Plants nutrition.

• Plants are called 'autotrophs', which mean 'self-feeding'
• Plants synthesise their own food from simple inorganic materials.
• Photosynthesis occurs in the chloroplast in the leaf cells.
• Conditions necessary for photosynthesis

  • light
  • water
  • carbon dioxide
  • Chlorophyll
  • Temperature.
• Photosynthesis is an enzymatic reaction, thus rate of photosynthesis is affected by temperature.
• When plants carry out photosynthesis, simple sugar will be produced and stored in the form of starch.
• Some of the glucose are converted into starch which acts as an ''energy store''
• Some glucose are used for respiration
• Glucose is converted into sucrose and transported to other parts of the plant in the phloem.
• Some of the glucose is converted into cellulose to build cell walls.
• Plants get nitrogen by absorbing nitrate ion from the soil.
• Glucose and nitrate are used to form amino acids to build proteins.
• Plants need proteins for: growth, cell repair, making of enzymes and hormones.
• Sugars are converted into oils which stores energy in the seeds.
• Leaf structure:

  • upper epidermis
  • Mesophyll tissues
  • Lower epidermis
  • Stomata
  • Vascular bundle
• Leaves have a large surface area for maximum absorption of light. A thin shape so that gases can diffuse easily. Has veins so that they support the leaf and transport water and mineral ions.

  Also has chloroplast which absorbs light for reaction.
• Upper Epidermis

  • Is transparent to allow light to reach the mesophyll tissues
  • Covered with cuticle to prevent water loss from evaporation
  • Cells are fitted together to protect the internal tissues from any damage.
• Palisade mesophyll

  • column like cells to absorb light efficiently
  • Converts glucose into starch which is stored temporarily
  • Has large area for maximum absorption of carbon dioxide.
• Spongy mesophyll

  • Large intercellular space to allow rapid diffusion of gases throughout the leaf.
  • Loosely packed together.
• Lower epidermis:

  • boarded by guard cells which regulates the passage of water vapour, carbon dioxide and oxygen through them
• Xylem:

  • Strengthen the leaf from tearing
  • transports mineral ions and water
• Phloem:

  • transports sucrose and amino acids throughout the plant
• Opening of stomata happens when the glucose is manufactured which lowers the water potential in the guard cell. Thus, water moves in the guard cell by osmosis and renders the cell turgid which opens the stomata.
• Stomata closing is when the cell gets an increase in water potential, water moves out by osmosis which closes the stomata.
• Nitrogen absorbed by plant in form of nitrate ions, to synthesis amino acids and protein along with chlorphyll.
• A lack in nitrate ions will lead to poor growth of plant and yellowing of leaf.
• Magnesium absorbed as magnesium ion to synthesis chlorophyll.
• Lack of magnesium ions will lead to yellowing of leaves.