Observing the relationship between photosynthesis and respiration lab

Photosynthesis & Respiration Lab - ppt video online download

observing the relationship between photosynthesis and respiration lab

LAB: Observing the Relationship between Photosynthesis & Respiration. Pre-Lab Discussion / Background info: Green plants bask in sunlight. They use the. Lab: Investigating Photosynthesis and Cellular Respiration. Background: All organisms are . What is the relationship between snails and Elodea? The snails perform only What observation supports this inference? The snails released both. Carbon cycle lab: Observing photosynthesis and cellular respiration cycle than to demonstrate the relationship between plants, animals, and.

While this is the method used by scientists who study photosynthesis, the potential lawsuit implications are staggering, and this won't be mentioned again. Note that if you raise the concentration of carbon dioxide in the water by raising that end of the rulerpH declines. If you decrease the amount of carbon dioxide in the water, pH increases.

As carbon dioxide uptake is one way to measure photosynthesis rates, and changes in carbon dioxide concentrations cause changes in pH, we can use pH changes as an indirect measure of photosynthesis rates. If we place a plant in water with dissolved carbon dioxide and oxygen, the plant will remove carbon dioxide from the water as it photosynthesizes, reducing carbon dioxide concentrations in the water, and raising the pH of the solution.

If we place a plant or seed in the water and it undergoes respiration, it will release carbon dioxide into the water, and lower the pH of the solution. So by monitoring the changes in the pH of a solution, you can determine if the plant or seed in the solution is photosynthesizing pH goes up or respiring pH goes down. By now, you see that we will be observing the processes of photosynthesis and respiration by observing changes in the pH of solutions containing aquatic plants or seeds.

So how do we measure pH? There are a variety of methods available, but we will be using a method commonly used in laboratory exercises like this one - bromothymol blue.

Bromothymol blue is a pH indicator solution that is blue when its pH is basic and carbon dioxide concentrations are low and yellow when its pH is acidic and carbon dioxide concentrations are high. Figure 3 shows these color changes as a function of solution pH.

  • Photosynthesis and Respiration Lab
  • Relationship Between Photosynthesis and Respiration lab

Note that the solution is blue when basic, greenish when neutral, and yellow when acidic. In today's lab you will be examining changes in solution pH to indirectly measure carbon dioxide concentrations in solutions containing Elodea plants and mung bean seeds.

Photosynthesis & Respiration Lab

By looking at changes in carbon dioxide concentrations over time, you will be able to observe firsthand the processes of photosynthesis and respiration. Photosynthesis In the first exercise, you will examine the processes of respiration and photosynthesis with the aquatic plant, Elodea. Elodea is commonly found in freshwater lakes and ponds, where it floats in the water column. Because it does not require a root system to survive, Elodea is commonly used in freshwater aquaria and can be purchased at pet stores.

When exposed to sunlight, Elodea will begin photosynthesizing and will remove carbon dioxide from the solution.

Photosynthesis and Respiration Lab

The plant will respire constantly regardless of light conditions, as its cells always need energy. Place about 75 ml of bromothymol blue into an ml Erlenmeyer flask the triangular glass containers at your work bench and return to your workstation.

Observe the color of the solution. The next step is to introduce carbon dioxide into the solution. We could do this by getting a carbon dioxide tank like those used for soda dispensers, and have you carbonate your solution, but that would be overkill.

observing the relationship between photosynthesis and respiration lab

Luckily, there is a ready source of cost-free carbon dioxide within you right now - your lungs. Use a straw from Station 1 to slowly blow carbon dioxide from your lungs into the solution until it just turns yellow. Carry the solution to the front board and compare its color to the printout showing the color of bromothymol blue at various pH's. Find the color on the printout that best matches the color of the solution.

If your color is between the colors shown, then use the pH value that is intermediate between them. Record the color of the solution Initial color and estimated pH Initial pH for each of the tubes in Table 1. When comparing or describing colors, be sure to hold the tubes in front of a white background and be as detailed as possible when describing the color e.

Pour the solution into three screw cap tubes, dividing it fairly evenly. Obtain 3-inch pieces of Elodea from the open dish at Station 1, place it in one of the tubes, and cap it.

Obtain two 3-inch pieces of Elodea from the covered dish at Station 1, place it in a second tube covered with contact paper to prevent the entry of lightand cap it. In both tubes, be sure the plant is completely submerged and the tube is full of the indicator solution. Cap the test tube that has no plant in it. Place the test tubes into a test-tube rack and put the rack about 8 to 10 inches from a lamp so that all three tubes are the same distance from the lamp. While you allow the experiment time to run, go ahead and set up the respiration experiment described on the next page.

observing the relationship between photosynthesis and respiration lab

Allow the plants to sit undisturbed for 50 minutes, and then compare the colors of the solutions by removing the plants and holding the tubes in front of a white background. Record the Final colors of all three tubes in Table 1, and estimate the pH for each as described above. After all measurements have been completed, return the Elodea to Station 1, putting it in the dish marked "Used Elodea". Rinse out your glassware. Respiration In the second exercise, you will examine the process of respiration with seeds of the mung bean Phaseolus aureus.

One problem with studying respiration in plants is that they will begin photosynthesizing when in the presence of sunlight, and this will counteract the increase in carbon dioxide concentrations we are attempting to measure.

As you saw in the first exercise, one way to measure respiration is by placing a plant in the dark. In this exercise, we'll use a slightly different approach. Seeds are immature plants that cannot yet photosynthesize, but are capable of respiring. By using seeds we can look at respiration in this group of organisms, and avoid conflicts with photosynthesis when interpreting our results.

Photosynthesis Lab - Elodea O2 Bubbles

From Station 2, obtain three jars and three jar covers. One jar should be empty, one partially filled with germinating seeds, and the other should contain an equal number of non-germinating seeds. Our germinating seeds have been soaked in water for about 48 hours or so.

Rinse out all jars without pouring out the seeds to ensure that each has a fresh supply of air, then partially fill each equally with bromothymol blue. The liquid level should be just above the top of the seeds.

observing the relationship between photosynthesis and respiration lab

Record the initial color and estimated pH of the solutions in Table 2. Cover the jars and set aside in the same place for 45 minutes, making sure that the two jars are in similar conditions. Filter the seeds out of the jars by pouring the solution through the provided strainer into a separate container. To control all your variables, do the same for the solution with no seeds even though there is nothing to filter out.

Compare the color of the solution in each of the jars against a white background. Record the final color and estimated pH of the solutions in Table 2. Return the seeds to Station 2 in a jar. Repeat this procedure for the other flask. Place a sprig of Elodea into each flask. Secure a piece of aluminum foil over the opening 4.

Place one flask in the dark for 24 hours and the other an area with light. After 24 hours, remove the flasks from their locations and make observations on the data table Observations: Change in color of flask in light and in dark.

What was the color of the bromothymol blue solution before you exhaled into it and then after you exhaled into it? What gas was added to the bromothymol blue solution when you blew into it?

observing the relationship between photosynthesis and respiration lab

What process produced the above substance? What was the color of the bromothymol blue solution in the flask that was placed in the dark and the one in the light after 24 hours? What gas was removed by the Elodea plant in the bromothymol blue solution in the light flask as it underwent photosynthesis?

What gas was added to the bromothymol blue solution by the Elodea plant in the light?

observing the relationship between photosynthesis and respiration lab

What gas was removed from the flask by the Elodea plant in the dark from the bromothymol blue solution? What gas was added to the flask by the Elodea plant in the dark to the bromothymol blue solution? For the plant in the light, what carbohydrate molecule did it produce as a result of photosynthesis? For the plant in the dark, what food substance did it break down to release energy for it to stay alive?