Lesson 2 part 2
• Heterogeneous Mixtures• Parts of the mixture are noticeably different from one
another
• Homogenous Mixtures• Evenly distributed, hard to tell the difference between one
part and another
• Type of homogenous mixture• When substances dissolve in another• Particles are too small to settle out, filtered or
scatter light
• Water has many properties, but one of the most important is that water acts as a UNIVERSAL solvent• Solvent – Substance that does the dissolving• Solute – Substance that dissolves in the solvent
• The solubility of a substance is its ability to dissolve another substance• Water is very good at dissolving• Hot water can hold more solute (can dissolve more) than
cold water
• Water’s polarity contribute to water as a universal solvent
• Salt is part metal, part nonmetal• Metal and nonmetal bonding form ionic bonds
• Ionic bonds form from IONS• Elements that have a + or – charge• Opposites Attract
• Ocean is filled with dissolved particles• Elements that have opposite electrical charges are called
SALTS• This makes a Saline solution• Na, Cl, Sulfate, Magnesium, Calcium, Potassium, Bicarbonate
• Distilled water = no salinity • Fresh water is .01% salt or less• Ocean average is 3.5% salt or more
• Every liter has 1.2 ounces of salt
• Water’s excellent ability to dissolve solutes means it is carrying materials with it• Water does the same in all organisms
• Where do these salts come from?• Fresh water & streams contain salts• Rivers dump into the oceans
• 4 billion tons of salts are emptied into the oceans each year
• Water also evaporates• Leaves behind salts
• Inside the Earth• Deep Sea Vents
• From the Atmosphere• Wind and Rain carry minerals• Human made
• Only removed by incorporating into rocks, sediments and organisms
• Marine organisms are designed to live in the salt water
• Brackish = in between salty or fresh• Mangrove forests and salt marshes
• Called estuaries• Where rivers meet oceans• Many juvenile organisms live here
• “Nursery of the Sea”
• Also protect coastlines from erosion
• Marine organisms go through Osmosis• Water moves from low salinity (high water concentration)
to high salinity (lower water concentration
• Osmoconformers-• Do not attempt to control solute/water balance• Their internal concentration varies as the salinity in the
water around them changes• Most can only tolerate a very narrow range of salinity
• Osmoregulators– These organisms control their internal concentrations– Can generally tolerate a wider range of salinities than
osmoconformers– Some animals require different amounts of salt for
different life-cycles– This can be done in a variety of ways such as secreting
very little urine or using specialized glands to secrete salts as examples
• Osmoregulation – Individual cells control the balance of water• Mangroves will release salt from their leaves
• Some sea turtles and marine birds have special salt glands that remove excess salt
• In high salt environments, fish and other organisms lose water to the salty sea • Must drink more water• Adding more salts
• Need a way to remove the excess salts and maintain homeostasis• Constant internal environment• Opposite for Freshwater Fish
• This way cells stay the same size
• Marine MAMMALS• Do not drink sea water
• Get water from the food they eat and have a higher urine salt concentration
• Maintain neutral buoyancy• Float, sink
Less dense than water