Nokea
Passive transport does not require energy input from the cell. Which of the following is an example of passive transport?
- A. Active transport of ions across a membrane
- B. Diffusion of small molecules across a concentration gradient
- C. Movement of large molecules using vesicles
- D. Endocytosis of particles into the cell
Correct Answer: B
Rationale: Passive transport refers to the movement of molecules across a cell membrane without the input of energy. Diffusion of small molecules across a concentration gradient is a classic example of passive transport, as it occurs spontaneously from an area of high concentration to an area of low concentration. Active transport (option A) requires energy input in the form of ATP to move substances against their concentration gradient. Movement of large molecules using vesicles (option C) involves processes like endocytosis and exocytosis that require energy in the form of ATP. Endocytosis of particles into the cell (option D) is an active process that requires energy expenditure by the cell to engulf and internalize extracellular substances.
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What is the periodic law?
- A. The statement that the properties of the elements are a periodic function of their atomic numbers.
- B. The statement that elements can be arranged in a table where elements with similar properties are grouped together.
- C. The statement that elements can be arranged in a table where the atomic number of an element is equal to the number of protons in its nucleus.
- D. The statement that elements can be arranged in a table where the atomic mass of an element is equal to the number of neutrons in its nucleus.
Correct Answer: A
Rationale: The periodic law states that the properties of elements are a periodic function of their atomic numbers. This means that when elements are arranged in order of increasing atomic number, there is a periodic repetition of their properties. This forms the basis for the modern periodic table. Option B describes the organization of elements in the periodic table, which is related to the periodic law but not the definition of it. Options C and D are incorrect as they describe concepts related to atomic structure (atomic number and atomic mass) rather than the periodic law itself.
How does electron configuration relate to the periodic table?
- A. Elements within the same period have identical electron configurations.
- B. Elements within the same group share similar electron configurations in their outermost shell.
- C. Electron configuration determines an element's position on the periodic table.
- D. An element's group on the periodic table is determined by the number of electron shells it possesses.
Correct Answer: B
Rationale: Elements within the same group share similar electron configurations in their outermost shell. The periodic table is organized based on the number of electrons in the outermost energy level, known as valence electrons, which significantly influence an element's chemical properties. Elements within the same group have the same number of valence electrons, leading to comparable chemical behaviors. Choices A and D are incorrect because elements within the same period, not group, have identical electron configurations, and an element's group is primarily determined by the number of valence electrons and not the number of electron shells. Choice C is incorrect because while electron configuration is crucial for understanding an element's properties, it is not the sole factor determining its position on the periodic table.
Which of the following is a unit of power?
- A. Newton-meter (N·m)
- B. Joule (J)
- C. Watt (W)
- D. Kilogram (kg)
Correct Answer: C
Rationale: The correct answer is C: Watt (W). Power is the rate at which work is done or energy is transferred. The unit of power is the watt (W), named after James Watt, the inventor of the steam engine. A Newton-meter (N·m) is a unit of torque, Joule (J) is a unit of energy, and Kilogram (kg) is a unit of mass, not power. Therefore, choices A, B, and D are incorrect as they represent units of torque, energy, and mass, respectively, and not power.
In physics, what does the term 'terminal velocity' refer to?
- A. Maximum velocity reached by an object in free fall
- B. Velocity when the object is at rest
- C. Instantaneous velocity of an object
- D. Velocity only reached by heavy objects
Correct Answer: A
Rationale: Terminal velocity in physics refers to the maximum velocity achieved by an object in free fall when the force of gravity equals the force of air resistance. At terminal velocity, the object stops accelerating and maintains a constant speed. This occurs when the opposing forces are balanced, leading to no further increase in speed. Choice B is incorrect as velocity when the object is at rest is zero, not at terminal velocity. Choice C is incorrect as instantaneous velocity refers to the velocity at a specific moment in time, not the maximum speed reached in free fall. Choice D is incorrect because terminal velocity is not exclusive to heavy objects; all objects in free fall can reach terminal velocity under the right conditions.
Which term is used to classify reactions that require light energy to proceed?
- A. Combustion reactions
- B. Endothermic reactions
- C. Photochemical reactions
- D. Double displacement reactions
Correct Answer: C
Rationale: Reactions that require light energy to proceed are classified as photochemical reactions. Photochemical reactions involve the absorption of light energy to initiate a chemical reaction. Combustion reactions involve the rapid combination of a substance with oxygen, endothermic reactions absorb heat from the surroundings, and double displacement reactions involve the exchange of ions between two compounds. Therefore, the correct term for reactions requiring light energy is 'photochemical reactions,' making option C the correct answer.