END OF YEAR SCIENCE Y8

• Photosynthesis


  The process plants use to make their own food, glucose. Carbon dioxide and water react, in the presence of light energy, to make oxygen and glucose.
• Photosynthesis


  1. Light energy

  2. Carbon dioxide

  3. Water

  4. Oxygen

  5. Glucose
• Organisms that make their own food are called producers
• Producers


  Use the glucose as an energy store and to build new tissues
• Photosynthesis


  A series of chemical reactions that uses light energy
• Photo


  Means 'light'
• Synthesis


  Means 'putting together'
• Photosynthesis is a vital process to ALL living things on Earth, not just to plants
• Reactants


  Light energy, carbon dioxide, water
• Products


  Oxygen, glucose
• Water comes from the soil, travels in through the roots and up the stem
• Carbon dioxide comes from the air, enters the leaf through small holes on the underside
• Sunlight gives the plant light energy
• Chlorophyll is the green substance inside chloroplasts, where the chemical reactions happen
• Photosynthesis happens in the palisade cells of a plant leaf
• Ways algae are different to plants

  • Live in water
  • Unicellular
  • No leaves, roots, flowers, or stems
• Without photosynthesis


  No oxygen would be added to the atmosphere and no carbon dioxide taken out
• Without oxygen


  Animals cannot survive
• Without carbon dioxide being removed


  It will build up, leading to enhanced greenhouse effect, global warming and climate change
• Without glucose


  No food for animals
• Photosynthesis requires light, and there is not enough light during the night
• Plants can store light during the day to use in photosynthesis during the night
• Plants make this food themselves

  • Plants take in some food from the soil
  • Plants take in some food from the air
• I am sure this is right
• I think this is right
• I think this is wrong
• I am sure this is wrong
• Plant cells need to be supplied with food to stay alive
• Plants take in substances from soil and air that they use to make their food


  • Plants make it by converting light into food
  • Plants use a process called photosynthesis to make their food
• What is the function of a leaf?

  To carry out photosynthesis
• How is a leaf adapted to perform its function?

  To answer this question, consider the similarities in features between all these leaves...
• How is a leaf adapted to its function?

  • Flat
  • Thin
  • Have veins
  • Are green
• Gives the leaves a large surface area so they can absorb more sunlight for photosynthesis
• More light can reach more cells therefore more chloroplasts in those cells
• To carry water to the leaf for photosynthesis
• Contain chlorophyll for photosynthesis
• But there are many more adaptations...
• So let's look more closely


  What does a leaf look like under the microscope?
• VASCULAR BUNDLE


  • can be positioned anywhere in spongy mesophyll layer)
  • To transport water to the leaf (in xylem). To transport sucrose from the leaf to other parts of the plant (in phloem).
• • Oxygen = red
  • Carbon dioxide = green
  • Water = blue