October 2021 Past Paper

Question 1

Suggest how protein analysis could enable ecologist to classify the larvae to the individual species instead of family (2)

Answer 1

. Compare amino acids sequence from sample
. Against sequence of identified insects

Question 2

Explain why the ecologist worked upstream from the first sample (2)

Answer 2

. Uncaught organism would flow downstream
. Working upstream will prevent more organism being caught than would be actually present in the sample area

Question 3

Suggest why quadrats were placed in the middle of each stream (1)

Answer 3

.To minimise effect of banks
. Similar flow of water

Question 4

Conclude and explain the effects of water temperature on the biodiversity of insects with aquatic larvae (2)

Answer 4

. The lower the temperature the lower the biodiversity
. Less kinetic energy for enzyme action

Question 5

Identify one other abiotic factor which is affected by the altitude and explain why this may reduce your confidence in ur conclusion (2)

Answer 5

. Higher altitude lower oxygen level
. Not enough oxygen available for respiration / only temp is tested

Question 6

Name domain x and describe how all the organism in this domain from those in other domains (2)

Answer 6

. Eukarya
. Nucleus /80s ribosomes/ membranes bound organelles

Question 7

What is the level of classification for y and z (1)

Answer 7

Kingdom

Question 8

Name groups y and z (1)

Answer 8

Y = plants
Z = animals

Question 9

Name one other distinguishing feature of y and Z used to place them in these groups (1)

Answer 9

. Y Plants cellulose cell wall
. Z no cell wall

Question 10

Suggest how told of ATP provides evidence that all organism have evolved from this single common ancestor (3)

Answer 10

. ATP used by all living organism
. As the universal energy currency
. For nearly all biochemical reaction / so must have common gene

Question 11

State the classification level given in the binomial name of an organism (1)

Answer 11

Genus + species

Question 12

Describe 2 ways in which meiosis in an animal is different from meiosis in a plant (2)

Answer 12

. Centrioles produces spindle fibres
. Cytokinesis / division of cytoplasm involves cleavage formation of new cell membrane

Question 13

In mitosis the cell formed during cytokines would re enter the cell cycle explain why this does not occur in the following the production of sperm cells (1)

Answer 13

Sperm cells Fully differentiated so cannot re enter the cell cycle

Question 14

Name one source of genetic variation during sexual reproduction that does not result from meiosis (1)

Answer 14

Random fertilisation

Question 15

Conclude why commercial apple growers in the UK are concerned that crossing the climate change boundary could result in lower yield of apples (4)

Answer 15

. Increased atmospheric temperature
. Trees that flower due to warmer air temperatures could flower earlier
. Day length not affected by climate change
. Cross pollination cannot take place
. Lower rates of pollination

Question 16

State whether the region of the protein labelled H contains amino acids which are hydrophobic or hydrophilic (2)

Answer 16

. Hydrophilic
. In contact with water / in aqueous solution

Question 17

Explain why blood test is preferable to either sampling the amniotic fluid surrounding the foetus or sampling tissue from the placenta (2)

Answer 17

. Non invasive / does not involve taking tissue from placenta
. No risk of test causing miscarriage or loss of foetus

Question 18

Determine the population which are homozygous dominant (2)

Answer 18

Square root 0.16
1-0.4=0.6

Question 19

Conclude why the allele frequencies for D and d are not constant (2)

Answer 19

. They are selected against a phenotype
. Population is not isolated / immigration and emigration takes place

Question 20

Both plants heterozygous for height of plants -Tt (1)

Answer 20

Phenotypes- tall short
3:1

Question 21

Both plants are heterozygous for height and flower colour Tt Pp (1)

Answer 21

9 tall purple
3 tall red
3 short purple
1 short red

Question 22

What is meant by the term linkage and explain why Mendel’s law or independent assortment only applied if the gene are not linked (2)

Answer 22

. Linkage gene present on the same chromosome
. Can only seperate independently if on different chromosomes

Question 23

State the null hypothesis (1)

Answer 23

No significant difference between the observed and expected number of each phenotype

Question 24

Use ur calculated value of chi^2 and data from the table to explain the conclusion (5)

Answer 24

. 7.36< critical value
. Of 7.82
. At 3df probability of 0.05
. Chi^2 very close to critical value
. The difference were not significant

Question 25

Explain how the information shown disproves one gene- one polypeptide hypothesis (1)

Answer 25

More than one polypeptide synthesised from same gene

Question 26

Explain why mutation in an exon might not affect the primary structure of a protein (1)

Answer 26

Some amino acid have more than one codon

Question 27

Describe how functional mRNA for dystrophin is produced and suggest why the mutation to exon 50 results in a shorter form of dystrophin in a person with DMD (5)

Answer 27

. DNA copied into mRNA . Description of role of enzymes . Contains exon and introns . Splicing can only take place up to exon 49 . So mRNA is shorter

Question 28

Suggest why mRNA does not contain exon 15 even though the mutation is in exon 50 (1)

Answer 28

Splicing between mRNA for exon 49 cannot bind to mRNA for 51

Question 29

Suggest why a person treated with a molecular patch to reduce the symptoms of DMD would still be able to pass on mutation to the next generation (1)

Answer 29

Therapy only in muscle tissue not germ-line

Question 30

State the main type of competition present (1)

Answer 30

800m it is infraspecific 1000m it is inter specific

Question 31

Identify 3 density dependant factors that could affect distribution (2)

Answer 31

Food Predators Disease

Question 32

Explain one advantage and disadvantage of this to species A (3)

Answer 32

. Species A can live at high altitude where there is less oxygen . Higher oxygen affinity means it can absorb more oxygen . Disadvantages is haemoglobin does not release oxygen as easily to the tissue

Question 33

Explain why evolution of these 2 species from the same common ancestor is an example of sympatric speciation (2)

Answer 33

. Both live in the same area . No physical / geographic barrier to interbreeding

Question 34

Explain how natural selection could account for the evolution of these 2 species (3)

Answer 34

. B. mutation (in gene for haemoglobin) (1) .gave birds with mutation for higher oxygen affinity (1) .more likely to survive and reproduce (1) .and pass on allele for high oxygen affinity to offspring (1)

Question 35

9 marker

Answer 35

HUMAN GENOME Identify genetic cause of disease / more accurate diagnosis • better prediction of the effect of drugs / improved design of drugs /develop new and improved treatments for disease. • sample size too small • all European origin / do not represent different ethnicities • anonymous so don’t know details of health of individuals / cannot relate findings to {genetic disorders / cancer} 100 K PROJECTS • people in sample selected based on their genetic disorders / cancer status • large samples so can identify variation • more ethnicities / not just Europe • include male / female / different ages • projects do not include eg., Africa, South America, Indian sub-continent • so not wholly representative of whole human population MALARIA / ANOPHELES • malaria still killing 1 000 000+ people per year/ • more people dying from malaria than genetic conditions • need to improve drug / insecticide development to control malaria more effectively • need to sequence genomes to find ways to combat high mutation rate in Plasmodium and Anopheles