Energy Transformation in Nature
Biology SSS 1 Third Term
WEEK 1
Energy Transformation in Nature
Performance Objectives
Student should be able to:
- Explain energy loss
- Gives the laws of thermodynamics
- Gives application of the law of thermodynamics
Content
An ecosystem is a basic functioning unit in nature. It is made up of living organisms (plants and animals) and their non-living environment. The biotic or living components such as the producers and consumers interact in their environment resulting in the ecosystem being a functional unit.
Energy Loss in Ecosystem
The energy from the sun passes through food chains. However, only a small portion of the sun's energy gets into the bodies of the final consumers. The rest of the energy is lost as heat along the food chain. This progressive loss of energy at each level of a food chain puts a natural limit on the total weight of living matter that can exist at each level. In autotrophs, the loss in energy affects primary production because there is less of photosynthesis which ultimately affects the yield.
In an ecosystem, energy is lost through the following:
- Vegetation
- Soil
- Air
- Heat
- Evaporation of water
- Effects of wind
Depending on the type of vegetation and climatic factors, only about 1-10% of the solar energy may be available to photosynthetic producers in most ecosystems.
The Laws of Thermodynamics
Thermodynamics ordinarily means heat changes. Heat is a form of energy and how it can be changed or converted from one form to another is governed by two laws. These laws are called the first and second laws of thermodynamics.
First Law of Thermodynamics
The first law of thermodynamics states that energy can neither be created nor destroyed. In other words, the law states that energy can neither be created nor destroyed although it can be changed from one form to another.
Second Law of Thermodynamics
The second law of thermodynamics states that in any conversion of energy from one form to another, there is always a decrease in the amount of useful energy. Put in another way, the law states that no transformation of energy from one state to another is ever 100 per cent efficient.
Application of law of thermodynamics
The ecological phenomena or events can be explained using the laws of thermodynamics. Ecological phenomena or events, in which the laws can be used to explain are food chain, pyramid of energy and energy flow.
Food Chain
(a) Using the first law: Energy is generated through the sun and is transferred from the producer to the final consumers. The green plant transfers the energy to the primary consumers which again transfer the energy to the secondary consumers. In all, the total of the energy remains constant.
(b) Using the second law: While the energy is transferred to the next trophic level, part of it is lost as heat. In other words, as the energy is being transferred from producers to primary consumers, to secondary consumers and finally to the tertiary consumers, energy is lost in each trophic level as heat. In that manner, it is clear that there is no transfer of energy from one level to another that is 100% efficient. This means that energy is lost to the environment in the form of heat.
Pyramid of Energy
(a) Using the first Law: It is discovered that energy is transferred from one trophic level to another. The energy of the producers at the base of the pyramid is higher and it is transformed gradually from one stage of the
trophic level to another. Even though energy is transformed into various other forms in the successive trophic levels, the total of the energy is constant.
(b) Using the second law: As the energy is transformed from one trophic level to another, part of it is converted into heat which is lost, causing a progressive drop in energy in successive trophic levels.
Energy Flow
(a) Using the first law: As the producers convert the solar energy to useful energy, this energy is progressively transformed from one trophic level to the next and so on. This means, energy flows from producers to primary consumers, then to secondary consumers and finally to tertiary consumers in a food chain. So the flow of energy in a food chain is in one direction only.
(b) Using the second law: The transfer of energy between trophic levels is not 100% or it is not completely transferred. Successive levels have less of useful energy and support fewer organisms or individual lives. Primary producers or plants have the highest amount of energy. When herbivores feed on plants, the energy level is reduced. When carnivores consume the herbivores, the energy level is further reduced.
Food Chain
The order of living organisms in a community in which one organism consumes others and is itself consumed by another organism to transfer energy is called a food chain. Food chain is also defined as "a chain of organisms, existing in any natural community, through which energy is transferred".
Every living being irrespective of their size and habitat, from the tiniest algae to giant blue whales, need food to survive. Food chain is structured differently for different species in different ecosystems. Each food chain is a vital pathway for energy and nutrients to flow through the ecosystem.
A food chain starts with a producer such as plants. Producers form the basis of the food chains. Then there are consumers of many orders. Consumers are organisms that eat other organisms. All organisms in a food chain, except the first organism, are consumers.
Plants are called producers because they produce their food through photosynthesis. Animals are called consumers because they depend on plants or other animals for food to get the energy they need.
In a certain food chain, each organism gets energy from the one at the level below. In a food chain, there is reliable energy transfer through each stage. All the energy at one stage of the chain is not absorbed by the organism at the next stage.