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SC BIOL 301 - Adaptations

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Biol 301 1nd Edition Lecture 6 Outline of Last Lecture I. TestOutline of Current Lecture II. Properties of waterIII. Adaptations to water, gasses, and temperatureCurrent LectureProperties of water – - Pure water becomes a solid below 0°C and vapor above 100°C.- When water contains dissolved compounds, such as salts, its freezing temperature drops below 0°C.- Water has a high specific heat; which is the energy required to raise water temperature by 1°C.- This makes water resistant to changing states; helps prevent water bodies from freezing solid during the winter.- Water is at its highest density at 4°C.- Above and below 4°C, the density of water decreases.- Ice is less dense than liquid water, so it floats on the surface. As a result, the lower layers of lakes and ponds are typically ice-free during winter- Viscosity: the thickness of a fluid that causes objects to encounter resistance as they move through it- Water is a powerful solvent that is able to dissolve many substances, which makes them accessible to organisms.- Water is polar; the negative oxygen end of one molecule is strongly attracted to the positive hydrogen end of another (i.e., hydrogen bonds).- Water attracts charged atoms or molecules (i.e., ions), which causes many substances (e.g., NaCl) to dissolve.- Precipitation dissolves some of the minerals in rocks and soils, and carries them through streams and to the ocean.- Oceans have a higher concentration of dissolved minerals than streams and lakes.- Every mineral has an upper limit of solubility in water, known as saturation.- Beyond saturation, minerals precipitate out of water.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- In solution, some water molecules break apart into H+ and OH– ions.- Acidity: the concentration of H+ ions in a solution.- Acidity is measured as pH:o pH = –log(H+ concentration).- Water with low pH is acidic, medium pH is neutral, and high pH is basic or alkaline.- Acidic water can dissolve toxic metals and negatively affect enzyme activity.Adaptations in water – - Some body tissues are more dense than water (e.g., bone); some are less dense (e.g., fats).- Organisms have developed many adaptations to cope with their tendencies to sink or float. People who are fat float easier, stronger, denser people with less body fat sink easier- Water has a high viscosity; many organisms have evolved streamlined bodies that reduce the drag caused by high water viscosity.- To take advantage of water’s viscosity, many tiny marine animals have evolved long, filamentous appendages that increase drag.- Aquatic organisms need variable amounts of essential elements, such as hydrogen, carbon, oxygen, nitrogen, phosphorus, potassium, and calcium to build organic compounds.- Solutes: dissolved substances in water.- Water inside and outside an organism often contains different concentrations of solutes.- Water moves to equalize solute concentrations in different locations.- Semipermeable membranes: membranes that allow only particular molecules to pass through; reduces free movement of solutes.- Osmosis: movement of water across a semipermeable membrane.- Osmotic potential: the force with which a solution attracts water by osmosis.- Osmoregulation: mechanisms organisms use to maintain a proper solute balance.o Hyperosmotic: tissue solute concentrations are higher than surrounding water.o Hyposmotic: tissue solute concentrations are lower than surrounding water.- Sharks and rays convert ammonia, a by-product of protein digestion, into urea.- Most urea is excreted, but some is retained in the bloodstream. This raises the osmotic potential of their blood to that of seawater, which balances water movement.- Animals can be harmed by exposure to abnormal salt concentrations.- Plants growing in salty environments also face major challenges of salt balance (e.g., root uptake of water).Adaptions in gasses – - Plants need carbon dioxide (CO2) for photosynthesis.- CO2 diffuses slowly through water; plants use CO2 faster than it diffuses into leaf tissues.- CO2 is rapidly converted to bicarbonate (HCO3–) or carbonate (CO3–) ions, which accumulate in massive quantities and can be used for photosynthesis.- Even when CO2 and HCO3– are abundant, they diffuse slowly and limit plant growth.- Boundary layer: a region of unstirred air or water that surrounds the surface of an object. Removed gases from this region are slow to be replaced; this further limits carbon availability.- Oxygen gas (O2) in air is 21% by volume; in water it is 1%. Not a problem for aquatic organisms that rise to the surface to obtain O2 from the air (e.g., whales).- The low solubility and slow diffusion of O2 can limit the metabolism of organisms that obtainO2 from the water. O2 can become severely depleted in waters that do not support photosynthesis (e.g., waterlogged sediments, deep water).- Countercurrent circulation is an adaptation where blood and water flow in opposite directions so that the concentration of O2 in water is always greater than the concentration in blood.- In deep oceans, many organisms have low activity rates, which reduces O2 demand.- When an environment becomes completely devoid of oxygen, it is referred to as anaerobic or anoxic.- Some plants (e.g., mangroves) extend their roots above the soil surface to absorb O2 from the air.- Many microbes live in anaerobic environments by using other sources of metabolic energy.Adaptions to Temperature – - Heat causes biological molecules to change shape.- Heat accelerates chemical reactions by increasing molecular movement.- The rate of most biological processes increases 2 to 4 times for each 10°C rise in temperature.- Q10 value: a ratio of a physiological process rate at one temperature to the rate of that process when the temperature is 10°C cooler.- Proteins and other biological molecules become less stable, may not function properly, and may denature (i.e., open up).- Fats become fluid with heat, and stiff with cold.- Thermal pollution: changing the temperature of an environment via human discharges (e.g.,effluent from nuclear power plants).- Some bacteria are thermophilic (heat-loving) and can live at temperatures up to 110°C.- The crystal structure of ice can damage living


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