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what is the biological medium on earth? |
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| all living organism require ___ more than any other living substance |
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| most cells are surrounded by water and cells themselves are about __ water |
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| The abundance of __is the main reason eath is habitable |
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| is water molecule polar or non-polar? |
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| water is a polar molecule mearning? |
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| the opposite ends have opposite charges |
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| __ allows water molecules to form hydrogen bonds with each other |
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| 4 emergent properties of water that facilitate an environment for life are? |
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Definition
1. cohesive behavior 2. ability to moderate temperature 3.expansion upon freezing 4.versatility as a solvent |
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| vollectively hydrogen bonds hold water molecules together, a phemomenon called __ |
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WHat helps the transport of water against gravity in plants? |
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| __ is a measure of how hard it is to break the surface of a liquid |
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| how is surface tension related to cohesion |
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Definition
1. water has a greater surface tension than most other liquids because hydrogen bonds among surface water molecules resis stretching or breaking the surface 2. water behaves as if covered by an invisible film 3. some animals can stand, walk, or run on water without breaking the surface |
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| how does water stabilize air temperatures? |
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Definition
| water stabilizes air temperatures by absorbing heat from water airm and releasing heat to cooler air |
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__ can absorb or release relatively large amounts of heat with only a slight change in its own temperature |
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| __ is the energy of motion |
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| _ is a measure of the total amount of kinetic energy due to molecular motion |
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__ measures the intensity of heat due to the average kinetic energy of molecules |
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Definition
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| the ___ of a substance is the amount of heat that must be absorbed or lost for 1 gram of that substabce to change its temperature by 1 degree celsius |
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Definition
the specific heat of a substance |
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| water's __ minimizes temperature fluctuations to within limits that permit life |
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Definition
water's high specific heat |
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| how does water's high specific heat minimize temperature fluctuations to within limits that permit life? |
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Definition
1. heat absorbed when hydrogen bonds break 2. heat is released when hydrogen bonds form |
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| __ is transformation of a substance from liquid to gas |
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_ is the heat a liquid must absorb for 1 gram to be converted to gas. |
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| as a liquid evaportates, its remaining surface cools, a process called |
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| ___ helps stabilize temperatures in organisms and bodies of water |
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| evaporation cooling of water |
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| why does ice float in liquid water? |
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Definition
| because hydrogen bonds in ice are more "ordered," making ice less dense |
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| what would happen if ice sank? |
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Definition
| if ice sank, all bodies of water would eventually freeze solid, making life impossible on earth |
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| instead, the surface water below which prevents what from happening? |
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Definition
| instead, the surface layer of ice insulates liquid from below, preventing it from freezing and allowing life to exist under the frozen surface |
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| _ is a liquid that is homogenous miixture of substances |
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| __ is the dissolving agent of a solution |
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| __ is a versatile solvent due to its polarity |
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an __ solution is one which water is the solvent |
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Definition
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| why is water an effective solvent? |
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Definition
| because it readily forms hydrogen bonds |
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| when an ionic compound is dissolved in water, each ion is surrounded by a sphere of water molecules called a |
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| not only are ionic compounds dissolves in water, but water can also dissolve __ molecules |
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| even large molecules such as proteins can dissolve in water if they have? |
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| a __ substance is one that has an affinity for water |
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| a _ substance is one that does not have an affinity for water |
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| most biochemical reactions occur in? |
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___ depends on collisions of molecules and therfore on the concentration of solutes in an aqueous solution |
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| _ is the sum of all masses of all atoms in a molecule |
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| numbers of molecules are usually measured in _ |
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| one mole is ___ molecules |
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| is the number of moles per solute per liter of solution |
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| a hydrogen atom in a hydrogen bond between two water molecules an shift from one to the other: |
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Definition
1. the hydrogen atom leaves its electron behind and is transferred as a proton, or hydrogen ion (H+). 2. the molecule wit the extra proton is now a hydronium ion (H30+). 3. the molecule that lost the proton is now a hydroxide ion (OH-) |
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H20 + H20 → H30+ + OH- this process can be described in a simplified way as? |
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Definition
| the seperation of a water molecule into a hydrogen ion (H+) and a hydroxide ion (OH-) |
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| though statisically rare, the __ has a great effect on organisms |
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Definition
| the dissociation of water molecules |
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Changes in concentrations of _ and _can drastically affect the chemistry of a cell. |
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| concentration of H+ and OH- are equal in? |
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| adding solutes called acids and bases, modifies? |
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modifies the concentration of H+and OH- |
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| biologist use something called __, to describe how acidic or basic a solution is |
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| an _ is any substance that increases the H+ concentration of a solution |
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| _ is any substance that reduces the H+ concentration of a solution |
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| the pH of a solution is determined by? |
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| the relative concentration of hydrogen ions |
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| acid solutions have pH values? |
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basic solutions have pH values of? |
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| most biological fluids have pH values in the range of? |
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the internal pH of most living cells must remain close to pH of ? |
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| _ are substances tha minimize changes in concentrations of H+ and OH- in a solution |
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Definition
| an acid-base pair that reversibly combines with H+ |
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one important buffer in human blood and other biological solutions is ? |
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| the chemical equilibrium between carbonic acid and bicarbonate acts as a? |
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Definition
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| how does the equilibrium shift? |
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| the equilibrium shifts right or left as other metabolic processes add or remove H+ from the solution |
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_ refers to rain, snow, or fog with a pH lower than 5.6 |
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| __ is caused mainly by the mixing of different pollutants with water in the air |
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_ can damage life in lakes and steams |
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| effects of acid precipitation on soil chemistry are contributing to ? |
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| the decline of some forests |
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