Top Banner
Data Analysis Practice General [65 marks] 1a. [1 mark] Sockeye salmon ( Oncorhynchus nerka) spend the first years of their lives in the freshwater lakes of Alaska before migrating to marine waters. Their first months in marine waters are spent foraging and growing near the shore line. They then move to offshore regions of the North Pacific Ocean for 2 to 3 years. The graph shows fork length frequency of juvenile O. nerka caught during their first months in marine waters in autumn 2008 and ocean age one O. nerka caught 15 months later during winter 2009 in the North Pacific Ocean. Identify the most frequent fork length for O. nerka caught during autumn 2008 and winter 2009. Autumn 2008: Winter 2009: Markscheme autumn 2008: 175mm or 180mm; (accept either 175mm or 180mm – do not accept in between values) winter 2009: 250mm or 255mm; (accept either 250mm or 255mm – do not accept in between values) (both needed) [2 marks] 1b. Distinguish between the fork lengths of O. nerka in autumn 2008 and winter 2009.
13

Data Analysis Practice General [65 marks]...Data Analysis Practice General [65 marks]1a. [1 mark] Sockeye salmon (Oncorhynchus nerka) spend the first years of their lives in the freshwater

Nov 22, 2020

Download

Documents

dariahiddleston
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Page 1: Data Analysis Practice General [65 marks]...Data Analysis Practice General [65 marks]1a. [1 mark] Sockeye salmon (Oncorhynchus nerka) spend the first years of their lives in the freshwater

Data Analysis Practice General [65 marks]

1a.[1 mark]

Sockeye salmon (Oncorhynchus nerka) spend the first years of their lives in the freshwater lakes of Alaska before migrating to marine

waters. Their first months in marine waters are spent foraging and growing near the shore line. They then move to offshore regions of

the North Pacific Ocean for 2 to 3 years.

The graph shows fork length frequency of juvenile O. nerka caught during their first months in marine waters in autumn 2008 and ocean

age one O. nerka caught 15 months later during winter 2009 in the North Pacific Ocean.

Identify the most frequent fork length for O. nerka caught during autumn 2008 and winter 2009.

Autumn 2008:

Winter 2009:

Markscheme

autumn 2008: 175mm or 180mm; (accept either 175mm or 180mm – do not accept in between values)

winter 2009: 250mm or 255mm; (accept either 250mm or 255mm – do not accept in between values) (both needed)

[2 marks]1b.

Distinguish between the fork lengths of O. nerka in autumn 2008 and winter 2009.

Page 2: Data Analysis Practice General [65 marks]...Data Analysis Practice General [65 marks]1a. [1 mark] Sockeye salmon (Oncorhynchus nerka) spend the first years of their lives in the freshwater

Markscheme

a. shorter salmon in autumn 2008 / longer salmon in winter 2009;

b. wider range of length in fish collected during autumn;

c. higher peaks in winter compared to autumn;

Accept numerical values if clearly stated that one is bigger than the other.

[1 mark]1c.

Suggest a reason for the variation in fork length of ocean age one O. nerka.

Markscheme

genetics/gender/ food availability/diet/water temperature/predators/age

1d.[2 marks]

Protein content in O. nerka was measured to evaluate possible differences during their first 15 months at sea. The graph shows the

relationship between fork length and total protein content per O. nerka caught during autumn 2008 and winter 2009.

Compare the protein content for O. nerka caught during autumn 2008 and winter 2009.

Markscheme

a. both show direct/positive correlation/linear relationship;

b. values for fish collected in winter 2009 are higher than for autumn 2008;

c. many common values in both sets of data;

d. differences between winter and autumn may not be significant because of the overlapping data;

Award [1 max] if only similarity or difference provided.

[1 mark]1e.

Outline the difficulty in predicting the age of O. nerka from fork length.

Markscheme

Difficult because of overlap in fork length between juvenile and ocean age one O. nerka / total protein depends on fork length/size, not

(only) age, so difficult to predict

Page 3: Data Analysis Practice General [65 marks]...Data Analysis Practice General [65 marks]1a. [1 mark] Sockeye salmon (Oncorhynchus nerka) spend the first years of their lives in the freshwater

[1 mark]1f.

Using the data, suggest one reason for the relationship between protein content and fork length.

Markscheme

Growth is a result of incorporating protein / larger fish have more protein/more muscle/more cells.

[2 marks]1g.

Scientists measured mercury levels in different fish. The table shows the results.

Compare the results shown in the table for monkfish and shark.

Markscheme

a. average/mean mercury concentration is higher for shark/lower for monkfish;

b. small number of samples for monkfish (so data less reliable) / large number of samples for shark (so data more reliable);

c. minimum for shark is well below minimum for monkfish / maximum for shark is well above maximum for monkfish;

d. range/standard deviation/variation is greater for sharks;

[1 mark]1h.

Suggest additional information that would be helpful in evaluating these data.

Markscheme

a. age of fish / details of the method used / chemical form of mercury / part of fish analysed / gender / trophic level of fish;

b. statistical calculations eg: t-test/mode;

c. exact location of sampling as some areas of environment may have more mercury pollution than others;

[1 mark]1i.

State which type of fish shows the most variation.

Markscheme

shark (shows the most deviation/variation)

Page 4: Data Analysis Practice General [65 marks]...Data Analysis Practice General [65 marks]1a. [1 mark] Sockeye salmon (Oncorhynchus nerka) spend the first years of their lives in the freshwater

2a.[1 mark]

The graph shows a sigmoid population growth curve.

Identify the phases labelled X and Y.

X:

Y:

Markscheme

X: plateau phase

Y: exponential growth / log phase

(both needed)

[2 marks]2b.

Outline how fossil records can provide evidence for evolution.

Markscheme

a. the sequence in which fossils appear matches the expected sequence of evolution;

b. comparisons with fossils and living organisms (morphology) shows change in characteristics from an ancestral form / OWTTE;

Vestigial organs and homologous structures are acceptable answers.

c. fossils of extinct species show that (evolutionary) change has occurred;

d. fossils can be dated with radioisotopes / geological depth/strata indicates (relative) age/date of organism;

e. can yield DNA for molecular clock analysis;

f. example of any of the above can earn one mark ( eg: reptiles follow amphibians);

[1 mark]2c.

The table summarizes the genome size of several organisms.

Distinguish between the terms genotype and phenotype.

Markscheme

genotype is the genetic make-up/set of alleles (of an organism) while phenotype is the characteristics (expressed/shown in an organism)

[1 mark]2d.

Outline a structural difference between the chromosomes of Helicobacter pylori and Homo sapiens.

Page 5: Data Analysis Practice General [65 marks]...Data Analysis Practice General [65 marks]1a. [1 mark] Sockeye salmon (Oncorhynchus nerka) spend the first years of their lives in the freshwater

Markscheme

chromosome from bacteria has no protein associated/naked DNA / bacteria is circular, H. sapiens is linear / (chromosomes of) H.

sapiens are much bigger/have many more base pairs than bacteria

N.B.: Answer must refer to "chromosomes" not genomes of the two organisms.

[1 mark]2e.

Deduce the percentage of adenine in Oryza sativa if the proportion of guanine in that organism is 30 %.

Markscheme

20 %

[1 mark]2f.

The figure shows a pedigree chart for the blood groups of three generations.

Deduce the possible phenotypes of individual X.

Markscheme

A, B, AB and O

All four phenotypes must be shown to award the mark.

[1 mark]2g.

Describe ABO blood groups as an example of codominance.

Markscheme

allele I and the allele I are (co)dominant as they are both expressed in the heterozygote/AB type blood / OWTTEA B

[1 mark]3a.

The micrograph shows a cell from the root of an onion ( Allium cepa) during mitosis.

Calculate the magnification of the image.

Markscheme

136 (accept answers in the range of 132 to 140)

Page 6: Data Analysis Practice General [65 marks]...Data Analysis Practice General [65 marks]1a. [1 mark] Sockeye salmon (Oncorhynchus nerka) spend the first years of their lives in the freshwater

[1 mark]3b.

Deduce the stage of mitosis shown in the micrograph.

Markscheme

anaphase

3c.[2 marks]The onion (Allium cepa) is an angiospermophyte. The honey bee (Apis mellifera) is an arthropod. State three structural differences

between the cells of an onion and a honey bee.

Markscheme

Award [1] for two correct, [2] for three correct answers.

To award the mark both parts of a comparison must be stated explicitly or unambiguously implied.

[1 mark]3d.

State what is indicated by the presence of polysomes in a cell.

Markscheme

much protein of one type needed/produced by polysomes;

mRNA is being repeatedly translated;

Page 7: Data Analysis Practice General [65 marks]...Data Analysis Practice General [65 marks]1a. [1 mark] Sockeye salmon (Oncorhynchus nerka) spend the first years of their lives in the freshwater

[2 marks]4a.

Diabetes is often associated with the failure of the β (beta) cells in the pancreas, but it is unclear what actually causes this failure.

FoxO1 is a protein which acts as a transcription factor to regulate the expression of genes involved in cell growth. FoxO1 also

regulates increase in number and differentiation in cells such as pancreatic β cells.

A study was conducted using mice lacking the gene for FoxO1 in β cells (IKO) as well as normal (control) mice. Blood glucose levels

after fasting were compared for four groups of mice: young (3 months old) male mice, young (3 months old) female mice, older females

(who have had several pregnancies) and aging males (16–20 months).

Compare blood glucose levels after fasting in young control mice and young IKO mice without FoxO1.

Markschemea. similar/same/nearly same (means)/very small difference/both at a low level;

b. means/averages (all) close to 0.8 mg ml ;

c. difference not (statistically) significant;

d. similar/same/nearly same range of values/spread of data;

All marking points are comparisons between control and IKO mice. Do not award marks for comparisons between male and female

mice.

–1

4b.[1 mark]Estimate the difference between mean blood glucose levels in control and IKO older female mice.

.................mg ml

Markscheme

1 mg ml (accept values between 0.8 – 1)

–1

–1

4c.[2 marks]Aging and having pregnancies are considered to be physiological stresses. Deduce the effect of stress on blood glucose levels.

Markscheme

a. stress causes increase in (mean) blood glucose/sugar;

b. older mice/males/females / aging mice show the increase;

Reject answers that only compare control and IKO mice or only compare male and female mice.

Page 8: Data Analysis Practice General [65 marks]...Data Analysis Practice General [65 marks]1a. [1 mark] Sockeye salmon (Oncorhynchus nerka) spend the first years of their lives in the freshwater

4d.[2 marks]Outline the relationship between blood glucose levels after fasting and lack of FoxO1 in the mice studied.

Markscheme

a. in young mice/3 month old mice lack of FoxO1/IKO/fewer beta cells does not affect/has little effect on blood glucose/sugar;

b. in older females/aging males blood glucose/sugar (much) higher with lack of FoxO1/IKO/fewer beta cells;

[1 mark]4e.

The levels of pancreatic hormones and β cell mass in older female control mice and older female IKO mice lacking FoxO1 were then

investigated.

State the correlation between lack of FoxO1 and pancreatic hormones in mice.

Markschemelack of FoxO1 (correlates) with low/decreased insulin and high/increased glucagon levels.

4f.[3 marks]Referring to the functions of insulin and glucagon, suggest how the differences in hormone levels help to explain the blood glucose

levels.

Markschemea. insulin used to take up/reduce glucose levels (after eating/when blood glucose levels high);

b. decrease in insulin in FoxO1 lacking/IKO mice would cause increase in glucose levels (as less is removed);

c. glucagon (used to convert stored carbohydrate to glucose) to increase glucose levels;

d. increase in glucagon (as seen in second graph, where IKO level higher than control) would mean more glucose added to

blood/increase in glucose levels (on first graph);

e. (on first graph) see older/stressed/adult female mice with much higher glucose levels than young mice;

Page 9: Data Analysis Practice General [65 marks]...Data Analysis Practice General [65 marks]1a. [1 mark] Sockeye salmon (Oncorhynchus nerka) spend the first years of their lives in the freshwater

[1 mark]5a.

Cells in the alveolus wall produce a surfactant. Its function is to prevent alveoli collapse at the end of expiration. Surfactants are used in

the treatment of respiratory system disease in premature babies.

The table shows some of the components of different surfactant preparations.

State the surfactant that contains the least amount of phospholipids.

Markscheme

natural human (surfactant)

[2 marks]5b.

Compare the composition of natural human surfactant with synthetic surfactants.

Markschememain component of all surfactants is phospholipids;

(natural human surfactant ) has less phospholipids (than synthetic surfactants);

(natural human surfactant) has more cholesterol (than (synthetic surfactant) A);

(natural human surfactant) has more free fatty acids than (synthetic surfactant) A and less than (synthetic surfactant) B; (comparison

with both synthetic surfactants required)

(natural human surfactant) has more proteins (than synthetic surfactants);

5c.[1 mark]Phospholipids found in the surfactants form a surface film on the moist lining of the alveoli. Outline how the hydrophilic and

hydrophobic parts of the phospholipids in the surfactants are aligned on the alveolar surface.

Markscheme

hydrophilic groups facing the surface/are in the moist lining/water and hydrophobic tails facing outwards/are in the air

Award [0] for a description of a phospholipid bilayer. The orientation of both hydrophilic and hydrophobic parts must be included.

Page 10: Data Analysis Practice General [65 marks]...Data Analysis Practice General [65 marks]1a. [1 mark] Sockeye salmon (Oncorhynchus nerka) spend the first years of their lives in the freshwater

[1 mark]5d.

The effect of three different surfactants on the growth of three types of bacteria was assessed. Group B streptococci (GBS),

Staphylococcus aureus, and Escherichia coli were incubated with three different concentrations of surfactant (1, 10 and 20 mg ml ).

The bar charts show whether each concentration of surfactant increased or decreased bacterial growth, compared with the growth

without surfactant. The difference in growth is shown as colony forming units (CFU) per millilitre.

Identify the effect of increasing the concentration of synthetic surfactant A on the growth of GBS.

Markscheme

growth reduced (by increases in concentration)/negative correlation

–1

5e.[3 marks]Compare the effect of the three surfactants, synthetic surfactants A and B and the modified human surfactant, on the growth of the

different bacteria at a concentration of 20 mg ml .

Markscheme

The question asks to compare how each surfactant affects each bacterium. However, some responses will instead compare how each

bacterium is affected by each surfactant. Accept both types of answer.

(synthetic surfactant) A decreases growth of GBS most and S. aureus and E. coli much less/slightly;

(synthetic surfactant) B decreases the growth of GBS (and of S. aureus slightly) but increases the growth of E. coli;

modified human surfactant decreases growth of GBS (and S. aureus) but no (significant) effect on E. coli;

GBS greatly inhibited by (synthetic surfactant) A but less/slightly by (synthetic surfactant) B and modified human surfactant;

S. aureus (slightly) inhibited by all three surfactants;

E. coli increased by (synthetic surfactant) B but (synthetic surfactant) A and modified human surfactant have no significant effect;

–1

[3 marks]5f.

Using all the data provided, evaluate the hypothesis that the presence of proteins in surfactants can decrease bacterial growth.

Page 11: Data Analysis Practice General [65 marks]...Data Analysis Practice General [65 marks]1a. [1 mark] Sockeye salmon (Oncorhynchus nerka) spend the first years of their lives in the freshwater

Markscheme

(hypothesis supported as)

(synthetic surfactant) A has proteins and decreases bacterial growth;

(hypothesis not supported as)

modified human surfactant has no proteins and decreases bacterial growth;

(synthetic surfactant) B has proteins and enhances growth (of E. coli);

GBS inhibited more by modified human surfactant which has no protein than (synthetic surfactant) B which has protein;

S. aureus inhibited more by modified human surfactant which has no protein than by the other (surfactants) which have protein;

Do not accept answer without reference to proteins.

[2 marks]6a.

Type I diabetes is an autoimmune disease resulting from destruction of the insulin-producing β cells in the islets of Langerhans. Islet

regeneration can occur when stem cells reach the pancreas after leaving the bone marrow.

Studies have shown a link between CXCL12 and type I diabetes. Mice predisposed to develop the disease were given an inhibitor of

CXCL12 for 3 weeks. The incidence of diabetes was measured after 28 weeks and compared to control mice that were not given the

inhibitor.

Outline the effect of CXCL12 inhibition on the incidence of diabetes.

MarkschemeCXCL12 inhibition initially decreases occurrence of diabetes;

in the first 25 / up to 26/27/28 weeks;

CXCL12 inhibition does not prevent occurrence of diabetes (just delays it) / eventually the same level of diabetes

[1 mark]6b.

Suggest how the breakdown of CXCL12 in the bone marrow may be related to diabetes.

MarkschemeCXCL12 breakdown allows stem cell mobilization reducing incidence of diabetes / stem cells from the bone marrow can regenerate the

islets (in pancreas)

[2 marks]6c.

Evaluate the possible use of isoprenaline in the treatment of diabetes.

Markschemeisoprenaline is an inhibitor of CXCL12 / inhibits synthesis of CXCL12 mRNA;

delays onset of diabetes / allows stem cell mobilization / allows islet regeneration;

does not cure the disease;

Page 12: Data Analysis Practice General [65 marks]...Data Analysis Practice General [65 marks]1a. [1 mark] Sockeye salmon (Oncorhynchus nerka) spend the first years of their lives in the freshwater

6d.[3 marks]

One important chemical in the mobilization of stem cells is a protein, CXCL12, which maintains the stem cells inside the bone marrow.

The breakdown of CXCL12 causes the mobilization of stem cells to the blood vessels.

The graph below shows the mobilization of stem cells and the production of mRNA for CXCL12 when the bone marrow is treated with

two different chemicals (isoprenaline and clenbuterol).

Stem cells in the bone marrow can be forced into blood vessels in a process called mobilization. Mobilization of stem cells from the

bone marrow into the blood vessels represents the basis for modern bone marrow transplantation procedures.

To test the effect of light on the mobilization of stem cells, mice were subjected to a simulated “jet lag” by advancing the light-dark cycle

by 12 hours. This was done by subjecting mice to a 24-hour light period before the results shown in the graph were recorded. The

results were compared to the stem cells in control mice under normal conditions of 12 hours of light ( ) and 12 hours of darkness

( ).

Research is being conducted into treatment for diabetes based on stem cells. Discuss the ethical issues involved in stem cell

research.

Markscheme

suffering of patients could be reduced / diseases could be cured / better treatments developed / might replace treatment with cure;

(possibly) less cost than treating disease/diabetes;

specific example of ethical conflict; (e.g. patient groups support use of embryotic stem cells but religious groups oppose / different views

on the moral status of an embryo)

restrictions on research in some countries due to cultural/religious traditions;

still in experimental stages / risk to patient;

specific example of risk; ( e.g. stem cells developing into tumours / rejection / need for immunosuppressants )

death of early-stage embryos / production of embryos for stem cell research;

use of stem cells from adults/patients could overcome these objections;

[1 mark]6e.

State the maximum number of stem cells per ml blood in the control mice.

Markscheme

83 (allow whole number answers in the range of 82 to 84 )

Determine the number of hours of light needed to release the maximum number of stem cells in blood in control mice.

Page 13: Data Analysis Practice General [65 marks]...Data Analysis Practice General [65 marks]1a. [1 mark] Sockeye salmon (Oncorhynchus nerka) spend the first years of their lives in the freshwater

Printed for St Leonard's College

© International Baccalaureate Organization 2018

International Baccalaureate® - Baccalauréat International® - Bachillerato Internacional®

6f.[1 mark]

Markscheme5 (allow 4)

Do not allow answers with two different numbers.

6g.[2 marks]Distinguish between the trends shown in the number of stem cells per ml blood by the mice subjected to jet lag and the control

mice.

Markscheme

more stem cells are formed in control / jet lag reduces the release of stem cells into blood stream / greater range in control;

graph is rhythmic in control / control has more regular pattern;

greater number of stem cells produced in light period in control, whereas greater number in dark period in jet lag;

graph is shifted to the right in jet lag / stem cells are released later in time in jet lag;

6h.[2 marks]Other studies suggest that a greater number of blood stem cells for transplantation may be obtained if they are harvested during

darkness. Evaluate this hypothesis.

Markscheme(hypothesis supported in control) if stem cells are harvested towards the end of the dark period / (hypothesis supported) as stem cells

start increasing in dark period;

(hypothesis not supported) in control as peak of stem cells occurs during light period/lowest number during dark period;

(hypothesis supported) if patient is jet-lagged as more stem cells are produced in dark period;

[1 mark]6i.

Explain how the amount of mRNA for CXCL12 gives an indication of the amount of protein CXCL12 produced.

Markscheme

mRNA is translated to protein / involved in protein synthesis.

[3 marks]6j.

Compare the effect of isoprenaline and clenbuterol with the normal release of stem cells and the production of mRNA for CXCL12.

Markschemeclenbuterol and isoprenaline both produce more stem cells than control;

clenbuterol releases fewer stem cells than isoprenaline / isoprenaline releases the most stem cells;

isoprenaline produces the least mRNA for CXCL12;

clenbuterol produces the same amount of mRNA for CXCL12 as control;