Nokea
Which of the following best describes a balanced force acting on an object?
- A. The object remains at rest
- B. The object moves with constant velocity
- C. The object accelerates
- D. The object's mass changes
Correct Answer: B
Rationale: When a balanced force acts on an object, the net force is zero, resulting in no acceleration. This means that the object will continue to move with a constant velocity if it was already in motion or remain at rest if it was initially stationary. Choice A is incorrect because the object can also move with constant velocity. Choice C is incorrect as acceleration only occurs when an unbalanced force is applied. Choice D is incorrect as the mass of an object is not affected by the balance of forces acting on it.
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How can a single gene mutation lead to multiple phenotypes depending on the organism?
- A. Pleiotropy describes the effect of one gene influencing multiple seemingly unrelated traits.
- B. Epigenetics involves environmental factors modifying gene expression without altering the DNA sequence.
- C. Genetic drift refers to random changes in allele frequencies within a population.
- D. Gene regulation controls the timing and level of gene expression within an organism.
Correct Answer: A
Rationale: A single gene mutation can lead to multiple phenotypes through pleiotropy, where one gene influences diverse traits or functions in an organism. This phenomenon occurs when the mutated gene affects different biochemical pathways, developmental processes, or cellular functions, resulting in a cascade of downstream effects that manifest as a variety of phenotypic outcomes. Choice B, epigenetics, involves modifications in gene expression influenced by environmental factors without altering the DNA sequence, which is not directly related to the question about single gene mutations causing multiple phenotypes. Choice C, genetic drift, refers to random changes in allele frequencies within a population, which is unrelated to the impact of a single gene mutation on multiple phenotypes. Choice D, gene regulation, focuses on controlling the timing and level of gene expression within an organism, which is not directly addressing how a single gene mutation can lead to diverse phenotypes.
Which type of reaction is represented by the equation A + B → AB?
- A. Synthesis
- B. Decomposition
- C. Single Replacement
- D. Double Replacement
Correct Answer: A
Rationale: The correct answer is 'Synthesis.' In a synthesis reaction, two or more reactants combine to form a single product. The equation A + B → AB represents a synthesis reaction where substances A and B combine to form compound AB. Choice B, 'Decomposition,' involves a single compound breaking down into two or more simpler substances, which is not the case in this equation. Choices C and D, 'Single Replacement' and 'Double Replacement,' involve the replacement of elements in compounds or the exchange of ions between compounds, neither of which is depicted in the given equation. Thus, 'Synthesis' is the most suitable classification for the reaction A + B → AB.
How does polarization affect the intensity of light passing through a polarizing filter?
- A. All light passes through regardless of polarization.
- B. Light with the same polarization as the filter passes through, while others are blocked.
- C. Light with higher intensity passes through, while weaker light is blocked.
- D. The intensity is reduced for all light, regardless of polarization.
Correct Answer: B
Rationale: A polarizing filter only allows light waves with a specific orientation (polarization) to pass through while blocking light waves with different orientations. Therefore, light with the same polarization as the filter will pass through, while light with different polarizations will be blocked. This results in a reduction in intensity for light passing through the polarizing filter. Choice A is incorrect because a polarizing filter selectively filters light based on its polarization. Choice C is incorrect as the intensity of light passing through is determined by its polarization, not solely its intensity. Choice D is incorrect because a polarizing filter affects light based on its polarization, not uniformly reducing the intensity for all light passing through.
What is the term for a solution that contains the maximum amount of solute that can dissolve at a specific temperature and pressure?
- A. Saturated solution
- B. Unsaturated solution
- C. Dilute solution
- D. Concentrated solution
Correct Answer: A
Rationale: A saturated solution is defined as a solution that has dissolved the maximum amount of solute possible at a specific temperature and pressure. In a saturated solution, any additional solute added will not dissolve, resulting in a visible precipitate. Choice B, unsaturated solution, refers to a solution where more solute can still be dissolved. Choices C and D, dilute solution and concentrated solution, do not specifically refer to the maximum amount of solute that can be dissolved at a given temperature and pressure, making them incorrect in this context.
Which skin condition is characterized by patches of inflamed, reddened skin and is often triggered by allergens or stress?
- A. Eczema
- B. Psoriasis
- C. Acne
- D. Vitiligo
Correct Answer: A
Rationale: Eczema is the correct answer. It presents as patches of inflamed, reddened skin and can be triggered by allergens, stress, or other factors. Psoriasis, on the other hand, is characterized by red, scaly patches rather than inflamed and reddened skin. Acne manifests as pimples and blemishes, not patches of inflamed skin. Vitiligo is characterized by the loss of skin color in patches, which is distinct from the symptoms described in the question.