What is the longest bone in the human body?
- A. Tibia
- B. Fibula
- C. Femur
- D. Humerus
Correct Answer: C
Rationale: The femur is indeed the longest bone in the human body. It extends from the hip to the knee, providing crucial support for the body's weight and enabling various movements. The tibia and fibula are bones in the lower leg, while the humerus is located in the upper arm. Therefore, choices A, B, and D are incorrect in this context.
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Which of the following is a characteristic of a solution with high viscosity?
- A. It flows easily
- B. It has a low resistance to flow
- C. It has a high resistance to flow
- D. It does not mix with other liquids
Correct Answer: C
Rationale: The correct answer is C: 'It has a high resistance to flow.' A solution with high viscosity exhibits a high resistance to flow. Viscosity measures the fluid's resistance to deformation or flow, with higher viscosity indicating thicker and slower-flowing fluids. Choice A is incorrect because high viscosity means the solution flows slowly, not easily. Choice B is incorrect as high viscosity implies a high resistance to flow, not a low one. Choice D is irrelevant to viscosity and does not describe a characteristic associated with high viscosity.
The dark, round structures observed within some bacterial cells are most likely:
- A. Ribosomes
- B. Flagella
- C. Endospores
- D. Capsules
Correct Answer: C
Rationale: Endospores are the correct answer. Endospores are dark, round structures observed within some bacterial cells. They are highly resistant dormant structures formed by certain bacteria in response to harsh environmental conditions. Ribosomes are not dark, round structures within bacterial cells; they are responsible for protein synthesis. Flagella are long, whip-like appendages used for movement and are not dark, round structures within bacterial cells. Capsules are outer layers of polysaccharides that some bacteria produce for protection and adherence, not dark, round structures within bacterial cells.
Which nervous system controls the involuntary 'fight-or-flight' response?
- A. Sympathetic nervous system
- B. Parasympathetic nervous system
- C. Enteric nervous system
- D. Sensory nervous system
Correct Answer: A
Rationale: The correct answer is the sympathetic nervous system. The sympathetic nervous system is responsible for activating the body's response to stress or danger, leading to the 'fight-or-flight' response. It prepares the body for action by increasing heart rate, dilating pupils, and redirecting blood flow to muscles. Choice B, the parasympathetic nervous system, is responsible for the body's 'rest-and-digest' activities, which are opposite to the 'fight-or-flight' response. Choice C, the enteric nervous system, primarily regulates the gastrointestinal system and is not directly involved in the 'fight-or-flight' response. Choice D, the sensory nervous system, transmits sensory information from the body to the central nervous system and is not responsible for the physiological changes associated with the 'fight-or-flight' response.
What phenomenon explains the formation of rainbows in the sky?
- A. Diffraction
- B. Interference
- C. Refraction and dispersion of sunlight by water droplets
- D. Reflection from clouds
Correct Answer: C
Rationale: Rainbows are formed due to the refraction and dispersion of sunlight by water droplets in the atmosphere. When sunlight enters a water droplet, it is refracted, then internally reflected, and finally refracted again as it exits the droplet. This dispersion of light into its component colors creates the beautiful rainbow we see in the sky. Choice A, diffraction, involves bending of light around obstacles or through narrow openings, not the splitting of light into colors as seen in rainbows. Choice B, interference, refers to the phenomenon where two or more light waves overlap and interact, producing a pattern of light and dark bands, which is not the case with rainbows. Choice D, reflection from clouds, does not accurately describe the process involved in the formation of rainbows through refraction and dispersion of light by water droplets.
What is the term for a solution that has a higher concentration of solute compared to another solution?
- A. Saturated solution
- B. Unsaturated solution
- C. Dilute solution
- D. Concentrated solution
Correct Answer: D
Rationale: The correct answer is D, a concentrated solution. A concentrated solution contains a higher concentration of solute compared to another solution. This means there is a large amount of solute dissolved in the solvent, making it more concentrated than other solutions. Choices A, B, and C are incorrect. A saturated solution is one in which no more solute can be dissolved at a given temperature, an unsaturated solution can dissolve more solute at the given conditions, and a dilute solution has a low concentration of solute relative to the solvent.