1. The source of energy that caused the wave shown in the gif is .

2. A wave transfers without transferring .

3. In the gif we are observing a change in the waves being reflected because the algae in the water, which causes a change in the of light being absorbed and reflected.

4. Many plants below the surface of the sea rely on light that filters down through hundreds of feet of water. When there’s an algal bloom, this stops almost all light from reaching these plants. These plants rely on the way light waves are water.

5. The change in the light waves is primarily due to the scales on the outside of these algae cells, called exoskeletons. What uses could these exoskeletons have in the world?

6. A student wants to revise the models in figure A to more accurately represent how different colors of light waves vary. Which of the following revisions would help show this?

• Make each color of light an arrow with a different length to show that the distance they travel varies.
• Change the arrowheads on each of the arrows to show the colors move in different directions.
• Draw each color of light as a wave with a different frequency.
• Draw the white light from the sun as a thicker wave compared to the individual colors.

7. Refer to figure A. Carsen states that their model shows light being absorbed, reflected, and transmitted. Which of the following colors is most likely shown as being absorbed by the water?

• Green
• Red
• Blue
• Yellow

8. Refer to figure B. The change in light waves when they encounter algae is primarily due to the scales that make up the exoskeleton on the outside of the algae. Considering that algae use light as energy for photosynthesis, how could the structure of these scales help algae?

• The scales transmit all colors of light
• The scales only interact with green light
• The scales allow more light to be absorbed
• The scales cause light to be reflected in more directions

9. Which of the following features is necessary to include in a model to clearly show how algal blooms affect light in order to make the water appear green?

• The amount of green light reflected from the water should be the same as the amount of green light transmitted through the water.
• More green light should be transmitted into the water when algae is present.
• More green light should be reflected from the water when algae is present.
• The amount of green light absorbed into the water should be the same as the amount of green light reflected from the water.

10. Refer to figure A. Which of the student models does a better job at explaining why deep water organisms experience less light when the algae is present and why?

• Carsen’s model, because the model shows not all the light is transmitted through the water.
• Myla’s model, because the model shows all the colors of light that get reflected off the surface of the water.
• Carsen’s model, because the model shows the light reflected to produce the color of algae seen above the surface.
• Myla’s model, because the model shows less light being absorbed into the surface of the water.

11. A classmate wants to make a model for how light interacts with the water surface when no algae is present and the water appears blue. Which of the following describes how they should model light waves interacting with the surface of the water?

• All of the colors should be reflected off and transmitted through the surface of the water and none of the colors should be absorbed.
• All of the colors should be absorbed into the surface of the water, but only blue light should be transmitted through the surface.
• Blue light should be reflected off the surface of the water, while green, red, and yellow light are absorbed and transmitted.
• Blue light should be absorbed into the surface of the water, while green, red and yellow light are reflected.

12. Refer to figure A. How can Myla’s model be revised to explain why an increase of algae reduces the light that reaches organisms deep in the water?

13. The algal blooms in the gif are influenced by light waves and water waves. How do these waves differ?

• Light waves don’t transfer energy and water waves do.
• Light waves don’t require matter to travel through and water waves do.
• Light waves can have different amplitudes, but water waves cannot.
• Light waves can have different frequencies, but water waves cannot.

14. Draw a model in the space below to show how light interacts with water without algae (left side), and with algae (right side). Be sure to use different colors in your model to show different colors of light.

15. Explain the differences in light wave behavior as shown in your model, using vocabulary such as reflection, transmission, and absorption. How do you think algae’s structure (figure B) affects the movement of light waves?

16. In order to see an object, light must travel from to .

17. When algal blooms are present, the surface temperature of the water can increase. This is caused by more light being into the matter at the surface.