Nokea
What is the principle behind the phenomenon of refraction, where waves bend when entering a new medium?
- A. Change in wavelength
- B. Change in frequency
- C. Change in wave speed
- D. None of the above
Correct Answer: C
Rationale: Refraction occurs due to a change in wave speed when waves enter a new medium. As waves travel from one medium to another, their speed changes, causing them to bend. This change in speed is responsible for the bending of waves during refraction. It is not the change in wavelength or frequency that causes refraction, but rather the change in speed as waves move through different mediums. Therefore, the correct answer is the change in wave speed (Choice C). Choices A and B are incorrect as refraction is not primarily influenced by changes in wavelength or frequency, but by changes in wave speed. Choice D is also incorrect as there is a specific principle, which is the change in wave speed, behind the phenomenon of refraction.
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What is the process of splitting a heavy nucleus into smaller nuclei, releasing a vast amount of energy called?
- A. Nuclear fusion
- B. Nuclear fission
- C. Radioactive decay
- D. Chain reaction
Correct Answer: B
Rationale: The correct answer is B: Nuclear fission. Nuclear fission is the process of splitting a heavy nucleus into smaller nuclei, releasing a vast amount of energy. This process is commonly used in nuclear power plants and nuclear weapons. It is a controlled chain reaction that generates energy. Option A, Nuclear fusion, is the process of combining two light nuclei to form a heavier nucleus, releasing energy. This process powers the sun and other stars. Option C, Radioactive decay, is the process by which an unstable atomic nucleus loses energy by emitting radiation. Option D, Chain reaction, is a self-sustaining reaction where the products of one reaction event stimulate further reaction events. While chain reactions can occur in both nuclear fission and fusion, the specific process of splitting a heavy nucleus into smaller ones is known as nuclear fission.
Which vitamin is essential for proper absorption of calcium and plays a role in lung function?
- A. Vitamin A
- B. Vitamin B12
- C. Vitamin D
- D. Vitamin E
Correct Answer: C
Rationale: The correct answer is Vitamin D. Vitamin D is crucial for the proper absorption of calcium in the intestines and is essential for maintaining lung function. It regulates calcium and phosphorus levels, crucial for healthy bones and teeth. Vitamin A is important for vision and immune function, not specifically for calcium absorption or lung function. Vitamin B12 is essential for nerve function and red blood cell production, not related to calcium absorption or lung function. Vitamin E is an antioxidant that helps protect cells from damage, but it is not directly involved in calcium absorption or lung function.
What is the primary function of hematopoietic tissue?
- A. Building and repairing bone
- B. Supporting and connecting tissues
- C. Production of blood cells
- D. Contracting for movement
Correct Answer: C
Rationale: The primary function of hematopoietic tissue is the production of blood cells. Hematopoietic tissue, primarily found in the bone marrow, is responsible for generating red blood cells, white blood cells, and platelets. These blood cells are vital for oxygen transport, immune response, and blood clotting. Choices A, B, and D are incorrect as they do not reflect the main function of hematopoietic tissue. Building and repairing bone is primarily carried out by osteoblasts and osteoclasts, supporting and connecting tissues is a role of connective tissues like tendons and ligaments, and contracting for movement is a function of muscle tissue.
What is the process of converting DNA into a protein called?
- A. Transcription
- B. Translation
- C. Replication
- D. Mutation
Correct Answer: B
Rationale: Translation is the correct answer. It is the process of converting the information in mRNA into a sequence of amino acids to form a protein. Transcription (Choice A) is the process of copying a segment of DNA into RNA. Replication (Choice C) is the process of making an identical copy of DNA. Mutation (Choice D) refers to a change in the DNA sequence that can lead to variations in proteins, but it is not the process of converting DNA into a protein.
What is the term for the chemical reaction that involves the loss of electrons?
- A. Reduction
- B. Oxidation
- C. Neutralization
- D. Precipitation
Correct Answer: B
Rationale: Oxidation is the process where a substance loses electrons. In an oxidation reaction, the substance being oxidized loses electrons, which are gained by another substance. Reduction is the opposite process, where a substance gains electrons. Neutralization is a reaction between an acid and a base to form a salt and water. Precipitation is the formation of a solid from a solution. Therefore, in the context of a chemical reaction involving the loss of electrons, the correct term is oxidation (Choice B).