Lesson 10 Feeding in plants

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Lesson 10 Feeding in plants
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Photosynthesis Equations
light and
chlorophyll

• Carbon water ---? glucose oxygen
  
• Dioxide

6C0 6H O -gt C H O
6 O 2 2 6 12
6 2
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• Step 1
• Put leaf in half full beaker of boiling water for
  4 minutes.

• Step 2 Remove from heat .
• Place leaf in tube and cover with ethanol. Place
  tube in water bath for 10 mins.

• Step 3
• Rinse leaf in small beaker of water

• Step 4
• Place flat leaf in petri dish. Add 3 drops iodine
  solution.

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Method Summary
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Risk Assessment

• Precautions
• 1. Use tongs to handle hot objects and wear
  safety goggles
• 2. Switch Bunsen burner off
• 3. Wash spills immediately

• Hazards
• 1 Boiling water
• 2. Ethanol is flammable
• 3. Iodine solution is an irritant poisonous

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• Which chemical tests for starch?
• Why was the leaf soaked in ethanol?
• Why was the plant left in the dark for 24 hours?
• What did your 3 leaves look like after
• you tested for starch?
• Leave blank till next lesson
• 5. What did you conclude from your results?
• Leave blank till next lesson

Iodine.
To remove the chlorophyll.
To remove all the starch.
The leaf only produced starch where sunlight was
able to be absorbed. Leaves need sunlight for
photosynthesis.
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Work to do While waiting for ethanol or iodine
to work

• Roberts page 222 Investigation 1
• Give aim and copy diagrams for apparatus
• and method. Then answer questions in text.
• Homework
• Answer question 2 from worksheet and draw
• diagrams

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Is sunlight needed?

• How would you prove this?

Would you take two identical plants place one in
a dark cupboard and one in sunlight?
What would you expect to happen?
The plant in the dark would be pale yellow, thin
and spindly and may die The plants in the
light would be normal healthy plant . Therefore
light is needed for survival BUT this is not a
fair test.
How can we improve this?
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A better way to prove sunlight needed.
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A better way to prove sunlight needed.The print
test.
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Print test 1 before iodine solution
Print test 2 after iodine solution
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To prove sunlight energy is needed

• Foil or black paper prevents light getting
  through.
• Which parts of the test leaf goes blue black with
  iodine solution?
• Why do the parts that were covered not contain
  starch?
• If you leave plant in light again will covered
  parts does it go back?
• How is this energy trapped?

• What do you we know about leaf structure?
• You will need to look inside the leaf.

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Chlorophyll is found in small packets called
Chloroplasts
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Inside a chloroplast
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Is chlorophyll needed?
Take a variegated leaf and test for
starch. Which part will turn black with iodine
solution? Where is starch produced?