Fresh Green Leaf With Water DropletsProfessional scientists, children learning the fundamentals of science, and every level in between use experiments to learn more about a particular subject matter. In introductory biology courses, such as this one offered on Udemy, photosynthesis not only makes up an important part of the lesson material but is also ideal subject matter for an easy experiment. Photosynthesis experiments can be done with minimal supplies, so even children can enjoy and learn.

What is Photosynthesis?

Photosynthesis is the process by which plants, algae, some bacteria, and other organisms convert light energy and carbon dioxide into oxygen and glucose. It is an essential part of the life cycle, and the reason that plants are at the bottom of the food chain. Photosynthesis is an important part of any biology test, and you can get help preparing for your exams with Udemy’s GCSE Biology course.

Each species undergoes photosynthesis slightly differently, but the basic process is the same. Typically, the plants take energy from the sun to convert the carbon dioxide molecules (carbon and two oxygen atoms) into glucose molecules, which are made up of carbon, hydrogen and oxygen. Oxygen gas is given off as waste during the process, and water is often used in the process as well.

The Stages of Photosynthesis

There are two stages in photosynthesis. The first is the light reaction, which creates the energy for the second stage, which is known as the Calvin cycle. During the light reaction, the energy from light is converted to the chemical energy needed for the secondary process of photosynthesis. A molecule in the chlorophyll absorbs a photon from the light and loses an electron, which is passed on into the electron transport chain that ultimately reduces NADP to NADPH, which is necessary for the Calvin cycle and creates ATP, an energy also required for the Calvin cycle.

The plants absorb the energy of light by proteins, held inside organelles known as chloroplast, with green chlorophyll pigments. The chloroplast is most abundant in the cells of the plant leaves. Some bacteria go through photosynthesis as well, and these proteins are present in their plasma membrane. The carbon dioxide for the process is likewise brought in from the atmosphere.

The Floating Leaf Experiment

One of the most popular photosynthesis experiments is the floating leaf experiment. Teachers often use this experiment, and then have their students write a biology essay about their findings. You can get help with your essay writing with Udemy’s A+ Research Paper in Biology course.

How this experiment works is that you take a leaf disk, which naturally floats. However, once the air spaces in the leaf becomes infiltrated with a bicarbonate solution, the density of the leaf increases, causing it to sink. A bicarbonate ion is one of the carbon sources for photosynthesis. As photosynthesis begins, oxygen is released into the interior of the leaf. This alters the buoyancy again, making the leaf disks float again. Cellular respiration occurs at the same time, which causes it to consume oxygen. This makes the rate of the disk rise an indirect measurement of the net rate of photosynthesis.

Materials for the Experiment

For this experiment, you need sodium bicarbonate, which is better known as baking soda, and some leaves. You also need liquid soap and a plastic syringe of at least 10 ccs, with any needle removed. Finally, you need a hole punch, plastic cups, a timer, and a light source. You can also use leaves of different ages to further the experiment.

The first thing you need to do is to create the bicarbonate solution, which needs to just be about 0.2 percent solution. This is the equivalent of about 1/8 of a teaspoon of baking soda in 300 milliliters of water. You want to add a drop of diluted liquid soap to the solution as well, as this will wet the hydrophobic surface of the leaf so that the solution will be drawn to the leaf. You do not want a sudsy soap; if you find you get suds, add more baking soda. Use the hole puncher to cut out 10 or more disks from the leaves. You want to use a leaf with a surface that is not too thick and is fairly smooth, without much hair. Ivy is one of the best leaves for this experiment, and spinach works well also.

Performing the Experiment

Put the leaf disks in into the barrel of the syringe, with only a small volume of air, less than 10 percent. Add a small amount of the bicarbonate solution to the leaf disks in the syringe to infiltrate the leaves with the solution. Create a vacuum and swirl the disks, then decrease the vacuum until the disks sink. You might have to try a few times. Then, put the disks and the solution into a clear cup, adding more bicarbonate solution. You should have a similar depth of solution in each trial, around 3 centimeters. You can create control solutions by infiltrating the disks with different solutions, such as only water or water and soap with no bicarbonate.

Place the leaf disks under the light source. Use your timer, and at each minute, record how many leaves are floating. Wait until all of them are floating and record how long it takes. You can compare results and discover the net photosynthesis time.

Create your Photosynthesis Experiment Today

There are other photosynthesis experiments you can do, such as covering up one of the leaves of a live plant using black construction paper. Leave it on for a few days, and then compare it to the rest of the leaves. You will notice how the leaf that lived without the sun will be less vibrant than those exposed to light, which demonstrates the necessity of sunlight in photosynthesis. These are just a few of the many easy and fun biology experiments you can do to understand the fundamentals of biology.

Understanding photosynthesis can do more than get you a good grade on your exam. It can also make you a better gardener, as you will understand what plants need and how to adjust certain elements to make them thrive. You can also learn more about gardening through taking an online gardening course such as that offered by Udemy.

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