
Rationale: During the S phase of interphase, DNA replication takes place. DNA polymerase is the enzyme responsible for synthesizing new DNA strands by adding nucleotides in a complementary manner to the template strand. It plays a pivotal role in accurately replicating the entire genome. While helicase unwinds the double-stranded DNA for replication, topoisomerase relieves the tension in the DNA strands, and ligase joins the Okazaki fragments on the lagging strand. However, DNA polymerase directly participates in the synthesis of new DNA strands during replication, making it the correct answer.
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 technical term for the free edges of your fingernails and toenails?
- A. Lunula (The lunula is the white crescent moon shape at the base of the nail)
- B. Matrix (The matrix is the area under the nail where new nail cells are produced)
- C. Hyponychium (This is the skin under the free edge of the nail)
- D. Free edge
Correct Answer: C
Rationale: The correct answer is C, hyponychium. The hyponychium is the skin under the free edge of the nail, responsible for sealing the nail to the fingertip and protecting the nail bed from bacteria and debris. The lunula (choice A) refers to the white crescent moon shape at the base of the nail. The matrix (choice B) is the area under the nail where new nail cells are produced. The free edge (choice D) is the part of the nail that extends beyond the fingertip or toe.
Beta waves, associated with alertness and focused attention, typically fall within the range of:
- A. 0.5-4 Hz
- B. 4-8 Hz
- C. 8-13 Hz
- D. 13-30 Hz
Correct Answer: D
Rationale: Beta waves, associated with alertness and focused attention, typically fall within the range of 13-30 Hz. These waves are present when individuals are engaged in cognitive tasks, problem-solving, or focused mental activities. Options A, B, and C are incorrect because these frequency ranges are not characteristic of beta waves. Beta waves are higher in frequency and are associated with more active mental states compared to the ranges mentioned in options A, B, and C. Therefore, the correct answer is 13-30 Hz (Choice D).
What property of a wave represents the distance between two successive identical points on a wave?
- A. Wavelength
- B. Amplitude
- C. Frequency
- D. Period
Correct Answer: A
Rationale: The wavelength of a wave represents the distance between two successive identical points on a wave, such as two crests or two troughs. It is typically measured in meters and is a fundamental characteristic of a wave, influencing its properties and behavior. Wavelength is crucial in wave physics, affecting phenomena like interference, diffraction, and the wave's speed in a medium. Amplitude refers to the maximum displacement of a wave from its rest position, frequency is the number of complete oscillations a wave makes in a given time, and period is the time it takes for a wave to complete one full cycle. These properties are different from wavelength and serve distinct purposes in describing waves.