Unit 2: Biological Molecules Flashcards

1. Water 2. Monomers and Polymers 3. Chemical Elements 4. Key Inorganic Ions 5. Tests

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1
Q

What type of bond holds water molecules together?

A

Hydrogen bonds, which gives water some very important properties

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2
Q

What are hydrogen bonds?

A

Weak forces of attraction that form between molecules or between parts of a larger molecule. E.g. in water there is an attraction between the oxygen atom and each of the hydrogen atoms

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3
Q

Why can hydrogen bonding occur between water molecules?

A

Water molecules are polar, which means there is an uneven distribution of charge. Oxygen atoms attract electrons more strongly than hydrogen atoms.

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4
Q

What do hydrogen bonds cause?

A

Cohesion

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5
Q

Properties of water

A

Between 0 and 100 degrees celsius, water molecules are held together loosely but can move past each other and water remains a liquid. In order to evaporate, H-bonds must be broken to allow the formation of a gas.

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6
Q

Why does ice float on water?

A

At lower temperatures, the molecules have less kinetic energy and move about less, meaning more H-bonds can form and at 0 degrees celsius enough would have formed to hold water molecules in a stationary position - rigid lattice, which holds molecules further apart, therefore it is less dense and floats

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7
Q

Water Properties: Thermal Stability

A

High specific heat capacity (a lot of heat needed to warm it up and therefore has a fairly consistent temperature, which is essential for life)

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8
Q

Water Properties: Freezing

A

Less dense than water so it floats, which insulates the water and prevents it fully freezing therefore living things can survive below the ice

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9
Q

Water Properties: Evaporation

A

A lot of energy is needed to cause evaporation, which is used to cool the surface of living organisms

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10
Q

Water Properties: Cohesion

A

The attraction of water molecules produces surface tension, which creates a habitat on the surface and continuous columns of water to be pulled up the xylem

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11
Q

Water Properties: Solvent

A

As water molecules are polar, water can dissolve a wide range of substances

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12
Q

Water Properties: Reactant

A

Water can be used in a wide range of reactions from hydrolysis to photosynthesis

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13
Q

Water Properties: Incompressibility

A

Water cannot be compressed into a smaller volume which means it can be pressurised and pumped in transport systems or used for support in hydrostatic skeletons

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14
Q

Monomer

A

Single, small molecules

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15
Q

Polymer

A

Long chains of repeated units (repeated monomers)

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16
Q

Carbohydrates (M&P)

A

Monosaccharides and Polysaccharides

17
Q

Proteins (M&P)

A

Amino Acids and Polypeptides

18
Q

Nucleic Acids (M&P)

A

Nucleotides and DNA/RNA

19
Q

Condensation Reaction

A

Making bonds, H2O produced

20
Q

Hydrolysis

A

Breaking bonds, uses H2O

21
Q

Carbohydrates

A

Made of elements C, H and O. Has a general formula of CH2O