2020 Paper 1

Question 1

Explain the function of ATP hydrolyse

Answer 1

1. (ATP to ADP + Pi ) Releases energy;

2. (energy) allows active transport of ions

Question 2

Movement of Na+ out of the cell allows the absorption of glucose into the cell lining the ileum

Answer 2

Generates a conc grad for Na+ from ileum into cell

Na+ moving in by facilitated diffusion

Question 3

Describe and explain 2 feature you would expect to find in a ell specialised for absorption

Answer 3

1) large numbers of Chanel proteins for active transport

2) large numbers of mitochondria so make more ATP

Question 4

Describe and explain how amino acids join to form a polypeptide

Answer 4

NH2 group joins to COOH group to form a peptide bond

Question 5

Explain differences in results for sample A and B

Answer 5

Triglycerides decrease because of the action of LIPASE
Triglycerides decrease because of hydrolysis
Triglycerides decrease because of digestion of ester bonds

Question 6

Why did scientists heat sample to 70 degrees for 10 mins

Answer 6

To denature enzymes

So no further digestion

Question 7

Describe the role of micelles in the absorption of fats into the cells lining the ileum

Answer 7

Micelles include bile salts and fatty acids
Make fatty acids more soluble in water
Carry fatty acids to cell of ileum.
Maintain high conc of fatty acids to cell
Fatty acids absorbed by diffusion

Question 8

At this time the rate of blood flow has not yet started to increase in aorta but pressure in left ventricle is increasing

Answer 8

Semi luna valve is closed

Pressure in aorta higher than in ventricle

Question 9

At Q on F3 there is a small increase in pressure and in rate of blood flow in the aorta. Explain how this happens and its importance

Answer 9

Elastic recoil

Maintains blood pressure

Question 10

Right ventricle curve

Answer 10

Same pattern

Lower pressure

Question 11

Heat rate of dog

Answer 11

167

Question 12

Name two other variable the student should have kept constant during this investigation

Answer 12

Temp

Concentration of ethanol

Question 13

Colorimeter and light absorbance

Answer 13

Higher absorbance = more anthocyanin
More membrane damage = more anthocyanin released
E + F greater than G as phospholipids dissolved in ethanol
E greater than F as acid denatures membrane proteins

Question 14

No colorimeter. Describe a method to prepare colour standards and use them to give data fo the total anthocyanin extracted

Answer 14

Known conc of blueberry extract
Dilution series
Compare with colour standards to give conc

Question 15

Describe the role of DNA polymerase in semi conservative replication of DNA

Answer 15

Joins adjacent nucleotides
Condensation reactions
Phosphodiester bonds

Question 16

Describe how an enzyme can be phosphorylated

Answer 16

Attachment of inorganic phosphate

Released from hydrolysis of ATP to ADP and pi

Question 17

Why higher than normal concentrations of cyclin D could result in a tumour

Answer 17

Shorter side interphase
Faster cell divisions
Group of abnormal cells

Question 18

Why death of alveolar epithelium cells reduces gas exchange in human lungs

Answer 18

Reduced SA
Increased diffusion distance
Reduced rate of gas exchange

Question 19

How one antibody can be specific to tick protein anf alpha gal

Answer 19

Have a similar structure

Antibody is complementary

Question 20

Was it an earlier immune response to tick Protein that cause the allergic reaction

Answer 20

Exposure to tick protein is followed by increase in antibody
Secondary faster increase in antibody = memory cells
Antibody increases during allergic reaction
During allergic reaction total antibody increases more than alpha gal antibody
So may be other antibodies

Question 21

Non coding base sequences and where they are positioned

Answer 21

DA that does not code for protein

Between genes

Question 22

Phylogenetic tree

Answer 22

C
T
L
R

Question 23

Evaluate how thus information affects the validity of the phylogenetic tree

Answer 23

More similar than with any other species
High variation in species T
Small sample

Question 24

Null hypothesis ans stats test

Answer 24

No correlation between conc of CO2 and stomata density

Correlation coefficient

Question 25

Increase in atmospheric CO2 conc could result in less transpiration evaluate

Answer 25

Increase in CO2 conc = decrease in stromata density
Decrease stomata = decrease transpiration
Don’t know size of stomata
Don’t know if leaf has changed
Don’t know how long stomata open for
Other factors affect transpiration rate

Question 26

How mRNA is formed by transcription in eukaryotes

Answer 26

HB break 
One DNA strand acts as template 
Free RNA nucleotides align by complementary base pairing 
U = A 
C = G 
RNA polymerase joins nucleotides 
By phosphodiester bonds 
Pre-mRNA is spliced

Question 27

Describe how a polypeptide if formed by translation of mRNA

Answer 27

MRNA attaches to ribosome
TRNA anticodon bind to complementary mRNA codons
TRNA brings specific amino acid
Amino acid join by peptide bonds
Use of ATP
TRNA released
Ribosome moves along mRNA to form the polypeptide

Question 28

Define gene mutation and how they can have no effect or positive effect

Answer 28

Change in bases
Formation of new alleles
No effect = genetic code is degenerate
Positive effect = may result in increased chance of survival

Question 29

Calculate time difference as a percentage decrease

Answer 29

33%

Question 30

Does data in figur 6 show a linear relationship

Answer 30

No
9% per 5

1.42/1.8 % per 5

Question 31

Calculate mean stomata density

Answer 31

171

Question 32

Number of stomata per mm2 per 10 year period

Answer 32

2.7