Student Guidance for writing IBDP Science Extended Essay with exemplar paragraphs showing critical thinking.

1. Science EE: Exemplars of Critical Thinking
Extended Essay Criteria
Criteria C: Critical Thinking is worth 12 out of 34 marks. This is 35% of the overall mark.
To achieve a high EE mark you MUST show high levels of critical thinking in your Background Information,
Analysis of Data, Conclusion and Discussion sections.
Below you will find student exemplars that show high levels of critical thinking for each section. Please
read these exemplars carefully and think about how you can show this level of analysis in your writing.
EXEMPLAR RESEARCH QUESTION AND INTRODUCTION
EXEMPLAR A
Introduction
Research question:
Does the length of the Porcel/io scaber individual(measured from head to telson, excluding
antennae) affect the frequency with which alternate turning behaviour is displayed within
an 'H' shaped maze?
In order to answer this question two further preliminary experiments were carried out to
determine whether:
• The specific population of na"ive Porcellio scaber individuals used in this study displays
alternate turning behaviour.
• Members of the P.scaber population and the Armadillidium vu/gore population display
the samefrequency of alternate turning behaviour.
These investigations enabled comparison with previous studies on alternate turning
behaviour across woodlicespecies. Porcellio scaber, (common rough woodlice), are
terrestrial crustaceans of order isopoda (Riggio 2013). Thespecies is identifiable from
similar species of woodlouseby its inability to roll into a ball, its rough texture and lack of
any striped marking, as well as its sizeand lack of characteristic long tails

2. Members of the species can grow to a maximum of 17mm in length (Riggio 2013) although
the maximum length of individuals used within this investigation was 14mm. Woodlice
increase in sizebetween their birth at which they are approximately 2mm until they reach
their maximum size through a series of irregular moults of their exoskeleton throughout
their adult life (Capinera 2008). P. scaber individuals have14 legs, two attached to each of
the seven body segments as well as two pairs of antennae arranged as one long and one
shortpair, they are bilaterally symmetrical(Riggio 2013). Similarly to other crustaceans, P.
scaber havegills as part of their respiratory system (Donaldson Becker 1936)alongside
mechanisms for breathing air in the form of pseudolungs situated on their abdomen (Riggio
2013). Damp living conditions are necessitated by the presence of these gills.
Like many other species of woodlouse, P.scaber prefer to live in aggregated groups (Broly et
al. 2012) in dark, damp areas and frequently inhabit grassland, woodland and coastal
habitats as well as domestic gardens (Harding and Sutton 1985). They feed on decomposing
matter such as decaying wood, leaves and fungias well as the bacteria living upon these
items (Broly et al 2012). They protectthemselves from desiccation and predation by living
under wood and rocks.
Factors affecting the frequency of turn alternation in Porcellio scaber (Common rough
woodlouse) P. scaber is a species of woodlouseoriginally native solely to mainland Europe
but which now populates all continents barring Antarctica (Riggio 2013) causing itto be
described as: "probably themost successfulwoodlousecolonizer" ( Woodlice in Britain and
Ireland: Distribution and Habitat pg.94). Itis listed in some areas of the world as an invasive
species (Global InvasiveSpecies Database2009) specifically as a threat to native
invertebrates on Gough and Marion Islands.

3. EXEMPLAR B

4. EXEMPLAR C

5. EXEMPLAR BACKGROUND INFORMATION
EXEMPLAR A
Studies havebeen conducted in order to gain more information aboutthe different plant
hormones. Pavlista (2008) used gibberellins in order to see if the early growth of winter
wheat could be improved with the help of plant hormones. He applied small amounts of
gibberellins, GA3, to wheat seeds, and found that the treated seeds grew taller and faster.
Since the earlier 1900th century plant physiologisthavefound that auxins, IAA, could be
used to modify flowering and growth in crop plants. "Thimann and Lane (1938) obtained
better vegetative growth accompanied by slight hastening of flowering with IAA on oat and
wheat". In 1949 Thimann and Leopod found that "both flowering and growth being
promoted by relatively low concentrations and inhibitedby higher concentrations of auxins".
H'~:ey and Greogyr (1954) observed theeffect of auxin, NAA, and found an increased

6. number on flower primordia] in Winter barley but found no effect on Petkus rye. In 1955
Bhardwaj and Rao used IAA and NAA on wheat and observed a higher vegetative growth
and grain yield with IAA and lower with NAA.
Only a small number of studies havebeen done on the effect of plant hormones in
rice.(Mitra & Gupta, 1945) However theAgronomy departmentat Yangzhou in China
demonstrated that negative phototropism of rice roots wereresults of an unequal lateral
distribution of IAA in root tips (Yi-wei eta!., 2004 ). Based on these earlier done studies it
can be believed that the effect of IAA on crop plants wheat and rice can be tested, using
different concentrations of IAA. Thereforea hypothesis can be proposed based on the
earlier findings by other scientist as discussed, thata higher vegetative growth and grain
yield would be produced by lower concentration of auxins. With the help of this experiment,
and its findings it could in a small way providesome useful information that then could be
used for futureresearch in enhancing growth of crop plants.
EXEMPLAR B
.
EXEMPLAR C

7. There is however some discussionover how the woodlice develop this behaviour.
Armadillidium vu/gore, another woodlousespecies has been shown during investigations to
increase "variantpatterns" (Moriyama 1999 pg 154) including escaping from the apparatus
as an investigation progressed, when tested though consecutiveT mazes in order to escape
fromdesiccation. The variation between different individuals adaption to the scenario is
argued to be due to "the bugs'own decision making" (Moriyama 1999 pg. 153) arguing that
they are capable of conscious decision and learning over time (Moriyama 1999). However it
has also been proposed that woodlice follow this pattern of behaviour due to the theory of
bilaterally asymmetricalleg movements (BALM) (Hughes 1985) which states that woodlice
place more stress on one side of the body when turning in a particular direction and so
redresses this by turning in the oppositedirection at the nearestpossibleopportunity. This
investigation aims to provideevidence for either one of these theories by answering the
research question stated above.
EXEMPLAR D
Activia, is a trademark under the brand of “Danone.” Itis completely probiotic yoghurtwith
probiotic bacteria. According to the adopted definition by Food and Agricultural
Organization(FAO) and World Health organization(WHO) probiotics are: “Live
microorganisms which when administered in adequate amounts confer a health benefit on
the host.” Also, “at the startof the 20th century, probiotics werethought to beneficially
affect the hostby improving its intestinal microbial balance, thus inhibiting pathogens and
toxin producing bacteria.”[4] In Activia, there are Lactobacillusbulgaricus and Streptococcus
thermophilisand Bifidobacterium lactis which are completely probiotic bacteria.
On the other hand, Yovita is a trademark of Sütaş and contains Bifidibacterium in common
with Activia. However, differently, there are Acidophilusbacteria and prebiotic fibers
present in Yovita. “The prebiotic definition does not emphasize a specific bacterial group.
Generally, however, it is assumed that a prebiotic should increase the number and activity
of bifidobacteria and lactic acid bacteria. The importance of the bifidobacteria is that these
groups of bacteria have severalbeneficial effects on the host, especially in terms of
regulating digestion, including enhancing mineral absorption and the effectiveness and
intrinsic strength of the immune system.” [5] Theseprebiotic fibers servea natural
environmentfor probiotic bacteria to stay alive in the way to the digestive system, as well.
“Bifidobacterium Lactis is a very powerfultransientprobiotic bacteria. Scientific studies
have proven that B. Lactis enhances immunity, improves digestion and can lower
cholesterol”[6].
EXEMPLAR OF WRTING METHOD FOR SECONDARY DATA EE (How was data selected?)

8. EXEMPLAR A
EXEMPLAR OF CRITICAL THINKING IN DATA ANALYSIS

9. EXEMPLAR A
The results indicate that lAA did not have any significant effect on the height of plants.· Wheat treated with
1ppm of IAA grew the tallest up to week 5 with and average of 57.6em but this growth could not be
maintained due to heavy tropical rains flooding the pots and seriously affecting the growth of seedlings of
all treatments. By the time of harvest of the wheat in the 8th week, the height of plants ranged from 43.1
em to 44.8em for all treatments indicating that IAA did not have any significant effect on the height of
wheat. Above graphs (Figure 7) supports this claims.

10. This graph shows the growth of the rice for a period of 5 weeks. In the methodology it was stated that the
plants would be grown for 8 weeks,however due to the fact that the rice died earlier the experiment had to
be cut short. There is no clear growth curve for all of the rice plants, like the one seen for wheat, and this is
due to the many limiting factors. Heavy rains killed some of the seedlings and later on a large numbers of
plants. Also a lot of birds eat the rice, by ripping the whole plant from the pot or biting it, so that only a few
centimeter high plants were left behind. However it can be seen that the height for both the control group
and the plants treated with a concentration of 10-4 ppm show a small increase in height. The tallest
average height of rice plants was seen for the plants receiving treatment with a concentration of 10-4 ppm,
and the average height at week 5 for these plants were 10.7 em, and the highest individual height was
23.7 em. However when looking closely at the graph the greatest increase in average height was for the
control group, as their height increased about a total of 1cm, but due to the fact that they were shorter
when treatment began their height never exceeded that of 10·4 ppm. To try to keep the rice growing for as
long as possible, fertilizer was given to all the plants on week 4, however no definite impact on the growth
of the rice due to the fertilizer can be seen. The plants treated with a concentration of 1 ppm of IAA
suffered the most from the environmental factors and had therefore the lowest average height of all the
plants.

11. EXEMPLAR B (ANALYSIS OF SECONDARY DATA)

12. EXEMPLAR OF CRITICAL THINKING IN DISCUSSION
Conclusions
EXEMPLAR A
The eFfect of IAA on wheat had a positive correlation for growth (in height). Figure.6 shows the growth
curve of wheat according to height (em) and it can be seen that the highest concentration of lppm caused
the greatest growth in height. It also shows that the height for the plants treated with 1ppm had the
greatest height throughout the whole experiment. Plant hormones and specially Gibberellins have been
used in a number of studies. Braas eta/, (2010) conducted a study using Gibberellins and they found that
overall a higher dose of hormones gave a greater growth. When they gave a low dose of Gibberellins the
plants stem height reached on average of 11.3 Cm in a week whereas with a larger dose of Gibberellins the
stem height was 20.9 em. The control group gave a significantly lower height of only 7.9cm. When
comparing Braas (2010) results with the present investigation the results are very similar, as the wheat
treated with IAA of 1 ppm gave a height of 28.2 em (see Appendix Al.) after one week Steven (2009) also
had similar findings, however he only used Gibberellins and not other hormones like Braas and his plants
treated with hormones grew 88cm during the first week and the control group only 64cm in height. Even
though both Braas and Steven.G studies were done using peas, Patium Sativa, and this investigation was
on wheat, it only indicates that overall plant hormones enhanced growth and that plants overall can be
treated with external hormones to enhance their growth. In Figure 9. It can be seen that the application of
IAA did not affect the flowering of the / wheat compared to the number of stems in a significant manner,
and this can be / supported by Misra & Sahu's findings in 1958, when they applied IAA on rice, Oryza sativa
and found no effect on grain yield or component of yield. However their findings would indicate that a
lower concentration of IAA would speed up the days it takes for rice to grow from a stage from soaking to
ear emergent. In average it took up to 113.13 days for the control plants, 112. 99 days for plants treated
with IAA of 500 ppm, 112.29 days when treated with 250 ppm and 112.19 days when treated with 100ppm.
When in my case it can clearly be seen in figure 9. that a higher concentration of IAA gives a faster
flowering rat for wheat, but as seen in figure 13, my results are in some ways similar to Misra & Sahu's,
with greater growth for rice plants treated with a lower concentration of IAA. However Misra & Sahu's
findings are supported for instant by Thimann & Leopod's (1949), who in Winter Barley observed " both
flowering and growth being promoted by relatively low concentrations and inhibited by higher

13. concentrations of auxins." According to figure. 11 the wheat heads would weigh more, as the
concentration of IAA increases, indicating a greater yield, which is also in contradiction with Misra & Sahu's
(1958) findings. Even though the study could not be fully continued to the end for the rice, there are
still some findings that are similar to does done by other researchers. According to Radi & Maeda (1986) a
higher concentration of IAA decreased the growth of rice roots and a relatively low concentration of IAA
stimulated root growth. In their study, Oryza sativa was used, and a concentration of 10-7 ppm gave a root
length of 369 em and for a concentration of 10·5 ppm a length of only 296 em, showing a gradual
difference. As there is a strong relationship between the growth of rice roots and the body of a rice plant,
which relates to the yield. (Abe & Morita, 1994) According to this and the present results for the rice
growth in height, figure.13, a similar phenomena can beseen, as the plants that received the highest
concentration of IAA grew least in height compared to the lower concentrations of IAA. The specific height
of rice plants can be seen in the Appendix B. Figure 14. shows the same results when it comes to the
number of leaves. This study clearly shows how different concentrations of IAA have affected the wheat
and rice grown. According to the present results a higher concentration of IAA would increase the
flowering rate and increase the yields for wheat, however these findings were not supported by other
researchers. Then again the findings of increased height due to higher concentrations of IAA and the fact
that the flowering itself was not affected by the different concentrations of IAA was supported by other
scientists./ However it has to be taken into account that the nature played its role, especially when it came
to growing the rice plants. It is also needed to keep in mind that a tropical climate might not be the best
conditions for growing wheat, which is often grown in colder and dryer places. This investigation could
have yielded better results if it would have been possible to grow the plants for a longer time and in
conditions not affected by the heavy tropical rains or being attacked by birds. In the future, it is advisable
to investigate the effect of other hormones on crop plants and also on vegetables such as peas, potatoes,
carrots If such research yielded positive results, it would help in solving the problem with scarcity of food
for the growing population.
EXEMPLAR B

14. EXEMPLAR C
1. As predicted within the hypothesis, this sampleof the population of woodlice did display
alternate turning behaviour. This confirms that members of the species P.scaber do exhibit

15. this behaviour and that this specific sampleused in the investigation do display this
behaviour.
2. In agreement with the hypothesis, A. vu/gore and P. scaber showed the same frequency
of alternate turning behaviour, with neither showing any change in trend of alternate
turning behaviour being displayed as the investigation progressed.
3. Contrary to the hypothesis, thereis no relationship between the length of the P. scaber
individual and the frequency with which alternate turning behaviour was displayed.
Similarly, there was no relationship between the number of times the individual woodlouse
had experienced the maze and the frequency of alternate turning behaviour, as the number
of alternate turns did not progress as thenumber of trials increased.
These investigations appear to contribute to the overall academic debate favouring a
mechanistic approach to the origin of alternate turning behaviour, such as BALM (Hughes
1985). This is because they show that the frequency alternate turning behaviour does not
increase over a long-term time scale, such as age, or a short-term time scale, such as over
the courseof the trials. This suggests that the woodlice do not learn alternate turning
behaviour as they grow older, and as woodlice of all ages display the behaviour to the same
extent, it suggests thebehaviour has a causethat is exhibited universally by woodlice of all
ages. The theory of BALM (Hughes 1985) would allow for this pattern and would appear to
supportthe results to a greater extent than the proposition of "variantpatterns" proposed
by Moriyama (1999 pg 154).
The behavioural adaptation of alternate turning behaviour is presentwithin multiple
arthropod species (Hughes 1985) and as its frequency increases when faced with
disadvantageous environmentalconditions (Hughes 1967) or thepresence of a predator
(Carbines, Dennis and Jackson 1992) itis likely to have developed as behaviour in order to
permit efficient escape of the individual from an otherwise dangerous situation in order to
reach a more advantageous one(Hughes 1967 and 1978, cited in Hughes 1985). As this
investigation shows thatthere is no increase in the frequency of this behaviour with
relation to body length (and therefore age of the woodlouse) it seems unlikely that this
behaviour is due to any kind of social or individual learning as this would be expected to
progress with age. The result also suggestthat it is unlikely that shortterm learning
behaviours used as there is no relationship between the trial number and the reaction of
the woodlice. This seems to contrastwith the evidence of Moriyama (1999) as there was a
little change in woodlousebehaviour over the courseof the experiment. However it could
be argued contrary to this that there was no incentive during the experiments investigated
in this paper for the individual woodlouseto turn in either direction as both turn directions
resulted in the sameoutcome - a dead end and subsequentremovalfrom the maze.
It therefore seems likely that bilaterally asymmetrical leg movements (BALM) (Hughes 1985)
are responsiblefor this action within woodlice. These movements are described as the
"mechanistic basis" (Hughes 1985 pg. 259) for alternateturning (or correcting) behaviour
and describethe process by which a forced turn stimulates the legs on one side of the
woodlouse's body to a greater extent than on the other side as they havefurther to walk.

16. For example a turn to the left would stimulate to a greater extent the outer set of legs on
the righthand side of the body. This then causes the woodlouseto favour a turn in the
opposite direction at the next available 'choice point' in order to favour the legs on the
other side of the body which haveexperienced less stimulation(Hughes 1985).
Evaluation of results

17. EXEMPLAR OF EVALUATION OF SECONDARY DATA EE
EXEMPLAR A
EXEMPLAR OF CONCLUDING SUMMARY PARAGRAPHS TO EE
EXEMPLAR A
This study clearly shows how different concentrations of IAA have affected the wheat and rice grown.
According to the present results a higher concentration of IAA would increase the flowering rate and
increase the yields for wheat, however these findings were not supported by other researchers. Then again
the findings of increased height due to higher concentrations of IAA and the fact that the flowering itself
was not affected by the different concentrations of IAA was supported by other scientists. However it has
to be taken into account that the nature played its role, especially when it came to growing the rice plants.
It is also needed to keep in mind that a tropical climate might not be the best conditions for growing wheat,
which is often grown incolder and dryer places.
This investigation could have yielded better results if it would have been possible to grow the plants for a
longer time and in conditions not affected by the heavy tropical rains or being attacked by birds. In the
future, it is advisable to investigate the effect of other hormones on crop plants and also on vegetables
such as peas, potatoes, carrots If such research yielded positive results, it would help in solving the
problem with scarcity of food for the growing population.

18. EXEMPLAR B

19. EXEMPLAR C

20. EXTENDED ESSAY FINALCHECKLIST
In order to gain the maximum credit possiblefor your extended essay it is crucial that
you can answer YES to the following questions before you finally submit the final
version of your essay and the completed Reflections on Planning & Progress form.
The maximum number of marks available for each criterion is given in brackets.
A:Focus & method (6)
1. Is the research question outlined and clearly stated in the introduction?
2. Is the research question focused and capable of being addressed
in 4000 words? Is the purpose and focus of the RQ set into
context of background knowledge and understanding of
chemistry?
3. Haveyou shown thata range of appropriatedifferent sources/methods
were considered?
4. Haveyou provided evidence of how you selected effective and
appropriatesources/method(s)?
5. Haveyou shown how the RQ was arrived at from the sources
gathered? Does the whole essay remain focused on the
research question?
B:Knowledge& understanding(6)
1. Is correctchemical terminology used consistently and appropriately
throughoutthe essay?
2. Haveyou shown thatyou understand the chemistry behind the
sources/method(s) used?
3. Havethe sources/method(s) chosen throughouttheessay been used
effectively to address theRQ?
C: Criticalthinking(12)
1. Is the research appropriateto the RQ and its application
consistently relevant? Haveyou critically analysed the
sources/method(s) used?
2. Haveyou developed an effective and reasoned argument from
your research? Is your argumentwell-structured?
3. Are all your conclusions effectively supported by the evidence and
relevant to the RQ? Have you analysed your research effectively and
stated any limitations and/or counter arguments?

21. D:Formal presentation(4)
1. Is your essay within the 4000 word limit?
2. Does your essay includeall the required elements (Title page, table of
contents, introduction, discussion, conclusion & bibliography)?
3. Is all illustrative material (graphs, tables, chemicalstructures etc.)
clearly and accurately labelled?
4. Does the bibliography include all, and only, those works thathave
been consulted? Is thebibliography set out in a standard format
that is consistently applied?
5. Is all the work of others clearly
acknowledged? Areall the pages
numbered?
6. Are all pages double-spaced and formatted using Arial font size12?
7. If you haveincluded an appendix does it only contain information
necessary to supportthe essay?
E: Engagement(6)
1. Haveyou engaged fully in discussions with your supervisorregarding
the planning and progress of your essay?
2. Haveyou shown how your reflections enabled you to refine the
research process? Haveyou shown how you responded to setbacks
and challenges during the research process?
3. Haveyou shown initiative, creativity and personalinput throughoutthe
research process?
4. Haveyou made suggestions as to how you can improveyour own working
practice?