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What energy conversion occurs in a solar cell?
- A. Electrical energy to light energy
- B. Chemical energy to electrical energy
- C. Solar energy to thermal energy
- D. Solar energy to electrical energy
Correct Answer: D
Rationale: Solar cells, also known as photovoltaic cells, convert solar energy from sunlight directly into electrical energy through a process called the photovoltaic effect. This process involves the absorption of photons from sunlight, which then generate an electric current. Choice A is incorrect because solar cells do not convert electrical energy into light energy. Choice B is incorrect as solar cells do not involve chemical energy conversion. Choice C is incorrect because solar cells do not primarily convert solar energy into thermal energy. Therefore, the correct answer is D) Solar energy to electrical energy.
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What is the largest bone in the human body?
- A. Femur (thigh bone)
- B. Tibia (shin bone)
- C. Humerus (upper arm bone)
- D. Scapula (shoulder blade)
Correct Answer: A
Rationale: The femur, also known as the thigh bone, holds the title of the largest bone in the human body. Situated in the upper leg, the femur plays a vital role in supporting the body's weight and enabling movement. While the tibia (shin bone), humerus (upper arm bone), and scapula (shoulder blade) are all essential bones, none of them match the femur in terms of size and importance. The tibia, humerus, and scapula are comparatively smaller bones with specific functions in their respective areas of the body, but they do not surpass the femur in size or significance.
What is the role of transfer RNA (tRNA) in protein synthesis?
- A. Transcribes DNA into mRNA
- B. Decodes the genetic code on mRNA
- C. Carries specific amino acids to the ribosomes
- D. Modifies the structure of proteins
Correct Answer: C
Rationale: A) Transcribes DNA into mRNA: This is the function of RNA polymerase, not transfer RNA (tRNA). tRNA is involved in protein synthesis, not transcription. B) Decodes the genetic code on mRNA: This is the function of tRNA during translation. tRNA molecules carry specific amino acids and recognize the codons on mRNA, ensuring the correct amino acid is added to the growing polypeptide chain. C) Carries specific amino acids to the ribosomes: This is the primary role of tRNA in protein synthesis. Each tRNA molecule is specific for a particular amino acid and carries it to the ribosome, where it is added to the growing protein chain. D) Modifies the structure of proteins: This is not a function of tRNA. Protein modification can occur after translation is complete and involves other cellular processes and molecules.
In the process of osmosis, the solvent moves from an area of...
- A. Low solute concentration to high solute concentration
- B. Hotter solution to colder solution
- C. Colder solution to hotter solution
- D. High solute concentration to low solute concentration
Correct Answer: D
Rationale: In the process of osmosis, solvent molecules move from an area of high solute concentration to low solute concentration. This movement occurs to equalize the solute concentrations on both sides of the semi-permeable membrane. As water tends to move towards higher solute concentrations, the solvent moves in this direction to balance the concentrations and establish equilibrium. Choices A, B, and C are incorrect because osmosis involves the movement of solvent, not solute, and it moves towards the area of higher solute concentration, not lower. Therefore, the correct answer is option D.
Which condition involves an overactive immune system attacking healthy tissues, leading to inflammation and damage?
- A. Immunodeficiency
- B. Autoimmune disease
- C. Allergy
- D. Cancer
Correct Answer: B
Rationale: Autoimmune diseases occur when the immune system mistakenly targets and attacks healthy tissues in the body, leading to inflammation and damage. This is different from immunodeficiency, where the immune system is weakened and unable to effectively protect the body against infections. Allergies involve an exaggerated immune response to harmless substances, while cancer is characterized by uncontrolled cell growth. Therefore, the correct answer is autoimmune disease (Choice B) as it specifically describes the scenario of an overactive immune system attacking healthy tissues, distinguishing it from the other conditions listed.
Which of the following is a property of amphiprotic substances?
- A. React with acids only
- B. React with bases only
- C. Can act as both acids and bases
- D. Are inert in chemical reactions
Correct Answer: C
Rationale: The correct answer is C: Can act as both acids and bases. Amphiprotic substances have the ability to donate a proton (act as an acid) or accept a proton (act as a base) depending on the reaction conditions. This dual nature allows them to participate in a wide range of chemical reactions, making them versatile and important in various chemical processes. Choices A and B are incorrect because amphiprotic substances are not limited to reacting with only acids or bases; they can interact with both. Choice D is incorrect because amphiprotic substances are not inert; they actively participate in chemical reactions by donating or accepting protons.