Chapter 8.1, Problem 5MI

Summary Introduction

To compare:

The laws about flow of energy and to give an example of each law

Introduction: There are many forms of energy like light energy, mechanical energy, heat energy and chemical energy. Energy can be converted from one form to another. In living organisms, chemical energy is stored in organic compounds and this energy is converted to other forms of energy.

Answer to Problem 5MI

	First Law of Thermodynamics	Second Law of Thermodynamics
Defined	Energy can be converted from one form to another but it cannot be created or destroyed.	Energy cannot be converted without the loss of usable energy.
Example	The body converts stored energy in food into chemical energy when we eat.	Some energy is lost as heat energy as energy is transferred through a food chain.

Explanation of Solution

Many chemical reactions and processes, that occurs in our cells uses energy. Macromolecules are being made and broken, substances are transported across cell membranes and genetic instructions are transmitted. All these cellular activities require lot of energy. Thermodynamics is the study of flow and transformation of energy in the living organisms.

There are two laws of thermodynamics. First law states that energy can be converted from one form to another but it cannot be created or destroyed. This law is also called law of conservation of energy. When we eat the energy stored in the food is converted to chemical energy and is used by our body.

The second law states that energy cannot be converted without the loss of usable energy. The lost energy is usually converted into thermal energy. Entropy is the measure of disorder or unusable energy in a system. Therefore, second law can also be stated as “entropy increases in a system”. So in a food chain the amount of energy that is available to the next trophic level decreases.