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Exam 1 Study Guide Marine Science

Terms in this set (31)

Ask learners to consider how animals (including humans) get the oxygen they need and what happens to the carbon dioxide they produce. They should realise that this happens through breathing using the lungs. Ask learners how animals in the sea (that aren't mammals, which need to breathe in air at the surface) get their gases and they should realise that these gases must dissolve in water. This sets the context for factors affecting the solubility of gases in water.Ask learners if they know the proportion of oxygen in the atmosphere (approximately 21 %).Give learners a table of data showing the solubility of oxygen in water at different temperatures, and compare the values with the percentage in air (they should realise that the amount of oxygen dissolved in water is low compared to the amount of oxygen in the atmosphere).Ask learners to plot a line graph of oxygen solubility against temperature (this will help develop their graph skills). Resource Plus•Show the Drawing Graphsvideo to your learners for tips and advice.Discuss with learners why increasing temperature decreases the solubility of gases such as oxygen (in terms of relative rate of diffusion into and out of the water and the kinetic energy of the gas particles).Provide learners with another table of data showing the solubility of oxygen in water at different salinities and ask them to plot a line graph of this data. Discuss why more saline water dissolves less gas in terms of the ability of water molecules to interact with other solutes when they are already surrounding many salt ions.Provide learners with a third table of data showing changes in oxygen concentrations with depth and ask learners to plot a line graph of this data. Discuss the reasons for the changes in oxygen concentration (e.g. high near the surface due to wave action and mixing with the air increasing diffusion into the water; some learners will be aware of the role of photosynthesis near the surface releasing oxygen into the water, and animals using oxygen in respiration which depletes dissolved oxygen levels as depth increases and light availability reduces and distance from the surface increases) then the gradual increase in oxygen levels again as depth and pressure increase and temperature decreases. Discuss how these changes might impact organisms for example at different depths, in a rock pool on a hot sunny day or in an estuary where fresh water meets the sea water.