Photosynthesis Makes Food and Biomass
Definition
Producer
An organism that makes organic substances from inorganic raw materials and forms the first trophic level in a food chain.
- A producer is an organism that makes organic substances from inorganic raw materials.
- Plants and algae are the main producers because they make glucose by photosynthesis.
- Glucose supplies carbon and stored chemical energy for building other biological molecules.
- Biomass is the total mass of living material in an organism or group of organisms.
- When plants and algae grow, glucose is converted into new cell material, so photosynthesis increases biomass.
- Consumers obtain this food and biomass directly by eating producers or indirectly by eating other consumers.
Key Idea
Nearly every food chain begins with photosynthetic organisms transferring light energy into chemical energy stored in biomass.
Photosynthesis Stores Light Energy
Definition
Photosynthesis
The endothermic process in which plants and algae use light energy to make glucose from carbon dioxide and water, releasing oxygen.
- Photosynthesis is the endothermic process in which plants and algae use light energy to make glucose from carbon dioxide and water, releasing oxygen.
- Endothermic means that energy is transferred into the reaction from the surroundings.
- Chlorophyll in chloroplasts absorbs light energy.
- The absorbed energy is transferred into chemical energy and stored in glucose.
- Carbon dioxide enters a leaf through the stomata, while water reaches the leaf through xylem vessels.
Common Mistake
Do not describe photosynthesis as releasing energy, because energy is taken in and stored in glucose.
The Photosynthesis Equations
- The word equation is ** carbon dioxide+water→light and chlorophyllglucose+oxygen\text{carbon dioxide} + \text{water} \xrightarrow{\text{light and chlorophyll}} \text{glucose} + \text{oxygen}carbon dioxide+waterlight and chlorophyllglucose+oxygen **.
- The balanced symbol equation is ** 6CO2+6H2O→light and chlorophyllC6H12O6+6O26CO_2 + 6H_2O \xrightarrow{\text{light and chlorophyll}} C_6H_{12}O_6 + 6O_26CO2+6H2Olight and chlorophyllC6H12O6+6O2 **.
- Carbon dioxide and water are the reactants, while glucose and oxygen are the products.
- Light and chlorophyll are written over the arrow because they are required conditions rather than reactants that are used up.
Example
- A leaf uses 666 molecules of CO2CO_2CO2 and 666 molecules of H2OH_2OH2O to form one molecule of C6H12O6C_6H_{12}O_6C6H12O6 and 666 molecules of O2O_2O2.
- The equation balances because both sides contain 666 carbon atoms, 121212 hydrogen atoms and 181818 oxygen atoms.
Check Your Understanding
Definition
Biomass
The total mass of living material in an organism or group of organisms.
- Photosynthetic organisms form biomass by converting glucose into substances used to make cells and tissues.
- This biomass passes through a food chain when one organism eats another.
Self review
- What is a producer?
- Why is photosynthesis an endothermic process?
- Write the balanced symbol equation for photosynthesis.
- How does photosynthesis provide biomass for consumers?
