IB Questionbank Biology11.The table below shows the level of hemoglobin measured in two different groups of athletes.

Hemoglobin /grams per 100 cm3Number ofathletes testedStandard deviation /grams per 100 cm3Group A12.62000.8Group B11.92203.2Which of the following statements is correct?A.Results from group B are more accurate because more athletes were tested.B.Results from group B are more reliable because it has a higher standard deviation.C.More athletes have their hemoglobin concentration close to the mean in group A than in group B.D.These results indicate that the level of hemoglobin follows a normal distribution.(Total 1 mark)

2.What does a small standard deviation signify?A.The data is not correlated.B.The data is widely spread around the mean.C.The data shows a close relationship between two variables.D.The data is clustered closely to the mean value.(Total 1 mark)

3.What do error bars on graphs show?A.If the data is correct or not.B.How variable the data is.C.Which result is closest to the true result.D.What statistical technique was used to eliminate incorrect results.(Total 1 mark)

4.Which hypothesis can be tested using the t-test?A.The difference in variation between two samples is not significant.B.The difference between observed values and expected values is not significant.C.The change in one variable is not correlated with a change in another variable.D.The difference between the means in two samples is not significant.(Total 1 mark)

5.The levels of iron in liver tissue from 12 rats fed on beef and 11 rats fed on plant oils were compared using the t-test to see if there was a significant difference at the 5% level.Part of the table showing the critical values for the t-test is shown below.

Degrees of freedomp = 0.1p = 0.05p = 0.01p = 0.001191.7292.0932.8613.883201.7252.0862.8453.850211.7212.0802.8313.819221.7172.0742.8193.792231.7142.0692.8073.767What is the critical value above which the two samples can be considered significantly different?A.2.086B.2.080C.2.074D.2.069(Total 1 mark)

6.The t-test is used to test the statistical significance of a difference. What is that difference?A.Between observed and expected resultsB.Between the means of two samplesC.Between the standard deviation of two samplesD.Between the size of two samples(Total 1 mark)

7.What does the following scatter graph show?A.No correlation between these variablesB.Strong positive correlation between these variablesC.Strong negative correlation between these variablesD.Weak negative correlation between these variables(Total 1 mark)

8.The graph below shows the correlation between the biomass of a marine worm, Arenicola, and the percentage of organic nitrogen in the sand where it lives.[Reproduced with permission from PJ Hayward Animals of Sandy Shores (1994) The Richmond Publishing Co. Ltd.]What statement can be made from the data?A.The increase in the biomass of the worm is due to an increase in the percentage of organic nitrogen.B.There is no relationship between the biomass of the worm and the percentage of organic nitrogen.C.The increase in the percentage of organic nitrogen is due to an increase in the biomass of the worm.D.As the biomass of the worm increases so does the percentage of organic nitrogen.(Total 1 mark)

9.In which of the following cells can more than one nucleus be found?A.An unfertilized eggB.NeuronC.Sertoli cellD.Muscle fibre(Total 1 mark)

10.Which functions of life are found in all unicellular organisms?A.growth, response and nutritionB.differentiation, response and nutritionC.metabolism, meiosis and homeostasisD.growth, metabolism and differentiation(Total 1 mark)

11.Which statement is part of the cell theory?A.Cells are composed of organic molecules.B.Cells have DNA as their genetic material.C.Cells have cytoplasm surrounded by a membrane.D.Cells come from pre-existing cells.(Total 1 mark)

12.Below is a micrograph of an E. coli bacterium undergoing reproduction.[Source: www.bio.mtu.edu/campbell/prokaryo.htm]The scale bar represents 0.5 m. How long are both cells in total?A.5.0 106 mB.5.0 109 mC.2.5 106 mD.2.5 109 m(Total 1 mark)

13.The grey partridge (Perdix perdix) is a species of bird that is found on farmland. Sparrowhawks (Accipiter nisus) and buzzards (Buteo buteo) are birds of prey that kill and feed on birds, including grey partridge. The number of grey partridges in a region of southern England was monitored from 1970 to 2004. The numbers of sparrowhawks and buzzards, seen from sampling positions during regular observation periods, were counted. The results are shown in the graph below.

[Source: Watson, M et al. 2007. Journal of Applied Ecology. Vol 44. Pp 972982. Reproduced with the permission of Wiley Blackwell.]

(a)Outline the trends, over the period of time shown in the graph, in the number of grey partridges, buzzards and sparrowhawks.Grey partridges: .................................................................................................................................................................................................................................................Buzzards: ...........................................................................................................................................................................................................................................................Sparrowhawks: ..................................................................................................................................................................................................................................................(3) The density of grey partridge (number per square kilometre) varied considerably in different areas within the study region. The graph below shows the correlation between the density of grey partridges and the density of birds of prey.[Source: The Journal of Applied Ecology by BRITISH ECOLOGICAL SOCIETY. Reproduced with permission of BLACKWELL PUBLISHING LTD. in the format Journal via Copyright Clearance Center]

(b)(i)Identify the correlation between the density of grey partridges and birds of prey.......................................................................................................................................................................................................................................................(1) (ii)Suggest a hypothesis to account for this correlation.............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2) The highest density of birds of prey was found in areas used for recreational shooting. In these areas, other species of partridge were bred and released. Food and shelter were provided for the released birds. These measures tended to increase the number of both released and wild birds.The causes of death of grey partridge were investigated in one of the areas that was used for recreational shooting. The pie chart below shows the causes of death. (c)(i)Calculate the percentage of deaths due to birds of prey.......................................................................................................................................................................................................................................................(1)

(ii)Using the data provided, discuss the causes of the correlation between the density of grey partridges and the density of birds of prey...................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3) (d)Suggest a conservation measure that would be most likely to prevent the extinction of grey partridges from southern England.........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(1)(Total 11 marks)

14.C[1]

15.D[1]

16.B[1]

17.D[1]

18.B[1]

19.B[1]

20.B[1]

21.D[1]

22.D[1]

indent3_14;indent1(a)(i);right;accept;attention;af;band;levelhead1;tablehead;quote;ex;Default;CM12;CM13;CM3;CM4;CM15;CM6;CM7;CM17;CM14;CM18;CM11;CM16;CM5;CM8;CM10;CM9;CM19;CM20;graph;23.A[1]

24.D[1]

25.C[1]

26.(a)grey partridge numbers/pairs reduced;buzzard numbers increased;sparrowhawk numbers no clear trend/no overall rise or fall/constant/stable/fluctuates;3 (b)(i)negative correlation/inverse proportion/bird of prey densityfalls as partridge density rises1 (ii)partridges eaten by birds of prey;fewer partridges present where more birds of prey present / morepartridges present where fewer birds of prey present;partridges move to areas with fewer birds of prey;fewer birds of prey enable growth (by reproduction) ofgrey partridge population;2 max (c)(i)18%/18.1% (18 needed but no penalty if significant figure error)1 (ii)birds of prey attracted from outside to shooting areas because ofabundant food (grey and released partridges) / birds of preyliving in shooting areas increase in numbers because of abundant food;non-hunting human involvement (food and shelter) influencedthe correlation between the densities;more grey partridges shot than killed by birds of prey / manygrey partridges shot in shooting areas;correlation not only due to birds of prey eating grey partridges/human involvement;grey partridges compete with released partridges for foodand shelter (decreasing the density of grey partridges);3 max (d)limit/ban shooting of grey partridge;train shooters to recognize difference between grey partridge andother species of partridge;protect/restore habitat of grey partridge;promote captive breeding of grey partridge (for release into ecosystem);remove birds of prey/foxes depending on laws;1 max[11]

27.No specific comment available.

28.Standard and Higher levelsNo specific comment available.

29. No Report available for this question.

30.Standard levelThere were a number of concerns raised by teachers regarding the appropriateness of this question. It is covered in topic one, but candidates did find the question one of the most difficult in the paper to answer.Higher levelProved to be a difficult first question, with fewer than half of candidates answering it correctly and a substantial number of candidates choose each of the distracters. As there is no ambiguity about the correct answer, this must be an area of relatively weak understanding, and teachers should ensure that t-test is carefully taught during the course.

31.There were some complaints on this question respecting its fairness. All the data was provided and all the candidates needed to know is how the t-test is applied. Not many candidates answered this question correctly, showing that this is a topic that needs to be covered in more depth while teaching. The question itself could be a good teaching resource.

32.Standard and Higher levelsThis seemed to be a very difficult first question; usually the first question is easy. The discrimination index was good, showing that the good candidates were able to answer it correctly and the weaker candidates incorrectly.

33.Standard and Higher levelsThere has been some concern about the relevance of this question in a Biology paper, although it is part of the mathematical requirement as interpretation of graphs are very important to all Biology candidates.

34.Many candidates confused correlation with causation. They believed the increase in biomass in the worm was due to the increase in organic nitrogen. This is causation, when the graph is really showing a correlation between biomass of the worms and percentage of organic nitrogen.

35.Was based on assessment statement 11.2.5. It is of course arguable whether a muscle fibre is a cell, but the question was a good discriminator and was answered correctly by over 70%, so this uncertainty does not appear to have worried candidates.

36.In the G2 forms, some teachers comment that answer C is also correct, as there are some unicellular organisms that perform meiosis before cell division. This may be true; nevertheless answer A is more correct as it applies to all unicellular organisms. Most good candidates had this answer correct, this question turning out to be a good discriminator.

37.Standard and Higher levelNo specific comment available.

38.Standard levelThe quality of the micrograph was not good; nevertheless this did not affect the performance of the candidates. Although the term chromatin is not in the syllabus, most candidates had question 5 correct.Higher levelThe quality of the micrograph was not good; nevertheless this did not affect the performance of the candidates.

39.(a)The answers here were usually fine, but sometimes candidates faltered because they never summarized an overall trend or reached any conclusion about a trend. Just noting yearly population fluctuations for individual bird species was not enough to gain marks. (b)(i)Answers were divided between giving the term negative correlation or inverse proportion or using a sentence such as birds of prey density goes down as grey partridge density rises. Either style was acceptable. (ii)Those answers that gained the maximum of two marks provided a prediction/observation supported by some reasoning. For example, fewer partridges are present when more birds of prey are seen because partridges are eaten by birds of prey. Another acceptable reason was that the partridges moved to areas with fewer birds of prey. Converse accounts also gained credit such as more grey partridges can exist (through reproduction) when fewer birds of prey are around. Some candidates just repeated their response from 1(b) (i) and gained no credit. (c)(i)A correct percentage was usually calculated. Although it was not required, many candidates applied significant figures rules in determining their answer. (ii)Answers were quite varied. Many candidates had difficulty using the data provided. The discussions of some candidates covered more than the maximum number of marks while others wrote vague and ambiguous explanations for no credit. Many candidates showed some sort of reasoning. All the marking points eventually appeared over the range of scripts. Often, candidates mentioned that birds of prey were attracted from outside to the shooting area because of the abundant food i.e. the released partridges and grey partridges. (d)Many thoughtful realistic answers were given for preventing the extinction of grey partridges. They matched up well with the markscheme. However, the banning of all sport shooting was not one of them.