Cellular Respiration
Thinking about Cellular Respiration
People and other organisms all use energy for their life processes. Where does this energy come from, and how is it converted into the different types of energy living organisms need? For example, consider competitive runners finishing a race. How do they get the energy needed to move so rapidly?
Energy is the ability to do work. It comes in a variety of forms. These different forms of energy can be converted from one form to another. Most organisms obtain their energy either from food or sunlight. Green plants, for example, use light as an energy source. They convert light energy into chemical potential energy (sometimes called chemical energy) using the process of photosynthesis. This chemical energy takes the form of chemical compounds that are manufactured from carbon dioxide and water. Photosynthetic organisms—mainly plants—store and use some of these chemical energy sources for other life processes. Often these food stores are eaten by animals before the plant can use them.
Think about the food you consume. What sort of chemical compounds is it made up from? Which of these are considered high-energy compounds? Where did these high-energy compounds come from? What do these compounds have in common with each other? How is energy released from them?
You have probably heard of respiration and know that it involves combining oxygen with food. You may think this process is the same as combustion, but in fact, it is much more complex than that. The process of respiration occurs in many steps and ultimately produces the substance adenosine triphosphate (ATP). This process is more precisely called cellular respirationglossary term (opens in a new window) because it occurs in every cell of your body, even when your body is resting. In fact, it occurs—in some form—in all living cells of all organisms, including plants and prokaryotes.
Explain Question
Explain the steps involved in converting food into the energy needed to move these athletes.
Teacher Note
Use this student response to formatively evaluate students’ prior knowledge of the concept. The Model Lesson provides information on common student misconceptions. Students should compare the answer they have given here to the one they give in Explain.
Before You Begin
What do I already know about cellular respiration?
Teacher Note
This item is a formative pre-assessment intended to provide the teacher with feedback on prior knowledge of this topic. In middle school, students should have learned that respiration has reactants and products and should have an understanding of what these are and how they are related. Use as a think-pair-share activity.
Teacher Note
Use this as a formative pre-test of these common student misconceptions. Students selecting A are probably incorrectly equating feeling hot as being caused by sweating. Students selecting B probably have the misconception that respiration is a form of burning or combustion. Students selecting D may think that cells only respire when used and are in use.
Teacher Note
This activity is a formative pre-assessment intended to provide the teacher with feedback on prior students’ knowledge of this topic. Its main focus is to determine whether students are aware that cellular respiration is a multistaged process and whether they are familiar with any of the steps or organelles involved with that process. Consider having students work in pairs on this pre-assessment.
Teacher Note
Students may have heard of ATP, and some may have an understanding of its role as a high-energy compound. This formative assessment will provide some feedback on their understanding of how ATP works. Use as a think-pair-share activity.
Find out More About...
- cell organelles
- ATP
- chemical reactions
Lesson Questions
- What are the steps involved in cellular respiration?
- What are the differences between aerobic and anaerobic respirationglossary term (opens in a new window)? How do organisms get their energy to live?
