2.2 Water Flashcards

1
Q

What to the hydrogen and oxygen share?

A

Each hydrogen shares a pair of electrons with the oxygen

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2
Q

Why does the oxygen pull the electrons closer?

A

It has a greater affinity for the electrons than the hydrogen

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3
Q

What is the the charge of the oxygen?

A

Slightly negative

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4
Q

What is the charge of the hydrogens?

A

Slightly positive

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5
Q

What type of molecule is water?

A

The different charged regions makes it a POLAR MOLECULE. Because it has two charged regions it is DIPOLAR.

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6
Q

How do water molecules bond?

A

HYDROGEN BONDING. The slightly negative charge on the oxygen atom makes it attract to the slightly positive hydrogen atom of another water molecule.

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7
Q

What do the numerous hydrogen bonds do to waters structure?

A

They make it very stable

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8
Q

What is the biological importance of water?

A

Water is necessary for transport, chemical reactions, temperature control, support, movement and reproduction

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9
Q

What is the structure of water?

A

H2O

Two hydrogen atoms covalently bonded to one oxygen atom

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10
Q

Give an example of how water is used in transport:

A
  • All transport fluids in mammals are water based (e.g: cytoplasm, blood, plasma, tissue fluid)
  • uptake of minerals in soil by plants occurs in solution (in water)
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11
Q

Give an example of how water is used in chemical reactions:

A
  • water is the ideal environment for reactions, photosynthesis, respiration and excretion occur in solution
  • water also acts as a reactant in hydrolytic reactions (e.g digestive enzymes)
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12
Q

Give an example of how water is used in temperature control:

A
  • water remains liquid over a huge temperature range, essential for metabolism and for aquatic organisms to avoid freezing
  • when water evaporates energy is released, this is involved in cooling mechanisms
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13
Q

Give and example of how water is used for support:

A
  • in plants water confers turgidity essential in maintaining maximum leaf surface area, which increases light absorption in photosynthesis
  • in animals water filled tissues contribute to skeletal support
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14
Q

Give an example of how water is used in movement:

A
  • water is involved in nastic movements, for instance the opening and closing of plants
  • earthworms use their hydrostatic skeletons to move, their muscles are able to contract against the watery fluid of the coelom for them to move
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15
Q

Give and example of how water is used in reproduction:

A
  • organisms use water to bring make and female gametes together in the process of fertilisation
  • in mammals the foetus develops in a water filled sac providing physical and thermal stability
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16
Q

What are nastic movements?

A

Those not involving growth in a particular direction

The non directional response to stimulus

17
Q

What is turgidity?

A

It refers to something swollen, giving it structure. Hence why plant cells are full of water, if not they would wilt

18
Q

Why does salt (NaCl) dissolve in water?

A

The positive sodium is attracted to the negative oxygen atom in a water molecule, whilst the negative chlorine is attracted to the positive hydrogen atoms. The salt is then pulled apart (it dissolves)

19
Q

What molecules are insoluble in water?

A

Non polar molecules like lipids because they do not attract to the atoms within the water molecule

20
Q

What does it mean that water has high latent heat evaporation, what is this used in?

A

It takes a lot of energy to break the hydrogen bonds between water molecules. So a lot of energy is used up when water evaporates (high latent heat of evaporation).
Used in cooling mechanisms

21
Q

What is cohesion?

A

Attraction between molecules of the same type

22
Q

Why are water molecules very cohesive?

A

Because of their polarity - water molecules tend to stick together

23
Q

What does waters polarity help it do?

A
  • flow
  • making it good for transport
  • all transport fluids in animals are water based (cytoplasm, blood, plasma)
24
Q

What else does waters polarity make it?

A

A good solvent