Extended Essay titles

Guidance on choosing a topic for a Biology Essay

It is best to help find topics that can be successfully completed by the students themselves. The aim is for students to follow a personal learning pathway. The more they can put their own ideas and skills to the essay process the more internal motivation they will have and the less need there will be for deadlines and pressure from the teacher.

Supervisors should try to help the student find the following:

• a reason to learn about the extended essay topic.

• a way of visualising the end point.

• links between what a student already knows and the EE topic.

However, this is no easy task. Students often arrive at a first meeting with their heart set on a really unsuitable topic, like finding a cure for cancer or a psychological study of the behaviour of their favourite pet.

Inappropriate research questions usually fall into one of these categories:

• those that are too broad in scope,

• those questions that are essentially trivial, the outcome is obvious from the start,

• those that focus on ethical, social and religious aspects of biological issues,

• those that focus on political and economic aspects of environmental policy,

• those that focus on the diagnosis and treatment of diseases,

• those that are not focused on the study of living organisms or life processes.

These students need to be guided to a more suitable topic while cherishing the student's internal motivation for their Extended essay.

One good way to begin is to ask about the data collection and the purpose which an experiment could have as pat of the essay. Students looking for answers to medical treatments quickly see the problems. The next step for the supervisor, once the student has realised that there needs to be some change, is to suggest a range of practical possibilities for related experiments.

A key point is to remember that this is an essay and not a lab report. The essay needs to be placed within the academic context of the topic, so an essay that deals only with the investigation will not likely be awarded the highest marks. Students, with their supervisor's support, need to recognise how their investigation connects to the bigger picture in order to gain the highest marks. An hourglass makes a nice model of how the essay begins broad, in the academic context, becomes sharply focused during the data collection and then returns to a broader contexts in the conclusions.

Here are ten examples of successful Biology extended essays.

The effect of different colours of light on the pupil reflex? This pupil was curious about the way camera red eye reduction works. Why is a red flash used for closing the pupil. The student experimented on her peers using a cardboard box a light source with coloured filters and a light intensity meter. By taking photos of the pupil in each experiment the student was ale to measure the change in pupil diameter in different colours of light.

The effect of circadian rhythms on amylase concentration of saliva. The student was interested in reasons for why food tasted different at different times of day. One proposed explanation was the fluctuating amounts of amylase in saliva. This was tested easily using a simple enzyme experiment and samples of saliva taken on three different nights. The student successfully showed that amylase concentration in saliva does fluctuate but whether this was the cause of the taste differences was not so sure.

The effect of wolf populations on the density of aspen tree growth through the process of "trophic cascade". This essay collected data from different studies of ecology in the same national park and compared the data from each to show that when wolf populations increased over a 10 year period so did the amount of tree growth. The student searched published papers and also contacted researchers and obtained unpublished data in order to complete her analysis. Of course the connexion was the large herbivore populations whose grazing patterns were disturbed by the presence of the wolves.

The effect of biometric ratios on long jump performance. The student was a keen athlete and wanted to understand why men were able to jump further than women, and also why some people were never going to be good long jumpers. After studying the research into animals she devised a method of measuring elite athlete height, leg length and mass as well as maximum jump length from athletics competition data and video images. The ratio of leg length to height proved the best correlating factor in humans, just as it seems to be in grasshoppers.

The effect of swimming stroke and distance on swimmers' heart rate- this was done by a student on the school swim team. The key here was to avoid the single human study. He recorded the pulse rates while resting and after exercise of 8 swim team members. (John McMurtry)

The effect of tadpole grazing on algal growth- this student built containment devices for a local pond. He was attempted to control the grazing by having tadpole-free enclosures and others where the tadpoles could graze. During his research, he discovered that other organisms that were not excluded also grazed the algae! This student demonstrated exceptional intellectual insight and creativity in his experimental design as he recorded the effect of position in the pond relative to the exposure to the sunlight even as the exposure changed over the time of his investigation. (John McMurtry)

The effect of leg length discrepancy on running gait-this student was an avid long distance runner who developed a leg pain. Her physiotherapist took a video of her running and analysed her motion to offer advice. This was the origin of her topic. She measured the leg lengths of all the girls in the school from grades five to twelve and found the ones with one leg longer than the other (the source of her problem). Supposedly we all have a difference in our leg lengths but she was looking for the ones with pronounced differences. Once she had her subjects, she put marks on their lower backs and on the back of their knees. She took videos and analysed the x-y motion of the marks using logger pro to see if there were asymmetries in motion. She asked them to bring in their old running shoes and used a calliper to measure differences in the wear of the tread on the right in the left and the inner and outer parts of the shoe. (David Mindorff)

Differences between perceived stress and physiological stress-- noting that the IB diploma is notorious for the stress it causes students, this student located a survey in the academic literature designed to measure the self-perceived levels of stress. Through the use of a kit, she measured levels of cortisol in the spit; she measured differences in pupil dilation and skin surface temperature; (David Mindorff)

The effect of stem density on the effectiveness of biological control -- Purple loosestrife is an invasive species in Ontario. It grows in wet areas which includes ditches and wetlands. The government releases a beetle for biological control. The student released beetles (in collaboration with a government scientist) in ditches and in open fields to determine whether beetles did more damage in areas of high stem density versus areas of low stem density. She measured percent of damaged plants; percent of plants infested; height differences and biomass differences. (David Mindorff)

The most effective strategy for rooting Jade plants -- natural versus synthetic rooting hormones; concentration differences; spray, soaking or painting application; outcome was number of leaves, number of rootlets and mean length of rootlets. (David Mindorff)

Comments 12

Hi David,

One of my student wants to do an extended essay on the effect of abscissic acid and glycolic acid on regeneration of the tail fin of Zebra fish. She will be cutting the zebra fish fin under anaesthesia so that pain is not inflicted on the fish and seeing the effect on regeneration and after regeneration of the fin she will be putting the zebra fish back into the natural environment so will this experiment be considered unethical?

Dear Deepti, The IB guidelines on using animals in experiments are strict. The justification is that as IB students are not carrying our groundbreaking research it would be unjustifiable to cause deliberate harm to any animals. The wording is like this, "investigations must not

manipulate the environment or diet beyond that which can be regarded as humane." It is best to look at the document yourself. It can be found on the Programme resource centre: resources.ibo.org ? using your myIB login. Personally, while the experiment sounds interesting I think it does cross the line into "considered unethical". If the student could replace the fish with a sample of cells, and look at cell growth instead, this would be a good compromise; replacing animals with cells is suggested by the IB.

I hope this helps,

Best wishes,

David

Hi David , i teach biology in german at my school ...what language should my students use when writing an EE?for my students is english easier as there's access to many resources in english .... Can a student relate 2 subjects in EE? for example : effect of radiation on certain diseases ...radiation is physics , disaeses are bio ....what should the student do ??

Hi Sherine,

This is a great question. It is possible now, since 2018, for students to do an Extended Essay looking at connections between two subjects. This is called an "Interdisciplinary essay". Students have three options for broad themes within which to choose a research question; Literature and performance, World studies, Environmental systems and societies. The science you mention, radiation and disease would perhaps fit best into "world studies" which could investigate the topic of, global health, or energy security. Both of these topics could connect Physics and Biology. There is a useful document on the programme resource centre of the IB website, here: ibpublishing.ibo.org .

Best wishes,

David

Hi. One of my students wants to do an EE on effects sleep deprivation. Could this be regarded as an EE on Psychology.

Dear Mila,

This is an interesting topic and, as you suggest, probably not one that is comfortably within the realms of IB Biology. I couldn't say if it fits well into Psychology, but I suspect that it would pose the same problems in Psychology as it does in Biology; it's not easy to imagine how it can comply with the Experimental guidelines, controlling variables will be very difficult and it will probably not produce enough data. The examiners' reports regularly mentions the unsuitable nature of this type of study.

Personally I like to encourage students to follow their interests as much as possible, so I would try to steer this topic to something more testable. Physiological responses at different times of day and night could be one direction to point the student. This could be an investigation of diurnal rhythms looking at something measurable, like reaction speed, pupil reflex, etc.

I hope that helps.

Best wishes,

David

Hi David

I have a student who wants to do a behavioral study on the harbour seal(common seal) and possibly the gray seal in her EE. She has access to study two harbour seals and one gray seal in captivity. Would it be okay with only 3 seals or is it to few? She would like to compare her study with litterature studies of the respective seals in their natural environment. I'm unsure if there is any aspects of a behavioral study that will be considered as a psychological study and not a biological one. Can you help me?

Best regards

Katharina

Dear Katharina,

Sorry I have taken so long to reply.

The best way to ensure that it is biology is to try to ensure that there is a biological explanation to any hypothesis that the student suggests. I think the danger would be if the student tries to find out some human type of behaviour in the seal. Enjoying a particular type of music for example.

Remember also the IB guidelines on animal experimentation.

Best wishes, David

Hi Sir,

My student wants to study the anatomical growth pattern of stem in a single local species of plant over a span of one month.How do we frame the research question for EE and is it a good choice for EE?

Dear Sreeja,

Thanks for your question. I think this is an interesting extended essay idea. The first thing to establish is which aspect of growth will be measured. It could be interesting to look at first flowering, or thickness of leaves, or number of chloroplasts in cells of the leaf, but whichever variable is chosen there really has to be a reason why it might be different in different plants. It's best if this reason can be explained by the student, and perhaps researched in other species by reading biological literature.

There are three important components to a research question, the Independent variable, the dependent variable and the scope of the study. Please see more about this on my page, thinkib.net . Although this page is in the investigation section, the same principals apply, although the student has more than 10 hours to complete the work in the EE of course.

I hope that helps, please do let me know what the RQ your student chooses is.

Best wishes, David

Hi David,

My student got interested in Raman Spectroscopy during an educational visit to a Lab. He is now interested to use raman Spectroscopy for determining cis and trans fattyacids in hydrogenated and patially hydrogentaed oil. I have few questions regarding this EE

1) after carrying out the spectroscopy in the lab, analysing and evaluating the result, my student wants to use secondary data to prove that biologically transfatty acids pose few health risks. I see no problem in this procedure but am not sure.

2) will this EE be considered as a biochemistry rather than a biology EE?

Thanks and best regards

Aasma Salman

Dear Aasma,

Thanks for your question. I wonder if your student also does Chemistry? If he does then perhaps you could suggest an Interdisciplinary Extended essay. This is a new possibility and it would allow your student, for instance, to make links between the chemistry of lipids in food production and health issues related to cis / trans fats. Collecting primary data and adding some secondary data is perfectly OK. I would recommend that you look carefully with your student at the research question. The question must not be too obvious, nor too broad. The student has to demonstrate an investigative approach including an analysis of different possible conclusions. This introduction to the Interdisciplinary essay, from the IB teachers' resource centre, could be useful. xmltwo.ibo.org . If you really have to stay within Biology then using the methodology of Raman Spectroscopy may not be so relevant, but the results of the work done by the lab might be useful secondary data for the biological research question. I hope that is some help. Best wishes, David