Nokea
Which of the following best describes a chemical change?
- A. Melting ice to form water
- B. Dissolving sugar in water
- C. Burning wood to produce ash
- D. Crushing a can to reduce its size
Correct Answer: C
Rationale: A chemical change involves a chemical reaction where new substances are formed. Burning wood to produce ash is an example of a chemical change because the wood undergoes a chemical reaction to form a new substance (ash). In this process, the chemical composition of wood changes to produce ash, which is a new substance. On the other hand, melting ice to form water, dissolving sugar in water, and crushing a can to reduce its size are examples of physical changes. In these instances, the substances may change their physical state or appearance but do not undergo a chemical reaction to form new substances. Therefore, choice C is the correct answer as it represents a chemical change, while choices A, B, and D represent physical changes.
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What is the primary factor that determines whether a solute will dissolve in a solvent?
- A. Temperature
- B. Pressure
- C. Molecular structure
- D. Particle size
Correct Answer: C
Rationale: The primary factor that determines whether a solute will dissolve in a solvent is the molecular structure. The compatibility of the solute's molecules with the solvent's molecules is crucial for dissolution to occur. While temperature, pressure, and particle size can influence the rate of dissolution, they are not the primary factors determining solubility. Molecular structure plays a key role in determining if a solute will form favorable interactions with the solvent, which is essential for dissolution to take place effectively. Temperature can affect solubility by changing the kinetic energy of molecules, pressure typically has a minor effect on solubility except for gases, and particle size influences the rate of dissolution by increasing surface area, but none of these factors are as fundamentally important as molecular structure in determining solubility.
Which of the following is NOT a mechanism that can directly cause evolution by natural selection?
- A. Mutations in genes
- B. Differential survival and reproduction based on traits
- C. Inheritance of acquired characteristics (like strong muscles from working out)
- D. Competition for resources in an environment
Correct Answer: C
Rationale: A) Mutations in genes can introduce new genetic variations into a population, which can be acted upon by natural selection.
B) Differential survival and reproduction based on traits is a key component of natural selection, as individuals with advantageous traits are more likely to survive and pass on their genes to the next generation.
C) Inheritance of acquired characteristics, also known as Lamarckism, is not a mechanism of evolution by natural selection. Traits acquired during an individual's lifetime (such as strong muscles from working out) are not passed on to offspring.
D) Competition for resources in an environment can drive natural selection by favoring individuals with traits that help them better compete for limited resources.
Therefore, the correct answer is C) Inheritance of acquired characteristics (like strong muscles from working out), as it is not a mechanism that can directly cause evolution by natural selection.
A symbiotic relationship where one organism benefits and the other is not harmed is called:
- A. Mutualism
- B. Commensalism
- C. Parasitism
- D. Predation
Correct Answer: B
Rationale: B) Commensalism: In commensalism, one organism benefits while the other is neither helped nor harmed. This is the relationship described in the question. The correct answer is Commensalism because it specifically fits the scenario where one organism benefits without affecting the other. A) Mutualism: In mutualism, both organisms involved benefit from the relationship. C) Parasitism: In parasitism, one organism benefits at the expense of the other organism, which is harmed. D) Predation: In predation, one organism (predator) kills and consumes another organism (prey) for food.
When ice melts, it undergoes a...
- A. Chemical change
- B. Physical change
- C. Nuclear change
- D. Radioactive decay
Correct Answer: B
Rationale: When ice melts, it undergoes a physical change, transitioning from a solid state to a liquid state. This change does not involve altering the chemical composition of the ice, making it a physical change rather than a chemical change, nuclear change, or radioactive decay. Choice A, 'Chemical change,' is incorrect because a chemical change involves a rearrangement of atoms resulting in new substances. Choice C, 'Nuclear change,' is incorrect as it refers to changes in the nucleus of an atom, not the phase transition of ice. Choice D, 'Radioactive decay,' is incorrect as it involves the spontaneous disintegration of an unstable atomic nucleus, which is not the process occurring when ice melts.
What is the name of the wart-like growths caused by the human papillomavirus (HPV)?
- A. Keloids
- B. Keloids
- C. Papillomas
- D. Carcinomas
Correct Answer: C
Rationale: The correct answer is 'Papillomas.' Papillomas are benign wart-like growths caused by the human papillomavirus (HPV). Keloids are raised scars that occur at the site of an injury due to excessive collagen formation, while carcinomas are malignant tumors arising from epithelial cells. When identifying the growths specifically related to HPV, papillomas are the most appropriate term.