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:

  1. CO2 enters the plant through the stomata in the leaves
  1. Water and mineral salts enter the roots
  1. Sunlight is absorbed by chlorophyll and a chemical reaction takes place
  1. Glucose or C6H12O6 is formed
  1. 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

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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