3.1.7 Water Flashcards

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1
Q

water is a d____ molecule

A

dipolar

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2
Q

why does water form hydrogen bonds?

A
  • water has unevenly distributed charges as the oxygen atom is slightly negative and the hydrogen atoms are slightly positive
  • the opposite charges mean that water molecules are attracted to each other
  • these forces of attraction are called hydrogen bonds
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3
Q

what are the five key properties of water?

A
  • it is a metabolite
  • an important solvent in reactions
  • has a relatively high heat capacity
  • has a relatively large latent heat of vaporisation
  • has strong cohesion between water molecules
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4
Q

what is the significance of water as a metabolite?

A

it is involved in many metabolic reactions such as photosynthesis, hydrolysis and condensation reactions

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5
Q

what is the significance of water being a good solvent?

A
  • polar/charged molecules dissolve readily in water since it is dipolar
  • slight positive charge on hydrogen atoms will attract any negative ions in solutes
  • slight negative charge on oxygen atoms will attract any positive ions in solutes
  • many essential polar substances dissolve in water, allowing them to be transported easily in the blood/xylem
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6
Q

what is the significance of water having a high specific heat capacity?

A
  • can gain/lose a lot of heat/energy without changing temperature
  • therefore acts as a buffer to changes in temperature
  • the internal temperature of organisms remains relatively stable
  • aquatic organisms are provided with a stable environment
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7
Q

what is the significance of water having a large latent heat of vaporisation?

A
  • a lot of energy is required to convert water in its liquid state to a gaseous state
  • means that water provides a significant cooling effect
  • when sweating, a large amount of heat energy from the skin is transferred to the water to evaporate it, this removes a lot of heat and cools the organism
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8
Q

what is the significance of water having a strong cohesion?

A
  • water molecules ‘stick’ together by hydrogen bonds
  • water moves up the xylem in plants due to transpiration as a continuous column of water
  • provides surface tension which enables small invertebrates to move and live on the surface
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9
Q

explain 5 properties that make water important for organisms (5 mark qs)

A
  • a metabolite in condensation/hydrolysis/photosynthesis/respiration
  • a solvent so metabolic reactions can occur and allows transport of substances
  • high specific heat capacity so buffers changes in temperature
  • large latent heat of vaporisation so provides a cooling effect through evaporation
  • cohesion between water molecules so supports columns of water in plants and produces surface tension supporting small organisms
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10
Q

what properties of water make it important in the cytoplasm of cells?

A
  • polar molecule so acts as a solvent
  • solvent so reactions occur faster
  • reactive so it takes place in hydrolysis/condensation reactions
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