Cell Bio Lab #11 - Algae Bead Photosynthesis- Review

430 nm (blue) and 662 nm (red)

What wavelengths of light do chlorophyll a pigments absorb the most? What colors do these wavelengths correspond to?

453 nm (blue) and 642 nm (red-orange)

What wavelengths of light do chlorophyll b pigments absorb the most? What colors do these wavelengths correspond to?

Wavelengths between 460 nm (blue) and 510 (blue-green)

What wavelengths of the visible light spectrum do carotenoid pigments absorb the most? What colors do these wavelengths correspond to?

Wavelengths between 500 nm and 620 nm are utilized the least. These wavelengths correspond to the colors green and yellow which are reflected by the plants and not absorbed.

What wavelengths of the visible light spectrum do plants utilize the least for photosynthesis? What colors do these wavelengths correspond to?

Photosynthesis consumes CO2

Does photosynthesis produce or consume carbon dioxide?

Red

A bicarbonate indicator solution may be used to show changes in the pH of a solution. When CO2 from the atmosphere dissolves into water containing a bicarbonate indicator at equilibrium, the pH value of the solution is measured at 8.6. What color is the indicator solution at a pH value of 8.6?

Yellow

Cellular respiration

When CO2 level increases, the indicator solution changes as CO2 dissolves in water to form carbonic acid. What color would the indicator solution change to in response to increased levels of CO2? During what process does this occur?

Purple

Photosynthesis

When CO2 levels decrease, the solution becomes more basic. What indicator color will be observed if the concentration of CO2 decreases in the control solution? During what process does this occur?

Purple. Photosynthesis removes CO2 from the environment, so there is a lower CO2 concentration than the control and it is less acidic (higher pH). Therefore, the color changes from red (control) to purple (low CO2 concentration)

Algae and plants perform both photosynthesis and respiration. Assume that algae are placed into a culture tube containing bicarbonate indicator solution with an initial pH value of 8 .6. After 24 hours, what color will the bicarbonate indicator become if photosynthesis is occurring at a greater rate than algal respiration? Explain why this may occur.

Yellow. Respiration produces CO2 as a by-product, so it will be released into the solution. The higher CO2 concentration compared to the control causes the solution to become more acidic (lower pH). Therefore, an increase in CO2 causes the color to change from red (control) to yellow (high CO2 concentration)

Assume that a glass culture tube containing algae beads and bicarbonate indicator solution is kept in the dark. After 24 hours, what color will the bicarbonate indicator become if algal respiration is occurring at a greater rate than photosynthesis? Explain what differences in dissolved carbon dioxide concentrations may cause this color change.

Wavelengths around 450 nm (blue) and 660 nm (red)

What wavelengths/colors of light do photosynthetic pigments absorb the most?

Red and Blue

Which colored filters provide the wavelengths of light necessary for maximum absorption by photosynthetic pigments?

Purple

If photosynthesis is occurring at a greater rate than respiration, what color should the indicator change to?

Yellow

IF there are not sufficient, appropriate wavelengths of light to perform the light-capturing process of photosynthesis, plant respiration will exceed plant photosynthesis. What color should the indicator change to when photosynthesis is compromised due to less than ideal inputs of light?

Respiration. Respiration releases CO2 as a by-product, so CO2 concentration increases. This makes the environment more acidic and causes the pH to decrease. These things are indicated by the yellow-colored solution

- Low pH (more acidic) = yellow

What process dominates if the solution is yellow? Why?

Photosynthesis. Photosynthesis consumes CO2 in the reaction, so CO2 concentration in the solution decreases. This makes the environment less acidic and raises the pH. These are indicated by the purple-colored solution

- High pH (less acidic) = purple

What process dominates if the solution is purple? Why?

Sodium alginate + algae was dropped into ice chilled calcium chloride to form the beads

What components were used to create the algae beads?

The tube with no covering and no algae beads, only the bicarbonate indicator solution. This ensured that neither respiration nor photosynthesis would occur without algae beads

Which tube was the negative control for the experiment? What was the purpose of this?

The tube with no covering but contained algae beads and the bicarbonate indicator solution. The tube was completely exposed to light and had the necessary components for photosynthesis to occur, so it should dominate the reaction process

Which tube was used for the positive control for photosynthesis? Why?

The tube with aluminum foil covering that contained algae beads and the bicarbonate indicator solution. This allowed the reaction to occur in the complete absence of light, so only respiration would occur. Photosynthesis could not possibly occur because of the lack of light

Which tube was used for the positive control for respiration? Why?

pH = 8.6

red

What was the pH and color of the bicarbonate indicator solution?

6CO2 + 6H2O ―(Light)→ C6H12O6 + 6O2

What is the net reaction for photosynthesis?

C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy

What is the net reaction for cellular respiration?

Chloroplasts. The light reaction occurs in the thylakoid membrane and the dark reaction occurs in the stroma

Where does photosynthesis occur in plant cells?

Mitochondria

Where does cellular respiration occur in plant cells?

CO2 + H20 ⇄ H2CO3 → HCO3- + H+

What is the equation that shows the production of bicarbonate from CO2 and H2O?

Photosynthesis

What process in aquatic algae and plants removes dissolved carbon dioxide from the environment?

The control bicarbonate solution has a pH of 8.6 and is the color red. The change in color is dependent on the concentration of CO2 in the environment, so cellular respiration and photosynthesis both affect CO2 concentration which causes a change in the color. Photosynthesis removes CO2 from the environment, lowering its concentration, raising the pH, decreasing acidity, and changing the color to purple. Cellular respiration releases CO2 into the environment, increasing its concentration, decreasing the pH, increasing acidity, and changing the color to yellow. The resulting color determines to what extent photosynthesis or cellular respiration occurs.

Explain how the color change in the bicarbonate indicator solution allows an experimenter to determine differences in the rate of photosynthesis between culture tubes