Cellular Energy

In this fourth unit we discuss the main source of energy on earth, the sun, and talk about how autotrophs and heterotrophs get/use nutrients for their energy needs.  I also show students a short video about chemotrophs and talk about a lesser known energy source on earth.  ​

​We discuss how plants transport energy to their different cells.  I mention the purpose of xylem and phloem in plant tissue.  As a class, we then review diffusion, passive transport, osmosis, and active transport from the previous unit.  I explain that the energy involved in active transport is provided by ATP.

​We spend some time on the basic differences in types of plants and science's current understandings about plant evolution.  Some important vocabulary I make students aware of (because they may see these words on the NY State Regents) includes:  monocot, dicot, cotyleden, vascularity, palisade layer, guard cells, and stomata.

​I teach students the formula for photosynthesis, the organelle involved, and the light and dark reactions (Calvin Cycle).  I follow up with some classroom activities, a video (see below), and laboratory activity all related to chromatography.

​Factors which influence photosynthesis (light intensity, temperature, and light wavelength) are discussed and reinforced with this activity.

​I begin the respiration portion of the cellular energy unit by telling students that plants (autotrophs) need to perform respiration to make energy just like animals and all other organisms. Students then complete the lab: Respiration in Plants.

​Following this, I give students some basic information about anaerobic and aerobic respiration. I discuss the formula for respiration and the organelle in which it occurs. In discussing anaerobic respiration I mention glycolysis, lactic acid and alcoholic fermentation.

​I then briefly review photosynthesis and the factors which influence the process. I show them how photosynthesis is nearly an opposite process to respiration using the formulas for each. Students later complete "Cellular Energy Key Ideas" which helps solidify their understandings about the two processes.

Next we focus in more detail about the process of fermentation. I follow this discussion with a lab: Fermentation in Yeast.

​When I return to the topic of aerobic respiration I review the Krebs Cycle and Electron Transport Chain.  I discuss how this process happens in humans and students later complete a lab: Exercise and Cellular Respiration.

​I briefly discuss how energy moves through the biosphere. This discussion is actually a precursor to the Ecology unit.

The unit "wrap-up" includes videos which highlight the complimentary processes of photosynthesis and cellular respiration. I also review previously taught information about how molecules move across the cell membrane because active transport requires the use of energy (relevant to this unit).

The Presentation and Student Notes files are available here. ​