4.12–4.16: Cellular respiration converts food molecules into ATP, a universal source of energy for living organisms.

Living organisms extract energy through a process called cellular respiration in which glucose and oxygen are converted to carbon dioxide, water, and energy.

Question 4.25

Plants rely on water:

  • a) to provide the protons necessary to produce chlorophyll.
  • b) to concentrate beams of sunlight on the reaction center.
  • c) to replenish oxygen molecules that are lost during photosynthesis.
  • d) to replace electrons that are excited by light energy and passed down an electron transport chain.
  • e) to serve as an energy source.

Question 4.26

During photosynthesis, which step is most responsible for a plant’s acquisition of new organic material?

  • a) the “building” of NADPH during the Calvin cycle
  • b) the excitation of chlorophyll molecules by photons of light
  • c) the “plucking” of carbon atoms from the air and fixing of the carbons to organic molecules within the chloroplast
  • d) the loss of water through evaporation
  • e) ATP made during the light reactions

Question 4.27

During C4 photosynthesis:

  • a) plants use less ATP in making sugar.
  • b) plants can produce sugars even when they close their stomata to reduce water loss on hot days.
  • c) plants are able to generate water molecules to cool their leaves.
  • d) plants produce more rubisco.
  • e) plants are able to produce sugars without any input of carbon dioxide.

Question 4.28

During cellular respiration:

  • a) oxygen is used to transport chemical energy throughout the body.
  • b) metabolic oxygen is produced.
  • c) light is converted to kinetic energy.
  • d) ATP is converted to water and sugar.
  • e) energy from the chemical bonds of food molecules is captured.

Question 4.29

During cellular respiration, most of the energy contained within the bonds of food molecules is captured in:

  • a) the conversion of the kinetic energy of food to the potential energy of ATP.
  • b) the Krebs cycle and electron transport chain.
  • c) digestion.
  • d) glycolysis.
  • e) None of the above. Energy is lost, not gained, during cellular respiration.

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