Nokea
Which property of a wave remains constant when it crosses a boundary between two different media?
- A. Frequency
- B. Wavelength
- C. Amplitude
- D. Speed
Correct Answer: D
Rationale: When a wave crosses a boundary between two different media, its speed is the property that remains constant. This is due to the principle of conservation of energy. While the frequency and wavelength of a wave may change as it moves from one medium to another, the speed of the wave remains constant. This phenomenon is a result of the wave adjusting its frequency and wavelength to maintain a consistent speed in different media. Therefore, choices A, B, and C are incorrect. Frequency and wavelength may change when a wave moves across media, and amplitude may also be affected by the medium, but the speed of the wave will remain constant.
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What is the general formula for an alkene?
- A. CnH2n+2
- B. CnH2n
- C. CnH2n-2
- D. CnH2n+1
Correct Answer: B
Rationale: The general formula for an alkene is \(C_nH_{2n}\), indicating the presence of a double bond between carbon atoms.
Through what tubes does urine travel from the kidneys to the bladder?
- A. Urethra
- B. Ureters
- C. Renal arteries
- D. Renal veins
Correct Answer: B
Rationale: The correct answer is 'Ureters.' The ureters are the tubes that transport urine from the kidneys to the bladder. The urethra, not a choice in this question, is the tube responsible for carrying urine from the bladder out of the body. Renal arteries and veins are blood vessels that respectively supply and drain the kidneys, not involved in the transport of urine to the bladder.
What are isotopes?
- A. Atoms of the same element with different numbers of protons.
- B. Atoms of the same element with different numbers of neutrons.
- C. Atoms of different elements with the same number of protons.
- D. Atoms of different elements with the same number of electrons.
Correct Answer: B
Rationale: Isotopes are atoms of the same element with different numbers of neutrons. While isotopes share the same number of protons, which determines the element, they differ in the number of neutrons. This variance in neutron count results in isotopes having different atomic masses. Choice A is incorrect because isotopes have the same number of protons (same element) but differ in the number of neutrons. Choice C is incorrect as it describes atoms of different elements, not isotopes of the same element. Choice D is also incorrect because isotopes can have different numbers of electrons, but what defines isotopes is the variation in neutron numbers.
Which type of joint allows for the widest range of motion, similar to the shoulder joint?
- A. Hinge joint
- B. Ball-and-socket joint
- C. Gliding joint
- D. Fixed joint
Correct Answer: B
Rationale: The correct answer is B: Ball-and-socket joint. Ball-and-socket joints, like the shoulder joint, allow for the widest range of motion in multiple directions. This type of joint consists of a rounded bone (the 'ball') fitting into a cup-like socket, enabling movements such as flexion, extension, abduction, adduction, and rotation. Choice A, Hinge joint, allows movement in one plane, like a door hinge, and does not offer the same range of motion as a ball-and-socket joint. Choice C, Gliding joint, permits limited motion in various directions but not as wide as a ball-and-socket joint. Choice D, Fixed joint, does not allow any motion as it is immovable, unlike the shoulder joint which is highly mobile.
Why is biodiversity important for healthy ecosystems?
- A. Increases stability and resilience to disturbances
- B. Provides stability and resilience to disturbances
- C. Slows down nutrient cycling
- D. Reduces the number of decomposers
Correct Answer: B
Rationale: Biodiversity refers to the variety of living organisms in a particular area. A diverse ecosystem is better able to withstand and recover from disturbances such as natural disasters, climate change, or human impacts. This is because different species play unique roles in the ecosystem, and a higher level of biodiversity means there are more species available to fulfill these roles. For example, if one species is negatively affected by a disturbance, other species may be able to compensate for its loss, maintaining the overall functioning of the ecosystem. Therefore, biodiversity provides stability and resilience to disturbances, making ecosystems healthier and more sustainable. Choice A is incorrect because biodiversity doesn't increase competition for resources but rather helps in maintaining a balance within the ecosystem. Choice C is incorrect as biodiversity does not slow down nutrient cycling; in fact, it enhances nutrient cycling by ensuring a variety of species involved in the process. Choice D is incorrect as biodiversity does not reduce the number of decomposers but instead supports a diverse community of decomposers that are essential for nutrient recycling in ecosystems.