Question

A Photosynthesis and Cellular Respiration Lab was done: 10 algae beads were placed in cuvettes labeled LIGHT and DARK with a color indicator and then LIGHT was placed under a bright lamp and DARK was placed next to it but wrapped in tinfoil. The pH was taken per the color indicator and the Absorbance was also taken (every 5 minutes for 45 minutes).

It was calculated that the slope LIGHT is 0.1261 and the slope DARK is -0.1491. pH increased the fastest in the LIGHT all the way up to 9.0 after 45 minutes and the ph DARK began at 8.0 but then slowly decreased to 7.0 after 45 minutes

I believe that the negative number indicates CO2 rate increases in the dark but decreases in the light as seen by the positive number ---

The question asks---> 1. Look up current ocean pH values. How do the current values compare to those from previous years? ((my answer: 8.1 pH today and 8.2 pH previously (slightly basic with a 0.1 pH drop). This represents a 25% increase in acidity over the last 2 centuries.)). Next, consider what you have just learned about algae and how the chemistry of the indicator used in the experiments you just performed works. Hypothesize why oceans are at their current pH. How is the pH of the ocean changing and why? How might this affect the organisms that live in the ocean?

Answer 1

1. The current ocean pH is 8.1 but from last 3 to 4 decades it is decreasing which was somewhere near to 8.3 inturn making the ocean more and more acidic with time

2. As more light becomes available, photosynthesis dominates. However, as conditions become darker, photosynthesis is retarded and respiration takes over as the main process.​ The product of photosynthesis of algea using light energy from the sun and carbon dioxide generate carbohydrates and oxygen. further carbohydrate generate acidic waste products when needed which gives the acidity when the algae beads were placed in cuvettes labeled light and dark with a color indicator.   when colour indicators are used photosynthetic rate can be calculated, it changes to yellow when more carbon dioxide is used and changes through red to a deep purple colour when carbon dioxide is used in very less amount.

3. The pH of ocean is becoming more and more acidic.

Oceans play an important role in keeping the Earth's carbon cycle in balance. As the amount of carbon dioxide in the atmosphere rises, the oceans absorb it. In the ocean, carbon dioxide reacts with seawater to form carbonic acid. This causes the acidity of seawater to increase.

Main cause for changing ocean pH is climate change

burning of fossil fuels makes the more availability of CO2

Increase in pollution due to man-kind

4. Increasing acidity will make it harder for corals to build skeletons and for shellfish to build the shells they need for protection. Corals are particularly important because they provide homes for many other sea creatures.  The loss of coral reefs will reduce habitats for many other sea creatures, and it will disrupt the food web that connects all the living things in the ocean.

Changes in ocean chemistry can affect the behavior of non-calcifying organisms as well. The ability of certain fish, like pollockoffsite link, to detect predators is decreased in more acidic waters. Decreased pH levels also affect the ability of larval clownfish to locate suitable habitat. When subjected to lower pH levels, the larval clownfish lost their chemosensory ability to distinguish between their favored and protective anemone habitat among the reefs and unfavorable habitats like mangroves.

More acidity impairs the ability to distinguish between the "smell" of their own species and that of predators, which will create an increased risk of predation. Inturn will destroy the food web slowly.