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

8. Respiration

Pyruvate Oxidation

General Biology

8. Respiration

Pyruvate Oxidation

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Multiple Choice

In preparing pyruvate to enter the citric acid cycle, which of the following steps occurs?

Pyruvate is reduced, and a molecule of carbon dioxide is removed. The electrons removed in this process are used to oxidize NAD⁺ to NADH.

Pyruvate is oxidized, and a molecule of carbon dioxide is removed. The electrons removed in this process are donated to NADH to produce NAD⁺.

Pyruvate is reduced to acetyl-coA, which involves the reduction of pyruvate, the addition of a carbon dioxide from the environment, and its reduction by NADH.

Pyruvate is ionized directly to acetyl-coA.

Pyruvate is oxidized, and a molecule of carbon dioxide is removed. The electrons removed in this process are used to reduce NAD⁺ to NADH.

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Verified step by step guidance

Understand that pyruvate must be converted to acetyl-CoA before entering the citric acid cycle. This process is known as pyruvate decarboxylation.

Recognize that during this conversion, pyruvate undergoes oxidation. This means it loses electrons.

Identify that a molecule of carbon dioxide (CO2) is removed from pyruvate during this process, which is a decarboxylation reaction.

Acknowledge that the electrons removed from pyruvate are transferred to NAD+, reducing it to NADH. This is a key step in cellular respiration as NADH carries electrons to the electron transport chain.

Conclude that the correct description of the process is: Pyruvate is oxidized, and a molecule of carbon dioxide is removed. The electrons removed in this process are used to reduce NAD+ to NADH.