Photosynthesis and Respiration

Science, Grade 6

Photosynthesis and Respiration

Multimedia Lesson

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Table Of Contents: Photosynthesis and Respiration

1. Cell Energy

2.1. The Sun Is the Main Source of Energy
Every cell in an organism needs energy to survive. The sun is the source of energy for most living organisms, either directly or indirectly.
2.2. How Do Organisms Obtain Energy?
Plants use the sun's energy to make their food. Other organisms eat plants to obtain energy. We obtain energy through the food we eat.
2.3. Autotrophs and Heterotrophs
Plants and some bacteria are called autotrophs because they make their own food. Other organisms are called heterotrophs because they do not make their own food.

2. Overview of Photosynthesis

3.1. What Is Photosynthesis?
Photosynthesis is the process that green plants use to capture energy from the sun and convert it to food. Some bacteria and protists also use photosynthesis.
3.2. Plants Need Water and Carbon Dioxide
In addition to the sun's energy, plants also need water and carbon dioxide to carry out the process of photosynthesis.
3.3. Plants Produce Oxygen and Food
Plants produce oxygen and food in the form of sugar during the process of photosynthesis.

3. Leaf Structure and Photosynthesis

4.1. Where Does Photosynthesis Occur?
Photosynthesis primarily occurs in the plant leaves.
4.2. Chloroplasts
The entire process takes place in an organelle called the chloroplast. Inside each chloroplast there are green pigment molecules called chlorophyll.
4.3. Chlorophyll
Chlorophyll absorbs light energy from the sun. This pigment gives plants their green color.
4.4. Water Movement to the Leaves
The water needed for photosynthesis travels to the leaves through the plant's vascular system. Leaf veins deliver the water to the chloroplasts.
4.5. Leaf Stomata and Carbon Dioxide
Carbon dioxide needed for photosynthesis enters the leaf through tiny pores called stomata (singular stoma) found on the underside of the leaf.
4.6. Guard Cells Respond to the Environment
Each stoma is made up of a pair of cells called guard cells. These cells change size in response to the environment, causing the pore to open or close.
4.7. Pore Is Open in Daylight
The pore is usually open during the daylight, when photosynthesis occurs.

4. Process of Photosynthesis

5.1. Chemical Equation for Photosynthesis
Photosynthesis can be summarized in a simple chemical equation. Carbon dioxide and water are converted to glucose and oxygen, with the use of the sun's energy.
5.2. Stage One of Photosynthesis
Photosynthesis occurs in two stages. The first stage occurs when light is captured by the chlorophyll pigments in the leaves and converted to energy in the chloroplast.
5.3. Water and Oxygen in Stage One
Water molecules are split and oxygen is formed in stage one.
5.4. Stage Two of Photosynthesis
In stage two the energy is used to change carbon dioxide and water into glucose. This requires a complex series of chemical reactions.
5.5. How Does the Plant Use Glucose?
The glucose sugar that is produced is used as plant food, converted to more complex compounds like cellulose, or stored for future use.
5.6. Oxygen Produced and Released
The oxygen that is produced exits the plant cells through the leaf stomata.

5. Pause and Interact

6.1. Review
Use the whiteboard tools to complete the activity.
6.2. Chemical Equation for Photosynthesis
Click on the Terms button. Then click and drag each term to the correct box. Use the reset button to clear the terms and start over. Use the gear button to customize the draggable terms.
6.3. Photosynthesis
Click on the Terms button. Then click and drag each term to the correct box. Use the reset button to clear the terms and start over. Use the gear button to customize the draggable terms.

6. Overview of Cellular Respiration

7.1. What Is Cellular Respiration?
Cellular respiration is a process by which cells break down glucose to release stored energy.
7.2. Who Uses Cellular Respiration?
Both autotrophs and heterotrophs use cellular respiration to obtain energy from stored sugar molecules.
7.3. Cellular Respiration Equation
Cellular respiration can be summarized in a simple chemical equation. Glucose and oxygen are broken down to carbon dioxide and water, and energy is produced.

7. Process of Cellular Respiration

8.1. Two Stages of Cellular Respiration
Cellular respiration occurs in two stages. Stage one occurs in the cell's cytoplasm and stage two occurs in the mitochondria.
8.2. Stage One of Cellular Respiration
During stage one, glucose is broken down into smaller molecules and a small amount of energy is released.
8.3. Stage Two of Cellular Respiration
In stage two the smaller molecules combine with oxygen to produce water, carbon dioxide, and a large amount of energy.
8.4. Energy and Cellular Respiration
The energy produced is in the form of ATP and heat.
8.5. What is ATP?
ATP is a molecule that fuels cellular activities. The heat energy helps an organism maintain a healthy body temperature.
8.6. Products of Cellular Respiration
The carbon dioxide and water that is produced during respiration leaves our bodies through exhalation.

8. Pause and Interact

9.1. Review
Use the whiteboard tools to complete the activity.
9.2. Chemical Equation for Cellular Respiration
Click on the Terms button. Then click and drag each term to the correct box. Use the reset button to clear the terms and start over. Use the gear button to customize the draggable terms.
9.3. Cellular Respiration
Click on the Terms button. Then click and drag each term to the correct box. Use the reset button to clear the terms and start over. Use the gear button to customize the draggable terms.

9. Connection between Photosynthesis and Respiration

10.1. Opposite Processes
Photosynthesis and cellular respiration are opposite processes.
10.2. Comparing Equations
The products from one process are used as the raw materials for the other process. Energy is required for photosynthesis, but energy is released during cellular respiration.
10.3. Cycle of Oxygen and Carbon Dioxide
Together, these two processes form a cycle that helps maintain constant levels of oxygen and carbon dioxide in the Earth's atmosphere.

10. Fermentation

11.1. What Is Fermentation?
Fermentation is a cellular process that breaks down sugar molecules and produces energy, without the use of oxygen.
11.2. Alcoholic Fermentation
Alcoholic fermentation occurs when single-celled organisms, such as yeast, break down sugar into carbon dioxide and energy.
11.3. What Does Yeast Do in Bread Dough?
When yeast is added to bread dough, carbon dioxide is released that causes the bread to rise.
11.4. Lactic Acid Fermentation
Lactic acid fermentation occurs in our muscles during heavy exercise, when oxygen levels have been depleted in our muscle cells.
11.5. Lactic Acid and Sore Muscles
Without oxygen, the cells use fermentation to obtain energy. Lactic acid is also produced and causes muscles to feel weak and sore.

11. Pause and Interact

12.1. Review
Use the whiteboard tools to complete the activity: Compare and contrast the processes of photosynthesis, cellular respiration, and fermentation.

12. Vocabulary Review

13.1. Vocabulary Matching Review
Photosynthesis and cellular respiration are opposite processes.

13. Virtual Investigation

14.1. The Effects of Carbon Dioxide and Light on Photosynthesis
In this virtual lab investigation you will determine how carbon dioxide concentration and light intensity affect the rate of photosynthesis in the aquatic plant, Elodea. You will measure the rate of photosynthesis by counting the number of oxygen bubbles that are released from the plant over a period of time.

14. Assessment

15.1. Photosynthesis