Answer Key for Cell Energy Assignment, Due in Week Three

Cellular respiration:

What is cellular respiration and what are its three stages?

It is the “aerobic harvesting of chemical energy from organic fuel molecules” (Simon, Reece, & Dickey, 2010, p. 94). The three stages are glycolysis, citric acid cycle, and electron transport. Refer to p. 96 of the text.

What is the role of glycolysis? Include the reactants and the products. Where does it occur?

The role of glycolysis is to split a glucose molecule into two pyruvic acid molecules with a net gain of two ATP. Glucose is a reactant and pyruvic acid and ATP are the products. It occurs in the cytoplasm of cells. Refer to pp. 96 & 97 of the text.

What is the role of citric acid cycle? Include the reactants and the products. Where does it occur?

The citric acid cycle completes the breakdown of glucose into CO2 while collecting electrons and generating a small amount of ATP. The reactants are acetic acid, ADP, NAD+ and FAD; products are CO2, ATP, NADH, and FADH2. It occurs in the matrix of the mitochondria. Refer to pp. 96 & 98 of the text.

What is the role of the electron transport system? Include the reactants and the products. Where does it occur?

During electron transport, electrons captured from glucose fall down the electron transport chain to oxygen to release energy in the form of ATP. The reactants are NADH, FADH2, and oxygen; the products are H2O and ATP. It occurs across the inner mitochondrial membrane in the mitochondria. Refer to pp. 96 & 99 of the text.

Photosynthesis:

What is the overall goal of photosynthesis?

The goal is to use light energy to transform carbon dioxide and water into chemical energy of sugar. Refer to p. 108 of the text.

Because photosynthesis only occurs in plants, why is it essential to animal life?

A waste product of photosynthesis, oxygen, fuels cellular respiration in animals. Animals also depend on plants to convert carbon dioxide into sugars via photosynthesis. Refer to pp. 93 & 109 of text.

What is the role of the light reactions? Include the reactants and the products. Where does it occur?

During the light reactions, chlorophyll absorbs solar energy which is converted into chemical energy of ATP and NADPH. The reactants are water, NADP+ and ADP; the products are ATP, NADPH and oxygen (O2). It occurs in the thylakoid membranes inside chloroplasts. Refer to p. 110 of the text.

What is the role of the Calvin cycle? Include the