Thermodynamically, heat energy is defined as the energy transferred from one system to another that is not doing work. In every energy transfer, some amount of energy is lost in a form that is unusable. None of the energy transfers we’ve discussed, along with all energy transfers and transformations in the universe, is completely efficient. However, the second law of thermodynamics explains why these tasks are harder than they appear. Examples of the types of work that cells need to do include building complex molecules, transporting materials, powering the beating motion of cilia or flagella, contracting muscle fibers to create movement, and reproduction.Ī living cell’s primary tasks of obtaining, transforming, and using energy to do work may seem simple. Energy in ATP molecules is easily accessible to do work. Chemical energy stored within organic molecules such as sugars and fats is transformed through a series of cellular chemical reactions into energy within molecules of ATP. Living cells have evolved to meet this challenge very well. The challenge for all living organisms is to obtain energy from their surroundings in forms that they can transfer or transform into usable energy to do work. Some examples of energy transformations are shown in. Plants perform one of the most biologically useful energy transformations on earth: that of converting the energy of sunlight into the chemical energy stored within organic molecules ( ). Gas stoves transform chemical energy from natural gas into heat energy. Light bulbs transform electrical energy into light energy. The transfers and transformations of energy take place around us all the time. According to the first law of thermodynamics, energy may be transferred from place to place or transformed into different forms, but it cannot be created or destroyed. In other words, there has always been, and always will be, exactly the same amount of energy in the universe. It states that this total amount of energy is constant. The first law of thermodynamics deals with the total amount of energy in the universe. The laws of thermodynamics govern the transfer of energy in and among all systems in the universe. Like all things in the physical world, energy is subject to the laws of physics. Energy is exchanged between them and their surroundings, as they consume energy-storing molecules and release energy to the environment by doing work. A closed system is one that cannot transfer energy to its surroundings.īiological organisms are open systems. The stovetop system is open because heat can be lost into the air. An open system is one in which energy can be transferred between the system and its surroundings. There are two types of systems: open and closed. Energy is transferred within the system (between the stove, pot, and water). For instance, when heating a pot of water on the stove, the system includes the stove, the pot, and the water. The matter and its environment relevant to a particular case of energy transfer are classified as a system, and everything outside of that system is called the surroundings. Thermodynamics refers to the study of energy and energy transfer involving physical matter. Explain the first and second laws of thermodynamics.By the end of this section, you will be able to:
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