Activity 8: For You To Do

1. a) Student answers will vary. The plant kept in the dark for three days will have less starch content than the plant exposed to sunlight.

7. a) The leaf marked with four notches is the control for the experiment. It will be used as a standard to compare the results using the other leaves.

11. b) The iodine test on Day 2 was to determine the role of sunlight in the production of starch.

14. b) The leaf coated with petroleum jelly on its upper surface has the greatest amount of photosynthetic activity as shown by its more pronounced blue-black coloration. The leaf with its lower surface coated and the leaf with both of its upper and lower surface coated had the least photosynthetic activity as shown by the lack of blue-black coloration with the iodine test.

Teaching Tip
Using Blackline Master Ecology 8.4: The Structure of a Leaf, ask the students where gas exchange is possible. Also ask them to explain their response. Connect their experimental results with the structure of the leaf. Have them figure out what part of the leaf should not be coated with the petroleum jelly to allow carbon dioxide to get to the leaf.