1.
1Photosynthesis
" Definition:
Photosynthesis is the process by which plants use light energy to produce glucose and
Oxygen from water and carbon dioxide.
Word Equation:
Water + Carbon dioxide Light energy Glucose + Oxygen
Key Components:
Reactants: Water (H,O) and Carbon Dioxíde (CO2).
" Products: Glucose (CçH12O6) and Oxygen (O2).
Role of Chlorophyll: Agreen pigment in chloroplasts that absorbs light energy.
Importance of Photosynthesis:
1. Produces oXygen essential for respiration.
2. Generates glucose, which forms the base of food chains.
Experiments:
Collecting oxygen from aquatic plants.
Investigating light intensity and photosynthesis rates.
1.2 More About Photosynthesis
Where It Occurs:
" Inside chloroplasts, primarily in the palisade layer of leaves.
KeyProcesses:
Water is transported via veins.
Carbon dioxide enters through stomata.
" Nutrients for Photosynthesis:
" Magnesium: Needed for chlorophyll production.
Nitrate: Required for protein synthesis and chlorophyll formation.
Testing for Photosynthesis:
Starch Test: lodine turns blue-black in presence of starch, indicating ph
occurred.
1.3The Carbon Cycle
Carbon Flow:
Photosynthesis: Removes CO, from the air and incorporates it into carbohydrates.
Respiration: Releases CO back into the atmosphere.
Decomposition: Returns carbon to the air or soil.
Combustion: Burning fossil fuels releases stored carbon.
Role of Organisms:
Plants convert CO, into carbohydrates.
Animals and decomposers obtain carbon by consuming plants or other organisms.
Fossil Fuels:
Formed over milions of years from decomposed organisms.
Combustion of these fuels contributes to rising CO, levels.
1.4Climate Change
Greenhouse Effect:
Greenhouse gases like CO, and methane trap heat, maintaining Earth's warmth.
Past Climate Changes:
lce Ages: Periodic cycles of freezing and warming.
Asteroid Impacts: Reduced sunlight and triggered mass extinctions.
Modern Climate Change:
Caused by increasing C0, levels from human activities.
" Impacts include:
Rising global temperatures
More extreme weather events.
Melting ice caps and risingsea levels.
Practical Applications and Investigations
Effect of Light Intensity:
" As light intensity increases, so does the rate of photosynthesis, evidenced by bubble
production in aquatic plants.
Testing Climate Effects:
Experiments model how melting ice and rising temperatures affect sea levels.
Key Terms to Remember
Photosynthesis: Conversion of light energy into chemical energy.
Carbon Cycle: Movement of carbon among air, organisms, and fossil fuels.
Greenhouse Effect: Trapping of heat by gases in the atmosphere.
This summary ensures you are well-prepared for exams with aconcise understanding of key
scientific principlesfrom Unit 1. Let me know if you'd like additional clarifications or diagrams
included!
