Biology Aqa As Year 1 - Section 1

Front 1

(Example question and recall)

Aspartic acid and proline are both amino acids. Describe how two amino acids differ from one another.

Back 1

They would have a different R group

Front 2

Why are lipids useful as storage molecules?

Back 2

Don't dissolve in water, therefore, don't affect osmotic balance of cells have higher calorific value than carbohydrates can yield more energy per gramme oxidation

Front 3

In what ways do the properties of saturated and unsaturated fats differ?

Back 3

Saturated fats are solid and unsaturated fats form oils.

Unsaturated fats have lower m.p. than saturated fats

Front 4

In what way would the structure of a phospholipid differ from this triglyceride?

Back 4

One fatty acid molecule replaced by phosphate molecules

Front 5

'Amino acids are amphoteric.' What does this mean?

Back 5

Their molecules contains both acidic and basic group

Front 6

State how structural differences between starch and cellulose

Back 6

Starch contains a-glucose only and cellulose b-glucose only.

Cellulose is unbranched and starch is branched

Front 7

What is meant by the statement that 'all living things have the same biochemical basis'?

Back 7

All living organisms are made of carbohydrates, lipids and proteins

Front 8

What is a monomer

Back 8

Small units which form a larger molecule

Front 9

What is a polymer?

Back 9

Large molecules made from a large number of monomers

Front 10

Examples of monomers?

Back 10

Monosaccharides, glycerol, fatty acids, amino acids and nucleotides.

Front 11

How does a condensation reaction join two molecules together?

Back 11

It removes a water molecule to form a bond which joins monomers

(look at hint for a diagram)

Hint 11

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Front 12

What is a hydrolysis reaction?

Back 12

Hydrolysis is a reaction that breaks a chemical bond between two molecules, involving the use of a water molecule

Front 13

What are larger carbohydrates made from?

Back 13

Monosaccharide monomers

Front 14

Common monosaccharides:

Back 14

Glucose, galactose, mannose and fructose

Front 15

How are long chain carbohydrates formed?

Back 15

A condensation reaction between two monosaccharides which formed a glycosidic bond


___O___ (glycosidic bond)

Front 16

How are disaccharides formed?

Back 16

Condensation reaction between two monosaccharides

Front 17

What is maltose?

Back 17

Disaccharide formed by two alpha glucose molecules

Front 18

What is sucrose?

Back 18

Disaccharide formed by the condensation reaction of alpha glucose and fructose

Front 19

What is lactose?

Back 19

Disaccharide formed by the condensation of an alpha glucose molecule and a galactose molecule

Front 20

What are the isomers of glucose?

Back 20

a–glucose and ß–glucose

Front 21

Draw the structure of a–glucose

Back 21

Back (Definition)

Hint 21

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Front 22

Draw the structure of ß–glucose

Back 22

Back (Definition)

Hint 22

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Front 23

How are polysaccharides formed?

Back 23

The condensation of many glucose units

Front 24

How are glycogen and starch formed?

Back 24

By the condensation of a–glucose

Front 25

How is cellulose formed?

Back 25

By the condensation of
ß–glucose

Front 26

What is the structure and function of glycogen?

Back 26

1. A highly branched chain of a–glucose molecules
2. Storage of energy in animals

Front 27

What is the structure and function of starch?

Back 27

1. Made of two molecules called amylose and amylopectin
Amylose:helix shaped chain of a–glucose
Amylopectin: branched structure of a–glucose with 1,4 and 1,6 glycosidic bonds.
2.storage of energy in plants

Front 28

What is the structure and function of cellulose?

Back 28

1. Micro fibrils of ß–glucose lying alongside each other. Each myofibril is joined to adjacent ones by hydrogen bonding.
2. Structural strength in cell walls

Front 29

Describe the relationship of structure to function of glycogen.

Back 29

–highly branched which prevents it from dissolving in water and therefore allowing it to be stored, glycogen contains many glucose molecules which are used during respiration to produce energy.

Front 30

Describe the relationship of the structure to the function of starch.

Back 30

–made of amylose and amylopectin, both are large molecules which prevents starch from dissolving in water and therefore allowing it to be stored, starch contains many glucose molecules which are used during respiration to produce energy.

Front 31

Describe the relationship of structure to function of cellulose

Back 31

Cellulose is made of myofibrils of ß–glucose which are joined to each other by hydrogen bonds.
This will give strength to the cell wall.

Front 32

Describe the biochemical test for reducing sugars using Benedict's solution:
Desc

Back 32

1. Prepare the sample
2. Add Benedict's reagent
3.heat 🔥
4. If colour changes from blue to orange/red

Front 33

Describe the biochemical test for non–reducing sugars using Benedict's reagent.

Back 33

1. Prepare the sample
2. Add HCl and boil for 1 minute
3. Add sodium hydrogen carbonate untill neutral
4.add Benedict's reagent
5.heat 🔥
6.if colour changes from blue to orange/red this shows a positive result.

Front 34

Describe the biochemical test for starch using iodine/ potassium iodide.

Back 34

1. Place sample in a test tube
2.add iodine
3. If colour changes from orange to blue/black starch is present

Front 35

What are the two groups of lipids?

Back 35

Triglycerides and phospholipids

Front 36

How are triglycerides formed?

Back 36

Condensation reaction of one molecule of glycerol and three molecules of fatty acid

Front 37

How is an ester bond formed

Back 37

Condensation reaction between glycerol and a fatty acid
RCOOH

Front 38

which part of a fatty acid may be saturated or unsaturated?

Back 38

The R group of a fatty acid

Front 39

What is a phospholipid?

Back 39

Similar to a triglyceride, however, one f the fatty acids of a triglyceride is substituted by a phosphate –containing group

Front 40

Describe the differences between the properties and structures of triglycerides and phospholipids

Back 40

1. Triglycerides are immiscible (cannot mix) as they have hydrophobic fatty acid tails.
2. Phospholipids have a hydrophobic tail and a hydrophilic head so they can be mixed with water and will form miscelles (sub–microscopic congregation of molescules) which can be mixed with water as they form small droplets

Front 41

Describe the emulsion tests for lipids.

Back 41

1. mix the sample with distilled water
2.add ethanol
3.shake
4.change from clear to cloudy shows a positive result

Front 42

describe this molecule

Back 42

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Hint 42

a saturated fatty acid

Front 43

describe this molecule

Back 43

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Hint 43

an unsaturated fatty acid
(has double carbon – carbon bonds

Front 44

what are proteins made up of?

Back 44

monomers called amino acids

Front 45

draw the general structure of an amino acid

Back 45

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Front 46

how do the twenty amino acids that are common in all organisms differ?

Back 46

They differ in their side group (R group)

Front 47

how is a peptide bond formed?

Back 47

A condensation reaction between two amino acids forms a peptide bond

Front 48

How are dipeptides formed?

Back 48

Dipeptides are formed by the condensation of two amino acids

Front 49

How are poly–peptides formed?

Back 49

formed by the condensation of of many amino acids.

Front 50

what are the functional proteins made of?

Back 50

may contain one or more polypeptides

Front 51

what types of bonds are involved in folding polypeptide chains to make proteins?

Back 51

hydrogen bonds, ionic bonds, and disulphide bridges

Front 52

what are proteins used for?

Back 52

a variety of functions within al living organisms

Front 53

Describe the relationship between primary, secondary, tertiary and quaternary structure and protein function?

Back 53

1. the primary structure is folded to make the secondary structure,
2. the secondary structure is further folded to form the tertiary structure,
3. two or more tertiary structures are joined to make the quaternary structure,
4. if the original structure is niot formed correctly there could be a different folding pattern resultiung in a non–functional protein.

Front 54

describe the biuret test for proetins?

Back 54

1. place the sample in a test tube
2. add the biuret solution
3. colour change from blue to mauve (purple) gives a positive result

Front 55

can you relate the structure of proteins to the properties of a variety of proteins?

Back 55

Enzymes have a globular structure with a specific active site formed by specific folding of the protein.
Haemogoblin is a quaternary structure with an iron prosthetic group which helps to carry oxygen around the body for respiration,
actin and myosin form fibres that form muscles.

Front 56

How do enzymes work?

Back 56

each enzymes lowers the activation energy of the reaction it catalyses

Front 57

what is the induced fit model of enzyme action?

Back 57

When a substrate joins with an enzyme the shape of the active site changes and fits around the substrate.

Front 58

Explain what the properties of an enzyme relate to the tertiary structure of is active site and its ability to combine with complimentary substrate(s) to form an enzyme–substrate complex?

Back 58

The folded tertiary structure of the enzyme forms an active site where specific bonds can be formed
this allows the enzyme to be substrate specific
when the substrate bonds with the active site an enzyme–substrate complex is formed

Front 59

Describe the specificity of enzymes?

Back 59

enzymes are able to join with specific substrates due to the structure of the active site
this only bonds with complimentary substrate molecules

Front 60

what is the effect of enzyme concentration on the rate of enzyme–controlled reactions?

Back 60

Increase in enzyme concentration causes an increase in enzyme–substrate collisions increases the rate of reaction.

Front 61

What is the effect of substrate concentration on the rate of enzyme–controlled reactions?

Back 61

increase in substrate concentration causes an increase in enzyme substrate collisions increases the rate of reactions.

Front 62

What is the effect of concentration of competitive and non competitive inhibitors on the rate of enzyme–controlled reactions?

Back 62

increase in concentration of competitive and non–competitive inhibitors decrease in the amount of enzyme–substrate collisions due to blocked active sites decreases the rate of reaction.

Front 63

What is the effect of low temperature on the rate of enzyme–controlled reactions?

Back 63

less kinetic energy causing less collisions so less enzyme substrate complexes are formed which lowers the rate of reaction.

Front 64

what is the effect of a high temperature on the rate of enzyme–controlled reactions?

Back 64

denatures the enzymes so active site changes shape, so substrates can no longer bind with the active site so it reduces the rate of reaction.

Front 65

Describe how models of enzyme action have changed over time?

Back 65

Lock and key mechanisms showed active site as complimentary to substrate while induced–fit mechanism shows an active site that alters as the substrate binds.

Front 66

What is the function of enzymes?

Back 66

Enzymes catalyses a wide range of intracellular and extra–cellular reactions that determine structures and functions from cellular to whole–organism level.