Table of contents

1. Introduction to Biology2h 42m
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 Transport1h 2m
- Water Potential
  1h 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 System1h 10m
- Digestion
  1h 3m
- Blood Sugar Homeostasis
  7m
40. Circulatory System1h 57m
41. Immune System1h 12m
42. Osmoregulation and Excretion50m
- Osmoregulation and Excretion
  50m
43. Endocrine System1h 4m
- Endocrine System
  1h 4m
44. Animal Reproduction1h 2m
- Animal Reproduction
  1h 2m
45. Nervous System1h 55m
- Neurons and Action Potentials
  1h 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

9. Photosynthesis

Light Reactions of Photosynthesis

General Biology

9. Photosynthesis

Light Reactions of Photosynthesis

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0:49 minutes

Problem 6

Textbook Question

In mechanism, photophosphorylation is most similar to
a. Substrate-level phosphorylation in glycolysis.
b. Oxidative phosphorylation in cellular respiration.
c. Carbon fixation.
d. Reduction of NADP⁺.

Verified step by step guidance

Understand the concept of photophosphorylation: Photophosphorylation is the process by which ATP is formed using the energy of sunlight during photosynthesis. It occurs in the chloroplasts of plant cells.

Compare photophosphorylation with substrate-level phosphorylation: Substrate-level phosphorylation occurs in glycolysis and involves the direct transfer of a phosphate group to ADP from a phosphorylated intermediate. This process does not involve an electron transport chain.

Compare photophosphorylation with oxidative phosphorylation: Oxidative phosphorylation occurs in cellular respiration within the mitochondria. It involves the electron transport chain and chemiosmosis, where ATP is synthesized using energy derived from the transfer of electrons through a series of complexes.

Consider the role of carbon fixation: Carbon fixation is part of the Calvin cycle in photosynthesis, where CO2 is converted into organic molecules. It does not directly involve the formation of ATP through an electron transport chain.

Evaluate the reduction of NADP+: The reduction of NADP+ to NADPH occurs during the light reactions of photosynthesis, but it is not directly involved in the phosphorylation of ADP to ATP.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Photophosphorylation

Photophosphorylation is the process by which ATP is formed using the energy of sunlight during photosynthesis. It occurs in the chloroplasts of plant cells, where light energy is captured by chlorophyll and used to drive the synthesis of ATP from ADP and inorganic phosphate. This process is crucial for converting solar energy into chemical energy.

Oxidative Phosphorylation

Oxidative phosphorylation is a metabolic pathway that uses energy released by the oxidation of nutrients to produce ATP. It occurs in the mitochondria during cellular respiration, where electrons are transferred through a series of complexes in the electron transport chain, ultimately reducing oxygen to water and driving the synthesis of ATP. This process is similar to photophosphorylation in its use of a proton gradient to generate ATP.

Electron Transport Chain

The electron transport chain is a series of protein complexes located in the inner mitochondrial membrane (or thylakoid membrane in chloroplasts) that transfer electrons from electron donors to electron acceptors via redox reactions. This transfer of electrons is coupled with the pumping of protons across the membrane, creating a proton gradient that drives ATP synthesis. Both photophosphorylation and oxidative phosphorylation rely on this mechanism to produce ATP.