Which best explains the role of plant pigments in photosynthesis?
Produce photon energy
Absorb light energy
Provide electrons
Convert heat to electricity
The Correct Answer is B
Choice A rationale: Plant pigments do not produce photon energy, but rather capture it from the sun. Photon energy is the energy carried by particles of light, called photons. Different types of electromagnetic radiation, such as visible light, have different amounts of photon energy depending on their wavelength¹.
Choice B rationale: Plant pigments absorb light energy and use it to initiate photosynthesis. Photosynthesis is the process by which plants convert light energy into chemical energy, stored in the bonds of sugar molecules. Plant pigments are specialized organic molecules, such as chlorophyll and carotenoids, that are found in the chloroplasts of plant cells. They absorb specific wavelengths of light and reflect others, giving plants their characteristic colors²³.
Choice C rationale: Plant pigments do not provide electrons, but rather transfer them to other molecules. Electrons are negatively charged subatomic particles that are involved in chemical reactions. In photosynthesis, plant pigments absorb light energy and use it to split water molecules, releasing electrons, protons, and oxygen. The electrons are then passed along an electron transport chain, generating a proton gradient that drives the synthesis of ATP, an energy molecule. The electrons are also used to reduce NADP+ to NADPH, an electron carrier⁴.
Choice D rationale: Plant pigments do not convert heat to electricity, but rather convert light to chemical energy. Heat and electricity are both forms of energy, but they are not directly involved in photosynthesis. Heat is the kinetic energy of molecules, while electricity is the flow of electrons or electric charge. Plant pigments absorb light energy and use it to drive the chemical reactions of photosynthesis, which produce sugar and oxygen as products⁵.
Choice E rationale: Plant pigments do not reduce NADP, but rather donate electrons to it. Reduction is a chemical reaction in which a molecule gains electrons, while oxidation is a chemical reaction in which a molecule loses electrons. NADP+ is an oxidized form of NADP, which stands for nicotinamide adenine dinucleotide phosphate. It is an electron carrier that accepts electrons from plant pigments in photosystem I, a complex of proteins and pigments in the thylakoid membrane of the chloroplast. The reduced form of NADP is NADPH, which carries electrons and hydrogen for the dark reaction of photosynthesis, which uses CO2 to produce glucose⁶.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Choice A rationale: The solute concentration of the cytoplasm inside the cell is correct because tonicity is a measure of how the solution affects the movement of water across the cell membrane by osmosis. Osmosis is the process by which water moves from a region of high water concentration to a region of low water concentration. The water concentration of a solution is determined by the solute concentration of the solution. The higher the solute concentration, the lower the water concentration, and vice versa. Therefore, tonicity compares the solute concentration of the solution outside the cell to the solute concentration of the cytoplasm inside the cell.
Choice B rationale: The permeability of the cell membrane is incorrect because permeability is a property of the cell membrane that determines how easily molecules can pass through it, not a measure of tonicity. The cell membrane is selectively permeable, meaning that it allows some molecules to cross, but not others. The cell membrane is permeable to water, but not to most solutes.
Choice C rationale: The swelling of the cell is incorrect because swelling is a result of tonicity, not a measure of it. Swelling occurs when a cell is placed in a hypotonic solution, which has a higher concentration of water and lower concentration of solute than the cell. In a hypotonic solution, water moves into the cell and out of the solution by osmosis, causing the cell to swell.
Choice D rationale: The number of cell fragments inside the cell is incorrect because cell fragments are pieces of broken cells that have no relation to tonicity. Cell fragments can be produced by mechanical damage, apoptosis, or necrosis, but they do not affect the solute concentration of the cytoplasm or the solution.
Choice E rationale: The presence of a cell wall is incorrect because the cell wall is a structure that surrounds the cell membrane in some cells, such as plant cells, but it does not affect tonicity. The cell wall is made of cellulose, a polysaccharide that is resistant to water. The cell wall provides mechanical support and prevents the cell from bursting in a hypotonic solution, but it does not change the solute concentration of the cytoplasm or the solution.
Correct Answer is C
Explanation
Choice A rationale: Sudan IV is not a reagent for protein detection, but a reagent for lipid detection. Sudan IV is a red dye that binds to non-polar molecules, such as fats and oils. Sudan IV stains lipids red, while leaving water-soluble molecules, such as proteins, unstained¹.
Choice B rationale: Benedict's is not a reagent for protein detection, but a reagent for sugar detection. Benedict's is a blue solution that contains copper sulfate, sodium carbonate, and sodium citrate. Benedict's reacts with reducing sugars, such as glucose and fructose, and reduces the copper ions from blue to orange-red².
Choice C rationale: Biuret is a reagent for protein detection. Biuret is a blue solution that contains copper sulfate and sodium hydroxide. Biuret reacts with peptide bonds, which are the bonds that link amino acids in proteins. Biuret changes color from blue to violet when it binds to protein molecules³.
Choice D rationale: Iodine is not a reagent for protein detection, but a reagent for starch detection. Iodine is a brown solution that forms a complex with starch, a polysaccharide composed of glucose units. Iodine changes color from brown to blue-black when it interacts with starch molecules⁴.
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