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A Level Biology OCR > 2.2 Biological Molecules > Flashcards

2.2 Biological Molecules Flashcards

1
Q

Why is water a good habitat?

A

It has a high specific heat capacity due to its hydrogen bonds, and doesn’t experience rapid temperature changes.

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2
Q

What is a benefit of water having a high latent heat of evaporation?

A

Lots of energy is used when water evaporates by breaking hydrogen bonds, so organisms can use water to cool themselves e.g. sweat

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3
Q

What is cohesion/surface tension of water and why is it useful?

A

Water molecules are attracted to eachother, helping them to transport substances e.g. transpiration

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4
Q

Why is water a good solvent?

A

The partial charges are attracted to the charges on ions and surround them, seperating the ion.

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5
Q

Water is less _____ when solid.

A

Dense

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6
Q

Why does ice float on the surface of water?

A

Water molecules are held further apart by hydrogen bonds making a lattice structure which is less dense than liquid water.

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7
Q

What is the difference between a and b glucose?

A

a glucose has the OH level whereas b glucose has the OH reversed.

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8
Q

How is glucose structure suitable for its function?

A

Soluble to be transported, and its chemical bonds contain a lot of energy

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9
Q

Monosaccharides are joined together by _______ bonds.

A

Glycosidic

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10
Q

What is a condensation reaction?

A

When compounds are added together in a reaction to release/eliminate a water molecule.

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11
Q

What is a hydrolysis reaction?

A

When water is added to split a polymer into its monomers.

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12
Q

What is maltose made of?

A

2 a-glucose

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13
Q

What is sucrose made of?

A

a-glucose and fructose

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14
Q

What is lactose made of?

A

Galactose and glucose

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15
Q

What is starch?

A

Plant storage molecule of glucose

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16
Q

What is starch made up of?

A

Amylose and amylopectin

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17
Q

What monomer is starch made of?

A

a-glucose

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18
Q

What is the structure of amylose?

A
  • Unbranched a-glucose chain

- Coiled and compact

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19
Q

What is the structure of amylopectin?

A

-Branched a-glucose chain

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20
Q

What bond connects 2 a-glucose molecules in a straight line?

A

a 1-4 glycosidic bond

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21
Q

What bond connects 2 a-glucose molecules as a branch?

A

a 1-6 glycosidic bond

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22
Q

What is glycogen?

A

Animal glucose storage molecule

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23
Q

What is the structure of glycogen?

A

Branched molecule of a-glucose

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24
Q

What is the benefit of having many branches on a storage molecule?

A

Glucose can be released by hydrolysis quickly, and its more compact.

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25
Q

What is cellulose?

A

Makes up plant cell walls

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26
Q

What monomer is cellulose made of?

A

b-glucose

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27
Q

What is the structure of cellulose?

A

Straight chains of alternating b-glucose, which are hydrogen bonded together to form microfibrils and macrofibrils

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28
Q

What bond connects b-glucose monomers?

A

b 1-4 glycosidic bonds

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29
Q

What are the properties of cellulose?

A

High tensile strength, fully permeable, difficult to digest

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30
Q

What are triglycerides composed of?

A

3 fatty acids ester bonded to a glycerol

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31
Q

By which process are triglycerides made?

A

Esterification

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32
Q

What is the difference between saturated and unsaturated fatty acids?

A

Saturated have no C=C double bond but unsaturated do

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33
Q

What are phospholipids comprised of?

A

2 fatty acds, a glycerol and a fatty acid

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34
Q

The phosphate group on a phospholipid is ________.

A

Hydrophilic

35
Q

Why are triglycerides good for energy storage?

A

They’re insoluble, and their bonds contain a lot of chemical energy

36
Q

What are the main uses of triglycerides?

A

Energy source, Insulation, Buoyancy, Shock absorption

37
Q

What is the main use of phospholipids?

A

Comprise the cell surface membranes of cells- phospholipid bilayer

38
Q

What is cholesterol?

A

A steroid

39
Q

What is the function of cholesterol?

A

To bind to fatty acid tails in the phospholipid bilayer and make the membrane more rigid

40
Q

Amino acids are joined by _______(amide) bonds.

A

Peptide

41
Q

What is primary protein structure?

A

Sequence of amino acids

42
Q

What is secondary protein structure?

A

The initial folding due to hydrogen bonds, causing a-helix and b-pleated sheets

43
Q

What is tertiary protein structure?

A

The final 3D structure of a single polypeptide due to different bonds

44
Q

What is quaternary protein structure?

A

Multiple polypeptide chains joining together to form one protein e.g. haemoglobin

45
Q

What can be used to study protein structure?

A

Computer modelling

46
Q

What are hydrophobic and hydrophilic interactions?

A

Hydrophobic groups clump together, pushing hydrophilic groups to the outside of the molecule

47
Q

Globular proteins are ______ in water due to ______ _______.

A

Soluble due to hydrophobic and hydrophilic interactions

48
Q

What is a conjugated protein?

A

A protein that contains a non-protein prosthetic group attached

49
Q

What type of functions do globular proteins normally have?

A

Hormones and enzymes

50
Q

What type of functions do fibrous proteins normally have?

A

Structural such as collagen

51
Q

What are some properties of fibrous proteins?

A

Structurally strong, insoluble, metabolically unreactive

52
Q

What is the function of collagen?

A

To provide mechanical strength to connective tissue such as bones, tendons and arteries

53
Q

What is the structure of insulin?

A

2 polypeptide chains held together by disulfide bridges

54
Q

What is the function of amylase?

A

Enzyme that calalyses the breakdown of starch into glucose

55
Q

What is the function of keratin and why does its structure make it suitable for this?

A

Function is to make things hard and waterproof. It is rich in cysteine so contains a lot of disulfide bridges

56
Q

What are the properties of elastin?

A

Strong and extensible, able to recoil back to its original shape after being stretched.

57
Q

What is the use of Ca2+ ?

A

Involved in transmission of nerve impulses and insulin secretion, also a cofactor for many enzymes

58
Q

What is the use of Na+ ?

A

Involved in nerve impulses, muscle contraction and osmoregulation

59
Q

What is the use of K+ ?

A

Involved in nerve impulses, muscle contraction and osmoregulation.

60
Q

What is the use of H+ ?

A

Acidity, and photosynthesis

61
Q

What is the use of (NH4)+ ?

A

Nitrogen source for plants

62
Q

What is the use of (NO3)- ?

A

Nitrogen source for plants

63
Q

What is the use of (HCO3)- ?

A

Maintains blood pH

64
Q

What is the use of Cl- ?

A

Involved in CO2 transport, action potentials, cofactor for amylase

65
Q

What is the use of (PO4)3- ?

A

Involved in photosynthesis and respiration, and for making P biological molecules.

66
Q

What is the use of OH- ?

A

pH regulation

67
Q

What does Benedicts reagent test for?

A

Sugars

68
Q

How do you modify the tests for sugars to account for non-reducing sugars?

A

Add dilute HCl then heat in water bath, then neutralise with sodium carbonate

69
Q

What colour shows for a low concentration of glucose in the benedicts test?

A

Green/yellow

70
Q

What colour shows for a medium/high concentration of glucose in the benedicts test?

A

Orange/ brick red

71
Q

Other than the benedicts test, what else can test for glucose?

A

Test strips coated in reagent which have a colour change with glucose which you compare to a chart

72
Q

What can be used to test for starch?

A

Adding iodine solution, and will change to blue-black if starch is present

73
Q

What tests for proteins?

A

The biuret test

74
Q

How do you carry out biurets test?

A

Add NaOH, then CuSO4 - goes from blue to purple if protein is present.

75
Q

What does the Emulsion test test for?

A

Lipids presence

76
Q

How do you carry out the emulsion test for lipids?

A

Shake substance with ethanol, then pour into water. Milky layer appears if lipid is present.

77
Q

What is a colorimeter?

A

A device that measures the strength of a coloured solution by shining a light through it and seeing how much light is absorbed by the solution.

78
Q

What is a biosensor?

A

A device that uses a biological molecule to e.g. an enzyme to detect a chemical. The enzyme produces a signal which is converted to an electrical signal via a transducer

79
Q

What is chromatography?

A

A method used to seperate a mixture, to then identify the components.

80
Q

What are the 2 types of chromatography?

A

Paper chromatography and Thin-layer chromatography

81
Q

What is the mobile phase?

A

The liquid solvent, e.g. water or ethanol

82
Q

What is the stationary phase?

A

Where the molecules cant move, so the chromatography paper or the TLC plate

83
Q

How do you calculate the Rf value?

A

Rf= spot distance/solvent distance

A Level Biology OCR (28 decks)

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