Nokea
What term describes the functional unit of a skeletal muscle responsible for muscle contraction?
- A. Myofibril
- B. Sarcomere
- C. Tendon
- D. Myoglobin
Correct Answer: B
Rationale: The correct answer is B, 'Sarcomere.' The sarcomere is indeed the functional unit of a skeletal muscle responsible for muscle contraction. It is composed of actin and myosin filaments that interact to generate muscle contraction. Choice A, 'Myofibril,' is incorrect as myofibrils are composed of sarcomeres, not the functional units themselves. Choice C, 'Tendon,' is incorrect as tendons connect muscles to bones and do not directly participate in muscle contraction. Choice D, 'Myoglobin,' is incorrect as myoglobin is a protein that stores oxygen in muscle cells and is not directly involved in muscle contraction.
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What is the periodic table?
- A. A table of elements that are arranged in order of increasing atomic number.
- B. A table of elements that are arranged in order of increasing atomic mass.
- C. A table of elements that are arranged in order of their reactivity.
- D. A table of elements that are arranged in order of their color.
Correct Answer: A
Rationale: The periodic table is a tabular arrangement of the chemical elements, organized based on their atomic number, electron configurations, and recurring chemical properties. Elements are placed in rows (periods) and columns (groups) with similar properties. The elements are listed in order of increasing atomic number, which is the number of protons in the nucleus of an atom. This arrangement reveals a periodic repetition of chemical properties, forming the basis of the periodic law. Choice B, which suggests arranging elements based on increasing atomic mass, is incorrect because the periodic table is primarily organized by atomic number, not atomic mass. Choices C and D are also incorrect as the periodic table is not based on reactivity or color of elements, but rather on atomic number and properties.
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 gradual change in a species over time is called:
- A. Adaptation
- B. Evolution
- C. Speciation
- D. Natural selection
Correct Answer: B
Rationale: - Adaptation refers to the process by which a species becomes better suited to its environment over time. While adaptation is a component of evolution, it specifically refers to the changes that help a species survive and reproduce in its environment.
- Speciation is the process by which new species arise from a single ancestral species. It involves the evolution of reproductive isolation between populations.
- Natural selection is a mechanism of evolution where individuals with advantageous traits are more likely to survive and reproduce, leading to the increase in frequency of those traits in a population.
- Evolution is the gradual change in a species over time, encompassing all the processes such as adaptation, speciation, and natural selection that drive these changes.
Which element has the same number of protons and neutrons?
- A. Carbon (C)
- B. Oxygen (O)
- C. Lithium (Li)
- D. Helium (He)
Correct Answer: D
Rationale: The correct answer is Helium (He). Helium has an atomic number of 2, meaning it has 2 protons. It also has 2 neutrons, which gives it a total mass number of 4. Therefore, Helium is an example of an element with an equal number of protons and neutrons.
Choice A (Carbon) has 6 protons and usually has more neutrons than protons. Choice B (Oxygen) has 8 protons and 8 neutrons, so the numbers are not equal. Choice C (Lithium) has 3 protons and usually has more neutrons than protons, so it does not fit the criteria of having the same number of protons and neutrons.
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.