Quiz 4

Which of the following statements about enzymes is FALSE?

>A specific enzyme can catalyze a variety of chemical reactions. (Extra - Enzymes are highly specific and generally only catalyze a single type of chemical reaction. The other statements are part of the definition used to categorize a catalyst as an enzyme.)

The molecule ________ is produced to carry energy and is broken down during cellular processes to use that energy.

>ATP (Extra - ATP fuels metabolic reactions. Energy is released when it is broken down to ADP and a free phosphate.)

During which cellular process is ATP NOT released?

>Calvin cycle (Extra - While the majority of ATP produced during cellular respiration is generated from the process of oxidative phosphorylation, some ATP is released during the Krebs cycle as well as in the process of glycolysis. The electron transport chain of photosynthesis produces ATP, but the Calvin cycle does not.)

Which of the following is used in photosynthesis and released during cellular respiration?

>H2O (Extra - Both H2O and CO2 are used during photosynthesis to help make glucose and are produced during the breakdown of glucose that occurs during cellular respiration. While sunlight is used in photosynthesis, it is not involved in cellular respiration.)

Which of the following is closely associated with mitochondria?

>Krebs cycle (Extra - Chloroplasts (not mitochondria) contain thylakoids. The Calvin cycle occurs in the chloroplast while the Krebs cycle occurs in the mitochondria. Glycolysis occurs in the cytoplasm.)

Which of the following ultimately provides the O2 used during the process of oxidative phosphorylation?

>Light reactions of photosynthesis (Extra - Oxygen is made when H2O molecules are split to generate electrons during the light reactions of photosynthesis.)

Which of the following statements about energy metabolism is FALSE?

>Plants provide the H2O and CO2 that animals need to carry out respiration. (Extra - Cellular respiration does not use H2O or CO2 as reactants; these are actually two of the products of respiration. Plants provide the glucose and O2 that make respiration possible.)

Which of the following statements regarding photosynthesis and cellular respiration is FALSE?

>The process of photosynthesis does not require the input of energy (Extra - Recall that the process of photosynthesis is driven by the energy of sunlight. This energy is used to assist in the process of fixing CO2 to produce glucose.)

Which of the following is NOT directly used in the Calvin Cycle?

>Water (Extra - While water is used in the light reactions of photosynthesis, it is not used in the Calvin cycle. In the Calvin cycle ATP helps to fuel the fixation of carbon from carbon dioxide into glucose, and this reaction is catalyzed by the enzyme rubisco.)

Metabolic reactions that break down complex molecules into smaller compounds, thereby releasing usable energy for the cell, are best described as

>catabolic (Extra - This is the definition of catabolic reactions. Photosynthesis is anabolic)

Glycolysis takes place in the ________ and produces ________, which in the presence of O2 then enters the ________.

>cytoplasm; pyruvate; mitochondrion to complete cellular respiration (Extra - Glycolysis is the only portion of cellular respiration that occurs outside the mitochondria. If oxygen is present, pyruvate can enter the mitochondrion to complete cellular respiration.)

The Krebs cycle takes place in the

>matrix of the mitochondrion (Extra - The cytoplasm is the site of glycolysis, the Krebs cycle occurs in the mitochondrial matrix, and oxidative phosphorylation takes place in and around the inner mitochondrial membrane.)

During cellular respiration, ________ is the step that produces the greatest number of ATP molecules.

>oxidative phosphorylation (Extra - Over 80 percent of the ATP produced during cellular respiration is the result of oxidative phosphorylation.)

The ultimate source of energy for most living systems is

>sunlight (Extra - Although glucose is used by cells to produce ATP, the glucose must first be made through photosynthesis. Sunlight provides the energy needed to make glucose through the process of photosynthesis. Organisms that perform photosynthesis, like plants, some bacteria, and some protozoans, can use this glucose directly, while organisms that eat photosynthesizers or other consumers get this glucose indirectly.)

Oxidative phosphorylation is to respiration as ________ is to photosynthesis.

>the light-dependent reaction (Extra - Both processes use an electron transport chain that ultimately generates ATP.)