NATS1675 Food, Energy & Raw Materials Review PDF

NATS1675 – REVIEW: Food, Energy and Raw Materials – Topic Outline (L2) This review is only a summary of key points. For details refer to the lecture notes. 1. Requirements for Life a. The human body is a collection of atoms...

NATS1675 – REVIEW: Food, Energy and Raw Materials – Topic Outline (L2) This review is only a summary of key points. For details refer to the lecture notes. 1. Requirements for Life a. The human body is a collection of atoms b. Atoms interact in precise ways to form molecules c. Molecules interact to form cells and body structures 2. Food – provides raw materials and energy – for what purposes? 3. The 4 Biological Molecules – what are they? examples of each? 4. The human body is highly organized & designed to acquire and use raw materials and energy 5. Humans are members of ecosystems – Ecology a. Raw materials, energy, oxygen, water b. Molecules and chemical bonds c. Photosynthesis and cellular respiration – definitions and the relationship between these d. Energy, raw materials, and organization of the body 6. Ecosystems are characterized by energy flow and chemical cycling. a. Compare and contrast the flow of nutrients and energy through a typical ecosystem b. Definitions of each, with some examples i. Producers ii. Consumers iii. Decomposers 7. Delivery of Nutrients, energy, oxygen, etc... describe and compare in adults and during development The Earth Is a Closed Ecosystem with Sunlight Energy As the Only Input Energy Flows in ONE Direction through Ecosystems from Producers to Consumers Food chains and food webs depict feeding relationships Energy is lost as it is transferred through trophic levels Chemicals (Nutrients) Cycle through Ecosystems © B. Barbara Czaban, Ph.D., Review: Food, Energy, Raw Materials, NATS1675 1 Thinking About the Concepts (not all may apply to the topics covered in this course, so just ignore them) 1. Explain how energy flows through an ecosystem. Answer: Producers capture the sun energy by photosynthesis producing sugars for energy. Consumers eat producers for energy. Decomposers get energy from dead consumers and producers, then release nutrients to be used by the producers to help capture more sun energy. 2. Define the following terms: producer, primary consumer, secondary consumer, and decomposer. Explain the role each plays in cycling nutrients through an ecosystem. Answer: (a) Producers – photosynthetic organisms capable of storing light energy as sugars. Also, chemosynthetic organisms capable of storing energy from specific chemical reactions. (b) Primary consumers – eat the producers. (c) Secondary consumers – eat the primary consumers. (d) Decomposers eat dead producers and consumers and release nutrients that producers need to store energy. 3. Explain why the feeding relationships in a community are more realistically portrayed as a food web than as a food chain. Answer: A food web accounts for varied diets of animals whereas a chain just shows the line from producer to tertiary consumer. 4. Explain the reasons for the inefficiency of energy transfer from one trophic level to the next higher one. Why does this loss of energy limit the number of possible trophic levels? Answer: With energy transfer, 90% is lost as heat. Because of this, less and less energy is available to the next trophic level, limiting the size of the trophic level. 5. What does a pyramid of energy mean? Answer: This is a pyramid-shaped depiction of the energy available to trophic levels from the producers at the bottom and the tertiary consumers at the top. 6. Define biological magnification. Explain how biological magnification is a consequence of the energy loss between trophic levels. Why should humans be concerned about biological magnification? Answer: Biological magnification is the tendency of a certain non-degradable chemical to become more and more concentrated in the cells of organisms as it passes along the food chain. With each successive trophic level many prey are consumed, which can lead to 1000 times the original concentration. Humans must avoid eating tertiary consumers that are concentrating toxic chemicals in their cells. Sickness and even death can occur from eating contaminated food. 7. Explain why more people could be fed on a vegetarian diet than on a diet in which meat provides most of the protein calories. Answer: If humans eat lower on the food chain, there will be 10 times more energy (calories) available to them. 8. Which human activities are primarily responsible for the rising level of atmospheric carbon dioxide? Answer: Deforestation without replanting and burning fossil fuels. © B. Barbara Czaban, Ph.D., Review: Food, Energy, Raw Materials, NATS1675 2 9. What is meant by the greenhouse effect? Explain why there is concern that the rising level of atmospheric carbon dioxide could lead to global warming. Answer: The greenhouse effect is a natural phenomenon where certain gases in the atmosphere reduce the amount of heat able to escape and reflect it back to the earth, increasing the temperature. It is the rate of rising levels of carbon dioxide that concerns scientists because organisms may not be able to adapt to the rising temperatures and major changes in climate temperature may cause increased storm activity, increased ocean levels, and droughts. 10. The greenhouse effect is due to: (a) phosphorus. (b) nitrogen. (c) carbon dioxide. (d) carbon monoxide. Answer: (c) carbon dioxide. 11. An animal that eats an herbivore is called a ___________. Answer: secondary consumer More Questions (not all may apply to the topics covered in this course, so just ignore them) 1. Why do we need to eat? 2. What are the 4 important biological molecules? 3. Which 4 kinds of organisms perform photosynthesis? 4. Which organisms perform chemosynthesis? – and where do they do this? 5. What is a main difference between a decomposer and a detritivore? 6. About how much of the available energy in one trophic level is transferred to the next trophic level? Go to next page for answers… © B. Barbara Czaban, Ph.D., Review: Food, Energy, Raw Materials, NATS1675 3 Answers to Questions 1. Food provides raw materials – for what purpose? i. (1) with which to form body structures during embryonic development ii. (2) to add new molecules to body structures as previously existing molecules are lost, used up, or destroyed Food also provides energy – for what purpose? i. (1) to maintain molecular structures (to maintain the chemical bonds holding atoms together) ii. (2) to drive metabolism 2. Carbohydrates, Proteins, Lipids, Nucleic Acids 3. Plants, algae, photosynthetic prokaryotes (bacteria), and photosynthetic protozoa 4. Archaebacteria - At hydrothermal vents 5. Decomposers ‘absorb’ nutrients from non-living matter Detritivores ‘eat’ non-living matter 6. About 10% © B. Barbara Czaban, Ph.D., Review: Food, Energy, Raw Materials, NATS1675 4