Photosynthesis is defined as the process in which plants produce carbohydrates using raw materials from light energy
Balanced Equation for Photosynthesis:
6CO2 + 6H2O → C6H12O6 + 6O2 (in the presence of light and chlorophyll)
In word form, this is...
Carbon dioxide + Water → Glucose + Oxygen in the presence of light and chlorophyll
Process of photosynthesis
- The plant takes in carbon dioxide (CO2) and water (H2O) from the air and soil
- The carbon dioxide and water and rearranged to transform into glucose and oxygen
- Chlorophyll captures red and blue light waves and reflects green light waves
- The chloroplasts convert the energy from the light waves and convert it to energy molecules (ATP and NADPH)
- These energy molecules are used to rearrange the reactants to make the products
- Oxygen diffuses back into the air and the glucose is used for respiration to release energy and used to make substances needed in the plant
- Chlorophyll is important as it captures light waves to use for energy to convert raw materials into energy
- Light is essential as it is used as energy for photosynthesis to occur
- Carbon Dioxide is essentail, as it is one of the reactants that is used to perform photosynthesis
The effect of temperature and light intensity on the rate of photosynthesis
- The rate of photosynthesis can be investigated by cutting one end of pondweed and placing it in water, and seeing how many bubbles are produced per minute
- When the light intensity is higher, so is the rate of photosynthesis (because of the amount of energy)
- You can change light intensity by moving a lamp closer or further away from the plant
- When the temperature increases (as long as it is below 40°C), so is the rate of photosyntehsis (as heat energy increase kinetic energy for the particles)
- You can change the temperature of the water by using a hot plate
Features of a leaf
- Chloroplasts: an organelle that converts light energy to chemical energy through photosynthesis
- Cuticle: A transparent waxy layer that stops water vapour from escaping and reflects excess sunlight
- Guard Cells: Cells in pairs that are in charge of controlling gas exchange through opening during the day and closing the stomata during the night
- Stomata: Tiny holes (often on the bottom of the leaf) for gas exchange where carbon dioxide, oxygen, and water vapour diffuse in and out of the leaf
- Upper Epidermis: Transparent cells coated by the cuticle while allowing light to shine through to the mesophyll cells for photosynthesis
- Lower Epidermis: A layer at the bottom of the cell containing the stomata and guard cells
- Palisade Mesophyll: Cells below the epidermis which are elongated and are packed with chloroplasts to absorb more light for photosynthesis
- Spongy Mesophyll: A layer of cells that contain gaps, increasing the surface area to volume ratio and allowing gases to diffuse (mostly carbon dioxide)
- Vascular Bundles: Contains the xylem and phloem to transport substances
- Xylem: Transports water and minerals from the roots of the plant to the leaf for photosynthesis in the mesophyll cells and transpiration in the stomata
- Phloem: Transports sucrose and amino acids around the plant
Structure of a Leaf
Nitrate ions and magnesium ions
Magnesium ions are extremely important in plants
- They make chlorophyll for photosynthesis
- In the case of a deficiency of magnesium ions, the veins of the plant will become yellow and growth of the plant with slow
Nitrate ions are important as well, because...
- They are in charge of making amino acids for proteins and growth and contain nitrogen, an important component in chlorophyll
- When nitrate ions are lacking, the amount of chlorophyll will reduce, and the leaves therefore lose their green colour from the chlorophyll and become yellow. Growth will also slow because amino acids are not made as much.
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