This topic summary covers Knowledge Organiser within Photosynthesis for GCSE Biology. Topic 1: Photosynthesis It is section 12 of 13 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 12 of 13
Practice
15 questions
Recall
20 flashcards
Knowledge Organiser
Key Terms
- Photosynthesis — light energy → glucose
- Chlorophyll — green pigment, absorbs light
- Chloroplast — site of photosynthesis
- Limiting factor — factor controlling rate
- Endothermic — absorbs energy from surroundings
- Glucose — product; used in respiration, starch, cellulose, lipids, proteins
- Starch — insoluble storage carbohydrate
- Rate — volume O2 produced per minute
Must-Know Facts
- Word equation: CO2 + H2O + light → glucose + O2
- Balanced: 6CO2 + 6H2O + light → C6H12O6 + 6O2
- Three limiting factors: light intensity, CO2 concentration, temperature
- Photosynthesis is endothermic (takes in energy)
- Occurs in chloroplasts, which contain chlorophyll
- High temperature denatures enzymes — rate falls irreversibly
- Plants respire 24/7; photosynthesise only in light
- Inverse square law: intensity ∝ 1/d2
Common Marks Lost
- Omitting "light energy" from the equation
- Saying photosynthesis is exothermic (it is endothermic)
- Listing only 1-2 uses of glucose (need at least respiration, starch, cellulose)
- Not explaining plateau on rate graphs (another factor became limiting)
- Saying temperature above optimum "slows" enzymes — it denatures them
- Saying plants get food from soil (they make it via photosynthesis)