Table of contents

1. Introduction to Biology2h 40m
2. Chemistry3h 40m
3. Water1h 26m
4. Biomolecules2h 23m
5. Cell Components2h 26m
6. The Membrane2h 31m
7. Energy and Metabolism2h 0m
8. Respiration2h 40m
9. Photosynthesis2h 49m
10. Cell Signaling59m
11. Cell Division2h 47m
12. Meiosis2h 0m
13. Mendelian Genetics4h 44m
14. DNA Synthesis2h 27m
15. Gene Expression3h 20m
16. Regulation of Expression3h 31m
17. Viruses37m
- Viruses
  37m
18. Biotechnology2h 58m
19. Genomics17m
- Genomes
  17m
20. Development1h 5m
21. Evolution3h 1m
22. Evolution of Populations3h 52m
23. Speciation1h 37m
24. History of Life on Earth2h 6m
25. Phylogeny2h 31m
26. Prokaryotes4h 59m
27. Protists1h 12m
28. Plants1h 22m
29. Fungi36m
- Fungi
  19m
- Fungi Reproduction
  17m
30. Overview of Animals34m
- Overview of Animals
  34m
31. Invertebrates1h 2m
32. Vertebrates50m
33. Plant Anatomy1h 3m
34. Vascular Plant Transport2m
- Water Potential
  2m
35. Soil37m
- Soil and Nutrients
  20m
- Nitrogen Fixation
  16m
36. Plant Reproduction47m
- Flowers
  33m
- Seeds
  14m
37. Plant Sensation and Response1h 9m
38. Animal Form and Function1h 19m
39. Digestive System10m
- Digestion
  3m
- Blood Sugar Homeostasis
  7m
40. Circulatory System1h 57m
41. Immune System1h 12m
42. Osmoregulation and Excretion50m
- Osmoregulation and Excretion
  50m
43. Endocrine System4m
- Endocrine System
  4m
44. Animal Reproduction2m
- Animal Reproduction
  2m
45. Nervous System55m
- Neurons and Action Potentials
  8m
- Central and Peripheral Nervous System
  46m
46. Sensory Systems46m
- Sensory System
  46m
47. Muscle Systems23m
- Musculoskeletal System
  23m
48. Ecology3h 11m
49. Animal Behavior28m
- Animal Behavior
  28m
50. Population Ecology3h 41m
51. Community Ecology2h 46m
52. Ecosystems2h 36m
53. Conservation Biology24m
- Conservation Biology
  24m

7. Energy and Metabolism

ATP

General Biology

7. Energy and Metabolism

ATP

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Multiple Choice

When 1 mole of ATP is hydrolyzed in a test tube without an enzyme, about twice as much heat is given off as when 1 mole of ATP is hydrolyzed in a cell. Which of the following best explains these observations?

Cells are less efficient at energy metabolism than reactions that are optimized in a test tube.

The amount of heat released by a reaction has nothing to do with the free energy change of the reaction.

In cells, ATP is hydrolyzed to ADP and P_i, but in the test tube it is hydrolyzed to carbon dioxide and water.

Cells have the ability to store heat; this cannot happen in a test tube.

In the cell, the hydrolysis of ATP is coupled to other endergonic reactions.

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Verified step by step guidance

Understand the concept of ATP hydrolysis: ATP (adenosine triphosphate) is a molecule that releases energy when it is hydrolyzed to ADP (adenosine diphosphate) and inorganic phosphate (Pi). This process is exergonic, meaning it releases energy.

Recognize the difference between reactions in a test tube and in a cell: In a test tube, ATP hydrolysis occurs without any coupling to other reactions, resulting in the release of heat as the primary form of energy dissipation.

Consider the role of coupling in cellular reactions: In cells, ATP hydrolysis is often coupled to endergonic reactions, which require energy input. This coupling allows the energy released from ATP hydrolysis to be used directly for cellular work, rather than being lost as heat.

Evaluate the efficiency of energy use in cells: Cells are efficient at using the energy from ATP hydrolysis to drive necessary biological processes, reducing the amount of energy lost as heat compared to an isolated reaction in a test tube.

Conclude with the explanation: The observation that less heat is released during ATP hydrolysis in cells compared to a test tube is best explained by the coupling of ATP hydrolysis to other endergonic reactions in the cell, which utilizes the energy for cellular functions rather than dissipating it as heat.