What Waste Material Is Produced During Photosynthesis?
Fill a large, clear, plastic cup about halfway full with sodium bicarbonate solution. The sodium bicarbonate solution is a source of carbon dioxide.
Place a freshly cut Elodea plant (with the cut stem at the bottom) in a large test tube. Fill the tube with sodium bicarbonate solution. CAUTION: Handle the test tube carefully.
Hold your finger over the mouth of the test tube. Turn the test tube over, and lower it to the bottom of the cup. Make sure no air is trapped in the test tube.
Place the cup in bright light.
After no fewer than 20 minutes, look closely at the elodea leaves. Record your observations.
Observe What did you observe on the Elodea leaves?
Infer What substance accumulated on the leaves? Should that substance be considered a waste product? Explain.
Apply Concepts Which plant organelle carries out photosynthesis and produces the gas?
Review Why are pigments such as chlorophyll needed for photosynthesis?
Predict How well would a plant grow under pure yellow light? Explain your answer.
Review What is the function of NADPH?
Explain How is light energy converted into chemical energy during photosynthesis?
Infer How would photosynthesis be affected if there were a shortage of NADP+ in the cells of plants?
Review Describe the overall process of photosynthesis, including the reactants and products.
Interpret Visuals Look at Figure 8–7. Into which set of reactions—light-dependent or light-independent—does each reactant of photosynthesis enter? From which set of reactions is each product of photosynthesis generated?
VISUAL THINKING
Create your own labeled diagram of a chloroplast. Using Figure 8–5 as a guide, draw and label the thylakoids, grana, and stroma. Indicate on your drawing where the two sets of photosynthesis reactions take place.
Draw two leaves—one green and one orange. Using colored pencils, markers, or pens, show which colors of visible light are absorbed and reflected by each leaf.