Chapter 8 Photosynthesis

Interest Grabber Saving for a Rainy Day Section 8-1 Saving for a Rainy Day Suppose you earned extra money by having a part-time job. At first, you might be tempted to spend all of the money, but then you decide to open a bank account. 1. What are the benefits of having a bank account? 2. What do you have to do if you need some of this money? 3. What might your body do when it has more energy than it needs to carry out its activities? 4. What does your body do when it needs energy?

Energy and Life Autotrophs Heterotrophs Plants and some other types of organisms are able to use light energy from the sun to produce food Heterotrophs organism that obtains energy from the foods it consumes; also called a consumer

Chemical Energy and ATP Living things use chemical fuels. ATP (adenosine triphosphate) is the main chemical compound used to store and release energy in cells The energy stored in ATP is released by breaking the third phosphate bond (ATP --> ADP) ENERGY RELEASED ADP can be “recharged” by adding a third phosphate to it (ADP --> ATP) ENERGY STORED Adenosine Ribose 3 Phosphate groups

Figure 8-3 Comparison of ADP and ATP to a Battery Section 8-1 ADP ATP Energy Energy Adenosine diphosphate (ADP) + Phosphate Adenosine triphosphate (ATP) Partially charged battery Fully charged battery

Figure 8-3 Comparison of ADP and ATP to a Battery Section 8-1 ADP ATP Energy Energy Adenosine diphosphate (ADP) + Phosphate Adenosine triphosphate (ATP) Partially charged battery Fully charged battery

Using Biochemical Energy What are some ways that ATP is used in a cell? Active transport (energy requiring) ion pumps Protein synthesis at ribosomes ATP can be used to produce light - fireflies Cells do not have large stores of ATP Long term storage of energy is in the form of glucose 1 molecule of glucose has 90 times the energy of one ATP

Interest Grabber Trapping Energy Section 8-2 Trapping Energy Have you ever used a solar-powered calculator? No matter where you go, as long as you have a light source, the calculator works. You never have to put batteries in it.

Interest Grabber continued Section 8-2 1. A solar-powered calculator uses solar cells that are found in rows along the top of the calculator. Into what kind of energy is the light energy converted so that the calculator works? 2. Recall that plants use light energy from the sun to make food. Into what kind of energy is the light energy converted by plants? 3. Most plants, no matter what size or shape they are, have some parts that are green. Which parts of a plant are usually green? 4. What does the green color have to do with the plant’s ability to convert light energy into the energy found in the food it makes?

Investigating Photosynthesis The experiments performed by van Helmont, Priestley, and Ingenhousz led to work by other scientists who finally discovered that in the presence of light, plants transform carbon dioxide and water into carbohydrates, and they also release oxygen.

Photosynthesis: Reactants and Products Section 8-2 Light Energy Chloroplast CO2 + H2O Sugars + O2

The Photosynthesis Equation Photosynthesis uses the energy of sunlight to convert water and carbon dioxide into high-energy sugars and oxygen.

Figure 8-5 Chlorophyll Light Absorption Section 8-2 Light and Pigment In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll, a molecule in chloroplasts. Plants gather the sun's energy with light-absorbing molecules called pigments. The plants' principal pigment is chlorophyll There are two main types of chlorophyll: chlorophyll a and chlorophyll b.

Interest Grabber A Look Into the Future Section 8-3 A Look Into the Future It is 100 years in the future and you are a research scientist. An enormous volcanic eruption has recently sent huge quantities of dust and ash into the atmosphere. Working with a partner, make a list of how this event will affect each of the following: 1. photosynthesis 2. plant life 3. animal life 4. human societies

The Reactions of Photosynthesis Photosynthesis takes place inside chloroplasts The chloroplasts contain saclike photosynthetic membranes called thylakoids. Thylakoids are arranged in stacks called grana Proteins in the thylakoid membrane organize chlorophyll and other pigments into photosystems. Photosystems are the light collecting unit of the chloroplasts

Concept Map Photosynthesis Light- dependent reactions Calvin cycle Section 8-3 Photosynthesis includes Light- dependent reactions Calvin cycle takes place in uses use take place in Thylakoid membranes Stroma NADPH ATP Energy from sunlight to produce of to produce ATP NADPH O2 Chloroplasts High-energy sugars

Factors Affecting Photosynthesis Water - shortage of water can slow or even stop photosynthesis Temperature - photosynthesis depends on enzymes that function best between 0°C and 35°C Light Intensity - increasing light intensity increases the rate of photosynthesis, however at a certain intensity plants hit a maximum rate

Figure 8-7 Photosynthesis: An Overview Section 8-3 Light O2 Sugars CO2 Chloroplast Chloroplast NADP+ ADP + P Light- Dependent Reactions Calvin Cycle ATP NADPH

Click a hyperlink to choose a video. ATP Formation Photosynthesis Videos Click a hyperlink to choose a video. ATP Formation Photosynthesis Light-Dependent Reactions, Part 1 Light-Dependent Reactions, Part 2 Calvin Cycle Video Contents

Click the image to play the video segment. ATP Formation Click the image to play the video segment. Video 1

Click the image to play the video segment. Photosynthesis Click the image to play the video segment. Video 2

Click the image to play the video segment. Light-Dependent Reactions, Part 1 Click the image to play the video segment. Video 3

Click the image to play the video segment. Light-Dependent Reactions, Part 2 Click the image to play the video segment. Video 4

Click the image to play the video segment. Calvin Cycle Click the image to play the video segment. Video 5

Go Online ATP activity Interactive test For links on Calvin cycle, go to www.SciLinks.org and enter the Web Code as follows: cbn-3082. For links on photosynthesis, go to www.SciLinks.org and enter the Web Code as follows: cbn-3083. Internet

Interest Grabber Answers 1. What are the benefits of having a bank account? To save money and earn interest. 2. What do you have to do if you need some of this money? Go to the bank and take out the money you need. 3. What might your body do when it has more energy than it needs to carry out its activities? Students will likely say that the body stores the energy. 4. What does your body do when it needs energy? Student answers may include that energy is gotten from food. Section 1 Answers

Interest Grabber Answers 1. A solar-powered calculator uses solar cells that are found in rows along the top of the calculator. Into what kind of energy is the light energy converted so that the calculator works? They convert light energy into electrical energy. 2. Recall that plants use light energy from the sun to make food. Into what kind of energy is the light energy converted by plants? Plants convert light energy into chemical energy. 3. Most plants, no matter what size or shape they are, have some parts that are green. Which parts of a plant are usually green? Leaves are green, as are some stems. 4. What does the green color have to do with the plant’s ability to convert light energy into the energy found in the food it makes? The green color is the pigment chlorophyll, which absorbs light energy from the sun and converts it to chemical energy in the process of photosynthesis. Section 2 Answers

Interest Grabber Answers Working with a partner, make a list of how this event will affect each of the following: 1. photosynthesis The rate of photosynthesis will decrease due to reduced sunlight. 2. plant life Plants will grow more slowly or die off due to decreased rate of photosynthesis. 3. animal life Animal populations will decrease after a while due to fewer plants for herbivores to eat. Fewer herbivores will eventually result in fewer carnivores. Also, less oxygen will be available. 4. human societies Human societies will have to adjust their eating habits as some food species die out. Section 3 Answers

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