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Biology 3.1 Biological molecules > water > Flashcards

water Flashcards

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1
Q

in water, which atom’s nucleus has electrons closer to it and why?

A

oxygen because it has more protons in the nucleus which means that there is a greater force of attraction between protons (in nucleus) and electrons(in shells)

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2
Q

in water, what charge does the oxygen atom have?

A

slightly negative (s-)

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3
Q

in water, what charge do the hydrogen atoms have?

A

slightly positive (s+)

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4
Q

what is a hydrogen bond?

A

the electrostatic attraction between a slightly positive charge on the atom of one molecule and the slightly negative charge of a different atom

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5
Q

which properties of water do we only need to know the basics for?

A

transparent
low viscosity(runny)
adhesion
non-compressible

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6
Q

which properties of water are required to know at alevel?

A

cohesive
good solvent
metabolite
high specific heat capacity
high latent heat of vaporisation

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7
Q

why does water have a high specific heat capacity?

A
  • many hydrogen bonds between water molecules
    -lots of energy is needed to overcome these many bonds
    -this happens first before energy can be transferred to the actual water molecule to increase the kinetic energy and heat the water
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8
Q

what is the phrase which says that water helps maintain a stable temperature which is an advantage for living things?

A

water buffers temperature changes

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9
Q

why is water buffering temperature changes important for living things?

A

it keeps temp inside a living thing stable so provides the optimum temperature for reactions and enables thermoregulation

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10
Q

what is specific heat capacity?

A

the amount of energy required to raise the temperature of one gram of a substance by one degree

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11
Q

what is latent heat of vaporisation?

A

the amount of heat energy required to change the state of a substance from a liquid to a gas

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12
Q

why is the latent heat of vaporisation of water high?

A

because a lot of energy is required to break the many hydrogen bonds between molecules

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13
Q

what is sweat made from?

A

water and ions

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14
Q

how is sweat able to evaporate?

A

water molecules absorb heat energy from the body. heat energy breaks the hydrogen bonds and the molecules have more kinetic energy so evaporate

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15
Q

what is the benefit to living things that sweat?

A

evaporation of sweat has a large cooling effect- preventing rises in body temperature so enzymes don’t denature and chemical reactions occur at the optimum rate

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16
Q

why does the evaporation of sweat have a large cooling effect?

A

a lot of energy is removed from the body in order to break the hydrogen bonds in the water molecules of sweat so it can evaporate

17
Q

what is a solvent?

A

a substance that can dissolve another substance (a solute)

18
Q

what are polar substances?

A

substances with a charge (positive or negative)

19
Q

what kind of polar is water and why?

A

dipolar because it has both a slightly positive and negative charge

20
Q

why can’t water dissolve lipids?

A

fats are non polar

21
Q

what are the two benefits or water being a good solvent for living things?

A
  1. substances dissolved in water can be transported around the body/structure
  2. it provides a medium for chemical reactions to take place (collisions=reactions)
22
Q

what is a metabolite?

A

a reactant or product of a metabolic reaction

23
Q

what is a condensation reaction?

A

a chemical reaction that joins two molecules to form a single molecule, releasing a smaller molecule (e.g. water)

24
Q

what is a hydrolysis reaction?

A

a reaction where a molecule of water breaks one or more chemical bonds

25
Q

what is cohesion of water?

A

one water molecule ‘sticks’ to the next via hydrogen bonding

26
Q

explain why water is cohesive?

A

hydrogen bonds form between water molecules due to the slightly positively charged hydrogen atoms of one molecule being attracted to the slightly negative charged oxygen atom of a second molecule

27
Q

explain why water is a good metabolite?

A

water can be a reactant in a chemical reaction because the bonds in the water molecule can break and the atoms can bond with other atoms- water can also be a product that is made in chemical reactions

28
Q

explain why water is a good solvent?

A

can dissolve polar substances because it too has polarity.

For example, the s+ charge on the hydrogen atom allows water molecule to be attracted to s- charges.

An ion would therefore become surrounded by water and be dissolved

29
Q

why is water buffering temperature changes important for aquatic organisms?

A

the temperature of water they live in does not change rapidly- temp more stable than air

30
Q

how can water having a high latent heat of vaporisation be important for plants?

A

transpiration of water (evaporation of water from leaves) cools plants

31
Q

why is water being cohesive important for xylem vessels?

A

water molecules can form a continuous column of water so mass flow can occur. If one water molecule moves then the other water molecules will flow with since they’re joined via h bonds - therefore there can be bulk transport of substances down pressure gradients

so mass flow of water from roots to leaves in xylem

32
Q

how does surface tension of water enable small animals to walk on the surface of water?

A

surface tension of water occurs because the top layers of water molecules do not have any water molecules above them to which they can be attracted - there is a net attraction downwards and surface tension produced supports body of an insect

33
Q

give an example of where water is used as a metabolite in a hydrolysis reaction?

A

ATP is hydrolysed to release the energy for the cell’s activities

34
Q

give two examples of where water is used as a metabolite in a condensation reaction?

A

when amino acids are joined together to produce proteins

join ADP and Pi to make ATP during respiration

35
Q

give examples of how substances dissolved in water can be transported?

A

blood plasma is mainly water and dissolved within this water are glucose, ions, carbon dioxide , urea etc; when blood flows these dissolved substances are transported

plants transport dissolved substances in water of xylem.

Biology 3.1 Biological molecules (8 decks)

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