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 same frequency of alternate turning behaviour. These investigations enabled comparison with previous studies on alternate turning behaviour across woodlice species. Porcellio scaber, (common rough woodlice), are terrestrial crustaceans of order isopoda (Riggio 2013). The species is identifiable from similar species of woodlouse by its inability to roll into a ball, its rough texture and lack of any striped marking, as well as its size and lack of characteristic long tails

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 size between 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 have 14 legs, two attached to each of the seven body segments as well as two pairs of antennae arranged as one long and one short pair, they are bilaterally symmetrical (Riggio 2013). Similarly to other crustaceans, P. scaber have gills 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 fungi as well as the bacteria living upon these items (Broly et al 2012). They protect themselves 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 woodlouse originally native solely to mainland Europe but which now populates all continents barring Antarctica (Riggio 2013) causing it to be described as: "probably the most successful woodlouse colonizer" ( Woodlice in Britain and Ireland: Distribution and Habitat pg.94). It is listed in some areas of the world as an invasive species (Global Invasive Species Database 2009) specifically as a threat to native invertebrates on Gough and Marion Islands.

EXEMPLAR B

EXEMPLAR C

EXEMPLAR BACKGROUND INFORMATION

EXEMPLAR A

Studies have been conducted in order to gain more information about the 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 physiologist have found 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 the effect of auxin, NAA, and found an increased

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 have been done on the effect of plant hormones in rice.(Mitra & Gupta, 1945) However the Agronomy department at Yangzhou in China demonstrated that negative phototropism of rice roots were results 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. Therefore a hypothesis can be proposed based on the earlier findings by other scientist as discussed, that a 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 provide some useful information that then could be used for future research in enhancing growth of crop plants.

EXEMPLAR B

.

EXEMPLAR C

There is however some discussion over how the woodlice develop this behaviour.

Armadillidium vu/gore, another woodlouse species has been shown during investigations to

increase "variant patterns" (Moriyama 1999 pg 154) including escaping from the apparatus

as an investigation progressed, when tested though consecutive T mazes in order to escape

from desiccation. 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 asymmetrical leg 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 opposite direction at the nearest possible opportunity. This

investigation aims to provide evidence for either one of these theories by answering the

research question stated above.

EXEMPLAR D

Activia, is a trademark under the brand of “Danone.” It is completely probiotic yoghurt with 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 start of the 20th century, probiotics were thought to beneficially affect the host by improving its intestinal microbial balance, thus inhibiting pathogens and toxin producing bacteria.”[4] In Activia, there are Lactobacillus bulgaricus and Streptococcus thermophilis and 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 Acidophilus bacteria 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 several beneficial 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] These prebiotic fibers serve a natural environment for probiotic bacteria to stay alive in the way to the digestive system, as well. “Bifidobacterium Lactis is a very powerful transient probiotic 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?)

EXEMPLAR A

EXEMPLAR OF CRITICAL THINKING IN DATA ANALYSIS

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.

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.

EXEMPLAR B (ANALYSIS OF SECONDARY DATA)

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

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

EXEMPLAR C

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

this behaviour and that this specific sample used 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, there is 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 the number 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 course of 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 the behaviour has a cause that is exhibited universally by woodlice of all ages. The theory of BALM (Hughes 1985) would allow for this pattern and would appear to support the results to a greater extent than the proposition of "variant patterns" proposed by Moriyama (1999 pg 154).

The behavioural adaptation of alternate turning behaviour is present within multiple arthropod species (Hughes 1985) and as its frequency increases when faced with disadvantageous environmental conditions (Hughes 1967) or the presence of a predator (Carbines, Dennis and Jackson 1992) it is 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 that there 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 suggest that it is unlikely that short term learning behaviours used as there is no relationship between the trial number and the reaction of the woodlice. This seems to contrast with the evidence of Moriyama (1999) as there was a little change in woodlouse behaviour over the course of 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 woodlouse to turn in either direction as both turn directions resulted in the same outcome - a dead end and subsequent removal from the maze. It therefore seems likely that bilaterally asymmetrical leg movements (BALM) (Hughes 1985) are responsible for this action within woodlice. These movements are described as the "mechanistic basis" (Hughes 1985 pg. 259) for alternate turning (or correcting) behaviour and describe the 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 have further to walk.

For example a turn to the left would stimulate to a greater extent the outer set of legs on the right hand side of the body. This then causes the woodlouse to 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 have experienced less stimulation(Hughes 1985).

Evaluation of results

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.

EXEMPLAR B

EXEMPLAR C

EXTENDED ESSAY FINAL CHECKLIST

In order to gain the maximum credit possible for 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. Have you shown that a range of appropriate different sources/methods were considered?

4. Have you provided evidence of how you selected effective and appropriate sources/method(s)?

5. Have you 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 correct chemical terminology used consistently and appropriately throughout the essay?

2. Have you shown that you understand the chemistry behind the sources/method(s) used?

3. Have the sources/method(s) chosen throughout the essay been used effectively to address the RQ?

C: Critical thinking (12)

1. Is the research appropriate to the RQ and its application consistently relevant? Have you critically analysed the sources/method(s) used?

2. Have you developed an effective and reasoned argument from your research? Is your argument well-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?

D: Formal presentation (4) 1. Is your essay within the 4000 word limit? 2. Does your essay include all the required elements (Title page, table of

contents, introduction, discussion, conclusion & bibliography)? 3. Is all illustrative material (graphs, tables, chemical structures etc.)

clearly and accurately labelled? 4. Does the bibliography include all, and only, those works that have

been consulted? Is the bibliography set out in a standard format that is consistently applied?

5. Is all the work of others clearly acknowledged? Are all the pages numbered?

6. Are all pages double-spaced and formatted using Arial font size 12? 7. If you have included an appendix does it only contain information

necessary to support the essay?

E: Engagement (6) 1. Have you engaged fully in discussions with your supervisor regarding

the planning and progress of your essay? 2. Have you shown how your reflections enabled you to refine the

research process? Have you shown how you responded to setbacks and challenges during the research process?

3. Have you shown initiative, creativity and personal input throughout the research process?

4. Have you made suggestions as to how you can improve your own working practice?