June 2022 Component 2 Past Paper

Question 1

What is meant by polymorphism (1)

Answer 1

. Many alleles
. For same game
. Cannot be maintained by mutation alone

Question 2

State the null hypothesis (1)

Answer 2

. No statistical difference between the observed and expected results

Question 3

Explain how the vegetation of the soil type at site A and B shown in image 1.2 could have caused the difference in banding of the snail at the 2 sites (3)

Answer 3

. Vegetation acts as a selection pressure
. Site A short grass and dark soil more bands and site B fewer bands provide better camouflage
. Better camoflaged increased chance of survival
. So can reproduce and pass on advantageous alleles

Question 4

Suggest how the location and habitat of the sites has led to significant changes in frequency of the allele between the 2 population of this species of snail (3)

Answer 4

. Sea acts a geographical barrier between the population / allopathic speciation
. Different selection pressures
. Different alleles for random mutation will be different in each population
. Genetic drift due to no interbreeding

Question 5

Describe the production of amylase was triggered in the barley seeds

Answer 5

. Absorption of water
. Gibberlins released by embryo/ hydrolysed
. Caused release of amino acids from aleurone layer
. Amino acid used to synthesise amylase

Question 6

Explain why it was important that the same concentration of agar and the same concentration of starch was used in all Petri dish (2)

Answer 6

. Agar no effect on rate of diffusion
. Starch same number of molecules to digest
. Both are controlled variable

Question 7

Explain why range bars are drawn on a graph (2)

Answer 7

. From maximum to minimum
. Increased reliability

Question 8

Suggest a reason for the decrease in amylase activity after 8 days of germination (3)

Answer 8

. Leaves appear at 8 days
. Which is able to photosynthesis
. So plant can produce it own glucose
. Therefore less starch needed to be broken down

Question 9

Identify A-G (3)

Answer 9

A
A
F
C

Question 10

Name the type of epithelium found in both B and the trachea and describe the function of one tissue in both location (3)

Answer 10

. Cillated
. B = moves blastocyst/ fertilised ovum
. Trachea move mucus out of breathing system

Question 11

Explain why the cell harvested from the grafian follicle is a secondary occyte and not a female gamete (2)

Answer 11

. Has not completed meiosis / meiosis 2 only completed on entry of sperm
. Chromosome still have 2 chromatids / has not released second polar body

Question 12

Describe how the entry of more than one sperm into the secondary oocyte would be prevented (2)

Answer 12

. Cortical reaction releases content of cortical granules
. Zona pellicuda thicken

Question 13

Suggest why the type of IVF shown in image 3.2B has a higher rate of success in producing an embryo (2)

Answer 13

. In B sperm does not have to digest a path to secondary oocyte / does not need acrosome reaction
. In B nucleus injected directly into 2nd oocyte
. A may no be able to penetrate the zona pellicuda

Question 14

Explain the advantage to the zygote of this unequal division of cytoplasm during the formation of the secondary oocyte (2)

Answer 14

. Zygote contains nearly all of the cytoplasm
. So can divide rapidly with less time needed between cell division

Question 15

Name the tissue in plant where these specialised protein molecule would be found and explain why the solution used in the hydroponic systems needs to be oxygenated (3)

Answer 15

. Endodermis
. Cadmium have to be actively transported into cells
. Synthesis of ATP

Question 16

State the type of variation in all 3 population (1)

Answer 16

. Continuous

Question 17

Exaplin why it would be inappropriate to use either a chi test a student t test to determine the significant difference between the survival of seedlings grown from seeds collected from A and B (2)

Answer 17

. Cannot use chi2 because data is continuous
. Cannot use t test because data is not normally distributed

Question 18

Scientists conducted a long term project to reduce cadmium concentration to safe level in a habitat with a cadmium concentration of 15.au.. evaluate decision (4)

Answer 18

. At high conc only C can survive
. But C can only survive at Cd above 10 Au
. So would die out as Cd falls
. So need to grow B then A
Because B would die out when Cd falls below 2au

Question 19

Type of reaction and bond (2)

Answer 19

Condensation reaction
Ester
Glycosidic
Peptide

Question 20

Deduce the identify of these bases giving reason for your answer (3)

Answer 20

Base X = guanine
Base Y = cytosine
. X is a double ring and Y is a single ring
. Cannot be adenine and thymine as T not found in RNA

Question 21

Explain why the addition of dideoxyribonucleotide to end of a DNA strand prevent further bases being added to the chain (1)

Answer 21

. DNA polymerase active site is not complementary

Question 22

Explain why the fragments have seperated as shown (3)

Answer 22

. Fragments are negatively charged
. Some move towards the positive electrode
. Smaller fragments move faster
. Because they can move through the pore in the gel more easily

Question 23

State one medical advantage of using NGS rather than Sanger sequencing (1)

Answer 23

. Faster diagnosis
. Treatment can be tailored to individual patients

Question 24

Find epu

Answer 24

28 epu

Question 25

Explain why the microscope would need to be recalibrated before calculating actual size when using an objective lens of a different magnification (1)

Answer 25

. Eyepiece graticule is a fixed scale but values of 1 epu differ at different magnification . Stage micrometer appears to have a diffrent size at diffrent magnification

Question 26

Find mm

Answer 26

2.7mm

Question 27

Describe evidence that cats produce multiple offspring (1)

Answer 27

Several graffian follicle are visible

Question 28

Structure Y is a primary follicle. Describe the stages in oogenesis that occur during the maturation of a primary follicle (2)

Answer 28

. Primary oocytes undergo meiosis . To produce a secondary oocyte and the first polar body

Question 29

State the type of cell diving that produces both primary oocyte and primary spermatocytes and explain the significance of this process(2)

Answer 29

. Mitosis . Large number of sperm + increase chance of fertilisation

Question 30

State what is meant by an X -linked condition (1)

Answer 30

Carried out on X chromosome

Question 31

Suggest why individuals such has 3 and 8 want genetic counselling (2)

Answer 31

. Find out if they are carriers . May want to know the risk of having sons with DMD . Know whether to screen the embryo if they are pregnant