Three categories of environmental science interact to influence all life: physical, chemical and biological. The study of plants and photosynthesis permits a solid understanding of environmental factors and investigations in these categories provide a foundation for good investigative science and successful experimenting. Upon completion of this unit, students will examine the world around themincluding what they hear and seewith a more critical eye.
Students will understand and appreciate our plants as “air purifiers”. After identifying and describing air pollutants, students will assess air quality in their neighborhood. In our area, the air quality is poor. Given our reliance on oxygen, “clean air”, students will investigate solutions. Upon the discovery of oxygen production in photosynthesis, students will conclude diverse plant life is critical to their comfort and health because photosynthesisthe process through which plants manufacture foodis necessary for our survival.
Students will validate the process of photosynthesis in which light energy is converted to chemical energy. In plants, energy is stored chemically in starch which is made of glucose, a form of sugar. From this process oxygen, upon which most living things rely, is released. Plants need sunlight in order to combine carbon dioxide and water to produce sugar. They will identify the chemical process:
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6 H2O & 6 CO2 ((light(( (CH2O)n & 6 O2.
Sunlight is pure energy. However, sunlight itself is not a very useful form of energy; it cannot be eaten and it cannot be stored. To be beneficial, the energy in sunlight must be converted to other forms. This is what photosynthesis is all about. It is the process by which plants change the energy in sunlight to kinds of energy that can be stored for later use. One of the major energy-harvesting processes in plants involves using the energy of sunlight to convert carbon dioxide from the air into sugars, starches, and other high-energy carbohydrates. Oxygen is released in the process, and it is this byproduct that may thwart the negative effects of development and lessen air pollution.
As the CO2 to O2 conversion is central to the unit, students will describe the physical and chemical properties of air. Physical properties identify an objectand students will conclude gasses and air are objectsby their shape, form, size and color. They will calculate the density of various gasses. Because air has weight and takes up space, students will deduce it is considered matter and has all the other physical and chemical properties that define matter. One of these chemical properties is the ability to form compounds with other substancesan important concept of photosynthesis.
