Table of contents

1. Introduction to Biology2h 42m
2. Chemistry3h 37m
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 6m
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 53m
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 49m
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

8. Respiration

Review of Aerobic Cellular Respiration

General Biology

8. Respiration

Review of Aerobic Cellular Respiration

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4:17 minutes

Problem 4

Textbook Question

Most of the CO₂ from cellular respiration is released during
a. Stage 1: Glycolysis
b. Stage 2: Pyruvate oxidation
c. Stage 2: The citric acid cycle
d. Stage 3: Oxidative phosphorylation

Verified step by step guidance

Understand the stages of cellular respiration: Cellular respiration consists of three main stages: glycolysis, pyruvate oxidation (including the citric acid cycle), and oxidative phosphorylation. Each stage has distinct roles in energy production and carbon dioxide release.

Recall the role of glycolysis: Glycolysis occurs in the cytoplasm and breaks down glucose into two molecules of pyruvate. This process does not release CO2 because glucose is only partially oxidized.

Examine pyruvate oxidation: Pyruvate oxidation occurs in the mitochondria, where pyruvate is converted into acetyl-CoA. During this process, one molecule of CO2 is released per pyruvate molecule, but this is not the primary stage where most CO2 is released.

Analyze the citric acid cycle: The citric acid cycle (also known as the Krebs cycle) occurs in the mitochondrial matrix. Acetyl-CoA is fully oxidized, releasing two molecules of CO2 per cycle. This is the stage where most of the CO2 from cellular respiration is released.

Consider oxidative phosphorylation: Oxidative phosphorylation involves the electron transport chain and chemiosmosis, which generate ATP. This stage does not release CO2, as it focuses on energy production rather than carbon oxidation.

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Key Concepts

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

Cellular Respiration

Cellular respiration is the metabolic process by which cells convert glucose and oxygen into energy, carbon dioxide, and water. It consists of several stages, including glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation. Understanding this process is crucial for identifying where CO2 is produced and released.

Citric Acid Cycle

The citric acid cycle, also known as the Krebs cycle, is a key component of cellular respiration that occurs in the mitochondria. It processes acetyl-CoA derived from pyruvate and generates high-energy electron carriers, while releasing CO2 as a byproduct. This cycle is significant for understanding the main source of CO2 during cellular respiration.

Glycolysis

Glycolysis is the first stage of cellular respiration, occurring in the cytoplasm, where glucose is broken down into pyruvate, producing a small amount of ATP and NADH. Importantly, glycolysis does not produce CO2; thus, it is essential to differentiate it from later stages where CO2 is released.