8.1 Energy and Life Lesson Objectives Describe the role of ATP in cellular activities. Explain where plants get the energy they need to produce food. BUILD Vocabulary A. The chart below shows key terms from the lesson with their definitions. Complete the chart by writing a strategy to help you remember the meaning of each term. One has been done for you. Term Definition How I m Going to Remember the Meaning Adenosine triphosphate (ATP) Autotroph Heterotroph Compound that cells use to store and release energy A living thing that makes its own food A living thing that gets its food by consuming other living things ATP makes a cell able to do work. Photosynthesis Process by which autotrophs use sunlight, water, and carbon dioxide to produce carbohydrates and oxygen B. As you work through this lesson, you may find these terms in the activities. When you need to write a key term or a definition, highlight the term or the definition. BUILD Connections ATP as a Charged Battery An analogy takes two things that seem to be different and shows how they can be similar. 1. How is a partially charged battery like ADP? 2. Why do cells contain only a small amount of ATP? A. ATP cannot store large amounts of energy for a long time. B. ATP releases energy too quickly. C. ATP cannot carry out active transport. D. ATP has only two phosphate groups. 110
BUILD Understanding Compare/Contrast Table Use a compare/contrast table when you want to see the similarities and differences between two or more objects or processes. As you read, place an X in the box next to characteristics that are true of an autotroph or a heterotroph. One has been done for you. Autotroph Heterotroph Directly uses sunlight for energy X An oak tree is an example. A mushroom is an example. Makes its own food Consumes other living things to get energy Is capable of photosynthesis Chemical Energy and ATP Chemical Energy Living things use chemical fuels. One of the most important compounds that cells use to store and release energy is ATP. Follow the directions. Then answer the questions. 1. Trace the outlines of the adenosine molecule and the three phosphate groups. 2. Cut out each phosphate group. 3. Arrange the phosphate groups on the adenosine molecule to form a molecule of ATP. 4. When ATP is changed to ADP, it releases energy. Change your ATP molecule so that it forms ADP. What change did you make? 5. ADP can be converted into ATP. Change your ADP molecule into ATP. What change did you make? 6. Fill in the blanks with two or three. The primary difference in the structures of ATP and ADP is that ATP has phosphate groups and ADP has phosphate groups. 111
Heterotrophs and Autotrophs Look at the feeding relationships in each food chain. Each food chain contains an autotroph and one or more heterotrophs. Follow the directions. 1. Color the autotrophs green. 2. Color the heterotrophs blue. grass worm robin coyote grass mouse hawk grass rabbit cougar tree/shrub deer cougar Answer the questions. 3. Which animal would be most affected if many trees died from disease? A. deer B. mouse C. worm D. None would be affected. 4. The organisms listed in the box belong to a food chain. Use the words in the box to fill in the food chain in the correct order. bear insect salmon grass 5. Explain how top-level consumers such as hawks depend on sunlight for their food. 112
8.2 Photosynthesis: An Overview Lesson Objectives Describe the role of light and pigments in photosynthesis. Explain the role of electron carrier molecules in photosynthesis. State the overall equation for photosynthesis. BUILD Vocabulary A. The chart below shows key terms from the lesson with their definitions. Complete the chart by writing a strategy to help you remember the meaning of each term. One has been done for you. Term Definition How I m Going to Remember the Meaning Chlorophyll Primary pigment in plants Chlorophyll gives plants their green color. Lightdependent reactions Lightindependent reactions NADP + Pigment Reactions in photosynthesis that require light and lightabsorbing pigments Reactions in photosynthesis in which carbon dioxide and energy-carrying molecules are used to produce high-energy sugars Carrier molecule that transports high-energy electrons Light-absorbing molecule Stroma Thylakoid Fluid portion of the chloroplast that surrounds the thylakoid membrane Photosynthetic membrane sac found inside chloroplasts B. As you work through this lesson, you may find these terms in the activities. When you need to write a key term or a definition, highlight the term or the definition. 113
BUILD Understanding KWL Chart A KWL chart will help you to get the most out of your reading. In the first column, write what you already Know about photosynthesis and the needs of plants. One fact has been added to the chart for you. In the second column, write what you Want to find out. In the last column, write what you ve Learned after reading the lesson. Fill in the chart as you read Lesson 2. K (What I know) W (What I want to know) L (What I learned) Plants make food by using water, carbon dioxide, and energy from the sun. CHAPTER MYSTERY Out of Thin Air? In concluding that the extra mass of his tree came from water, van Helmont had only half the answer. In the space below, draw yourself using the photosynthesis equation to explain to van Helmont why he needs to consider carbon dioxide. 114
Chlorophyll and Chloroplasts In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll. Inside chloroplasts are thylakoids. The region outside the thylakoid is the stroma. A model of a chloroplast is shown below. Follow the directions. 1. Color the stroma blue. Label it. 2. Color each thylakoid green. Label one. 3. Circle the granum in red. Label it. Chloroplast Answer the questions. 4. Where do the light-dependent reactions occur? Circle the correct answer. thylakoids stroma 5. Where do the light-independent reactions occur? Circle the correct answer. thylakoids stroma 6. Is the following statement true or false? In plants, photosynthesis takes place in the chloroplasts. 7. The function of chlorophyll is A. to protect a plant from losing water. B. to help plants absorb oxygen. C. to protect the plant cell. D. to capture energy from the sun. 115
Chlorophyll and Chloroplasts Photosynthesis in plants takes place in organelles called chloroplasts. Within each chloroplast is a fluid-filled area called the stroma. Also inside each chloroplast are many saclike membranes called thylakoids. Thylakoids are connected to each other in stacks. Each stack is a granum. Complete the Venn diagram to compare the stroma and a granum in a chloroplast. Use the phrases below. One has been done for you. contains pigments fluid portion of chloroplast are a part of photosynthesis light-dependent reactions located within a chloroplast stacks of thylakoids Answer the questions. Circle the correct answer(s). 1. Which reactions change the energy of sunlight to energy-rich carriers? light-dependent reactions light-independent reactions 2. Which two reactants are needed for light-dependent reactions? carbon dioxide light oxygen water 3. Which two reactants are needed for light-independent reactions? carbon dioxide energy-rich compounds oxygen stroma 116