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.

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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.

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 connection 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 caliper 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)