Chapter 7: The Working Cell – Energy from Food
Concept Check 7.1
1.Compare and contrast autotroph and heterotroph.
An autotroph ( such as a tree) produces it own food. A heterotroph (such as a bear) obtains food
by eating another organism.
2.Explain the role of food (Glucose) in both photosynthesis and cellular respiration.
Glucose is a product of photosynthesis and an ingredient in cellular respiration.
3.Explain how life on earth depends on the sun.
Most producers use the sun”s energy to perform photosynthesis. Both producers and consumers
rely on the products of photosynthesis for food.
Concept Check 7.2
1.Identify the types of energy you have at the top of a staircase and as you go down it.
Potential energy at the top; converted to kinetic energy as you go down.
2. Explain how your body uses chemical energy during exercise.
Exercise causes your cells to increase their rate of cellular respiration, increasing the conversion
of chemical energy to ATP and heat.
3. If a food has 10 kcal of energy, how much could it increase the temperature of 100g of water?
100 degrees Celcius
Concept Check 7.3
1.In what ways is ATP like a compressed spring?
Compressed springs and ATP molecules store potential energy. Potential energy is released
when one of the ATP molecules’ chemical bonds is broken, particularly between the phosphate
groups in the ATP tail. The phosphate groups repel each other because they have like charges.
2.List three main types of cellular work.
Chemical, mechanical, and transport work.
3.What is the source of energy for regenerating ATP from ADP?
Chemical energy from organic molecules
Concept Check 7.4
1.Compare and contrast breathing and respiration.
Both involve the exchange of O2 and CO2 In cellular respiration, cells take Oxygen from their
surroundings and release CO2. In breathing, the exchange takes place in the ungs and results in
exchange of gases between blood and air.
2.List the reactants and products in cellular respiration.
Reactants: Glucose, oxygen; Products: carbon dioxide, water, ATP
3.What is meant by “falling electrons” to oxygen? How does this process release energy?
Oxygen nucleus exerts an electrical pull on negatively charged electrons. As electrons “fall”
toward oxygen potential energy is released.
4.How does an electron transport chain result in the gradual release of energy stored in glucose?
High energy electrons from glucose are transferred from one electron carrier to another, a small
amount of energy is released at each step.
Concept Check 7.5
1.How is the mitochondrion’s structure suited to its function?
The complex folding pattern of the mitochondria creates many sites where cellular respiration can
occur.
2 .Identify the three stages of cellular respiration, where in the cell each takes place, and how many
ATP molecules it produces.
Glycolysis in the cytoplasm yields 2ATP net; Krebs cycle in the matrix yields 2ATP; Electron
transport chain & ATP synthase from inner membrane of mitochondria yield 34 ATP
3. Summarize the use and production of ATP in one cycle of cellular respiration.
Glycolysis uses 2 ATP & makes 4 ATP. Krebs cycle uses 0 ATP and makes 2 ATP; Electron
transport uses 0, produces 34 ATP.
Concept Check 7.6
1.How is fermentation different from cellular respiration?
Fermentation does not require oxygen to make ATP. Produces only 2 ATP per glucose molecule.
2.Describe one example of how fermentation in microorganisms produces human foods.
Microbes transform milk into cheese or yogurt; soybeans into soy sauce; cabbage into sauerkraut.
3.What is the waste product of fermentation in your muscle cells?
Lactic acid