REVIEW All organisms (plants and animals) need energyto carry out their life processes. The chemical reaction which provides this energy is called. In larger animals it is often called respiration because the reaction takes place in the. Therefore, to obtain energy, every organism must have a strategy to get the reactants to the cell. The reactants for this process are and. The products for this process are and. The gases for this process are and. Scientists have determined the critical steps for how the cells of every organism obtain these reactants and how and what they do with the products as follows: diffusion (B09) gas exchange (B07, B09, B11) digestion (B11) DIFFUSION Diffusion is a natural process where particles move from an area of high concentration to an area of low concentration. http://www.williamsclass.com/seventhsciencework/cellsorganization.htm good resource for review GAS EXCHANGE The gases involved in respiration are and. must diffuse into the cell and must diffuse out of the cell. Once inside the cell, oxygen will be used up during. This will keep the of oxygen low enough to allow for more oxygen to flow into the cell. Similarly, the carbon dioxide produced during the reaction results in a high in the cell. As a result, carbon dioxide will out of the cell. It is important to note that both gases will dissolve in water before diffusion takes place. This is an advantage for aquatic species because the gases are already dissolved. Like coffee grinds, the coffee molecules cannot pass through the paper filter membrane until it gets wet. The dissolved coffee molecules easily pass through the wet membrane!! GAS EXCHANGE IN LARGER ANIMALS For humans, oxygen diffuses first into the in our. Because our volume is so large compared to our, our lungs have evolved into having many to compensate. Our lungs, flattened, would take up the same area as a tennis court! When the blood cells are rich with oxygen they are said to be and appear red. The blood stream then carries the oxygen to all the cells in our body where it again across a membrane into the for the purposes of respiration. The surface area of the blood stream is increased to make this process more efficient and these blood vessels are called. The products to this reaction are and. CO 2 diffuses back into the blood stream where it out of our in the lungs. http://media.wwnorton.com/college/biology/animations/ch22a03.swf Shows the diffusion of gases into the blood stream http://www.youtube.com/watch?v=hit621prro0&feature=related 1
B12 Interrelation of Organ Systems note Oct 29.notebook GAS EXCHANGE IN VARIOUS ORGANISMS 2
DIGESTION IN LARGER ANIMALS Larger animals obtain their energy through a process called. The two reactants in this reaction are and. Larger food must be broken down a process called in order for it to diffuse into a cell. In large organisms, a system must carry this energy source to all cells if the cells are to stay alive. In humans, the diffusion of sugar takes place in the and the carries this sugar throughout the individual. In all animals, there are 4 basic steps involved in getting food to the cell regardless of the size of the organism..... DIGESTION IN VARIOUS ORGANISMS Small Single Celled Eukaryotic organism Amoeba http://sciencevideos.wordpress.com/2007/09/24/amoeba feeding endocytosis/ 3
DIGESTION IN A PARAMECIUM http://bcs.whfreeman.com/thelifewire/content/chp28/2802001.html DIGESTION IN EARTHWORMS http://www.naturewatch.ca/english/wormwatch/virtual_worm/introduction.htm only digestion works DIGESTION IN HUMANS http://kitses.com/animation/swfs/digestion.swf 4
HOMEWORK 1. a) Is there more oxygen available for diffusion in air or in water? Why? b) Is there more oxygen in warm water or cold water? Why? 2. What must oxygen (in the air) do before it can diffuse across a membrane? 3. What advantage does a flat organism have when it comes to diffusing gases in and out of the cell? 4. What is meant by the following statement: "All gases must be in solution if they are to move across the cell membrane."? 5. What strategy must a desert animal have regarding gas exchange? 6. What system must larger organisms possess to facilitate gas exchange? 7. Do gases only diffuse into organisms? Why? 8. What role does water play in the diffusion process? 5
Attachments animation how_diffusion_works.webloc