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A Level Biology > Biological Molecules Unit 1 > Flashcards

Biological Molecules Unit 1 Flashcards

1
Q

What’s a monomer

A

Monomers are the smaller units from which larger molecules are made

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2
Q

What’s a polymer

A

Molecules made from a large number of monomers joined together

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3
Q

What are the types of monomers?

A

Monosaccharides, amino acids and nucleotides

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4
Q

What’s an isomer

A

Same molecular formula different structure

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5
Q

What are monosaccharides

A

Monomers of carbohydrates

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6
Q

Examples of monosaccharides

A

Glucose, fructose and galactose

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7
Q

Glucose exists as 2 isomers

A

Alpha and beta

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8
Q

What are disaccharides?

A

Made of 2 monosaccharides. Joined by a glycoisidic bond. Formed via a condensation reaction.

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9
Q

Examples of disaccharides

A

Maltose, lactose, sucrose

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10
Q

What’s a condensation reaction?

A

Joining 2 molecules together and forms a chemical bond and releases water.

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11
Q

What’s a hydrolysis reaction?

A

Breaks chemical bond between monomers and uses water

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12
Q

Types of polysaccharides

A

Starch, cellulose, glycogen

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13
Q

What’s starch created from

A

2 polymers of alpha glucose.

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14
Q

Where’s starch found

A

Starch grains inside plant cells

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15
Q

What’s the function of starch and glycogen?

A

Insoluble store of glucose

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16
Q

Wheres glycogen found

A

In muscle and liver cells on animals

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17
Q

Structure of glycogen

A

Highly branched molecule Has 1-4 glycosidic bonds and even more 1-6 glycosidic bonds than amylopectin. Can be compacted easily. [ fit large amount of glucose in small space) is a polysaccharide of alpha gluc9se

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18
Q

What’s cellulose formed from?

A

Beta glucose

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19
Q

Where’s cellulose found

A

Cell wall of plant cells

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20
Q

What’s function of cellulose

A

Provid3s structural strength to cell wall

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21
Q

Structure of cellulose

A

1-4 glycosidic bonds. Long straight chains line up parallel to eachother. Held in place by many hydrogen bonds. This is a fibril. Provides structural strength due to the number of hydrogen bonds. - individual hydrogen bond is weak

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22
Q

How does the structure of starch lead to its function?

A

Helical so compact
Branched structure increases surface area for rapid hydrolysis back to glucose,so glucose is (easily) released for Respiration;.
Large (molecule) so cannot leave cell/cross
cell-surface membrane
Insoluble - won’t affect water potential

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23
Q

How does the structure of cellulose lead to its function?

A

Many hydrogen bonds provide collective strength.
Insoluble - won’t affect water potential

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24
Q

How does the structure of glycogen lead to the function?

A
  1. Insoluble (in water), so doesn’t affect water
    potential;
  2. Branched helix, so makes molecule compact;
  3. Polymer of (α-)glucose so provides glucose for respiration;
  4. Branched so more ends for fast breakdown
  5. Large so can’t cross the cell membrane
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25
Q

What are the 2 groups of lipids?

A

Triglycerides and phospholipids

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26
Q

How are triglycerides made?

A

Involves 3 seperate condensation reactions with 1 glycerol. Forms 3 ester bonds and 3 molecules of water (since its removed to be bonded)

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27
Q

What are R groups

A

Fatty acids which can be saturated or unsaturated

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28
Q

What’s the difference between saturated and unsaturated fatty acids?

A

Saturated fatty acids only have single bonds between carbons. Whilst unsaturated fatty acids have atleast one double bond between carbons

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29
Q

Properties of triglycerides (how structure results in properties)

A

1) Energy storage- due to large ratio of energy- storing carbon- hydrogen bonds compared to the number of carbon atoms, a lot of energy is stored in the molecule

2) due to the high ratio of hydrogen to oxygen atoms they act as a metabolic water source. Triglycerides can release water if they are oxididised. This is essential of animals in the desert ,such as camels.
3) triglycerides do not affect water potential and osmosis. This is because they are large and hydrophobic, making them insoluble in water.

4) lipids have a relatively low mass. Therefore a lot can be stored without increasing the mass and preventing movement

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30
Q

What’s the structure of phospholipids?

A

Made of a glycerol molecule two fatty acid chains and a phosphate group. (Attached to the glycerol)
The 2 fatty acids also bond to the glycerol via 2 condensation reactions resulting in 2 ester bonds

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31
Q

What happens when phospholipids are put into water?

A

Arrange themselves in 2 layer structure- phospholipid bilayer. Have 2 charged regions so they’re polar, The heads are hydrophilic so they’re attracted to water whilst tails are hydrophobic so they are repelled from water.
This forms a phospholipid bilayer membrane structure which makes up the plasma membrane around the cells

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32
Q

What are proteins made up of?

A

Amino acids. Amino group, carboxylic group, R( variable group) hydrogen.

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33
Q

Describe how amino acids are joined together to form a dipeptide

A

Condensation reaction, water is removed. Peptide bond forms between OH of carboxyl and H of amine group

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34
Q

What is a protein?

A

Polymer, made up of the monomer amino acids

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35
Q

What is the primary structure of a protein?

A

Order of amino acids in a polypeptide chain. This is a polymer.
(All joined by several condensation reactions the polypeptide chain holds the amino acids together this is extra info)

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36
Q

What is the secondary structure of amino acids?

A

The sequence of amino acids causes parts of a protein molecule to bend in a helic shapes or fold in b pleated sheets. Secondary structure held in place by hydrogen bonds.

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37
Q

Whats the location of the hydrogen bonds in the secondary stage?

A

Hydrogen bonds form between the C=O groups of the carboxyl group of one amino acid and the H in the amine group of another amino acid

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38
Q

What’s the tertiary structure of amino acids?

A

The further folding of the secondary structure to form a unique 3D shape. Held in place by ionic hydrogen and disulphide bonds

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39
Q

Wats the location of the ionic and disulfide bonds in the tertiary structure of amino acids?

A

The ionic and disulfide bonds form between the R groups of different amino acids. Disulphide bonds only sometimes occur, as there must be a sulfur in the R groups for this bond to occur (S—-S) (disulphide bond that occurs between 2 different sulfurs)

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40
Q

What’s the quaternary structure of amino acids?

A

A protein made up of more than one polypeptide chain.

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41
Q

What does it mean if a protein denatured?

A

If a protein is denatured, this means that bonds which hold the tertiary and secondary structure in shape break, and therefore the unique 3D shape is lost.(eg enzymes lose their unique active site shape)

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42
Q

Whys the sequence of amino acids the key importance in the definition ?

A

(The exact sequence of amino acids is what determines the ionic, hydrogen and disulfide bonds form in a tertiary structure and where those bonds form determines the unique 3d shape. )So, even if one amino acid in the sequence is different then it will cause the ionic/hydrogen/ disulfide bonds to form in a different location. This results in a different 3D shape
Enzymes will have diff shaped active site(will be non functionaling)
Carrier proteins will have a different shaped binding site (molecules no longer complementary and cannot be transported across membranes

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43
Q

What might cause a change to amino acid sequence?

A

Mutations. Change in dna sequence might code for a different amino acid sequence and therefore,primary structure changes

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44
Q

What’s the role of hydrogen bonds, ionic bonds, and disulfide Bridges in the structure of proteins?

A

The position of the bond, which is determined by the amino acid sequence, determines how the protein folds. Therefore, the position of the bond determines the final 3D shape and the function of the protein,

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45
Q

What are enzymes?

A

Tertiary structure proteins which catalyse reactions.
Whilst enzymes are Relatively large molecules, it’s only a small part of the enzymes that attaches to a substrate to catalyse a reaction. This site is known as active site

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46
Q

What do enzymes do. And models

A

When enzymes attach to the substrate they can lower the activation energy needed for the reaction to occur, and therefore speed up the reaction
Lock and key model and induced fit model

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47
Q

What’s the lock andkey model

A

This model suggests that the enzyme is like a lock and that the substrate is like a key that fits into it due to their complementarity in shape.
It suggests that the enzyme acitive site is a fixed shape and that due to random collisions the substrate can collide and attach to the enzyme. This forms an enzyme substrate complex
Once the enzyme substrate complex has formed the charged groups within the active site are though to distort the substrate and therefore lower the activation energy. The products are then released, and the enzyme active site is empty and ready to be reused

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48
Q

How do non competitive inhibitors affect enzymes

A

Non competitive inhibitors attacu to the allosteric site.this causes the active site to change shape. No longer complementary in shape less enzyme substrate complexes form and can’t be overcome by increasing substrate

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49
Q

What does dna do

A

Deoxyribonucleic acid (DNA) codes for the sequence of amino acids in the primary structure of a protein, which in turn determines the final 3d shape structure and function of protein.
It’s essential therefore that cells contain a copy of genetic code and that it can be passed onto new cells without being damaged
The dna polymer is a double helix

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50
Q

What is RNA and function

A

Is a polymer of a nucleotide formed of a ribose, a nitrogenous base and a phosphate group.
The nutrogenous bases in RNA are adenine, guanine, cytosine, uracil
The function of the RNA is to copy and transfer the genetic code from DNA in the nucleus to the ribosomes. Some RNA is combined with proteins to create ribosomes

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51
Q

What’s MRNA

A

Messenger RNA is a single stranded straight chained molecule, made of bases which are read in triplets called codons
It’s role is to carry the genetic code out of the nucleus to the ribosome for the formation of 1 polypeptide. 1 codon codes for 1 amino acid

mRNA short because its only the length of one gene

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52
Q

What’s TRNA

A

Transfer RNA found in the cytoplasm. It’s single stranded but folded to create a shape that looks like a cloverleaf. This shwp3 ishelf by hydrogen bonds.
The function of tRNA is to attacg one of the 20 amino acids and transfers this amino acid to the ribosome to create the polypeptide chain. Specific amino acids attach to specific tRNA molecules and thusis determined by 3 bases found on the tRNA which are complementary to the 3 bases on mRNA
These are called the anticodon because they’re complementary to the codon on mRNA

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53
Q

What’s RRNA

A

Ribosomal RNA is the type of RNA that makes up the bulk of ribosomes.

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54
Q

What’s the biomedical test for a reducing sugar

A

Benedicts reagent.
1) Add excess Benedicts to the test solution
2) Boil the mixture
3) If a reducing sugar is present the solution will change from blue to green, yellow, orange brick red

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55
Q

What do reducing sugars mean

A

It means they can donate electrons to other molecules to reduce them

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56
Q

Whas the biochemical test for a non reducing sugar

A

Sucrose is a non reducing sugar. Negative result with benedicts reagent.
1) add benedicts regeant and heat if it remains blue the following steps
2) add hydrochloric acid and heat it
3) neutralise the acid with sodium hydroxide
4) add benedicts reagent and boil.
5) if the solution now turns red then a non reducing sugar was initially present

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57
Q

Biochemical test for starch

A

Iodine dissolved in potassium iodide reacts with starch, resulting in a colour change from orange - brown to blue black
Qualitative test accurate conc can’t be determined.

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58
Q

Biochemical test for lipids

A

1) mix sample with ethanol
2) add water
3) milk white emulsion will appear if the result is positive

59
Q

Suggest how glycogen acts as a source of energy

A

Hydrolysed to glucose which is then used in respiration

60
Q

Biochemical test for protein

A

1) add biuret reagent
2) if there’s a positive result it turns purple/ lilac

61
Q

How does low pH affect the rate of enzyme controlled reactions

A

too low a pH will interfere with the charges in the amino acids in the active site due to an excess of H+ ions.
This can break the ionic and hydrogen bonds holding the tertiary structure in place and therefore the active site changes shape. Therefore the enzyme denatures and fewer enzyme - substrate complexes form

62
Q

How does high pH affect rate of enzyme controlled reactions

A

Too high a pH will interfere with the charges in the amino acids in the active site due to an excess of OH- ions
This can break the ionic and hydrogen bonds holding the tertiary structure in place and therefore the active changes shape. Therefore the enzyme denatures and fewer enzyme substrate complexes form.

63
Q

How does enzyme concentration affect enzyme controlled reactions?

A

At a low concentration, enzyme concentration is the limiting factor so as more enzyme is added, the rate increases as there will be more available active sites.
The rate plateaus at high enzyme concentrations because the substrate concentrations the limiting rate.

64
Q

Describe how substrate concentration effects enzyme controlled reactions

A

At low concentrations, the substrate concentrations thelimit8ng factor. As more substrate is added the rate increases as there will be more successful collisions between the enzyme and substrate

65
Q

What’s dna replication

A

Dna replication occurs during interphase. It ensures accurate replication of DNA before a cell divides
The process of dna replication is semi Conservative replication. (New molecule of dna contains one original strand and one strand which is newly synthesised)

66
Q

Process of DNA replication

A

1) DNA helicase seperates the DNA strands by breaking the hydrogen bonds between base pairs
2) each strand acts as a template.
3) Free DNA nucleotides attach to the exposed bases by complementary base pairing
4) DNA polymerase joins nucleotides on new strands forming a phosphodiester bond.this creates the sugar phosphate backbone. H bonds reform
5) each new molecule of DNA contains one original strand and one new strand, made up of new nucleotides.

67
Q

Semi Conservative replication hypothesis

A

Each replicated dna molecule contains one of the original DNA strands strand and one newly synthesised dna strand

68
Q

Function of ATP

A

Immediate source of energy for biological processes. Metabolic reactions in cells must have a constant, steady supply of ATP

69
Q

ATP STRUCT7RE

A

Adenine , a nitrogenous base ribose and 3 inorganic phosphate groups (bc the don’t contain any carbon atoms)

70
Q

How’s ATP produced

A

ATP is made during respiration from ADP, adenine diphosphate, by the addition of an organic phosphate via condensation reaction and using the enzyme ATP synthase.
This takes energy to create

71
Q

How atp an immediate source of energy

A

ATP can be hydrolysed into ADP + Pi using enzyme ATP hydrolase.
The bonds between the phosphate groups are weak and are easily hydrolysed, when the terminal bonds hydrolysed energy’s released
Small amount of energy released

72
Q

How can ATP transfer energy

A

ATP can also transfer every to different compounds. The inorganic phosphate released during the hydrolysis of ATP can be bonded onto different compounds to make them more reactive . This is known as phosphorylation and this happens to glucose at the start of respiration to make it more reactive

73
Q

Properties of ATP. Atp vs glucose

A

Immediate energy souce
1) releases energy in small manageable amount so no energy is wasted (so cells don’t overheat)
2) it’s small and soluble to easily transported around the cell
3)only 1 bond has to be hydrolysed in one step to release energy (glucose would need several bonds to be broken
4)it can transfer energy to another molecule by transferring one of its phosphate groups
5)atp can’t leave cells through membranes(cell can run out of glucose but will always have constant supply of ATP

74
Q

Biochemical test to confirm presence of amylase

A

Add biuret solution, becomes purple
Add start(leave for a bit) test for reducing sugar

75
Q

ATPs uses and properties as an energy source 5 mark

A

1) releases relatively small amount of energy/little energy lost as heat
2) releases energy instantaneously
3) phosphorylates other compounds, making them more reactive
4) can be rapidly re synthesises
5) doesn’t leave cells

76
Q

ATP structure compared with DNA nucleotide

A

1) atp has ribose and DNA has ozy ribose
2) ATP has 3 phosphates and DNA nucleotide has 1 phosphate
3) base is always adenine in atp whilst in dna they vary, (agc or t)

77
Q

Structure of water

A

Bipolar molecule. Has an uneven distributed charge as oxygen is slightly negative and hydrogen are slightly positive

78
Q

Five properties of water

A

Hydrogen bonds form Between water molecules between the oxygen and a hydrogen atom.
1) it’s a metabolite In condensation/eg more
2) solvent so metabolic reactions can occur
3) high specific heat capacity, so buffers changes in temperature
4) has high latent heat of vaporisation, providing a cooling effect with loss of water through evaporation
5) has strong cohesion between water molecules, this supports water coloumns and provides surface tension

79
Q

What does water being a metabolite mean

A

Waters involved in many reactions eg photosynthesis hydrolysis ans condensation
One reas

80
Q

What does water being a good solvent mean

A

Many substances dissolve in it due to the fact that its dipolar. Acts as transport medium as some chemicals dissolve n it eg blood

81
Q

What does water having high specific heat capacity mean

A

A lot of energy is required to raise the temperature of water. This is because some of the heat energy is used to break the hydrogen bonds between water molecules . Prevents large fluctuations in water temp

82
Q

What does water having a large latent Heat of vaporisation mean

A

Lot of energy is required to convert water in its liquid state to a gaseous state. Cooling effect

83
Q

What does water having a strong cohesion mean

A

Water molecules stick together by hydrogen bonds
Provides high surface tension- allows some organism to walk on surface
Tall coloumns of water can be drawn up xylem vessels in tall trees

84
Q

What’s an ion

A

Charged particle that has either chained or lost electrons

85
Q

Sodiums function

A

Used in the co port of glucose because sodium moved by active transport. Creates sodium concentration and affects water potential

86
Q

Hydrogen function

A

Changes the pH of the solutions by making it more acidic
Can also be used to create electrochemical gradients in the production of ATP

87
Q

Iron function.

A

Component of heamaglobin in red blood cells
Haemoglobin binds with oxygen

88
Q

Phosphate funtion

A

Joins nucleotides in dna, used to produce atp
Affects water potential and phosphorylates and is hydrophilic

89
Q

What’s a polymer

A

Long chains made up of many monomers chemically bonded together in a repeating pattern

90
Q

Student investigated difference in reducing sugar of 2 juices. He used colorimeter with each test result.
Describe how results from colorimeter can identify fruit juice containing higher sugar content

A

Higher absorbance (has more sugar)
Lower transmittion (has more sugar)

91
Q

Other method other than using colorimeter to measure the quantity of reducing sugar in a solution

A

Filter and dry the precipitate
Find mass

92
Q

Why would using a colorimeter in investigation improve the repeatability of results

A

Quantitative

93
Q

What is the function of phospholipids

A

To form a phospholipid bilayer in cell membranes and cell organelles

94
Q

Give the differences in the structure and properties of triglycerides and phospholipids

A
  1. Both contain ester bonds
  2. Both contain glycerol;
  3. Fatty acids on both may be saturated or unsaturated;
  4. Both are insoluble in water;
  5. Both contain C, H and O but phospholipids also
    contain P;
  6. Triglyceride has three fatty acids and phospholipid has two fatty acids plus phosphate group;
  7. Triglycerides are hydrophobic and phospholipids have hydrophilic and hydrophobic region;
  8. Phospholipids form bilayer (in water) but triglycerides don’t;
95
Q

Describe the biochemical test for lipids

A

Emulsion test
Add ethanol then water and mix
A milky emulsion forms

96
Q

Explain why a phospholipid has both hydrophobic and hydrophilic regions

A

Phospholipid has hydrophilic head
Since the phosphate group has a negative charge and so attracts water
And a hydrophobic tail
Since the fatty acids have no charge and so repel water

97
Q

Describe how a triglyceride molecule is formed

A

One glycerol and three fatty acids
Condensation and removal of 3 molecules ofbwater
Ester bonds formed

98
Q

Why would scientists use a data logger to measure the length of the root rather than a ruler

A

To increase accuracy because reduces risk of human error

99
Q

Explain why phospholipids can form a bilayer but triglycerides cannot

A

Phospholipid polar/ both hydrophobic and hydrophilic
Triglycerides only hydrophobic
Hydrophilic attracts water

100
Q

If % of unsaturated fatty acids increased how would this increase fluidity

A

Increase in fluidity caused by increased unsaturated fatty acids
Unsaturated fatty acids cause bend in fatty acid tail

101
Q

Give the difference between globular and fibrous proteins

A

Globular are soluble proteins and biochemical function is enzymes and hormones
Fibrous are insoluble proteins and have structural functions
Eg keratin In naiks and hair

102
Q

Describe how a peptide bond is formed between 2 amino acids to form a dipeptide

A

Condensation reaction
Between amine and carboxyl

103
Q

Describe how the secondary structure of a polypeptide is produced by bonds between amino acids

A

Hydrogen bonds
Between NH group of one amino acid and C=O group

104
Q

Explain why 2 proteins have same number of amino acids but different tertiary structure
3 marks

A

Different sequence of amino acids
Form ionic/hydrogen/disulfide bonds in different places
Resulting in different folding and 3d shape

105
Q

Describe how a quaternary protein is formed from its monomers

A

Amino acids joined by peptide bonds
By condensation reaction
Secondary structure is formed by hydrogen bonding
Tertiary structure formed by interactions between R groups
Quaternary structure contains more turn one polypeptide

106
Q

A solution contained mixture of 3 amino acids, scientists passed electric current
Why would 2 move to the negative electrode and one is further away

A

Because positively charged
Spots move different distances bc they have different charge
One spot has 2 amino acids becuase they have the same charge

107
Q

Describe the effect of temp on the rate of activity of amylase
Using gtapj

A

Rate increases from (temp to temp)
Increase in kinetic energy
More successful collisions
Optimum is (highest rate reached on graph)
Above optimum rate or reaction decreases
Bc hydrogen bonds break
Active site changes shape so less enzyme substrate complexes formed

108
Q

Why would reaction come to end / become slower

A

Enzyme denatured breaking of hydrogen bonds
Less enzyme substrate complexes formed

109
Q

Explain how the active site of an enzyme causes a high rate of reaction

A

Lowers activation energy
Induced fit causes active site to change shape
So enzyme substrate complex cause bonds to break

110
Q

Student investigated effect of substrate concentration without inhibitor and it had the largest rate why? 2 marks
(Graph)

A

Increases bc more enzyme substrate complexes are formed
Levels off because all enzyme molecules involved in enzyme substrate complexes

111
Q

Describe the structure of DNA

A

Polymer of nucleotides
Each nucleotide formed from deoxyribose, phosphate nitrogenous base
Phosphodiester bonds
Double helix
Hydrogen bonds between adenine thymine and cytosine guanine

112
Q

Compare and contrast the structure of RNA and DNA 5 marks

A

Both polynucleotides
Both joined by phosphodiester bonds
Dna is a long molecule while RNA is short
Dna has deoxyribose sugar whilst rna has oxyribose
Dna has thymine in base whilst rna has uracil

113
Q

Describe how the structure of DNA is related to its functions 6 marks

A

dna is long so It allows information to be stored
dna is double stranded so each strand can be used as a template for dna replication
Dna has sugar phosphate backbone which provides strength and stability
Dna has weak hydrogen bonds so it can be easily unzipped for dna replication
Dna is a helix so it’s compact
Dnas base sequence allows information to be stored

114
Q

Describe how the structure of DNA results in accurate replication

A

1) 2 strands therefore semi Conservative replication possible
2) hydrogen bonds hold strands together
3) hydrogen bonds weak allows strands to seperate
4)bases act as a template
5) complementary copy
6) DNA has one original strand and only newly synthesised strand

115
Q

Whys DNA helicase important in DNA REPLICATION

A

Because it seperates the DNA strands by breaking the hydrogen bonds so nucleotides can attach

116
Q

Describe the role of DNA polymerase

A

Joins nucleotides
Catalyses condensation reactions
Catalyses formation of phosphodiester bonds

117
Q

Describe how an enzyme can be phosphorilated

A

Attachment of inorganic phosphate
Released from hydrolysis of ATP

118
Q

Whys ATP important in biological processes 4 marks

A

1) releases energy in small amounts
2) broken down in one step
3) phosphorylates
4) reformed

119
Q

What does water being polar mean

A

Acts as solvent

120
Q

Explain how the organic bases in DNA help to stabilise the structure of It

A

Hydrogen bonds between base pairs
Holds 2 strands together
Many hydrogen bonds provide strength

121
Q

Describe how a phosphodiester bonds formed between 2 nucleotides within a DNA molecuke 3 marks

A

Condensation reaction forming phosohodiester bond between phosphate group and deoxyribose and the removal of water
Catalysed by DNA polymerase

122
Q

Name the protein associated with the DNA in a Chromosome

A

Histose

123
Q

Explain why new nucleotides can only be added in a 5’ to 3’ direction 3 marks

A

Dna polymerase synthesises new DNA strands which is specific
Only complementary with 3’ end of strand
Shapes of 5’ end and 3’ are different

124
Q

Give 2 ways in which the hydrolysis of ATP is used in cells

A

To provide energy for other reactions
To add phosphate to other substances & make them more reactive

125
Q

Describe competitive and non competitive inhibition of an enzyme. 5 marks

A

Inhibitors reduce binding of enzyme to substrate
Competitive- similar shape to substrate. Binds to active site. Can be overcome by substrate
Non competitive- binds to allosteric site. Changes shape of active site . Cannt be overcome by adding more substrate

126
Q

What’s a t test

A

Looking for differences between 2 means
Differences are significant

127
Q

How would students know pH of solution didn’t change

A

Use buffer

128
Q

What happens in graph with high temperature when reaction stops earlier and it goes straight across

A

High temp causes denaturation of all of enzyme
Reaction stops sooner because shape of active site changed
Substrate still available but no converted to product

129
Q

How do formation of enzyme substrate complexes increase the rate of reaction? 2 marks

A

Reduces activation energy due to bending bonds

130
Q

Student investigated affect of lipase concentration on the hydrolysis of lipids
He placed pH probe. Why did he not use buffer

A

Student was measuring change in pH
( buffer would maintain pH)

131
Q

How to test piece of food for presence of lipid

A

Dissolve In alcohol then adds water
White emulsion test shows presence of lipids

132
Q

What’s the role of bases on one strand of DNA

A

Determines sequence of amino acids

133
Q

What’s the role of single stranded dna fragments 1)
2) dna nucleotides

A

1)acts as template and determines order of nucleotides
2) joins complementary pairs

134
Q

Arrows in figure 2 show Directions in which new dna strands being produced
Explain why arrows point in different directions 4 marks

A

DNA has antiparallel strands
Shape of nucleotide is different
Enzymes have an active site with specific shape
Only 3’ end can bind with active site of enzyme

135
Q

Compare and contrast the processes by which water and inorganic ions enter cells

A

Both move down concentration gradient
Both move through channels in membrane
Ions can move against a concentration gradient by active transport

136
Q

2 properties of water that would be important in cytoplasm

A

Polar molecule so as solvent
Solvent so reactions occur faster in solution

137
Q

Why is DNA replication described as semi Conservative

A

Each strand acts as template
Dna molecule contains one original strand and one newly synthesised strand

138
Q

Give 2 ways prokaryotic dna is different from eukaryotic dna

A

Non linear
Not associated with protein

139
Q

What’s standard deviation and advantages of it instead of the range

A

Measure of how spread out your repeats are from your mean
Range only diff between higher and lowest value whilst sd shows spread of data around mean
Sd reduces affect of anomalies

140
Q

Name the type of petidase which will hydr9l6se tye bond formed in a polypeptide chain

A

Endopetidase

141
Q

Describe the induced fit model

A

Substrate binds to the active site
Active site changes shape so it’s complementary to substrate
Reduces activation energy

142
Q

Draw diagram to show structure of Triglyceride

A

H
H -C.-OOCR
H -C- OOCR
H.-C.- OOCR
H

143
Q

describe induced fit model

A

before reaction active site not complementary.
shape of active sit changes as substrate binds
bending bonds reduced activation energy

A Level Biology (3 decks)

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