1.6.3 ~ water Flashcards

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1
Q

how much of a cell is water

A

75-90% of the mass of a cell

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2
Q

how is water involved in metabolic reactions

A

it is the medium where metabolic reactions take place in cells

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3
Q

what is water made of

A

-oxygen molecule
-2 hydrogen atoms
-covalent bonded

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4
Q

polarity of water

A

-water is a polar molecule
-although water as a whole is electrically neutral, the sharing of electrons between oxygen and hydrogen atoms is unequal
-the oxygen atom attracts the electrons more strongly than the negative hydrogen atoms, resulting in a weak negatively charged region on oxygen atom (δ-) and weak positively charged region on hydrogen atoms (δ+)
-this results in an asymmetrical shape

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5
Q

dipole in water

A

-separation of charge due to the electrons in covalent bonds being unevenly shared is a dipole
-water molecule has one end that is positively charged and one that is negative so it is a polar molecule

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6
Q

hydrogen bonding in water

A

-hydrogen bonds form between water molecules as a result of polarity between the positive and negative charges regions of adjacent water molecules
-hydrogen bonds are weak so are contently being broken and reforming. however, there large numbers give a strong structure

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7
Q

6 properties of water

A

-an excellent solvent
-high specific heat capacity
-high latent heat of vaporisation
-less dense when a solid
-high surface tension and cohesion
-acts a reagent

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8
Q

water as a solvent

A

-water is a polar molecule so many ions and covalently bonded polar molecules will dissolve in it
-this allows chemical reactions to occur within cells (as the dissolved solutes are more chemically reactive when they are free to move about)
-metabolites can be transported efficiently

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9
Q

specific heat capacity definition

A

The specific heat capacity of a substance is the amount of thermal energy required to raise the temperature of 1kg or (gram) of that substance by 1°C

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10
Q

waters specific heat capacity

A

4200 J/kg°C

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11
Q

what does a high specific heat capacity mean

A

a relatively large amount of energy is needed to raise its temperature

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12
Q

why does water have a high specific heat capacity

A

many hydrogen bonds, takes a lot of thermal energy to break these bonds and a lot of energy to build them, so temperature of water of water does not fluctuate greatly

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13
Q

advantage of high specific heat capacity of water for habitats

A

-buffers temperature change
-able to maintain a constant temperature as water is able to absorb a lot of heat without big temperature fluctuations
-this is important for maintaining temperatures for optimum enzyme activity

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14
Q

specific heat capacity of water useful for transferring heat around the body

A

-water is in blood plasma
-as blood passes through more active regions of the body, heat energy is absorbed but the temperature remains fairly constant
-water in tissue fluid also plays an important role maintaining a constant body temperature

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15
Q

why does water have a high latent heat of vaporisation

A

-to change sate a large amount of thermal energy must be absorbed by water to break the hydrogen bonds and evaporate

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16
Q

why is high latent heat of vaporisation and advantage for living organisms

A

-a little water is required to evaporate for the organism to lose a great amount of heat
-this provides a cooling effect for living organisms, for example the transpiration from leaves or evaporation of water in sweat on the skin

17
Q

why does water have strong cohesion and adhesion

A

hydrogen bonds between water molecules allow for strong cohesion between water molecules

18
Q

what does strong cohesion of water allow for

A

-columns of water to move through the xylem of plants and through blood vessels in animals
-this also enables surface tension where a body of water meets the air, these hydrogen bonds occur between the top layer of water molecules to create a sort of film on the body of water –> allows insects such as pond skaters to float

19
Q

water adhesion

A

-able to hydrogen bonds to other molecules such as cellulose
-also enables water to move up xylem due to transpiration