How do living things get and use energy?
Learning Targets Learning Experiences
Learning Targets Learning Experiences
Misconceptions
V Substances in soil are food for plants. V Plants have multiple food sources, not just the sugars they make from water and car- bon dioxide. V Food enters a plant through the roots. V Plants make sugars from minerals or minerals and water. V Plants get organic food substances such as carbohy- drates or protein from the soil. V Plants photosynthesize only during the day and plant cellular respiration occurs only at night. V Carbon fixation occurs only at night. Teacher Tips This approach is profoundly different from the way these topics have traditionally been broached in biology classrooms. Traditional instruction in photosynthesis and respiration has revolved around teacher and text-based explanation of these phenomena. Mastering this standard will require students to have multiple opportunities to observe and collect data about the phenomena. The teacher’s role should largely center around sense-making conversations, quality questioning, and supplying needed vocabulary after those learning experiences. The aquatic plant Elodea is often used to visualize gas formation in photosynthesis. The gas produced is not pure oxygen, as often claimed. As photosynthetic oxygen dissolves, some of the nitrogen comes out of solution. Bubble formation on leaves submerged in water is not always caused by photo- synthesis. If the water is cold, bubbles form on leaves as the water warms and gases become less soluble. bit.ly/teaching-plants
50 I can collect and analyze data to identify the reactants and products of photosynthesis and respiration. (6) 51 I can use evidence to describe the relationship between photosynthesis and respiration and illustrate that relationship. (6)
Students begin this photosynthesis and respi- ration content sweep by answering the question “Where does the mass of a tree come from?” They then watch an online video, pausing at multiple points to revise their original answer if necessary. Students return to prior conversations about cellular organelles (learning target #20), focusing on how the unique structure of mitochondria and chloroplast allow for the cycling of matter and the flow of energy. Previously constructed mitochondria and chloroplast models help anchor these conversations. Students analyze data to determine the relation- ship between CO2 and O2 in photosynthesis and respiration, recognizing that the reactants of one process are the products of the other. Data may be provided or student-generated from a number of different sources. Students create a diagram that shows the relationship between photosynthesis and respiration.
52 I can plan and carry out an investiga- tion that provides data to support the premise that light energy is absorbed by pigments during photosynthesis. (6a) 53 I can formulate a scientific question about how energy is stored and/or released in living systems. (6, 6a, 8) 54 I can relate evidence from an experiment to light absorption and reflec- tion in photosynthetic organisms. (6a) 55 I can analyze and interpret data from experiments related to photosynthesis to draw conclusions about the cycling of matter and energy. (6, 6a, 8)
Students engage in a series of activities focused on the function of energy (in the form of light) in the process of photosynthesis and the way plants capture this energy. A flashlight and prism – or image of light passing through a prism – reminds students that visible light is composed of a spectrum of various wavelengths of light. Building on this prior knowledge, students examine a simplified image of photosyn- thesis and write about the relationship between the light spectrum and photosynthe- sis. Students revisit this entry after further experimentation and conversation. Laboratory activities highlight the role of plant pigments in photosynthesis (see resources). Before beginning the lab, students review an image of the electromagnetic radiation spectrum. After analyzing the results of the experiments, students return to this image and predict which wavelengths are involved in the process of photosynthesis. A number of investigation strategies are available to help students comprehend the role of pigments in the process of photosynthesis. Several are listed in the resource list and educators are encouraged to use available materials and equipment for student experimentation. If students perform individualized small group experiments, provide opportunities for students to share results with classmates. After completing these activities, students reexamine their initial response to the prism question, refining their explanations to reflect a deeper understanding of the role of light in photosynthesis. Investigate plant pigments using common pigment extraction activities. Alternatives include chromatography of pen ink as a model for pigment chromatography. Pigment extraction lab options are included in the resource list. Allow the students an opportunity to reexamine their initial response to the prism question. Students should refine their explanations, demonstrating a deeper understanding of the role of light in photosynthesis.
Teacher Resources
Alien Gases — Teacher Created Student use their own breath, elodea, and bromothymol blue to explore the relationship between the reactants and products of photosynthesis and cellular respiration. The scenario involves investigating an alien life form. Student handouts and teacher resources can be found in the resources. www.hudsonalpha.org/compendium Where Does the Mass of a Tree Come From? — Veritasium YouTube ® channel Introduce photosynthesis using Veritasium YouTube video. Prior to showing video, pose the video title question and have students write their responses. Stop the video at multiple points to allow students to respond to the ques- tion from the video and revise their original responses. bit.ly/mass-of-a-tree
See Teacher Resources on page 32
Teacher Tips While plant pigments are the focus of the standard, students may use a wide variety of experimental methods and easily available materials to elucidate
Misconceptions
V Plants reflect all green wavelengths of light and therefore use no green light energy for photosynthesis. V Plants use oxygen during photosynthesis.
the relationship between plant pigments and light absorption and reflection. Several sample labs are included, but teachers are reminded that helping students ask scientifically testable questions is a major goal of this standard and doing so does not require sophisticated lab equipment. Some accessory pigments absorb green wavelengths of light and pass this energy to chlorophyll. These nuances of pigment function are outside the scope of the standard, but may come in student experimentation and questioning.
Notes: ___________________________________________________
V Water is food for plants. V Water is food for animals. V Food is a source of energy but not a source of building materials.
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A Field Guide to the Alabama Standards
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The Biology Compendium
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