Question 1
1
Diabetes in Youth is a study that examined diabetes (type I and type II) among children and adolescents in the United States. The graphs show the rate per year of new cases of type I and type II diabetes among young people (aged less than 20 years) by ethnicity between 2002-2005.
15 marks
Question 1(d)
1(d)
3 marks
Question 1(d)(i)
1(d)(i)
Compare the relative proportions of type I and type II diabetes between the different ethnic groups.
Mediumdata_response2 marks
Answer
Europeans/E have lowest rate of type II / only Europeans/E (10+) have a higher rate for type I (than type II); API/NA 10+ rate higher for type II (than type I); LA/A rates for both similar at 10+; NA(10+) has the lowest cases of type I but highest number of type II / NA under 10 have lowest rates for both types;
Question 1(d)(ii)
1(d)(ii)
Suggest a reason for the different rates of type II diabetes among the ethnic groups. Skeletal muscle fibres normally respond to insulin by absorbing glucose. Failure of skeletal muscle to respond to insulin is a major factor in the development of type II diabetes. A study was undertaken to investigate the effect of plasma lipids on the process of glucose absorption in response to insulin by muscle fibers. Muscle was bathed in a lipid solution for 5 hours. The lipid was then washed out over the next 3 hours. The graph shows the level of plasma fatty acids and the activity of an enzyme involved in glucose absorption in response to insulin over the period of the study. (Values are means ± standard error)
Mediumshort_answer1 marks
Answer
different genetic factors (affect fat metabolism); (rise) due to increase in fat/carbohydrate intake/junk food/low in fibre; "western" diet (in US) very different from traditional diets;
Question 1
1
Dementia is a term used to describe a group of symptoms that are caused by a decline in brain function. People with dementia have problems with memory, language and behaviour. Alzheimer's disease is the most common cause of dementia. Scientists investigated the effect of a drug called donanemab on people with Alzheimer's disease. They divided them into two groups: - The treatment group received regular injections of a solution containing donanemab. - The control group received regular injections of a solution without donanemab. The scientists used the Alzheimer's Disease Rating Scale (ADRS) to measure brain function. The lower the score on this scale, the worse the brain function. The scientists calculated the mean ADRS score for each group at intervals over 76 weeks. They then calculated the mean change from their initial score at the start of the investigation (baseline). Their results are shown in the graph.
structured10 marks
Question 1(d)
1(d)
SNAP-25 (Synaptosomal-Associated Protein) is a protein found in the brain. In a different investigation, scientists measured the concentration of SNAP-25 in the cerebrospinal fluid (CSF) of three groups of people: - 36 people without Alzheimer's disease (No AD) - 18 people with Alzheimer's disease who had mild dementia (AD mild) - 24 people with Alzheimer's disease who had severe dementia (AD severe) Their results are shown in the box-and-whisker plot. Estimate the median concentration of SNAP-25 in CSF for the AD mild group. ng L^-1
Easystructured1 marks
Answer
280 ( ng L^-1 ); Accept answers in the range 270-280.
Question 1(e)
1(e)
Using your knowledge of box-and-whisker plots, state what the data point shown as a triangle represents.
Easystructured1 marks
Answer
a. outlier; b. (both values) are more than 1.5 times the interquartile range/IRQ above the third/upper quartile/maximum height; 1 max
Question 1(f)
1(f)
Using all the information provided, evaluate the use of SNAP-25 concentration as a potential marker to help confirm a diagnosis of Alzheimer's disease.
Hardstructured3 marks
Answer
Supporting statements: a. (both) AD groups have a higher (median) level (of SNAP-25) than healthy people; b. great/high overlap for mild and severe AD BUT less/little overlap between no AD and the other groups; Non supporting statements: c. ranges/values of (all) groups overlap; d. (so) differences may not be significant/reliable OR (so) cannot distinguish between healthy people and Alzheimer's disease/mild dementia and severe dementia; e. small sample size for AD groups (so less representative of population); f. used only two groups for dementia / only looked at mild and severe dementia; If response only supports or doesn't support the use of SNAP-25 Max 2 awarded Responses need to cover both support and non-support but do NOT need to specifically say if a statement does support/not support as long as a conclusion is drawn. 3 max
Question 1
1
Bumblebees (Bombus terrestris) are insects that have both individual and social learning capacities. Scientists trained individual bumblebees to push either a blue tab or a red tab on a puzzle box to rotate the lid, exposing a reward consisting of a sucrose solution. Individual trained bumblebees were then mixed with untrained bumblebees to determine if the trained ones could teach the untrained ones how to expose the sucrose solution. All groups had the same number of bumblebees. Experimental groups: - B: 1 bumblebee trained to open the blue tab plus untrained bumblebees - R: 1 bumblebee trained to open the red tab plus untrained bumblebees - C (control): no trained bumblebees, only untrained bumblebees The bumblebees in each group were allowed to try and open the puzzle box. Untrained bumblebees were considered to have become "learners" when they opened the puzzle box twice. The line graph shows the number of learners per day in the different groups.
Data Response10 marks
Question 1(f)
1(f)
Determine which percentage of the B+R group had an LPI of 28 or less.
MediumData Response1 marks
Answer
50 (\%); Allow any values ranging from 47\% to 53\% (accept decimals)
Question A2
A2
7 marks
Question A2(c)
A2(c)
Explain how diet can reduce the consequences of phenylketonuria (PKU).
Mediumstructured3 marks
Answer
a. PKU caused by deficiency/ lack of enzyme (tyrosine hydroxylase); b. phenylalanine cannot be converted/metabolized (to tyrosine) so builds up in blood and tissues/remains high; c. so extra sources of phenylalanine in the diet must be controlled/reduced; d. diet should include fruit/grain/vegetables/special formula milk; e. diet must be undertaken very early in life; f. to reduce brain damage/mental retardation; g. symptoms occur from three/four months; Do not credit any references to genes.
Question 2
2
0 marks
Question 2(b)
2(b)
Explain the causes, consequences and treatment of phenylketonuria (PKU).
Mediumstructured3 marks
Answer
causes: genetic/inherited (homozygous recessive) disorder / mutation in (gene for) enzyme that converts phenylalanine into tyrosine / lack of phenylalanine hydrolase/PAH; consequences: phenylalanine converted to phenylketone / mental retardation / brain damage / seizures; treatment: low-phenylalanine diet / example of substances that cannot be eaten; (eg any food containing protein / aspartame)
Question 2
2
A student used two different methods to measure the left ring finger joint angles in 120 healthy people. The metacarpophalangeal (MCP), proximal interphalangeal (PIP) and distal interphalangeal (DIP) joint angles were measured while the finger was extended (straight) or flexed (bent). The box-and-whisker plots show the angle measurements at the different joints obtained for both methods.
structured0 marks
Question 2(a)
2(a)
0 marks
Question 2(a)(ii)
2(a)(ii)
Identify what is indicated by the circles in the plot.
Easystructured1 marks
Answer
outliers;
Question 2(b)
2(b)
Deduce whether method 2 is a good substitute for method 1 .
Mediumstructured1 marks
Answer
yes, as the results/medians/(IQR) ranges for both are very similar; Do not accept means instead of medians.
Question 8
8
What is a characteristic of the human Y chromosome? A. It is made of DNA and histones covered by phospholipids. B. It contains some genes that are not present on the X chromosome. C. It is the largest chromosome in the human karyotype. D. It has a condensed length of approximately \(100 \mu \mathrm{~m}\).
Easymcq1 marks
Answer
B
Question 2
2
Hemophilia is a sex-linked disease that affected some members of royal families in Europe during the 19th and 20th centuries.
0 marks
Question 2(a)
2(a)
0 marks
Answer
a parental alleles shown as \(\mathrm{X}^{\mathrm{H}}\) and \(\mathrm{X}^{\mathrm{h}}\) (female) and \(\mathrm{X}^{\mathrm{H}}\) and Y (male); b Punnett square with genotypes of offspring shown as \(\mathrm{X}^{\mathrm{H}} \mathrm{X}^{\mathrm{H}}\) and \(\mathrm{X}^{\mathrm{H}} \mathrm{Y}\) and \(\mathrm{X}^{\mathrm{H}} \mathrm{X}^{\mathrm{h}}\) and \(\mathrm{X}^{\mathrm{h}} \mathrm{Y}\); \cline { 2 - 3 } \multicolumn{1}{c|}{} & \(\mathbf{X}^{\boldsymbol{H}}\) & Y \(X^{\boldsymbol{H}}\) & \(X^{\boldsymbol{H}} X^{\boldsymbol{H}}\) & \(X^{\boldsymbol{H}} Y\) \(X^{\boldsymbol{h}}\) & \(X^{\boldsymbol{H}} X^{\boldsymbol{h}}\) & \(X^{\boldsymbol{h}} Y\) \end{tabular}
Question 2(a)(i)
2(a)(i)
Draw a Punnett square to show all the possible genotypes of Queen Victoria's children.
Mediumstructured2 marks
Question 2(a)(ii)
2(a)(ii)
Deduce the genotype of Queen Victoria's daughter Alice.
Mediumstructured1 marks
Answer
\(\mathrm{X}^{\mathrm{H}} \mathrm{X}^{\mathrm{h}}\);
Question 2(c)
2(c)
Explain gene linkage and its effects on inheritance.
Hardstructured2 marks
Answer
a located on the same chromosome; b genes/gene loci close together (on the same chromosome); c do not follow (the law of) independent assortment; d more chance of recombination if genes are further apart; e inherited together unless crossing over/recombination occurs; f ratios of offspring in dihybrid crosses are different from expected/non-Mendelian OR more offspring with parental phenotype combinations than expected; 2 max d a cortical reaction (after first sperm nucleus enters the egg); b vesicles/cortical granules release their contents/enzymes (from the egg/zygote); c zona pellucida/glycoprotein coat/outer coat hardened / fertilization membrane formed; d enzymes of sperm/acrosome cannot digest (hardened coat) OR glycoproteins/ZP3 (in zona pellucida) altered so sperm cannot bind; 2 max
Question 2
2
0 marks
Question 2(a)
2(a)
0 marks
Question 2(a)(ii)
2(a)(ii)
State two alleles in blood groups that are codominant.
Easystructured1 marks
Answer
(alleles for blood groups) A and \(\mathrm{B} / \mathrm{I}^{\mathrm{A}}\) and \(\mathrm{I}^{\mathrm{B}}\)
Question 2
2
In a strain of soybeans, high oil content (H) in seeds is dominant to low oil content (h) and four seeds in a pod (F) is dominant to two seeds in a pod (f). A farmer crosses two soybean plants, both with high oil content and four seeds in a pod. The offspring have a phenotypic ratio of 9: 3: 3: 1.
0 marks
Question 2(a)
2(a)
0 marks
Question 2(a)(i)
2(a)(i)
Identify the genotypes of the soybean plants with high oil content and four seeds in a pod that were used in the cross.
Easyshort_answer1 marks
Answer
\(\mathrm{HhFf} \times \mathrm{HhFf} /(\) both ) HhFf;
Question 2(a)(ii)
2(a)(ii)
Determine the genotypes of the gametes and offspring using a Punnett grid.
Mediumcalculation2 marks
Answer
gametes HF Hf hF hf HF HHFF HHFf HhFF HhFf Hf HHFf HHff HhFf Hhff hF HhFF HhFf hhFF hhFf hf HhFf Hhff hhFf hhff all gametes shown correctly on Punnett grid; all offspring genotypes correct;
Question 2(a)(iii)
2(a)(iii)
Identify the phenotypes of each part of the phenotypic ratio.
Easyshort_answer2 marks
Answer
ratio phenotypes 9 high oil four seeds; 3 high oil two seeds; 3 low oil four seeds; 1 low oil two seeds; Award [1] for any two correct phenotypes.
Question 2(b)
2(b)
The image shows the karyotype of a person who developed as a female.
0 marks
Question 2(b)(i)
2(b)(i)
Deduce the reason for the person developing as a female.
Mediumdata_response1 marks
Answer
no Y chromosome