Nokea
Which property of a wave remains constant when the wave enters a different medium?
- A. Frequency
- B. Wavelength
- C. Amplitude
- D. Speed
Correct Answer: A
Rationale: When a wave enters a different medium, its frequency remains constant. Frequency is an intrinsic property of the wave determined by its source, and it does not change when transitioning between different mediums. On the other hand, wavelength, amplitude, and speed of the wave can all be altered when the wave moves from one medium to another. Wavelength is dependent on the speed of the wave and can change when entering a different medium due to differences in propagation speed. Amplitude can also change as it is influenced by factors like energy loss or gain at the boundary of the mediums. Speed, determined by the medium's properties, typically changes when a wave transitions between different mediums due to variations in the medium's density and elasticity.
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Which of the following is an example of a chemical change?
- A. Dissolving sugar in water
- B. Boiling water
- C. Rusting iron
- D. Crushing ice
Correct Answer: C
Rationale: Rusting iron is an example of a chemical change because it involves a chemical reaction where iron reacts with oxygen in the presence of water to form iron oxide (rust). This reaction results in a change in the chemical composition of the iron, unlike dissolving sugar in water, boiling water, or crushing ice, which are physical changes. Dissolving sugar in water is a physical change as sugar molecules remain unchanged but disperse in water. Boiling water is also a physical change as water changes its state from liquid to gas due to heat. Crushing ice is a physical change as the solid ice changes its physical form without altering its chemical composition.
During embryonic development, most vertebrates exhibit structures called pharyngeal pouches. These pouches eventually develop into different structures in various vertebrate groups, such as the human jaw and inner ear. Pharyngeal pouches are an example of:
- A. Analogous structures with different evolutionary origins but similar functions
- B. Homologous structures with a common evolutionary origin but diverse functions
- C. Vestigial structures that no longer serve a vital function in some organisms
- D. Atavisms, the reappearance of a trait absent in recent generations
Correct Answer: B
Rationale: Pharyngeal pouches in vertebrates are an example of homologous structures because they share a common evolutionary origin. Despite developing into different structures in various vertebrate groups, such as the jaw and inner ear in humans, these structures originated from the same ancestral feature. This concept of homology highlights the evolutionary relationship between different species and how structures can be modified over time to serve different functions while retaining a common origin. Choice A is incorrect because analogous structures have similar functions but different evolutionary origins, which does not apply to pharyngeal pouches. Choice C is incorrect as vestigial structures are remnants of features that were functional in ancestors but have reduced or lost their original function, which is not the case for pharyngeal pouches. Choice D is incorrect because atavisms refer to the reappearance of traits absent in recent generations, which is not the characteristic of pharyngeal pouches.
What is the SI unit of measurement for momentum?
- A. Newton (N)
- B. Kilogram-meter per second (kg·m/s)
- C. Joule (J)
- D. Newton-second (N·s)
Correct Answer: B
Rationale: The correct SI unit of measurement for momentum is kilogram-meter per second (kg·m/s). Momentum is a vector quantity that is calculated by multiplying an object's mass (in kilograms) by its velocity (in meters per second), resulting in the unit kg·m/s. This unit represents the quantity of motion an object possesses, taking into account both the mass and velocity of the object. Choice A, Newton (N), is the unit of force, not momentum. Choice C, Joule (J), is the unit of energy, not momentum. Choice D, Newton-second (N·s), is the unit of impulse, not momentum.
What is the definition of work in physics?
- A. Force applied to an object at rest
- B. Force exerted by an object in motion
- C. Transfer of energy through motion along a direction
- D. Measure of an object's potential energy
Correct Answer: C
Rationale: In physics, work is defined as the transfer of energy through motion along a direction. When a force is applied to an object, and the object moves in the direction of the force, work is done on the object. The work done is calculated as the force applied multiplied by the distance the object moves in the direction of the force. Choices A and B do not fully capture the essence of work, as work is about energy transfer through motion, not merely applying force to objects at rest or in motion. Choice D is incorrect as work is not a measure of an object's potential energy; rather, it is the transfer of energy through motion.
What is the term for a genetic disorder caused by a mutation in a mitochondrial gene?
- A. Autosomal dominant disorder
- B. Autosomal recessive disorder
- C. Sex-linked disorder
- D. Mitochondrial disorder
Correct Answer: D
Rationale: A) Autosomal dominant disorder: This type of genetic disorder is caused by a mutation in one copy of an autosomal gene. It is not related to mitochondrial gene mutations. B) Autosomal recessive disorder: This type of genetic disorder is caused by mutations in both copies of an autosomal gene. It is not related to mitochondrial gene mutations. C) Sex-linked disorder: This type of genetic disorder is caused by mutations in genes located on the sex chromosomes (X or Y). It is not related to mitochondrial gene mutations. D) Mitochondrial disorder: Mitochondrial disorders are genetic disorders caused by mutations in genes located in the mitochondria, the energy-producing structures within cells. These disorders are inherited maternally and can affect various organs and systems in the body due to the role of mitochondria in energy production.