Question 1
1
Tufted ducks (Aythya fuligula) are found in lakes and lagoons throughout Europe. They eat molluscs, insects and plants, sometimes from the surface but mostly by diving under the water. The graph shows how the heart rate of a tufted duck changes when diving under the water. \footnotetext{ R. Stephenson, P. J. Butler and A. J. Woakes, "Diving behaviour and heart rate in tufted ducks (Aythya fuligula)", J Exp Biol (1986) 126:341359. Reproduced with permission. }
12 marks
Question 1(h)
1(h)
State the hormone that affects heart rate.
Easystructured1 marks
Answer
adrenaline / epinephrine / noradrenaline / norepinephrine
Question 1
1
Consumption of dark chocolate has been shown to have health benefits. A study was undertaken to see the effects of epicatechin (Epi), a substance in dark chocolate, on the aerobic capacity of leg muscles of mice. A group of adult mice was used to measure the effects of a low dose of Epi given over 15 days. The mice were divided into four groups and given either water or Epi and were either kept idle (no exercise) or made to exercise on a treadmill. After 15 days, the results were analysed. The blood capillary density in leg muscle was measured under the light microscope.
10 marks
Question 1(a)
1(a)
0 marks
Question 1(a)(i)
1(a)(i)
State the significance of the statement: p<0.05.
Easystructured1 marks
Answer
there is a significant «statistical» difference between two experimental values OR there is a less than 5 % chance that the difference is random OR 95 \% or more probability that results are due to the experiment «IV» and not random/can reject the null hypothesis OR there is a relationship/correlation between doing exercise and capillary density OWTTE
Question 1
1
Auxin can be used to promote the development of roots from stem and leafy cuttings in some plants. In a study into the distribution of auxin in the development of these roots, scientists measured the amount of auxin in different leaves of a shoot tip of Petunia hybrida. The figure indicates the numbering of leaves on the shoot, from L1 as the youngest and smallest to L6 as the largest and oldest leaf. The developmental stage of L5 and L6 was very similar, so L5 was not analysed. The stem base is the lowest part of the cutting where roots may form. The graph shows the auxin concentration in the different leaves.
13 marks
Question 1(a)
1(a)
Calculate the difference in the concentration of auxin found in L1 and L6. pmol g-1
Easystructured1 marks
Answer
45 «pmol \(\mathrm{g}^{-1}\) » Allow answers in the range of 44 «pmol \(\mathrm{g}^{-1}\) » to 46 «pmol \(\mathrm{g}^{-1}\) ».
Question 1(b)
1(b)
Identify the relationship between the concentration of auxin and the age of the different leaves.
Easystructured2 marks
Answer
less auxin as the leaves become older/larger OR negative correlation from L1 to L4 L4 and L6 leaves have least auxin concentration OR L4 and L6/older leaves have about the same concentration of auxin/do not have significantly different concentrations Vice versa
Question 1(c)
1(c)
N-1-naphthylphthalamic acid (NPA) is an inhibitor used to block auxin transport. NPA was sprayed onto the leaves of a set of cuttings for 14 days. Development of the roots in control (non-treated) and NPA-treated cuttings was measured 14 days after taking the cuttings. The table shows the influence of NPA on rooting. Analyse the effect of NPA on the formation of roots.
Mediumstructured2 marks
Answer
a. NPA decreased the «mean» number of roots per rooted cutting «by about \(5 \times\) » b. NPA decreased the «mean» length per root «by more than half» c. NPA decreased the «mean» total root length per planted cutting «to about 2 % of control» d. NPA inhibited the formation of roots OR decreased all three measures Accept other correct statements of overall changes in values. The word "mean" is not required. OWTTE OWTTE 2 max
Question 1(d)
1(d)
The scientists also measured the changes in auxin concentration in L6 and the stem base during the early period of root formation. They recorded the concentration in the control and NPA-treated cuttings for 24 hours after taking the cuttings.
0 marks
Question 1(d)(i)
1(d)(i)
Compare and contrast the changes in auxin concentration in the stem base over time for the control and NPA-treated cuttings.
Mediumstructured2 marks
Answer
a. both decrease up to 6 hours/initially b. NPA-treated decrease more/at a faster rate than control «up to 6 hours» c. after 6 hours, control increases while NPA treated continues to fall 2 max
Question 1(d)(ii)
1(d)(ii)
Deduce the effect of NPA on auxin transport between L6 and the stem base.
Mediumstructured2 marks
Answer
ii a. NPA «appears to have» no effect on concentrations/transport of auxin in L6 as control and NPA-treated remain at same «low» level b. NPA «probably» inhibits the auxin efflux pumps/transport «in the leaves» as the levels drop in NPA-treated in stem base «but not in control» c. the transport of auxin to the stem base must occur from younger leaves OR L6 is not the source of auxin in the stem base d. NPA inhibits the auxin pumps/transport «in the leaves» as the levels drop in NPA-treated in stem base OWTTE A valid reason must be given for the mark. OWTTE A valid reason must be given for the mark. 2 max
Question 1(e)
1(e)
Based on all the data presented and your knowledge of auxin, discuss the pattern of auxin production and distribution in the leaves and the possible relationship to root formation in leafy cuttings of Petunia hybrida.
Hardessay3 marks
Answer
a. L1 has the highest concentration of auxin so appears to be/is the main source/the producer of auxin b. as leaves age, they «appear to» decrease the production of auxin c. the stem base is an auxin sink as seen by the accumulation in the control stem base «where roots form» d. high concentration of auxin «in the stem base» promotes root formation Vice versa OWTTE Vice versa 3 max
Question 1
1
A study was conducted to look at the short-term effects of a change in diet on the risk of disease in young adults. The table shows data on the habitual diet of the participants as well as the study diet followed for two weeks.
12 marks
Question 1(c)
1(c)
Total blood plasma cholesterol levels were measured before the study began and once a week after starting the study diet. Mean results are shown in the bar chart, including the standard deviation. Calculate, showing your working, the percentage change in mean cholesterol level after one week on the study diet.
Mediumstructured2 marks
Answer
\(((165-150) \div 150) \times 100 ;\) (=) 10 (\%); Allow up to 167 = 11.3\% 1 mark for correct working if above 167.
Question 1(e)
1(e)
The hypothesis made before the study was that saturated fats in the diet affected the risk of coronary artery blockage and diabetes. Using all the data in question 1, evaluate whether this hypothesis is supported by the study.
Hardstructured3 marks
Answer
Hypothesis is partially supported a.Increased saturated fats in study diet resulted in increase in cholesterol levels; b. cholesterol level is risk for blockage of coronary arteries; Hypothesis is not supported c.high insulin levels are sign of (Type II) diabetes; d.insulin levels were the same in both diets so no increased risk; e. study only 2 weeks long; 3 max
Question 1
1
Type II diabetes, a widespread and challenging health problem, is due to insulin resistance, which results in raised blood glucose. Alpha-glucosidase enzymes catalyse the hydrolysis of carbohydrates. Inhibition of the enzymes slows the absorption of glucose in the intestine and thus slows the rise in blood glucose. A study examined the inhibitory effect of five species of seaweed (Palmaria palmata, Saccharina latissima, Fucus vesiculosus, Ascophyllum nodosum and Alaria esculenta) on alpha-glucosidase. Dried seaweed extracts made with water or ethanol were added to maltose. The solutions were incubated, then analysed for glucose content. The graph shows percent inhibition of alpha-glucosidase with different seaweed extracts compared with uninhibited enzyme activity (control).
structured13 marks
Question 1(g)
1(g)
Compare and contrast the HbA 1 c results of all seaweed and control treatments.
Hardstructured2 marks
Answer
a. all seaweed treatments have less HbA 1 c (than the control); OR A. esculenta and P. palmata have the same \% reduction in HbA1c OR all treatments show low variability; b. A.esculenta IP. palmata have levels of HbA 1 c higher than S. latissima OR the S. latissima has the lowest HbA 1 c ;
Question 1(h)
1(h)
Using all the data, evaluate the evidence for health benefits of adding dried S. latissima to the diet.
HardEssay3 marks
Answer
Benefit 2 marks max: a. (significantly) lowers mass gain so less increase in obesity; b. lowers HbA 1 c so blood glucose levels raised less of the time; c. these factors may decrease progression of diabetes; No benefit 2 marks max: d. does not inhibit alpha-glucosidase; e. so absorption of glucose in the intestine is not slowed; f. study was not performed in humans, so results would be different / seaweed extract may have health consequences in humans OR other factors such as level of activity affect the data; 3 max
Question 1
1
Cyanide, a chemical found in all living organisms, is known to stimulate seed germination in many plant species. Cyanide is also known to be an inhibitor of cellular respiration. Freshly harvested sunflower (Helianthus annuus) seeds were incubated with hydrogen cyanide for different periods of time and then exposed to the conditions required for germination. The graph shows the percentage of seeds that had germinated over fourteen days.
structured12 marks
Question 1(f)
1(f)
Ethylene is a chemical that promotes germination in sunflower seeds. Cyanide is known to activate ethylene production. Four groups of sunflower seed embryos were treated as follows: - D Control: dormant (not yet able to germinate) seed embryos not incubated with cyanide - D Cyanide: dormant (not yet able to germinate) seed embryos incubated with cyanide for 3 hours - ND Control: non-dormant (able to germinate) seed embryos not incubated with cyanide - ND Cyanide: non-dormant (able to germinate) seed embryos incubated with cyanide for 3 hours The graph shows the mean volume of ethylene emission by the four groups of seed embryos measured over a period of 5 hours at 20^ C. State the mean increase in ethylene emission in the dormant sunflower seed embryos due to the presence of cyanide.
Easystructured1 marks
Answer
0.5 nl h^-1 g^-1; Units required Accept answers between 0.4 and 0.5
Question 1(g)
1(g)
Calculate the percentage change in the ethylene emission in the non-dormant sunflower seed embryos due to the presence of cyanide.
Mediumstructured1 marks
Answer
135; Accept answers from 131 and 137.
Question 1(h)
1(h)
Compare and contrast the effects of cyanide incubation on mean ethylene production for dormant (D) and non-dormant (ND) seed embryos.
Mediumstructured2 marks
Answer
Similarity a. both D and ND (seed embryos) produced more ethylene with incubation in cyanide; Difference b. ND (seed embryos) produced more total ethylene than D OR D (seed embryos) show a bigger proportional increase than ND seeds OR D has a bigger spread of data;
Question 1
1
Angora rabbits (Oryctolagus cuniculus) have soft and silky coats with fine hairs that grow about 30 mm per month. These hairs can be collected and used as wool. Hair growth in mammals depends on stem cells in the base of hair follicles called dermal papilla cells. Research was carried out to investigate the role of the WIF1 gene in hair growth. Wool was collected from 6-month-old angora rabbits. Expression of the WIF1 gene was assessed by measuring the quantity of WIF1 mRNA produced in cells taken from each rabbit. The rabbits were divided into groups according to their rate of wool production (low or high). The table shows mean wool production per rabbit in the low and high wool production groups and relative expression of the WIF1 gene. Removed for copyright reasons
structured9 marks
Question 1(c)
1(c)
Identify the control treatment.
Mediumstructured1 marks
Answer
pcDNA / (control is the) plasmid/DNA without the WIF1 gene;
Question 2
2
Though a single nerve cell does not think, millions of them organized as a brain result in thinking. What kind of property does thinking represent? A. Anatomical B. Adaptive C. Extracellular D. Emergent
Easymcq1 marks
Answer
D
Question 5
5
Why do multicellular organisms have emergent properties? They have more genes than unicellular organisms. Properties of unicellular organisms are enhanced by having many cells. All of their genes are expressed whereas unicellular organisms express only some. They show properties that can only result from the interaction of many cells.
Mediummcq1 marks
Answer
D
Question 2
2
A wearable monitor can be used to measure heart rate before and after exercise on an aerobic stepper. A student asked 100 female classmates of approximately 14 years of age to take part in the investigation.
structured0 marks
Question 2(a)
2(a)
0 marks
Question 2(a)(i)
2(a)(i)
Suggest a research question that the student could investigate using this equipment.
Mediumstructured1 marks
Answer
research question (RQ) including independent (IV) / dependent variables (DV); This does not have to be in the form of a question. 2 1
Question 2(a)(ii)
2(a)(ii)
The student plans to conduct the investigation in the school. Identify two variables that should be controlled in this investigation. 1. 2.
Mediumstructured2 marks
Answer
a. temperature of the environment OR same room/gym; b. time spent exercising/resting; c. time of day when the investigation is conducted; d. diet/food/drink/caffeine intake of the participants; e. level of fitness/participation in sport of the participants; Accept other reasonable variables but do not accept age or gender as these are given in the stem. If more than two controlled variables are suggested, mark only the first two. 2 max
Question 2(b)
2(b)
Discuss how the student can ensure that the investigation is conducted in a safe and ethical way.
MediumEssay2 marks
Answer
a. signed consent form by participant/student/parent explaining investigation OR take steps to ensure confidentiality of data/data availability/access to data; b. questionnaire/interview on health status of participants / ensure all participants are healthy; c. responsible adult present/available; d. inform participants they can stop if they feel uncomfortable/unwell; e. check safety of equipment / participants wearing appropriate clothing; 2 max