Factors of Photosynthesis Process by 4 Scientific Tests

Photosynthesis is the process of turning light energy obtained from sun to Glucose – Foods – and Oxygen gas. Our previous post was all about photosynthesis process and how it began millions of years ago. So I assume you already know the factors of photosynthesis even before reading this post.

This process is a chemical reaction and every chemical reaction has 2 sides left and right. Left side contains the reactants while right side contains the products. Reactants are the substances used in a chemical reaction or in other words these are the inputs of the process.

Products are the outputted substances of chemical reaction.

Probably you realize the factors of photosynthesis is also reactants or inputted substances of photosynthesis chemical reaction. In case you forgot these factors of photosynthesis, I’d list them again below.

1. Sunlight
2. Water
3. Chlorophyll
4. Carbon Dioxide

Experiments to Test Factors of Photosynthesis

If you’re a school science student, then almost all the time your exam will ask you to write how to test for the photosynthesis factors. Actually, this isn’t a big deal and you’re going to learn #4 simple methods to test and prove the requirement of above 4 factors.

You can reach your home in multiple roads. 🙂 Right? Just like that there may be different ways to test these.

Sunlight Necessity Test For Photosynthesis

As it is oxygen for animals, sunlight is for plants. Sunlight or the light energy released by sun is one of the factors of photosynthesis and now you’re going to test its accuracy with below scientific test.

For this test, you need a plant rooted in a pot, bucket or something portable. Since many people don’t have big gardens or backyards, I assume you already got a potted plant in your home. Remember, this potted plant should be a Green Plant because other color plants usually don’t have chlorophyll which is another factor.

Here we need to choose the portable plant, because we need to keep this plant out of sunlight. If we choose a plant rooted in the ground directly, then it makes your test annoying in many ways. Okay, once you chose the plant take it to some other place. This place should be darker with no sunlight exposure. Your store room may be a good place, if it’s darker.

Keep the plant out of sunlight for 2 days, because we want to clear all the current energy stored in the plant.

After keeping it in the dark room for 2 days, take it out and cover 1 leaf part with a Black paper to cover the sunlight from touching that covered part of the leaf. Now allow the plant to get some sunlight for a few hours and then take it again to finish the final step of the test.

Take some iodine and put it on the leaf after removing the black paper to test the leaf for starch. You’d notice that the covered part doesn’t turned to blue color while the uncovered part has turned to blue. This means the covered part doesn’t contain food, because sunlight couldn’t touch that part. The uncovered part contains food due to sunlight exposure of the last few hours.

This experiment proves that Sunlight or Light Energy is one of the factors of photosynthesis process.

Carbon Dioxide Necessity Test For Photosynthesis

Carbon Dioxide or CO₂ is one of the factors and with this experiment you’re going to prove its necessity for photosynthesis.

Potassium Hydroxide is an inorganic solid compound which absorbs Carbon Dioxide gas. This means Potassium Hydroxide is something that can help us to do our experiment. Again, take that same potted plant and keep it in dark room for 2 days to clear its already stored starch.

Once the plant is ready, take 2 polythene bags and cover 1 branch or set of leaves of the plant tightly. Cover another set of leaves while placing few Potassium Hydroxide pellets in to the polythene bag.

Allow the plant expose to sunlight for few hours and test the leaves for starch in both bags. You can use the same method of using Iodine to test for starch.

As expected you won’t see blue color in the leaves that were in the bag with Potassium Hydroxide. Other bag leaves will turn to blue color, because starch is available on them.

This proves the Carbon Dioxide is one of the factors of photosynthesis again.

Chlorophyll Necessity Test For Photosynthesis

For this experiment you don’t need purely a green plant, because we’re testing for the chlorophyll necessity this time.

Select a multicolor plant that contains few green color parts with other colors. You can use plants such as Colacasia, Choleas or Hibiscus. It is good to keep this plant in dark as earlier.

Now choose few leaves or just one leaf that has green color as well as other colors. Keep it on sunlight and draw the leaf in a notebook to find out which parts have the starch. Make sure you mark all the green color and other color parts exactly the same as it appears in the actual leaf.

After that it’s time to do starch availability test. Before adding Iodine to the leaf, you have to clear the chlorophyll from the leaf by dipping it in a Alcohol heat bath.

Then compare the diagram you have drawn with the actual leaf. The result will be that the green color parts – Chlorophyll appearing parts – contain starch while the other color parts don’t have the starch.

Finally, Chlorophyll also a required factor for photosynthesis reaction.

Water Necessity Test For Photosynthesis

Water is similar to life blood of living beings, lack of water many times mean the death or dehydration. This is same for plants since they also belong to living beings on earth.

If you want to show water as a factor of photosynthesis by doing a test like above, then you need to remove water from the chosen plant leaves.

However, once you remove all the water from a plant, it’ll dry off and die quickly. This means you cannot design a test to experiment the necessity of water for photosynthesis.

As the plants die without water, we have to conclude that photosynthesis too stops without water which means water is also an essential factor of photosynthesis.

If you have a far better method to test each of the factors, We’d like to hear it in the comments section.