If humans could undergo the process of photosynthesis, lunch time would be much different. We would just sunbathe.

Approximately 85% of the world's oxygen is due to this process. That is why if the sun were to suddenly stop producing light, not only would it be dark; we would not be able to breathe much longer. These worksheets explore all aspects of the process of photosynthesis. This collective series of worksheets helps students investigate this process and examine where it happens. We move on to understand the chemistry that takes place in this process and how we have used that knowledge to mimic the process and create our own energy artificially. We also spend a good amount of time understanding the organisms that can perform this much needed activity.

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Printable Photosynthesis Worksheets

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What is Photosynthesis Worksheet

What is It?

Plant respiration is the opposite of ours, since we breathe out carbon dioxide and plants breathe out oxygen.

What is Photosynthesis Question Worksheet

What is It? Questions

Different kinds of plants need differing amounts of sunlight and water to thrive.

Photosynthesis and Cellular Respiration Worksheet

Photosynthesis and Cellular Respiration

Together, photosynthesis and cellular respirations are the basis of all life on Earth. The oxygen that is released by plants during photosynthesis is used by humans and almost all other organisms for our cellular respiration.

Photosynthesis and Cellular Respiration Question Worksheet

QUESTIONS: Photosynthesis and Cellular Respiration

Which process requires carbon dioxide and gives off oxygen?

Carbon Worksheet


Activities like eating and excretion are also part of the carbon cycle, as carbon is being taken into and passed back out of living organisms.

Carbon Question Worksheet


When we burn these substances, the energy that plants once captured from the sun through photosynthesis is released back out into the atmosphere.

Artificial Photosynthesis Worksheet

Artificial Photosynthesis

This technology, which is called direct solar water splitting, could also be adjusted in order to turn carbon dioxide back into fuel.

Artificial Photosynthesis Question Worksheet

QUESTIONS: Artificial Photosynthesis

Why is producing hydrogen fuel currently hard on the environment?

Photosynthetic Organisms Worksheet

Photosynthetic Organisms

Prokaryotic organisms are single-celled organisms that do not contain a nucleus.

Photosynthetic Organisms Question Worksheet

QUESTIONS: Photosynthetic Organisms

Plants, algae, and cyanobacteria all use the Calvin cycle to fix carbon dioxide.

Anoxygenic Photosynthesis Worksheet

Anoxygenic Photosynthesis

In this process while sunlight is still used to fix carbon, during the reaction something other than water donates an electron.

Anoxygenic Photosynthesis Question Worksheet

QUESTIONS: Anoxygenic Photosynthesis

How is green nonsulfur bacteria different from green sulfur bacteria?

Chloroplasts Worksheet


Only plants and photosynthetic organisms contain chloroplasts. Simple cells, like those of photosynthetic algae, may only contain several chloroplasts.

Chloroplasts Question Worksheet

QUESTIONS: Chloroplasts

Where exactly within the chloroplast is chlorophyll located?

Light and Dark Reactions Worksheet

Light and Dark Reactions

In the first step, sunlight is captured by the chloroplasts when molecules of chlorophyll absorb energy (in the form of sunlight).

Light and Dark Reactions Question Worksheet

QUESTIONS: Light and Dark Reactions

What other methods are there for an organism to use CO2 to make sugars?

Artificial Light Worksheet

Artificial Light

There are some key differences between sunlight and artificial light. Though artificial lights can mimic the full spectrum of natural light, the energy emitted by an artificial light in the red and blue spectrums does not have as much energy as the red and blue spectrums of natural sunlight.

Artificial Light Question Worksheet

QUESTIONS: Artificial Light

What kind of light was warm, indoor lighting contain a lot of?

Water and Heat Worksheet

Water and Heat

One of the characteristics of global warming is an increase of carbon dioxide in the air.

Water and Heat Question Worksheet

QUESTIONS: Water and Heat

How can prolonged stress from drought affect a plant?

How Photosynthesis Works

Photosynthesis is the primary source of oxygen in the Earth's atmosphere. As almost all living forms on the planet need oxygen, life would soon cease to exist without photosynthesis. 

Photosynthesis works through a process where plants (as well as algae and cyanobacteria) generate energy from sunlight, water, and carbon dioxide. Oxygen is then released into the atmosphere as a byproduct of the reaction.

All living things on the planet need energy in order to survive. Humans take their food in through their mouths as they eat all types of different things. Plants on the other hand get their energy from the light given off by the sun. Three things need to be present for a plant to be able to undergo photosynthesis this includes: carbon dioxide, sunlight, and water. Plants take the carbon dioxide in through little holes in their leaves called stomata. The plant absorbs water from the soil using roots and gets that water to the rest of the body. As the sunlight passes through the leaves of the plants it travels through ton of chloroplasts found within the leaf. Within those chloroplasts the water molecules are split into hydrogen and oxygen. The oxygen leaves the leaf and the remaining hydrogen and carbon dioxide are used to form glucose which is a usable form of energy for the plant.

The Mechanism of Photosynthesis

As mentioned, the three components essential for photosynthesis are sunlight, carbon dioxide, and water. Together, they transform light energy into chemical energy.

Plants convert solar energy into chemical energy that life forms can use. They also form the basis of the food chain, passing that energy to other species. The beauty of photosynthesis is that oxygen is released as a byproduct of the reaction, filling the atmosphere with the gas all living forms depend on. If you come to think about it, photosynthesis is probably the most important biological process of all.

However, it is important to note that while plants consume carbon dioxide and release oxygen during photosynthesis, they also have respiratory processes during which they do the opposite. About half the amount of carbon dioxide plants consume is released by them as a result of cellular respiration.

Light-Dependent Reactions

Light-dependent reactions happen during the day, as they require a constant supply of light.

Sunlight is absorbed by chlorophyll that is contained in chloroplasts. Chloroplasts are organelles contained in the leaves, and chlorophyll is a ferment that absorbs the energy from red and blue light waves. Chlorophyll also makes plants appear green, as it reflects green light.

Then, the light energy is converted into chemical energy. To perform this stage, plants need water. The light energy is used to start a reaction and split the water molecule, which allows releasing chemical energy in the form of Adenosine Triphosphate (ATP) and Nicotinamide Adenine Dinucleotide Phosphate (NADPH) molecules. While H (hydrogen) later becomes a part of a glucose molecule, O2 (oxygen) is released into the atmosphere as a byproduct.

Light-Independent Reactions

Light independent reactions do not require light streams and thus happen during the night. This stage is also known as the Calvin Cycle.

Carbon dioxide enters the pores called stomata which are usually located at the bottom of a leaf. Then, carbon dioxide molecules are diffused into the stroma, the protein-containing matrix between the thylakoid membranes and the chloroplast membranes.

Stroma is where the rest of the process happens. The chemical energy released during the previous stage in the forms of ATP and NADPH is used to extract carbon from carbon dioxide and later form a glucose molecule. It requires six molecules of carbon dioxide, and therefore six turns of the cycle, to create one molecule of glucose.

A Short Summary of Photosynthesis

Here's a brief overview of the steps involved in photosynthesis to help you quickly grasp how the process works.

  1. Light is absorbed by chlorophyll, a ferment contained in leaves.
  2. Light energy is converted into chemical energy: light energy is used to split a water molecule. The reaction releases chemical energy.
  3. Oxygen is released into the atmosphere as a byproduct of the reaction.
  4. Carbon dioxide enters through pores called stomata and is moved into a stroma.
  5. In the stroma, previously released chemical energy is used to extract carbon from carbon dioxide. Carbon is then used to form a glucose molecule (sugar).


While oxygen is produced as a result of photosynthesis, the primary function of the process for plants is producing energy in the form of sugars. Oxygen is only a byproduct that gets released into the atmosphere. Still, photosynthesis is not only the basic source of energy for all living creatures but also the primary source of oxygen in our atmosphere.