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When investigating the influence of light intensity on the rate of photosynthesis, how many steps are there?
- 7 steps
- 1. Cut elodea
- 2. Hook on paper clip, drop stem up into boiling tube
- 3. Place boiling tube into water bath (25*)
- 4. Switch on light, 15cm away. Wait 5min
- 5. Count + record no. of bubbles per min. X2
- 6. Repeat experiment varying distance
- 7. Plot a graph
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When investigating the influence of light intensity on the rate of photosynthesis, what factors are kept constant?
- CO2 concentration: by adding excess sodium bicarbonate to the water.
- Temperature: using water bath (25* for elodea)
- pH: using pH buffer (pH 7 for elodea)
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When investigating the influence of light intensity on the rate of photosynthesis, what plant is used?
Aquatic plant used is elodea. Pond weed
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When investigating the influence of light intensity on the rate of photosynthesis, how is CO2 concentration kept constant?
By adding excess sodium bicarbonate to the water
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When investigating the influence of light intensity on the rate of photosynthesis, how is the temperature kept constant?
By water bath , thermometer
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When investigating the influence of light intensity on the rate of photosynthesis, what temperature is suitable for the elodea?
25* C
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When investigating the influence of light intensity on the rate of photosynthesis, what pH is suitable for the elodea?
pH7
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When investigating the influence of light intensity on the rate of photosynthesis, how is the pH kept constant?
Using a pH buffer
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When investigating the influence of light intensity on the rate of photosynthesis, how is the sample elodea taken?
Cut the stem of the elodea at an angle. Remove several leaves from cut end of the stem.
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When investigating the influence of light intensity on the rate of photosynthesis, how is te elodea placed into a boiling tube?
Hooked paperclip, dropped stem up
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When investigating the influence of light intensity on the rate of photosynthesis, where is the lamp first placed?
Place water bath containing elodea 15cm from the lamp.
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When investigating the influence of light intensity on the rate of photosynthesis, what is observed?
- The bubbles being released from the cut end of the stem
- Count and record the number of bubbles released per min. Repeat twice.
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When investigating the influence of light intensity on the rate of photosynthesis, what do the x and y axis represent in the graph?
- Y rate of photosynthesis (how mean no. of bubbles)
- X light intensity
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When investigating the influence of light intensity on the rate of photosynthesis, how id the light intensity varied?
Vary the light by placing a lamp at different distances from the plant.
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When investigating the influence of light intensity on the rate of photosynthesis, how was the rate of photosynthesis measured?
The rate of photosynthesis at each light intensity was measured by counting the mean number of bubbles of O2 that were released from the cut stem.
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When investigating the influence of light intensity on the rate of photosynthesis, what could’ve a source of error?
Allow elodea to adjust to each light intensity for a few moments before counting the bubbles.
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When investigating the influence of light intensity on the rate of photosynthesis, what equipment is used?
- Knife to cut elodea
- Paper clip to hook around elodea
- Boiling tube (with pond water)
- Water bath at 25*
- Lamp
- Ruler to measure 15cm…..
- Stop watch to record per minute
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