Paper 1

• What is the process that produces food in plants?

  Photosynthesis
• What type of food do plants produce through photosynthesis?

  Glucose
• Where does photosynthesis occur in plants?

  In the leaves of all green plants
• What organelles are responsible for photosynthesis in plant cells?

  Chloroplasts
• What pigment in chloroplasts absorbs sunlight for photosynthesis?

  Chlorophyll
• What are the reactants of photosynthesis?

  Carbon dioxide and water
• Write the word equation for photosynthesis.

  Carbon dioxide + water LIGHT glucose + oxygen
• Write the symbol equation for photosynthesis.

  $6CO₂ +$$6H₂O \xrightarrow{\text{light}} C₆H₁₂O₆ +$$6O₂$
• Why is photosynthesis an important process for plants?

  It converts light energy to chemical energy stored in glucose
• What are the main parts of a typical leaf involved in photosynthesis?

  • Waxy cuticle
  • Upper epidermis
  • Chloroplast
  • Vascular bundle
  • Lower epidermis
  • Air space
  • Stoma
  • Guard cell
• How are leaves adapted for efficient photosynthesis?

  Leaves are broad, contain chloroplasts in the palisade layer, and have a transparent upper epidermis
• What is the function of the vascular bundles in leaves?

  They transport water and nutrients and support the leaf structure
• What role does the waxy cuticle play in leaves?

  It helps to reduce water loss by evaporation
• What are stomata and their function in leaves?

  Stomata are small holes that allow CO₂ to diffuse into the leaf
• What are the three main limiting factors affecting the rate of photosynthesis?

  Light intensity, CO₂ concentration, and temperature
• What happens to the rate of photosynthesis when light intensity increases?

  The rate of photosynthesis increases steadily up to a certain point
• What is a limiting factor in photosynthesis?

  A limiting factor is something that stops photosynthesis from happening any faster
• How does temperature affect the rate of photosynthesis?

  Temperature affects the enzymes involved in photosynthesis
• What happens to the rate of photosynthesis if the temperature exceeds 45 °C?

  The plant's enzymes will be denatured, causing the rate of photosynthesis to decrease
• What are the steps to test a leaf for starch?

  1. Boil the leaf in water to stop chemical reactions
  2. Place the leaf in boiling ethanol to remove chlorophyll
  3. Rinse in cold water and add iodine solution
• What does a blue-black color indicate when testing a leaf for starch?

  It indicates that photosynthesis has occurred and starch is present
• How can oxygen production be used to measure the rate of photosynthesis?

  The rate of oxygen production corresponds to the rate of photosynthesis
• What is the purpose of using sodium hydrogencarbonate in the pondweed experiment?

  To ensure the plant has enough carbon dioxide
• What is translocation in plants?

  Translocation is the movement of food substances around the plant
• What are the three main mineral ions that plants need for growth?

  • Nitrates
  • Phosphates
  • Potassium
• What do nitrates provide for plants?

  Nitrates provide nitrogen for making amino acids and proteins
• how can you show that chlorophyll is needed for photosynthesis? (experiment)


  • using varigated leaves (white an green - only the green parts contain chlorophyll)
  • record the sections of your leaf that are green and the ones that aren't
  • test the leaves for starch
  • the parts that go blue-black have starch
  • only green parts can photosynthesis and produce starch as they are the only parts that went blue-black
• how can you show CO2 is needed for photosynthesis? (experiment)

  • use a sealed bell jar with a plants and soda lime inside
  • set up a lamp/light source on the outside of the jar
  • the soda lime will absorb all the co2 in the jar
  • leave the plant in the jar for a while
  • test the leaves for starch
  • they wont turn blue black - no starch present
• how can you show light is needed for photosynthesis?(experiment)


  • grow a plant in cupboard for at least 48hrs - used up all its starch stores
  • test a leave for starch - iodine solution
  • it wont turn blue-black - no starch
• how can you see the rate of photosynthesis?


  pond weed experiment
• pondweed experiment method


  • set up the aparatus
  • add a source of white light a certain distance away (the distance will change)
  • leave the pondweed to photosynthesis for a certain amount of time
  • oxygen produced will collect in the capillary tube
  • at the end the syringe is used to draw the gas bubbles use along side the ruler - meaure it - proportional to the volume of oxygen produced
  • repeat for different variables
• pondweed experiment aparatus


  a test tube with pondweed and water (+sodium hydrogencarbonate) and a bung with a capillary tube (filled with water) coming out of it - place a ruler on top of the capillary tube and a syringe at the end of it.
• pondweed experiment variables that could be tested 


  • temperature
  • co2 levels
  • light intensity
• why is sodium hydrogencarbonate used in the pondweed experiment?


  to make sure it has enough co2 - it releases co2 in solution
• what happens if a plant doesnt get enough nitrate?


  it will be stunted and older leaves will turn yellow
• why does a plant need phospahtes?

  they contain phosphorus which is neede for making DNA and cell membranes and they're needed for respiration and growth
• what happens to a plant if it doesnt get enough phosphates?


  they have poor root growth and their older leaves are purple
• why do plants need potassium?


  to help the nezymes needed for photosynthesis and respiration
• what happens to plants if they dont get enough potassium?


  poor flower and fruit growth and discoloured leaves
• magnesium is also needed, in small amounts, by plants. why?


  it is one of the most significant as it is required for making chloropyll