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Name _______________________________________________________ Exam 2015 Prep – BIG IDEAS ANSWERS Write the equations for Photosynthesis and Cellular Respiration: CR: 6 O2 + C6H12O6  6CO2 + 6 H2O + NRG Photo: Sun Energy + 6CO2 + 6 H2O  6 O2 + C6H12O6 What is the purpose of Cellular Respiration? To use oxygen to break apart glucose to release stored energy (ATP) What is the purpose of Photosynthesis? To capture energy from sunlight and store it in glucose molecules How are these processes related? Photosynthesis is responsible for capturing energy and storing it in the glucose molecule (putting money in the piggybank). When an organism needs to actually use the energy stored in the glucose molecule to perform life functions (need to buy something), they use cellular respiration. CR uses oxygen to break apart the glucose molecule to release the stored energy in the form of ATP (oxygen is the hammer that breaks apart the glucose piggybank to release the ATP money). Why are these processes important? Organisms need energy to carry out ALL life functions – the BIG 7. Without energy, they cannot live, because they cannot carry out the BIG 7. Photosynthesis captures this energy and stores it in glucose. Cellular respiration allows the organism to access this stored energy and use it to carry out life functions. What types of organisms carry out each process? CR occurs in plants (autotrophs) and animals (heterotrophs) Photo occurs in plants (autotrophs) Surface Area What is it? Definition: The area of the outside surface of a 3D object. In cells, this refers to the membrane on organelles. In organisms, this refers to the membrane on organs. Why is it important? The important materials for life pass into cells/organelles through their membranes. If there is more membrane space then there is more room for these important materials to pass into the cell, meaning that the cell can get more important materials. Similarly, the cell must also get rid of waste through the membrane. More surface area means more membrane, which means that more waste can exit the cell, because there is more room. How does it help living things function more efficiently? (Give an example) Example: Fish gills increase surface area with gill filaments, lamellae, and gill layers. The more surface area on a gill means more oxygen can get into the blood stream and more carbon dioxide can get out. This is important, because oxygen is an ingredient for cellular respiration and carbon dioxide is a waste product of cellular respiration. More ingredients, means more cellular respiration, which means more energy – yay! More cellular respiration also means more waste, but because there is a big gill SA, the fish can get rid of it quickly – yay!
Diffusion/Passive Transport A. Define diffusion Diffusion is a form of passive transport – molecules move without the use of energy. Small, uncharged molecules move from an area of higher concentration to an area of lower concentration. This is “moving down the concentration gradient.” B. Describe how it works It happens, because molecules are always moving and bump into each other when tightly packed together. Eventually they spread out into less concentrated areas, because they are pushed away from each other when they collide. C. Explain why it is an important process in the functioning of organisms/cells (give an example) It is important, because organisms are able to get important materials for life functions into the cell without expending energy and release waste from the cell without expending energy. This makes life functions – BIG 7 – more efficient. D. How are diffusion, surface area, and cellular respiration related? Ingredients for CR (oxygen and glucose) move by diffusion into the cell. This is good, because getting ingredients does not require energy. Increased surface area means that there is more room for these ingredients to get into the cell. This makes cellular respiration more efficient and the cell better able to make ATP, because it can continually get ingredients quickly (large surface area) and without expending energy (diffusion). Similarly, increased rates of cellular respiration mean that there will be more carbon dioxide and water waste produced. That’s OK, because the increased surface area means that the waste can leave the cell quickly and diffusion means that waste can exit without the use of energy. Sexual Reproduction, Natural Selection, Evolution A. Why is genetic variation important in organisms? (What would be the problem if we were all genetically identical?) Genetic variation is important, because if we were all the same and one pathogen (virus or bacteria) evolved the ability to kill us, we would all have the exact same immune system and we would all be killed by the pathogen. Genetic variation means that we do no all have the same immune system, so some of us would be able to survive the pathogen, thus keeping the species alive. Additionally, genetic variation allows for new traits to develop, which allows for evolution and change in species to become better adapted to their environments. B. How does sexual reproduction ensure genetic variation? Sexual reproduction is when 2 organisms combine their DNA to create offspring with unique DNA. This means that organisms can develop helpful traits and adaptations that enable them to better survive. C. Define Natural Selection and Evolution Natural Selection is when one organism has a trait (based on genes) that makes it more likely to survive. Evolution is the gradual change in species over time. Natural Selection happens in 1 generation and can happen to 1 organism. D. How are sexual reproduction, natural selection, and evolution related? Sexual Reproduction causes Natural Selection, which then causes Evolution, because sexual reproduction continually produces new combinations of genes. Some of these genes make an organism more likely to survive and pass down that trait to its offspring (natural selection). When the trait is present in the majority of the organisms in a species, evolution has occurred. Evolution happens over A VERY LONG TIME and affects a whole population.