AP BIOLOGY UNIT 3 QUESTIONS WITH 100% CORRECT ANSWERS GRADED A+ 2025

ATP (adenosine triphosphate) - Correct Ans-An adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed. This energy is used to drive endergonic reactions in cells. ADP (adenosine diphosphate) - Correct Ans-Nucleotide with two phosphate groups that can accept another phosphate group and become ATP. free energy - Correct Ans-Chemical energy available to do work substrate level phosphorylation - Correct Ans-The enzyme-catalyzed formation of ATP by direct transfer of a phosphate group to ADP from an intermediate substrate in catabolism. reduction - Correct Ans-Gain of electrons by a chemical reactant; any reduction is accompanied by an oxidation. oxidation - Correct Ans-Relative loss of electrons in a chemical reaction; either outright removal to form an ion, or the sharing of electrons with substances having a greater affinity for them, such as oxygen. Most oxidations, including biological ones, are associated with the liberation of energy. oxidized - Correct Ans-loses electrons (becomes more positive) reduced - Correct Ans-gains electrons, becomes more negative NAD - Correct Ans-nicotinamide adenine dinucleotide - a coenzyme that is an electron carrier; NAD+ is oxidized, NADH is reduced reducing agent - Correct Ans-compound that loses electrons in a reaction oxidizing agent - Correct Ans-compound that gains electrons in a reaction cellular respiration - Correct Ans-The catabolic pathways by which electrons are removed from various molecules and passed through intermediate electron carriers to O2, generating H2O and releasing energy. aerobic - Correct Ans-Requiring molecular oxygen, O2 pyruvate oxidation - Correct Ans-pyruvate molecules are oxidized and produces acetyl-CoA, CO2, and NADH citric acid cycle - Correct Ans-In cellular respiration, a set of chemical reactions whereby acetyl CoA is oxidized to carbon dioxide and hydrogen atoms are stored as NADH and FADH2. Also called the Krebs cycle. energy-investing reactions - Correct Ans-endergonic stage of glycolysis in which glucose is converted into G3P energy-harvesting reactions - Correct Ans-exergonic stage of glycolysis in which G3P is converted into two molecules of pyruvate pyruvate - Correct Ans-Three-carbon compound that forms as an end product of glycolysis. NADH - Correct Ans-reduced electron carrier molecule formed in glycolysis Krebs cycle - Correct Ans-second stage of cellular respiration, in which pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions; synonym for Citric Acid Cycle acetyl CoA - Correct Ans-molecule formed from the oxidation of pyruvate FADH2 - Correct Ans-a reduced coenzyme similar to NADH, an electron carrier anaerobic - Correct Ans-Occurring without the use of molecular oxygen, O2. fermentation - Correct Ans-Speaking specifically about energy metabolism, the anaerobic degradation of a substance such as glucose to smaller molecules such as lactic acid or alcohol with the extraction of energy. (2) Speaking generally, metabolic processes that occur in the absence of O2. lactic acid fermentations - Correct Ans-Anaerobic series of reactions that convert glucose to lactic acid, in some bacteria and animal cells. alcoholic fermentation - Correct Ans-Anaerobic series of reactions that convert glucose to ethyl alcohol (ethanol) and carbon dioxide in some plants and yeast cells. photosynthesis - Correct Ans-photosynthesis: Metabolic processes carried out by green plants and cyanobacteria, by which visible light is trapped and the energy used to convert CO2 into organic compounds. light dependent reactions - Correct Ans-The initial phase of photosynthesis, in which light energy is converted into chemical energy. pigment - Correct Ans-A substance that absorbs visible light. chlorophyll - Correct Ans-Any of several green pigments associated with chloroplasts or with certain bacterial membranes; responsible for trapping light energy for photosynthesis. absorption spectrum - Correct Ans-A graph of light absorption versus wavelength of light; shows how much light is absorbed at each wavelength. action spectrum - Correct Ans-A graph of a biological process versus light wavelength; shows which wavelengths are involved in the process. light-harvesting complex - Correct Ans-in photosynthesis, a group of different molecules that cooperate to absorb light energy and transfer it to a reaction center. Also called antenna system. photosystem - Correct Ans-A light-harvesting complex in the chloroplast thylakoid composed of pigments and proteins. cyclic electron transport - Correct Ans-in photosynthetic light reactions, the flow of electrons that produces ATP but no NADPH or O2. noncyclic electron transport - Correct Ans-In photosynthesis, the flow of electrons that forms ATP, NADPH, and O2. Calvin cycle - Correct Ans-a series of enzyme-assisted chemical reactions that produces a three-carbon sugar autotroph - Correct Ans-An organism that is capable of living exclusively on inorganic materials, water, and an energy source other than the chemical bonds of organic compounds. Some autotrophs (photoautotrophs) use sunlight as their energy source. Others (chemoautotrop