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Edexcel IGCSE Biology 2.23 Photosynthesis Practical

Practise testing light, carbon dioxide and chlorophyll requirements and measuring oxygen or starch production.

Syllabus
First assessment 2019
Course
Biology 4BI1

Exam points

  • destarch a plant in darkness before changing one photosynthesis requirement
  • use iodine colour to map starch production in exposed and excluded leaf regions
  • measure oxygen production with repeats and control light, temperature and plant size

2.23 Photosynthesis practical question 1

[Maximum number: 6]

Photosynthesis is the process green plants use to convert light energy into chemical energy.

Question (a)

(a)

A student uses this method to show that carbon dioxide is needed for photosynthesis.

Step 1 place a plant in darkness for 48 hours
Step 2 remove a leaf and test it for starch
Step 3 enclose one leaf, still attached to the plant, in a flask containing a bag of solid sodium hydroxide (soda lime)

Step 4 place the plant in bright light for 24 hours
Step 5 test the leaf in the flask for starch
Step 6 test another leaf from the plant for starch

[ 6 ]

Question (i)

(i)

Explain why a leaf is removed from the plant and tested for starch in step 2.

[ 2 ]

Question (ii)

(ii)

Explain the expected result of the starch test in step 5.

[ 2 ]

Question (iii)

(iii)

Light is also needed for photosynthesis.

Describe how the student's method could be modified to show that light is needed for photosynthesis.

[ 2 ]
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