Nokea
What is the process by which damaged muscle tissue repairs and rebuilds itself?
- A. Degeneration
- B. Regeneration
- C. Hyperplasia
- D. Metaplasia
Correct Answer: B
Rationale: Regeneration is the correct answer. It is the process by which damaged muscle tissue repairs and rebuilds itself. New muscle cells are formed during regeneration to replace the damaged ones, allowing the muscle to heal and regain its function. Degeneration refers to tissue breakdown, hyperplasia is the increase in the number of cells in an organ or tissue, and metaplasia is the transformation of one type of tissue into another.
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Which radioactive isotope is commonly used in medical imaging techniques such as PET scans?
- A. Uranium-235
- B. Plutonium-239
- C. Potassium-40
- D. Fluorine-18
Correct Answer: D
Rationale: Fluorine-18 is the radioactive isotope commonly used in medical imaging techniques such as PET scans. It is frequently used in the form of fluorodeoxyglucose (FDG) to locate areas of heightened metabolic activity in the body, such as in cancer cells. Uranium-235 and Plutonium-239 are not typically employed in medical imaging, and Potassium-40, while a naturally occurring radioactive isotope found in the human body, is not commonly used in medical imaging techniques.
Which structure connects the two hemispheres of the brain, allowing communication and coordination between them?
- A. Corpus callosum
- B. Thalamus
- C. Hypothalamus
- D. Medulla oblongata
Correct Answer: A
Rationale: The correct answer is the corpus callosum. It is a thick band of nerve fibers that connects the two hemispheres of the brain, facilitating communication and coordination between them. The thalamus acts as a relay station for sensory information, the hypothalamus regulates basic functions like hunger and thirst, and the medulla oblongata controls vital functions such as breathing and heart rate. Therefore, choices B, C, and D are incorrect as they do not specifically connect the two hemispheres of the brain as the corpus callosum does.
What structure in plant cells provides rigidity and support?
- A. Cell membrane
- B. Golgi apparatus
- C. Plastid
- D. Cell wall
Correct Answer: D
Rationale: The correct answer is D, the cell wall. The cell wall is the structure in plant cells that provides rigidity and support. It is a tough, rigid structure located outside the cell membrane. Composed primarily of cellulose, the cell wall offers structural support to the cell, helping it maintain its shape and protect it from damage. The other choices, such as the cell membrane (choice A), Golgi apparatus (choice B), and plastid (choice C) do not provide rigidity and support to plant cells. The cell membrane is a selectively permeable barrier, the Golgi apparatus is involved in processing and packaging proteins, and plastids are organelles responsible for functions like photosynthesis and storage, but they do not provide the structural support that the cell wall does.
Photons, the basic unit of light, are:
- A. Charged particles
- B. Packets of energy with wave-particle duality
- C. Electromagnetic waves only
- D. Always absorbed by matter
Correct Answer: B
Rationale: Photons are not charged particles; they are packets of energy that exhibit wave-particle duality, meaning they can behave as both particles and waves. While photons are part of the electromagnetic spectrum, they are not electromagnetic waves themselves but rather discrete energy packets. They are not always absorbed by matter; they can be reflected, transmitted, or scattered.
When ice melts, it undergoes a...
- A. Chemical change
- B. Physical change
- C. Nuclear change
- D. Radioactive decay
Correct Answer: B
Rationale: When ice melts, it undergoes a physical change, transitioning from a solid state to a liquid state. This change does not involve altering the chemical composition of the ice, making it a physical change rather than a chemical change, nuclear change, or radioactive decay. Choice A, 'Chemical change,' is incorrect because a chemical change involves a rearrangement of atoms resulting in new substances. Choice C, 'Nuclear change,' is incorrect as it refers to changes in the nucleus of an atom, not the phase transition of ice. Choice D, 'Radioactive decay,' is incorrect as it involves the spontaneous disintegration of an unstable atomic nucleus, which is not the process occurring when ice melts.