Photosynthesis and Chlorophyll
A pigment is a substance that absorbs light of particular wavelengths. Plants contain multiple types of pigment such as chlorophyll and carotenoids. If you see a leaf that is green or green-yellow in color, that is due to a pigment in the leaf called chlorophyll. Sunlight, which is categorized as "white" light, contains all of the colors of the spectrum. When it shines on the plant leaf, the chlorophyll absorbs more of the red, orange, blue, and violet light wavelengths and it reflects back most of the green and yellow light wavelengths. That is why you see the green or green-yellow color.
A spectrophotometer is an instrument that can be used to measure the amount of light absorbed by a pigment. The graph below shows the percent of light energy absorbed for the different light wavelengths. The highest peaks represent the colors that the chlorophyll absorbs the most, and therefore, they are seen the least.
chlorophyll b
Absorbance
chlorophylla
400
500
600
Wavelength [nm]
700
blue
green
yellow
red
8. According to the graph above, which of the color is absorbed the most by chlorophyll b? (1 point)
Based on the graph, the color absorbed the most by chlorophyll b is blue.
9. According to the graph above, which chlorophyll is better at absorbing the red light wavelength? (1 point;
• chlorophyll b
• chlorophyll a
10. According to the graph above, which chlorophyll better at reflecting dark green light wavelengths and making plants look green to our eyes?
9. According to the graph above, chlorophyll a is better at absorbing the red light wavelength.
10. According to the graph above, chlorophyll b is better at reflecting dark green light wavelengths and making plants look green to our eyes.
11. A scientist fills a glass container with water and places an aquatic plant inside the container, then closes the lid and places the container in direct sunlight. The scientist observes small bubbles on the surfaces of the plant's leaves on days 1 and 2, but no bubbles on day 3. If the scientist concludes that the bubbles were caused by photosynthesis, then which reactant should be added to the water in order for the bubbles to reappear?
6 CO, + 6H,0
7 CHO6 + 602
(1 point)
• oxygen gas
• hydrogen gas
• carbon dioxide gas
• glucose sugar
The reactant that should be added to the water in order for the bubbles to reappear is carbon dioxide gas.
12. Using the chemical equation for photosynthesis, choose the correct number of atoms from the drop down box for the element shown in the reactants and products. (6 points)
6 CO, + 6 HO
764186+602
REACTANTS
Carbon
Hydrogen
Oxygen
PRODUCTS
Carbon
Hydrogen
Oxygen
REACTANTS
Carbon - 6
Hydrogen - 12
Oxygen - 18
PRODUCTS
Carbon - 6
Hydrogen - 12
Oxygen - 18
13-15. Match each phrase to the correct biochemical process. (3 points)
Photosynthesis
Cellular
Respiration
This chemical reactions is driven by the absorption of solar energy in sunlight.
This chemical reaction takes place in the presence of oxygen and releases stored energy.
The sugars produced from this process can be used immediately or stored for growth or later use.
13. Photosynthesis - This chemical reactions is driven by the absorption of solar energy in sunlight.
14. Cellular Respiration - This chemical reaction takes place in the presence of oxygen and releases stored energy.
15. Photosynthesis - The sugars produced from this process can be used immediately or stored for growth or later use.
16. Identify the products and reactants of cellular respiration. (4 points)
Reactant of Cellular Respiration
Product of Cellular Respiration
water
carbon dioxide gas
oxygen gas
glucose