Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
No Free Lunch The flow of energy within closed systems and the Universe is known as thermodynamics. The study of the flow of energy within living systems is known as ecology. The laws of thermodynamics apply to both equally. You have learned from the first law that the amount of energy is fixed and can be converted from one form to another. But from the second law you learned that useable energy is always declining in the Universe and so all matter is evolving towards a lowest possible energy state and disorder. Consider how living things rot and become simple compounds when they die and thus evolve from a highly ordered system to a much simpler disorderly system. Humans are animals that survive only within a complex flow of energy that includes other living organisms and a favorable environment that allows for the flow of energy. All organisms require a favorable environment tuned to their needs and must work to obtain their energy. Producers must have sunlight as well as a source of carbon and other nutrients to survive and consumers must have access to a larger number of producers to survive. Recall the energy pyramid and the unequal relationship of consumers to producers. All consumers on planet Earth survive on the backs of a vast majority of producers! Note that there are a few primitive organisms that can produce carbon based food without sunlight. These unique organisms are found where sunlight does not penetrate and are known as chemotrophs and are the producers of unique food pyramids at the depths of the oceans and far below ground. Chemotrophs do however requite particular chemicals to produce carbon based food. You may have heard the expression there is “no free lunch”. This old saying is as true today as it ever was. It means that organisms are always working to obtain energy and without which they die. Life is an ordered state of matter and life fights the second law. The closest example to a free lunch on Earth is the electromagnetic energy that comes from the Sun. Remember though that the Sun is a star and all stars evolve to become dwarf or neutron stars or black holes and change their energy regime as regards their surrounding planets. The important point here is that almost all the energy on Earth ultimately derives from the Sun. The tiny bit of remaining energy comes from the decay of radioisotopes releasing thermal energy inside the Earth. Because the Sun literally turns a tiny amount of energy (4 million tons of matter every second become energy in the Sun!) into a huge amount of energy which is delivered to Earth everyday across 93 million miles of Space, and because the Sun will continue to delver energy to Earth another 4-5 billion years this energy is as free as it gets for humans and the vast majority of organisms occupying Earth. But recall from the second law that energy is “lost” when sunlight is converted to other forms. In fact the majority of this energy is “lost” as thermal energy that cannot always be used as fuel. Remember fuels are useable forms of energy. So obtaining energy to live on Earth is work. Humans split from chimpanzees about 6.5 million years ago and modern Homo sapiens first evolved 200,000 years old – with the great cultural leap occurring about 50,000 years ago and modern civilization beginning at the end of the last ice age about 10,000 years ago. Today, in the developed industrial world we work to earn tokens, money, by trading our goods or services to obtain energy and create a suitable environment for our survival. Since the beginning of the Industrial age, 250 years ago, we have employed chemical energy in the form of fossil fuels to run machines and supplement the soil with nutrients in a clever way of reducing the labor invoiced in growing our carbon based food. But for most of our existence we have had to hunt, gather or more recently farm to obtain our energy and necessary resources. Hunting, gathering and farming by hand is incredibly hard work and requires a huge investment in time and energy. Remember we are consumers and must eat a larger number of producers to sustain ourselves. In other words, there is no free lunch for consumers – especially those at the top of the energy pyramid. And, as we will learn, if it wasn’t for the one time gift of finite hydrocarbon fossil fuels the majority of us would still be working today as farmers to obtain our energy – and far fewer humans could be sustained in such a world. Answer the questions below. 1. What is the flow of energy called? What is the study of the flow of energy in living systems called? 2. What have we learned from the first and second law about the flow of energy in the Universe? 3. What are chemotrophs? Where are they found? 4. What does the expression “there is no free lunch” mean? 5. Where does the vast majority of energy come from on Earth? Where does the remaining tiny fraction of energy come from? 6. Is all the electromagnetic energy from the Sun converted to fuels on Earth? What are fuels? 7. How old are humans? How old are Homo sapiens? How old is modern civilization? 8. How do we earn our energy today? How did humans earn their energy for most of human existence? 9. Is hunting, gathering and farming easy work? What have human’s employed to reduce the labor involved in growing carbon based food today? 10. What does finite mean?