Chapter 7 Plant Nutrition
Photosynthesis
Role of Energy in Photosynthesis
Definition: The process by which green plants, in the presence of chlorophyll and light energy, producing carbohydrates from carbon dioxide and water
Materials Needed:
Carbon Dioxide
Water and Mineral Salts
Steps:
- CO2 enters the plant through the stomata in the leaves
- Water and mineral salts enter the roots
- Sunlight is absorbed by chlorophyll and a chemical reaction takes place
- Glucose or C6H12O6 is formed
- Oxygen exits through the stomata
Light Energy
Chemical Energy
Converted to chemical energy
Used to split water molecules into hydrogen and oxygen
Combine hydrogen molecules with CO2 to form glucose
Minerals Needed:
Sulphur, Nitrogen, Phosphorous, Magnesium
Cross-Section of a Leaf
Waxy Cuticle- Protective Layer on the Top of the Leaf that prevents water from evaporating
Upper Epidermis- Thin and Transparent to allow light to enter the palisade mesophyll layer below it.
Palisade Mesophyll- Column Shaped Cells tightly packed with chloroplasts to absorb more light, maximising photosynthesis
Spongy Mesophyll- Contains internal air spaces that increases the SA: Volume Ratio for the diffusion of gases
Lower Epidermis- Contains guard cells and stomata
Guard Cell- Absorbs and loses water to open and close the stomata
Stomata- Where gas exchange takes place
Vascular Bundle- Contains phloem and xylem
Xylem- Transports water into the leaf
Phloem- Transports sucrose and amino acids around the plant
Equations
Word
Chemical
Photosynthesis: Carbon dioxide + Water → Glucose + oxygen
Respiration: Carbon dioxide + Water Glucose (sugar) + Oxygen → Energy
Photosynthesis: 6CO2 + 6H2O → C6H12O6 + 6O2
Respiration: CO2+ H20+ C6H12O6+ O2→ Energy