Activity 8: What Do You Think?

• The materials that make the mass of a mature tree come from the carbon in the carbon dioxide that it takes in through its leaves. This carbon dioxide, together with the water that it gets through its roots, plus the energy from the Sun allows the plant to manufacture its own “food” (starch or sugars) through photo-synthesis. This is where the plant gets its energy to grow and maintain itself.

Student Conceptions
Students only remember plants for their ability to do photosynthesis. They seem to not include them to be able to do the process of respiration.

As to the concept of respiration, most students still associate this with breathing. Emphasize the point that it is through cellular respiration that we can access the energy from the food that we eat. Our cells go through cellular respiration using the oxygen that we took in through breathing.

Unlike energy, inorganic nutrients are recycled. When organisms die, decomposers extract the last of the available energy and some are lost in the form of heat. The inorganic nutrients – phosphorous, iron, nitrogen and others found in the dead bodies are then returned to the soil or water to be recycled again.