Nokea
Which law of motion explains the behavior of rockets in space?
- A. Newton's First Law
- B. Newton's Second Law
- C. Newton's Third Law
- D. None of the above
Correct Answer: C
Rationale: The correct answer is Newton's Third Law. Newton's Third Law states that for every action, there is an equal and opposite reaction. In the case of rockets in space, the action is the expulsion of gas from the rocket engines, and the reaction is the forward motion of the rocket. This law explains how rockets are able to propel themselves forward in the vacuum of space. Choices A and B are incorrect because Newton's First Law (inertia) and Second Law (F=ma) do not directly explain the behavior of rockets in space. Choice D is incorrect as Newton's Third Law specifically addresses the principle behind rockets' motion in space.
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A population refers to a group of organisms of the same:
- A. Species living in the same area
- B. Genus competing for resources
- C. Kingdom inhabiting a specific biome
- D. Phylum found throughout the world
Correct Answer: A
Rationale: A population is defined as a group of organisms of the same species living in the same area and interacting with one another. Option A correctly describes this definition by specifying that the organisms are of the same species and share a common geographical location. Options B, C, and D are incorrect because they do not accurately define a population in biological terms. In this context, a population specifically refers to a group of organisms belonging to the same species, not higher taxonomic ranks like genus, kingdom, or phylum.
What is the primary function of the epiglottis in the respiratory system?
- A. Filtration of air
- B. Production of mucus
- C. Prevention of food entering the trachea
- D. Oxygen exchange in the alveoli
Correct Answer: C
Rationale: The primary function of the epiglottis in the respiratory system is to prevent food from entering the trachea. During swallowing, the epiglottis covers the opening of the trachea, guiding food down the esophagus to the stomach and preventing it from entering the airway. This mechanism safeguards the respiratory system from foreign objects, ensuring proper air passage and avoiding potential choking hazards. Choices A, B, and D are incorrect: A) Filtration of air is mainly performed by the nasal hairs and the mucous membranes of the respiratory tract. B) Production of mucus is primarily carried out by the mucous glands in the respiratory system to trap particles and humidify the air. D) Oxygen exchange in the alveoli occurs in the lungs and is related to the process of respiration, not the function of the epiglottis.
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.
What is the pH of a solution with a hydrogen ion concentration of (1x10^{-9}) M?
- A. 5
- B. 7
- C. 9
- D. 11
Correct Answer: C
Rationale: The pH of a solution can be calculated using the formula: pH = -log[H+]. Given that the hydrogen ion concentration is \(1 \times 10^{-9}\) M, the pH can be calculated as pH = -log(1 x 10^-9) = 9. Therefore, the correct answer is C) 9.
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.