Organism Energy Transfers (7.7B)
Overview
Student Expectation
The student is expected to illustrate the transformation of energy within an organism such as the transfer from chemical energy to heat and thermal energy in digestion.
Key Concepts
· Key Concept 1: Organisms transform chemical energy in the food they eat into other forms of energy.
· Key Concept 2: Organisms break down food during digestion, transforming chemical energy in food to thermal energy.
· Key Concept 3: In digestion, chemical energy is also transformed to mechanical energy as an organism uses its muscles to move.
Fundamental Questions
· How do organisms transform chemical energy in the food they eat into other forms of energy?
· What energy transformations take place before, during and after, digestion?
· How do muscles of an organism rely on chemical energy to produce motion?
Background Information
Objective(s):
Illustrate the transformation of energy within an organism such as the transfer from chemical energy to heat and thermal energy in digestion.
Foundation:
In our daily life, we actively and passively make use of energies and transform energies. When we use a flashlight, the battery contributes the chemical energy into electrical energy, which is further transformed and consumed by the light, which stands for light energy. And later it turns to thermal energy. If you light a match, the chemical reaction happens and the chemical energy turns to light energy directly. In people’s stomach, the digestion turns biochemical energy into other types of chemical energies, stored in substance such as fat or proteins. And later it consumes and gives out to support people’s activity, such as thinking, running, and finally it becomes thermal energy. Food chains and food webs illustrate how the energy flows from one type to another. The radiant energy from the sun is transformed into chemical energy in green plants, which are widely spread on earth. The plants are eaten by animals, and hence the energy is further stored in animals and consumed by them into mechanical energy when they are in motion.
Food contains energy; that is the reason why people need food. The type of energy contained in food is commonly known as chemical energy. In order to make use of this energy in the future, the chemical energy needs to be transformed into other proper types and stored in the body. Organisms have the ability to transform chemical energy from food into other types. This is vitally important, since the chemical energy in food cannot be directly used or stored in organisms. Other types of energy include thermal energy, mechanical energy and biochemical energy, such as the energy stored in fat.
During digestion, chemical energy can be transformed into heat and thermal energy. Generally, digestion is the process of breaking down large food particles to small individual biochemical molecules. Those molecules can be transported through the intestinal lining into the bloodstream. In this way, the chemical energy in food is transformed into heat and that is the reason why you may feel hot while digesting your meal. Thermal energy is used to keep the human body warm and maintain a certain temperature. Also, additional thermal energy is stored in the body, such as in fat. The abdomen is a commonly place to store fat. Losing weight typically means to lose fat. In the view of energy, this process loses potential thermal energy as well.
Digestion is a complex process controlled by your brain. Your body uses mechanical and chemical means to do this. The digestive muscles’ movements can be considered as mechanical motion, and thus part of the chemical energy is transformed and consumed in the form of mechanical energy. What is the energy type after mechanical movement of the muscles? The answer is thermal energy. The mechanical energy expressed during the organisms’ movement, and the chemical energy supporting this movement continuously provide part of energy for the mechanical energy. In addition, the result of the movement is to produce thermal energy to maintain the required temperature, and meanwhile, to break those big food particles into smaller pieces and into molecules.