Exam (elaborations) AP Biology Unit 3 Cellular Energetics

Alcohol dehydrogenase (ADH) is an enzyme that aids in the decomposition of ethyl alcohol (C2H5OH) into nontoxic substances. Methyl alcohol acts as a competitive inhibitor of ethyl alcohol by competing for the same active site on ADH. When attached to ADH, methyl alcohol is converted to formaldehyde, which is toxic in the body. Which of the following statements best predicts the effect of increasing the concentration of substrate (ethyl alcohol), while keeping the concentration of the inhibitor (methyl alcohol) constant? - ANSWER Competitive inhibition will decrease because the proportion of the active sites occupied by substrate will increase. A researcher claims that the synthesis of ATP from ADP and inorganic phosphate (Pi) is essential to cellular function. Which of the following statements best helps justify the researcher's claim? - ANSWER ATP hydrolysis is an energy-releasing reaction that is often coupled with reactions that require an input of energy. A researcher claims that only a portion of the light energy captured by green plants is available for growth and repair. Which of the following observations best helps justify the researcher's claim? - ANSWER As light energy is converted to chemical energy by metabolic processes, some of the energy is lost as heat. Figure 1. ATP production by three metabolic pathways following the start of an intense period of exercise Which of the following correctly uses the data to justify the claim that the phosphagen system is an immediate, short-term source of ATP for muscle cells? - ANSWER ATP production by the phosphagen system increases and decreases rapidly following the start of the exercise period. If the experiment is repeated at pH 11, the observed activity level of the enzyme will most likely be - ANSWER lower than the level at pH 9 A researcher claims that increased atmospheric carbon dioxide levels cause increased growth rates in plants. Which of the following statements best supports the researcher's claim? - ANSWER Atmospheric carbon dioxide is the raw material for photosynthesis, which plants rely on for producing sugars and other organic compounds. In chloroplasts, ATP is synthesized from ADP plus inorganic phosphate (Pi) in a reaction catalyzed by ATP synthase molecules that are embedded in the thylakoid membrane