Energy for Life
Thinking about the Energy for Life
After practicing for months, it is the day before the big race. Your data collection has shown that you are able to run for longer periods of time and also for greater distances. You have also noticed that your endurance has improved. You can now run for longer periods without tiring as easily. You feel confident you will be able cross the finish line in a reasonable amount of time. Since all living things need energyglossary term (opens in a new window), you need to be sure that the food you eat today will provide you with enough to finish the race tomorrow. What kinds of things should you eat? Will protein produce as much energy as carbohydrates?
How does your body get the energy from the food you eat? After the food enters your digestive system, it gets broken down by the various organs and chemicals. There are also a number of energy conversions that take place in order to release the energy contained within the food. While there are others, the main process with which you are most familiar is cellular respirationglossary term (opens in a new window).
In this lesson, you will learn about different forms of energy and how they are converted into other forms that are necessary for sustaining life. These conversions involve chemical reactions and are essential for powering your cells. Chemical reactions help our bodies convert energy into forms needed to maintain daily life processes.
You are an animal, which means you need to hunt for and eat your food in order to get the energy you need to survive. Do all organisms get their energy in this manner? How do plants get their energy?
You will remember that plants are autotrophs, which means they make their own energy. This process is called photosynthesisglossary term (opens in a new window). Plants will then take the sugars they synthesize and break them down using cellular respiration. Fungi and protists also use carbohydrates for energy. Have you ever seen a mushroom attached to a dead tree trunk on the floor of the forest? Well, this mushroom is absorbing the nutrients from that tree. It will then convert the nutrients into energy for itself. Protists are sort of the bridge between autotrophs and heterotrophs. There are some members that can make their own energy and others that need to hunt. In fact, there are even a few species that can perform both processes.
Unlike humans, who can get their energy from eating either meat, vegetables, or both, most other animals and all plants do not have a choice from where they get their food. They are very specific in their feeding habits. As organisms live together in communities, energy is transferred between each of the members. Called a food chain, the energy moves from producers to consumers to decomposers. Each time there is a transfer, some of the energy is lost. This is because the organism itself needs most of it to maintain its metabolism and remain at homeostasis.
Explain Question
Explain how and why energy is important to living things.
Teacher Note
Use this student response to evaluate students’ prior knowledge of the concept. The Model Lesson provides information on common student misconceptions. Have students answer the question and then revisit it later in the lesson.
Before You Begin
What do I already know about the energy for life?
Teacher Note
This formative assessment item is intended to provide the teacher with feedback on prior knowledge of this topic and to identify existing misconceptions. In middle school, students should have learned about the various organic molecules and should be familiar with the more common ones. Use this as a lesson opener, before a discussion of the different organic molecules. This activity will allow students to review what they already know about organic molecules and set up their learning for how carbohydrates are used for energy.
Teacher Note
This is a formative assessment item that assesses students’ knowledge of dimensional analysis. Use this as a lesson opener before reviewing metric conversions. Have students work on it together and then review as a class. Students selecting A are confused about how many millimeters there are in a meter and moved the decimal point the wrong way. Students selecting B are confused about how many millimeters there are in a meter and did not move the decimal point the correct way or enough places. Students selecting C have a misconception about how many millimeters there are in a meter and did not move the decimal point enough places to the right.
If a female lion runs a distance of 469.2 meters while chasing an antelope, how many millimeters did she run?
Teacher Note
This formative assessment item is intended to provide the teacher with feedback on prior knowledge of this topic. Use this as a lesson opener to review the topics. Have students work together to determine the answers and then review as a class. Its main focus is to determine whether students remember the main parts of cellular respiration and photosynthesis. Review of this information will be useful as they learn more about the energy both of these processes produce for living things.
Teacher Note
Use this formative assessment item as a quick review in between discussion points at the beginning of the lesson. Have students raise their hands to answer. Students should be aware of the relationship between energy and matter and that energy is needed for chemical reactions to take place.
Find out More About...
- food webs
- metric conversions
- cellular respiration and photosynthesis
Lesson Questions
- What is energy, and how does it contribute to maintaining life on Earth?
- What are kinetic and potential energyglossary term (opens in a new window)?
- What are the laws of thermodynamicsglossary term (opens in a new window)?
- What is the difference between endergonic and exergonic reactions?
- What is the difference between oxidationglossary term (opens in a new window) and reductionglossary term (opens in a new window) reactions?
