When Elodea leaves were placed in 10% NaCl, what was the result?
The cell membrane did not change at all because of the protection of the cell wall.
The cells burst because the solution was hypotonic.
The cell membrane shrank, but the central vacuole remained full.
The cell membrane shrank away from the cell wall because the solution was hypertonic.
The cell became turgid.
The Correct Answer is D
Choice A rationale: The cell membrane did not change at all because of the protection of the cell wall is incorrect because the cell wall does not prevent the movement of water across the cell membrane. The cell wall only provides mechanical support and prevents the cell from bursting in a hypotonic solution.
Choice B rationale: The cells burst because the solution was hypotonic is incorrect because the solution was hypertonic, not hypotonic. A hypertonic solution has a lower concentration of water than the cell, so water moves out of the cell and into the solution by osmosis, causing the cell to shrink.
Choice C rationale: The cell membrane shrank, but the central vacuole remained full is incorrect because the central vacuole also loses water in a hypertonic solution. The central vacuole is a large organelle that stores water and other substances in the plant cell. When water leaves the cell, the central vacuole shrinks and the cell loses its turgor pressure.
Choice D rationale: The cell membrane shrank away from the cell wall because the solution was hypertonic is correct because this is what happens when a plant cell is placed in a hypertonic solution. The cell membrane and the cytoplasm contract and pull away from the cell wall, creating a gap between them. This is called plasmolysis and it can damage the cell.
Choice E rationale: The cell became turgid is incorrect because the cell becomes turgid in a hypotonic solution, not a hypertonic one. A hypotonic solution has a higher concentration of water than the cell, so water moves into the cell and out of the solution by osmosis, causing the cell to swell and press against the cell wall. This is called turgor and it helps the cell maintain its shape and rigidity.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
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.
Correct Answer is A
Explanation
Choice A rationale: Iodine is a chemical element that forms a brown solution of iodine and potassium iodide, known as iodine solution. When this solution is added to a sample that contains starch, it forms a complex with the starch molecules, which changes the color of the solution to blue-black. This is based on the fact that starch is a polysaccharide that has a helical structure, which can trap the iodine molecules inside. ²
Choice B rationale: Biuret is a chemical compound that forms a blue solution of copper (II) sulfate and sodium hydroxide, known as biuret reagent. When this reagent is added to a sample that contains proteins or peptides, it forms a complex with the copper (II) ions, which changes the color of the solution to violet or pink. This is based on the fact that proteins and peptides have peptide bonds, which have nitrogen atoms that can coordinate with the copper (II) ions. ³
Choice C rationale: Benedict's is a chemical compound that forms a blue solution of copper (II) sulfate, sodium carbonate, and sodium citrate, known as Benedict's reagent. When this reagent is heated with a sample that contains reducing sugars, such as glucose or maltose, it reduces the copper (II) ions to copper (I) ions, which form a red, orange, or green precipitate of copper (I) oxide. This is based on the fact that reducing sugars have free aldehyde or ketone groups that can donate electrons to the copper (II) ions. ⁴
Choice D rationale: Phenol red is a chemical compound that forms a red solution that is used as a pH indicator. When this solution is added to a sample that has an acidic or neutral pH, it remains red or turns yellow. When this solution is added to a sample that has an alkaline pH, it turns pink or fuchsia. This is based on the fact that phenol red has a sulfonated hydroxyquinone group that can lose or gain protons depending on the pH of the solution. ⁵
Choice E rationale: Sudan IV is a chemical compound that forms a red powder that is used as a stain for lipids. When this powder is dissolved in a solvent and added to a sample that contains lipids, such as fats or oils, it dissolves in the lipids and stains them red. When this solution is added to a sample that does not contain lipids, it remains in the solvent and does not stain the sample. This is based on the fact that Sudan IV is a nonpolar compound that can dissolve in nonpolar substances like lipids, but not in polar substances like water. ⁶.
Whether you are a student looking to ace your exams or a practicing nurse seeking to enhance your expertise , our nursing education contents will empower you with the confidence and competence to make a difference in the lives of patients and become a respected leader in the healthcare field.
Visit Naxlex, invest in your future and unlock endless possibilities with our unparalleled nursing education contents today