biology photosynthesis and cellular respiration worksheet answers

NGSS Life Science

Photosynthesis worksheets.

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Photosynthesis Concepts

• Light Dependent Reactions - photosystem 2, photosystem 1, electron transport chain, NADP+.
• Light Independent Reactions - Calvin cycle , NADPH.
• Chloroplasts - thylakoid, granum, stroma, mesophyll, guard cells.
• Pigments - chlorophyll a, chlorophyll b.
• Electron Acceptors - O 2 , NADPH.
• Photorespiration - oxidative photosynthetic carbon cycle, C 2 photosynthesis.
• C 4 Pathway - C 4 carbon fixation.
• CAM Plants - crassulacean acid metabolism.

Lessons Organized by NGSS Standard

• LS1 From Molecules to Organisms
• LS2 Ecosystems
• LS3 Heredity
• LS4 Biological Evolution

Photosynthesis

Photosynthesis is the process by which green plants , algae , and some bacteria convert light energy , carbon dioxide , and water into glucose and oxygen . This process takes place in the chloroplasts of plant cells and involves two main stages: the light -dependent reactions and the light -independent reactions (Calvin cycle).

Light -Dependent Reactions:

• Light energy is absorbed by chlorophyll and other pigments in the thylakoid membranes of the chloroplasts .
• This energy is used to split water molecules into oxygen , protons , and electrons . The oxygen is released as a byproduct.
• The electrons are transferred through a series of proteins , creating a flow of hydrogen ions across the thylakoid membrane.
• This flow of hydrogen ions drives the production of ATP and NADPH , which are used to power the light -independent reactions.

Light -Independent Reactions (Calvin Cycle):

• The ATP and NADPH produced in the light -dependent reactions are used to convert carbon dioxide into glucose in a series of enzyme-catalyzed reactions.
• This process also regenerates the molecule that captures carbon dioxide , allowing the cycle to continue.

Respiration

Cellular respiration is the process by which cells break down glucose and other organic molecules to produce ATP , the primary energy currency of cells . This process occurs in the mitochondria of eukaryotic cells and involves three main stages: glycolysis, the citric acid cycle, and oxidative phosphorylation.

Glycolysis:

• Glucose is broken down into two molecules of pyruvate in the cytoplasm of the cell , producing a small amount of ATP and NADH.

Citric Acid Cycle:

• Pyruvate is transported into the mitochondria and converted into acetyl CoA, which enters the citric acid cycle.
• During the citric acid cycle, acetyl CoA is further broken down, releasing more ATP , NADH, and FADH 2 .

Oxidative Phosphorylation:

• The high- energy electrons carried by NADH and FADH 2 are used to generate a large amount of ATP through a series of protein complexes in the inner mitochondrial membrane.
• Oxygen acts as the final electron acceptor, forming water as a byproduct.

Study Guide

When studying photosynthesis and respiration , it's important to understand the key concepts, processes, and the interrelationship between the two. Here are some key points to focus on:

• Understand the overall chemical equations for photosynthesis and respiration , including the reactants and products involved.
• Learn the specific reactions and enzymes involved in each stage of photosynthesis and respiration , and the locations within the cell where these processes occur.
• Be able to explain the role of ATP , NADPH , NADH, and FADH 2 in energy production and transfer during these processes.
• Understand the relationship between the light -dependent and light -independent reactions in photosynthesis , as well as the interconnected nature of glycolysis, the citric acid cycle, and oxidative phosphorylation in respiration .
• Be able to compare and contrast the inputs, outputs, and overall purposes of photosynthesis and respiration in maintaining the energy balance of living organisms .

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Home > Science Worksheets > Photosynthesis

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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What is It?

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

What is It? Questions

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

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.

QUESTIONS: Photosynthesis and Cellular Respiration

Which process requires carbon dioxide and gives off oxygen?

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.

QUESTIONS: Carbon

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

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

QUESTIONS: Artificial Photosynthesis

Why is producing hydrogen fuel currently hard on the environment?

Photosynthetic Organisms

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

QUESTIONS: Photosynthetic Organisms

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

Anoxygenic Photosynthesis

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

QUESTIONS: Anoxygenic Photosynthesis

How is green nonsulfur bacteria different from green sulfur bacteria?

Chloroplasts

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

QUESTIONS: Chloroplasts

Where exactly within the chloroplast is chlorophyll located?

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).

QUESTIONS: Light and Dark Reactions

What other methods are there for an organism to use CO 2 to make sugars?

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.

QUESTIONS: Artificial Light

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

Water and Heat

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

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.

• Light is absorbed by chlorophyll, a ferment contained in leaves.
• Light energy is converted into chemical energy: light energy is used to split a water molecule. The reaction releases chemical energy.
• Oxygen is released into the atmosphere as a byproduct of the reaction.
• Carbon dioxide enters through pores called stomata and is moved into a stroma.
• 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.

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2.8: Cellular Respiration and Photosynthesis

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How do trees help you breathe?

Recall that trees release oxygen as a byproduct of photosynthesis. And you need oxygen to breathe. Do you know why? So your cells can perform cellular respiration and make ATP.

Connecting Cellular Respiration and Photosynthesis

Photosynthesis and cellular respiration are connected through an important relationship. This relationship enables life to survive as we know it. The products of one process are the reactants of the other. Notice that the equation for cellular respiration is the direct opposite of photosynthesis :

• Cellular Respiration: C 6 H 12 O 6 + 6O 2 → 6CO 2 + 6H 2 O
• Photosynthesis: 6CO 2 + 6H 2 O → C 6 H 12 O 6 + 6O 2

Photosynthesis makes the glucose that is used in cellular respiration to make ATP. The glucose is then turned back into carbon dioxide, which is used in photosynthesis. While water is broken down to form oxygen during photosynthesis, in cellular respiration oxygen is combined with hydrogen to form water. While photosynthesis requires carbon dioxide and releases oxygen, cellular respiration requires oxygen and releases carbon dioxide. It is the released oxygen that is used by us and most other organisms for cellular respiration. We breathe in that oxygen, which is carried through our blood to all our cells . In our cells, oxygen allows cellular respiration to proceed. Cellular respiration works best in the presence of oxygen. Without oxygen, much less ATP would be produced.

Cellular respiration and photosynthesis are important parts of the carbon cycle. The carbon cycle is the pathways through which carbon is recycled in the biosphere. While cellular respiration releases carbon dioxide into the environment, photosynthesis pulls carbon dioxide out of the atmosphere. The exchange of carbon dioxide and oxygen during photosynthesis (Figure below) and cellular respiration worldwide helps to keep atmospheric oxygen and carbon dioxide at stable levels.

• The equation for cellular respiration is the direct opposite of photosynthesis.
• The exchange of carbon dioxide and oxygen thorough photosynthesis or cellular respiration worldwide helps to keep atmospheric oxygen and carbon dioxide at stable levels.

Explore More

Use the resource below to answer the questions that follow.

• Photosynthesis and Respiration at http://www.youtube.com/watch?v=JEnjph9miK4 (3:46)

• What is needed for photosynthesis to occur? Be specific.
• What is needed for cellular respiration to occur?
• What is ATP?
• Do autotrophs need to carry out cellular respiration? Why or why not?
• How are the equations for photosynthesis and cellular respiration related?
• What keeps atmospheric oxygen and carbon dioxide at stable levels?

Photosynthesis and Respiration Model

Essential Question: What is the relationship between photosynthesis and respiration?

Scientific modeling is an activity that aims to make the world easier to understand. There are many types of models, some are mathematical, and some are graphical models that help us visualize the subject. The graphic below is a model that attempts to show the interdependence of two cellular processes: respiration and photosynthesis.

Your goal is to examine the model, focus on the key details to answer the essential question.

I. Examine Details

1. In what cell organelle does photosynthesis occur? cellular respiration?

2. What are the three things needed for photosynthesis? Highlight them on the diagram in green.

3. What are the two products of photosynthesis? Highlight yellow.

4. What are the two things needed for cellular respiration? Highlight blue.

5. What are the three products of cellular respiration? Highlight purple.

6. What things are recycled (used over and over again) during photosynthesis and respiration?

II. Apply (what you already know)

7. Sketch a model of typical plant cell and identify the mitochondria and chloroplasts.

8. What will happen to plants that are kept in the dark?

9. What will happen if you forget to water your plants?

10. What happens to animals that are deprived of oxygen?

III. Big Ideas

11. One hypothesis regarding the extinction of dinosaurs is that a meteor hit the earth causing an explosion so powerful that dust blocked out the sun. Consider the model above and explain why this would have caused a mass extinction.

12. When you walk your dog, you are using energy from the sunlight to power this activity. Explain.

13. Carefully and completely answer the "essential question" of this activity. Use complete sentences and details from the model to explain your position.

Essential Question: What is the relationship between photosynthesis and respiration?  

Other Resources on Photosynthesis

How Does Photosynthesis Work  – simple graphic for labeling, showing overall plant and a detailed image of the chloroplast with light reactions

Leaf Coloring  – color structures; xylem, phloem, bundle sheath, epidermis, and more.

How Do Chloroplasts Capture Energy  – coloring and reading worksheet focus on equation for photosynthesis and production of ATP

Reinforcement: Photosynthesis  – practice vocabulary with a list of terms and definitions

Chemiosmosis and ATP Synthesis in Chloroplasts  – advanced coloring activity detailing the events of photophosphorylation

Photosynthesis and cellular respiration

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cellular respiration and photosynthesis

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