Be sure to include a key for each sample set. It is added to facilitate photosynthesis. Oxygen released from the leaves that cause the leaves to float. Use a straw or hole punch to punch out disks from the leaves. The opal took the most time; only 4 disks had risen after 20 minutes.
When , the disks use the carbon dioxide and water to produce oxygen and glucose. The plant uses these molecules as immediate or stored energy sources, respectively. Place the cup underneath the fluorescent light and start the timer. As photosynthesis proceeds oxygen is released into the interior of the leaf which changes the buoyancy--causing the disks to rise. Continue until all of the disks are floating. The vacuum removes gas from the leaf tissues.
Photosynthesis will happen second most quickly in opal-covered light, then in uncovered light, then in yellow-covered light, and finally slowest in green-covered light. Procedure Data - Tables Data - Graphs The red light caused the disks to rise in the least amount of time 7 minutes. Conclusion - Solutions Some solutions include setting a precise position for the light and keeping it unchanged throughout the experiment, using more cellophane and wrapping the cups on the sides in addition to the tops, and using the same light for all of the cups. When visible light is absorbed by leaf pigments, such as chlorophyll a or b, during the light reactions of photosynthesis, electrons within each photosystem are boosted to a higher energy level and replaced by the splitting of H 2O molecules. If the leaf disks rise more quickly, what does that tell you about the rate of photosynthesis? Make a diluted solution of liquid detergent 2 drops of soap to 100 mL of water. Again, the exact distance is not critical, but it should be the same for all student groups unless they are testing to see if the distance from the light to the disks influences the rate of photosynthesis. While doing this, swirl the leaf disks into the solution.
We had predicted that red would result in the quickest rate of photosynthesis and, therefore, the leaves under red light would rise fastest due to the production of oxygen. Add 1 drop of concentrated liquid dishwashing detergent and 1 gram of sodium bicarbonate to 1 gallon of water. This experiment is extremely amenable to manipulations, making it possible for students to design investigations that will quantify the effects of different variables on the rate of photosynthesis. Continue until all of the disks are floating or until 20 minutes have passed. Inquisitive minds can come up with many additional projects. Plants take inorganic compounds carbon dioxide and water and convert them to G3P, an organic compound. Hold the vacuum for a few seconds, and then release the plunger, letting it snap back see photos below.
The longer waves of heat, microwaves and radio waves 103 nm to 103 meters do not possess enough energy and are absorbed by the water molecules in a plant. Bicarbonate ion serves as the carbon source for photosynthesis. Place 10 leaf disks into the syringe and pull in a small volume of the bicarbonate and soap solution. Tap the side of the syringe so that the disks are at the bottom, and then reinsert the plunger—being careful not to crush the leaf disks. The experiment should continue until all the disks are floating. List any factors that you think may affect the rate of photosynthesis.
You may need to tap on the plunger to release the bubbles in order to make all the leaf disks sink. The byproduct, oxygen, is what caused the disks to float. In plants, these proteins are held inside organelles called chloroplasts, while in bacteria they are embedded in the plasma membrane. However, respiration continues in the dark, so the disks will use the accumulated O 2 gas. Accumulation of O 2 on the disks causes them to float.
Start timing as soon as your sample is set up. Record the number of floating disks every minute, until all the disks are floating. When all the disks have floated, try putting the cup in a dark cabinet or room, or cover the cup with aluminum foil. Air spaces causes the leaf disks to float. Tip: If the disks do not sink, use fresh disks and a solution with a higher concentration of baking soda and a bit more detergent. Make a solution of sodium bicarbonate by mixing 300 mL of water to 3g of baking soda. This is easily graphed, with time on the x-axis and number of floaters on the y-axis.
Why was this necessary in Bozeman's situation? Repeat steps 5-7 with another set of 10 disks. After several minutes, the disks should begin floating to the top of the solution. It is also used to increase the density of the leaf disk. Without light energy, no photosynthesis will occur, so no more O 2 gas will be produced. Photosynthesis occurs in plants, algae, and many species of bacteria. Turn on the light, start a timer, and watch the leaf disks at the bottom of the cup. Add more solution to a depth of about 3 cm.