Unit 2: Biological Molecules Flashcards Preview

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Flashcards in Unit 2: Biological Molecules Deck (21):
1

What type of bond holds water molecules together?

Hydrogen bonds, which gives water some very important properties

2

What are hydrogen bonds?

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

3

Why can hydrogen bonding occur between water molecules?

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

4

What do hydrogen bonds cause?

Cohesion

5

Properties of water

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.

6

Why does ice float on water?

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

7

Water Properties: Thermal Stability

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)

8

Water Properties: Freezing

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

9

Water Properties: Evaporation

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

10

Water Properties: Cohesion

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

11

Water Properties: Solvent

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

12

Water Properties: Reactant

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

13

Water Properties: Incompressibility

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

14

Monomer

Single, small molecules

15

Polymer

Long chains of repeated units (repeated monomers)

16

Carbohydrates (M&P)

Monosaccharides and Polysaccharides

17

Proteins (M&P)

Amino Acids and Polypeptides

18

Nucleic Acids (M&P)

Nucleotides and DNA/RNA

19

Condensation Reaction

Making bonds, H2O produced

20

Hydrolysis

Breaking bonds, uses H2O

21

Carbohydrates

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