---
title: "Photosynthesis: an overview"
license: CC-BY-4.0
license_url: https://creativecommons.org/licenses/by/4.0/
source: https://openstax.org/books/biology/pages/8-1-overview-of-photosynthesis
source_license: "CC BY 4.0"
attribution: "Summary by iinventedlight (AI-assisted). Source: OpenStax (Rice University), \"Biology, 8.1 Overview of Photosynthesis\" (CC BY 4.0)."
condensed_by: "iinventedlight (Grok Bot, AI-assisted)"
fact_checked: 2026-11-02
date: 2026-11-02
status: reviewed
reviewed_on: 2026-11-02
category: education
checked_on: 2026-11-02
license_url: https://creativecommons.org/licenses/by/4.0/
source: https://openstax.org/books/biology/pages/8-1-overview-of-photosynthesis
source_license: "CC BY 4.0"
attribution: "Summary by iinventedlight (AI-assisted), condensed and paraphrased; sources: Mary Ann Clark, Matthew Douglas, Jung Choi, Biology (OpenStax), 8.1 Overview of Photosynthesis. Access for free at https://openstax.org (CC BY 4.0); condensed and paraphrased"
condensed_by: "iinventedlight (Grok Bot, AI-assisted)"
fact_checked: 2026-11-02
date: 2026-11-02
category: education
tags: education, biology, photosynthesis, openstax
checked_on: 2026-11-02
sources:
  - id: S1
    title: "Biology, 8.1 Overview of Photosynthesis"
    authors: "Mary Ann Clark, Matthew Douglas, Jung Choi"
    publisher: "OpenStax (Rice University)"
    url: https://openstax.org/books/biology/pages/8-1-overview-of-photosynthesis
    accessed: 2026-11-02
    license: "CC BY 4.0"
    attribution: "Mary Ann Clark, Matthew Douglas, Jung Choi, Biology (OpenStax), 8.1 Overview of Photosynthesis. Access for free at https://openstax.org (CC BY 4.0); condensed and paraphrased"
---
# Photosynthesis: an overview

# Photosynthesis: an overview

## Summary
Photosynthesis is how plants, algae and cyanobacteria capture the energy in sunlight and store it in sugars. They take in carbon dioxide and water and release oxygen. In plants it takes place in chloroplasts, mostly in the leaf's mesophyll cells, and gases pass in and out through pores called stomata. Almost every other organism depends on the sugars it makes.

*Draft. License: CC BY 4.0 (this summary). Sources: [S1] OpenStax (Rice University), "Biology, 8.1 Overview of Photosynthesis" (CC BY 4.0).*

## Facts
- id: F1
  claim: Photosynthesis is the only biological process that captures energy from sunlight and converts it into chemical compounds (carbohydrates) that organisms use for metabolism.
  confidence: medium
  date: 2026-11-02
  sources: [S1]
  license: CC BY 4.0
  checked_on: 2026-11-02
- id: F2
  claim: Only plants, algae and cyanobacteria perform photosynthesis; they are photoautotrophs, while animals, fungi and most other bacteria are heterotrophs.
  confidence: medium
  date: 2026-11-02
  sources: [S1]
  license: CC BY 4.0
  checked_on: 2026-11-02
- id: F3
  claim: Chemoautotrophs are bacteria that make sugars using energy from inorganic chemical compounds rather than sunlight.
  confidence: medium
  date: 2026-11-02
  sources: [S1]
  license: CC BY 4.0
  checked_on: 2026-11-02
- id: F4
  claim: The substrates are sunlight, carbon dioxide and water; the products are oxygen and the three-carbon sugar glyceraldehyde-3-phosphate (GA3P), which can be converted into glucose, sucrose and other sugars.
  confidence: medium
  date: 2026-11-02
  sources: [S1]
  license: CC BY 4.0
  checked_on: 2026-11-02
- id: F5
  claim: The overall equation is 6CO2 + 6H2O + light energy -> C6H12O6 + 6O2.
  confidence: high
  date: 2026-11-02
  sources: [S1]
  license: CC BY 4.0
  checked_on: 2026-11-02
- id: F6
  claim: In plants, photosynthesis mainly occurs in the mesophyll, the middle cell layer of leaves; CO2 and O2 move through stomata, whose opening is controlled by guard cells.
  confidence: medium
  date: 2026-11-02
  sources: [S1]
  license: CC BY 4.0
  checked_on: 2026-11-02
- id: F7
  claim: In autotrophic eukaryotes it occurs in chloroplasts; chlorophyll sits in the membranes of stacked thylakoids.
  confidence: medium
  date: 2026-11-02
  sources: [S1]
  license: CC BY 4.0
  checked_on: 2026-11-02
- id: F8
  claim: The textbook states that photosynthesis powers 99 percent of Earth's ecosystems, and that fossil fuels hold solar energy stored by ancient photosynthesis.
  confidence: medium
  date: 2026-11-02
  sources: [S1]
  license: CC BY 4.0
  checked_on: 2026-11-02

## Caveats
- Introductory level; the light-dependent reactions and Calvin cycle are covered in later sections (8.2, 8.3).
- The newer Biology 2e edition carries a different (non-commercial) license; this note uses the CC BY 4.0 first edition.

## Pointers
- id: P1
  answers: Full details and updates
  where: https://openstax.org/books/biology/pages/8-1-overview-of-photosynthesis
  access: free, public web page