Do not move to evidence 5 until instructed to do so Evidence 4

Starch in plants

Plants need glucose (a kind of sugar) to perform cellular activities The sugars are stored together as starch until the plant needs it. Glucose Starch

Scientists wanted to learn more about where starch is stored in a plant, so they did an experiment.

They chose a plant that had leaves with white stripes.

Ask your partner: Predictions Before moving to the next slide, make a prediction with your partner: How do you think the different colors of the plant relate to the number of chloroplasts? Do you think the white or green part will have more chloroplasts? Do both colors have the same number of chloroplasts? WHY?? Move to the next slide when you and your partner have provided solid reasoning for your prediction

They used a microscope to look at the white part and the green part of the leaf to see if there were any differences. Green Part of leaf White Part of leaf

Ask your partner Before moving to the next slide, ask you partner: Which part of the leaf had the most chloroplasts? Move to the next slide when you and your partner agree on an answer

Then, the scientists used iodine to see what parts contained starch.

Parts that turn blue show that starch is present. Brown areas are where there is no starch.

Ask your partner Before moving to the next slide, ask you partner: What color did the white part of the plant turn when exposed to iodine? What does that mean? Move to the next slide when you and your partner agree on an answer

Ask your partner Before moving to the next slide, ask you partner: What color did the green part of the plant turn when exposed to iodine? What does that mean? Move to the next slide when you and your partner agree on an answer

Ask your partner Before moving to the next slide, ask you partner: Which part of the plant indicated starch? Which part of the plant did not? Move to the next slide when you and your partner agree on an answer

They took a leaf and covered part of it with a black piece of paper. Then they exposed the plant to light.

Ask your partner Before moving to the next slide, ask you partner: What purpose does the black paper have? What is the independent variable (what is changed) in this experiment? Move to the next slide when you and your partner agree on an answer

They removed the paper, and observed that the covered part of the leaf that was green had become much lighter in color. There was no change to the white part.

Ask your partner: Predictions Before moving to the next slide, make a prediction with your partner: Why did the part of the leaf that was covered by the black paper get lighter? Why did the white part of the leaf stay the same? Move to the next slide when you and your partner have provided solid reasoning for your prediction

Then, the scientists used iodine to see what parts contained starch.

Parts that turn blue show that starch is present. Brown areas are where there is no starch.

Ask your partner Before moving to the next slide, ask you partner: What color did the plant under the black paper turn? What does that mean? Move to the next slide when you and your partner agree on an answer

Ask your partner Before moving to the next slide, ask you partner: How are starch, chloroplasts, and light related? How do you know? Move to the next slide when you and your partner agree on an answer

Based upon the evidence you have seen, construct and initial model explaining what the chloroplast does, and how! Do not move to evidence 5 until instructed to do so End of Evidence 4

Evidence 5

Evidence 5: What makes chloroplasts work? Chloroplasts have smaller structures called grana inside them. In normal chloroplasts, the grana are stacks of little disks with chlorophyll in them. Chlorophyll is a green chemical found in the grana. Scientists are interested in whether the grana influences how much glucose is produced by chloroplasts.

Ask your partner Before moving to the next slide, ask you partner: Where are grana found and what are scientist’s trying to study about grana? Move to the next slide when you and your partner agree on an answer

Evidence 5: Procedure We studied the structure of chloroplasts from barley. Sometimes plants have mutated chloroplasts. Mutated chloroplasts do not have normal grana. We looked at barley plants with normal chloroplasts, mutated chloroplasts, and very mutated chloroplasts by looking through very powerful microscopes. You can see what we saw on the next slides. We also measured how much glucose is produced in each kind of barley plant.

Evidence 5: Results Plant typeWhat the chloroplasts look like through a very powerful microscope Leaf color How much glucose was produced in the leaves? Barley plants with normal chloroplasts dark green Large amounts of glucose Barley plants with mutated chloroplasts pale green Small amounts of glucose Barley plants with very mutated chloroplasts yellowNo glucose

Ask your partner Before moving to the next slide, ask you partner: What happened to the color of the leaves as the barley chloroplasts became more mutated? Move to the next slide when you and your partner agree on an answer

Ask your partner Before moving to the next slide, ask you partner: What happened to the amount of glucose produced in the leaves as the barley chloroplasts became more mutated? Move to the next slide when you and your partner agree on an answer

Ask your partner Before moving to the next slide, ask you partner: How are color of chloroplasts and glucose production related? Move to the next slide when you and your partner agree on an answer