Mastering Biology: How Cells Harvest Chemical Energy

In the equation shown below, during cellular respiration _____ is oxidized and _____ is reduced. Summary equation for cellular respiration: Glucose plus Oxygen becomes Carbon Dioxide plus Water plus Heat. ATP ... oxygen oxygen ... ATP carbon dioxide ... water glucose ... oxygen

glucose ... oxygen In cellular respiration, electrons and hydrogen are removed from glucose and added to oxygen.

In the citric acid cycle (also called the Krebs cycle), ATP molecules are produced by _____. cellular respiration photosynthesis oxidative phosphorylation substrate-level phosphorylation photophosphorylation

substrate-level phosphorylation A phosphate group is transferred from GTP to ADP.

In glycolysis, ATP molecules are produced by _____. photophosphorylation substrate-level phosphorylation cellular respiration photosynthesis oxidative phosphorylation

substrate-level phosphorylation A phosphate group is transferred from glyceraldehyde phosphate to ADP.

In glycolysis there is a net gain of _____ ATP. 5 3 2 1 4

2 It takes 2 ATP to produce 4 ATP.

How many NADH are produced by glycolysis? 4 3 2 5 1

2 Two NADH molecules are produced by glycolysis.

In glycolysis, what starts the process of glucose breakdown? ADP ATP FADH2 NADPH Pyruvate

ATP Some ATP energy is used to start the process of glucose oxidation.

Which of these is NOT a product of glycolysis? pyruvate ATP FADH2 NADH + H+ water

FADH2 FADH2 is a product of the citric acid cycle.

As shown below, an electron carrier, such as __________, acts as an energy-storage molecule when it is __________. A pair of redox reactions occurring simultaneously. NADH ... oxidized NAD+ ... oxidized NAD+ ... reduced NADH ... reduced

NADH ... reduced NADH is the reduced form of this molecule and it carries high energy electrons. This makes it an energy storage molecule.

Through respiration, humans breathe in O2 and breathe out CO2. However, what would happen if we did not breathe in O2? We would not have enough enzymes to catalyze reactions. We would not make enough ATP to meet our energy requirements We would not be able to perform lactic acid fermentation. We would not be able to synthesize organic molecules from inorganic molecules.

We would not make enough ATP to meet our energy requirements The electron transport chain accepts electrons from the breakdown products of glycolysis and the citric acid cycle, and it passes these electrons from one molecule to another until they are passed (along with two hydrogen ions) to oxygen to form water.

Which of these is NOT a product of the citric acid cycle (also called the Krebs cycle)? NADH + H+ CO2 FADH2 acetyl CoA ATP

acetyl CoA Acetyl CoA enters the citric acid cycle.

Which of these enters the citric acid cycle (also called the Krebs cycle)? acetyl CoA pyruvate glucose NADH + H+ G3P

acetyl CoA Acetyl CoA is a reactant in the citric acid cycle (also called the Krebs cycle).

In an experiment, mice were fed glucose (C6H12O6) containing a small amount of radioactive oxygen. The mice were closely monitored, and in a few minutes, radioactive oxygen atoms showed up in __________. NADH ATP carbon dioxide water

carbon dioxide Cellular respiration, or the oxidization of glucose, involves the release of CO2.

A single glucose molecule produces about 38 molecules of ATP through the process of cellular respiration. However, this only represents approximately 38% of the chemical energy present in this molecule. The rest of the energy from glucose is _____. used directly for energy converted to heat stored as fat used to make water from hydrogen ions and oxygen

converted to heat The majority of the energy in a molecule of glucose is lost as heat.

In muscle cells, fermentation produces _____. pyruvate carbon dioxide, ethanol, NAD+, and ATP lactate and NAD+ lactate and NADH carbon dioxide, ethanol, NADH, and ATP

lactate and NAD+ These are the products of fermentation as it occurs in muscle cells.

Sports physiologists at an Olympic training center want to monitor athletes to determine at what point their muscles begin to function anaerobically. They could do this by checking for a buildup of _____. ATP lactic acid carbon dioxide ADP

lactic acid In humans, muscle cells switch to lactic acid fermentation after becoming anaerobic.

Lungs are to breathing as _____ are to cellular respiration. mitochondria alveoli chloroplasts bronchi

mitochondria Two of the three main stages of cellular respiration occur in the mitochondria.

A scientist wants to study the enzymes of the citric acid cycle in eukaryotic cells. What part of the cell would she use as a source of these enzymes? mitochondrial matrix cytoplasm mitochondrial inner membrane plasma membrane

mitochondrial matrix The water-soluble citric acid cycle intermediates and enzymes of a eukaryotic cell are found in the mitochondrial matrix, where the newly synthesized NADH and FADH2 diffuse to proteins of the electron transport chain held within the inner mitochondrial membrane.