l' A Hodel of the Process of Photosynthesis Plants are called producers because they use sunlight energy to make food by the process of photosynthesis. .1 :! Procedure :1.. Hake a photosynthesis model using colored paper clips by following these instructions: Separate the paper clips by color. The bag contains: • 6 large blue paper clips (carbon) o 12 large yellow paper clips (hydrogen) ° 18 large green paper clips (oxygen) 2. Read the paragraphs below and follow the instructions to build a model of photosynthesis. Answer the questions that follow each step. Plants are called producers because they use sunlight energy to make food by photosynthesis. Plant cells contain green chloroplasts that can be seen using a microscope. Chloroplasts get their green color from chlorophyll, which is able to absorb sunlight energy and use it to build chemical energy in a food called glucose, The chemical equation for photosynthesis is: 6C02 + 6H20 -9 C6H1206 + 602 carbon dioxide + water yields glucose + oxygen Describe how light is trapped for the process of photosynthesis, Carbon dioxide is a gas in the air and mustbe present as a reactant or raw material for photosynthesis to occur. It seems unusual that a gas from the air can change into food! The chemical formula for carbon dioxide is CO2, which means it contains one carbon atom and two oxygen atoms joined together. TAKS Preparation Booklet Grade 7 Science © Permission granted to copy student pages for purchaser's class, 94 ) I b Make a model of CO2 molecules, using one blue and two green paper clips from the bag. Look at the chemical equation for photosynthesis. The coefficient in front of CO2 is six. This means there are six molecules of CO2. How many more COÿ molecules should be made? How many of each colored paper clips will you need . from the bag? Plants also need water as a reactant for photosynthesis. The chemical formula for water is HÿO. There are two hydrogen atoms and one oxygen atom present in one H20 molecule, lVlake a model of H20 using one green and two yellow paper clips 1 from the bag. b Look at the chemical equation for photosynthesis. The number coefficient in front of H20 in the equation is six which means that there are six water molecules. . How many of each color of paper clips will you need from the bag? b b . Look at the right side"of the photosynthesis equation to see the products or the result of the reaction. The chemical formula for glucose is C6HlzO0. Using the H20 and COÿ models, are there enough paper clips to build glucose? b b 1 Build a glucose molecule by taking apart the HÿO and COs models and combining them in a new way to form glucose. How many glucose models are formed? How many oxygen paper clips remain after the production of glucose? Oxygen does not usually exist as a single atom, so each of the leftover green paper clips bonds with another oxygen atom. How many 0z molecules remain? b Grade 7 Science TAKS Preparation Booklet b @ Permission granted to copy student pages for purchaser's class, 95 • ,::::@ ' i'i ÿJi 10, Use the photosynthesis equation to help you complete the T-chart to show the number of atoms of each element on each side of the equation, 4 , 6C02 + 6H20 ÿ C6H120ÿ + 602 I Reactants of raw materials Products Atoms of Each Element Atoms of Each Element q C C H H 0 0 11. Did you have any paper clips left over? 4 Were you lacldng any paper clips? What does this tell you about a chemical reaction? 12. Summarize the photosynthesis equation by filling in the blanks in the paragraph below. 4 Photosynthesis begins when i< r:antured by chloroplasts in plant cells. Other raw materials needed for photosynthesis to begin are from the air and ., which is transported from the roots to the leaves by stems. As a result of photosynthesis, formed and is is given off. TAKS Preparation Booklet Grade 7 Science © Permission granted to copy student pages for purchaser's class, 96 13. Label the diagram by filling in the squares next to arrows. Use the word bank provided. Word Bank oxygen given off carbon dioxide water light energy glucose formed Grade 7 Science TAKS Preparation Booklet © Permission granted to copy student pages for purchaser's class, 97
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