1: Photosynthesis Experiment

Correct Response

• OXYGEN with an explanation that explicitly refers to photosynthesis (or equivalent).
  • Examples:
    • Photosynthesis takes place. Plants use carbon dioxide from the water and give off oxygen.

Partial Responses

• OXYGEN with a minimal explanation based on carbon dioxide/oxygen exchange involving plants. [No explicit mention of photosynthesis.]
  • Examples:
    • Plants take in carbon dioxide and give off oxygen.
    • Plants give off oxygen.
• Gives an explanation that explicitly refers to photosynthesis, but checks CARBON DIOXIDE or AIR.
  • Examples:
    • CARBON DIOXIDE. The plant undergoes photosynthesis.
    • AIR. When the plant photosynthesizes it takes in carbon dioxide and gives off air.

Incorrect Responses

• OXYGEN with no explanation or an incorrect explanation not related to plant processes.
  • Examples:
    • Because the heat has evaporated the water and the oxygen pressure is too great.
    • Because water is made up of 2 parts hydrogen and 1 part oxygen. Some hydrogen has detatched from the oxygen, leaving the oxygen in the top of the tube.
• CARBON DIOXIDE with no explanation or an incorrect explanation (not based on photosynthesis).
  • Examples:
    • There is carbon dioxide in the water and it bubbles up when it is heated by the light.
• AIR with no explanation or an incorrect explanation (not based on photosynthesis).
  • Examples:
    • The plant has dissolved half the water and there is nothing in the tube left but air.
    • When the water gets warm enough it will start to evaporate into air.
• VACUUM with no explanation or an incorrect explanation.
  • Examples:
    • The plant has taken in the oxygen from the water and left a vacuum at the top.
• Other incorrect

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