2: Water and Life Flashcards

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1
Q

State 4 unusual but very useful types of properties of water.

A
  1. cohesive
  2. adhesive
  3. thermal
  4. solvent
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2
Q

How can the 4 ‘unusual but useful’ types of properties of water be explained? What is this a good example of?

A
  • using the theories of dipolarity and hydrogen bonding

- theories being used to explain natural phenomena

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3
Q

Explain the ‘cohesive’ properties of water in terms of hydrogen bonding and dipolarity. Give an example of a benefit to living organisms this property provides.

A

Explanation:
- water molecules cohere because of hydrogen bonds that form between them

Example:
- strong pulling forces exerted to suck columns of water up to the tops of the tallest trees in tubes called xylem vessels. These columns rarely break

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4
Q

Explain the ‘adhesive’ properties of water in terms of hydrogen bonding and dipolarity. Give an example of a benefit to living organisms this property provides.

A

Explanation:
- dipolarity of water molecules makes them adhere to surfaces that are polar and therefore hydrophilic

Example:

  • adhesive forces between water and cellulose in cell walls in the leaf
  • cause water to be drawn out of xylem vessels, keeping the cell walls moist and able to act as a gas exchange surface
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5
Q

Explain the ‘thermal’ properties of water in terms of hydrogen bonding and dipolarity. Give an example of a benefit to living organisms this property provides.

A

Explanation:
- due to hydrogen bonding, water has high melting and boiling points, high latent heat of vaporization and high specific heat capacity

Example:

  • thermal properties cause water to be liquid in most habitats on earth = suitable for living organisms
  • high specific heat capacity makes its temp change slowly so it is a stable habitat
  • high heat of vaporization makes it an effective coolant in leaves or in sweat
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6
Q

Explain the ‘solvent’ properties of water in terms of hydrogen bonding and dipolarity. Give an example of a benefit to living organisms this property provides.

A

Explanation:
- many substances dissolve in water due to its polarity, including those composed of ions or polar molecules

Example:
- most chemical reactions take place with all of the substances involved in the reaction dissolved in water, so water is the medium for metabolic reactions

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7
Q

What happens in a condensation reaction?

A

two molecules are joined together to form a larger molecule plus a molecule of water

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8
Q

What sort of reactions are anabolic reactions?

A

condensation reactions

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9
Q

What is a dimer?

A

a pair of monomers - single sub-units - bonded together

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10
Q

What is a polymer composed of?

A

a long chain of monomers

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11
Q

What would you call two amino acids joined together?

A

a dipeptide

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12
Q

What sort of reaction joins two amino acids together?

A

a condensation reaction

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13
Q

What would a long chain of amino acids be called?

A

a polypeptide

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14
Q

What bond links amino acids together?

A

a peptide bond

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15
Q

Draw a condensation reaction between two amino acids. (p19)

A

-

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16
Q

Name three macromolecules that are built through condensation reactions.

A
  1. proteins
  2. carbohydrates
  3. lipids
17
Q

What is the basic sub-unit of carbohydrates?

A

monosaccharides

18
Q

What would a condensation reaction between two monosaccharides form?

A

a disaccharide + H2O

19
Q

What does a long chain of monosaccharides form?

A

a polysaccharide

20
Q

What are glycerides made from?

A

fatty acids and glycerol

21
Q

What is the maximum number of fatty acids that can be added to glycerol? What does this form?

A

3 - a triglyceride + 3 water molecules

22
Q

What happens in a hydrolysis reaction?

A

a large molecule is broken down into a smaller molecule

23
Q

What is used up in a hydrolysis reaction?

A

water

24
Q

How is water used in a hydrolysis reaction?

A
  1. -H and -OH split (hence lysis = splitting)

2. -H and -OH needed to make new bonds after a bond in the macromolecule has been broken

25
Q

Give 3 examples of hydrolysis reactions.

A
  1. polypeptides + H2O –> dipeptides or amino acids
  2. polysaccharides + H2O –> disaccharides or monosaccharides
  3. glycerides +H2O –> fatty acids + glycerol