This page is a simple list of general biological ideas for investigations.  It will be useful for students who are lost for an idea, or teachers who are looking for something to inspire a particular student. 

Of course the ideas are just ideas, nothing is specified and all the details will need to be explored and evaluated by students during their investigations.

Testing the effectiveness of different types of toothpaste.

Toothpaste is labelled according to how natural or how chemical the contents are.  This study could be an investigation of how effectively the toothpaste inhibits the growth of bacteria according to the scale of the chemicals in the toothbrush. A challenge is to work out the biological reasons behind you hypothesis, and it may be a good idea to branch away from toothpaste to test a specific chemical from the ingredients in the toothpaste.

Testing spoilage of milk in different conditions.

Lactobacilli reproduction and growth is the cause of milk spoilage.  What effect do conditions, such as temperature, sunlight have on the rate of spoilage.  This is a nice wet laboratory project and there are some simple ways to measure the growth of the bacteria but these can be fiddly to work out, and concentrations of bacteria used in inoculations will need working out.

Tomato online simulation photosynthesis lab (Leaf lab)

Using LeafLab - plant physiology/photosynthesis to test the effectiveness of different colours of light on the photosynthesis rate of tomato plants.  The data collection using the online lab may be easy enough, but the challenge is going to be designing a meaningful experiment and collecting enough results to complete the analysis well.

Investigation of Age and reaction speed

This is an investigation to test a hypothesis that reaction time wll slow down with age.  By testing people of different ages to see if there is a difference in their reaction time it may seem like a simple study, but there are a lot of factors which need to be controlled and it will be difficult to find enough participants to create a large enough data set.  There are also many factors to consider in the type of reaction speed test that is used and there are also problems associated with the learning of the skill during the experiment.

Examining the relationship between cases of a disease and weather patterns.

This investigation tries to establish a pattern between the weather and the spread of a disease. Using nationally published data on epidemiology and weather data is certainly possible and it could happen that there are correlations between climate and some disease outbreaks this will need explaining in terms of the mechanisms of transmission of the specific disease.  Some diseases spread through direct contact, others are transmitted by an insect vector.

Testing the accuracy of colour vision using online colour tests

There are some quite nice online tests of colour vision, and also many telephone apps.  This investigation is Design an experiment to investigate a factor which affects the precision of colour vision, age, tiredness, gender, eye colour, etc. http://www.xrite.com/online-color-test-challenge.

Flowering stages of a plant at different altitudes

The climate is different at different altitudes and the growing season begins later at high altitude. This investigation relies on the recording of abiotic data and data about the stage of the flowering cycle using the number of flowers / fruit / buds etc in a single species at different altitudes up a mountain.  Of course there will be other factors to consider, for example local feature of the habitat where the plants are growing and the aspect of the flowers' location, not to mention grazing and grass cutting.

The effect of river pollution on the presence of a single species

It is quite easy to record the number of individual plants / animals of a single species in a river at different distances above and below a possible source of pollution. If some abiotic factors can also be recorded including the pollution level, eg nitrate level, BOD, turbidity etc. then this could be a very good study.

The effects of antibiotics on the germination of seeds or the growth of plants -

This looks like an interesting topic of study.  Many methods are possible, and there has been some very recent research suggesting that antibiotics can affect the growth of seeds and plants.
ref P.W. Brian and also Louis G. Nickell and Alexander C. Finlay in the Journal of agricultural and Food chemistry, 2015

Do plants grow faster in soil which has more microbial activity (respiration)

This investigation  could be a nice way to combine two standard procedures, one to estimate the rate of respiration in the soil and another to estimate the rate of growth of a plant. Soil respiration can be measured using a CO₂ probe and a data logger the same equipment could be used to measure the rate of photosynthesis, although growth (or photosynthesis) can be measured in other ways too. There are lots of practical problems to overcome, most importantly how to change the soil so that it has different amounts of respiration. One idea would be to make a series of soils using active compost and sand.  it might even be possible to use mesocosms to perform this investigation as these would make it easier to control more of the other variables.

The effect of pets on the diversity of plants in a garden lawn.

This is a nice idea for an investigation into the number of species found in a garden in houses where there are pets and no pets.  Ecological techniques and quadrat sampling could be used together with mapping of digging or scratching to establish whether the presence of a pet increases plant diversity or not.  There are many possible variations, perhaps the presence of animal excrement could be the causal factor, otherwise some species may be more resistant to scratching and disturbance, caged animals can selectively graze on parts of a lawn, just to mention a few ideas.

The effect of temperature / light on the ripening of fruit, e.g. bananas, cherries, tomatoes.

The challenge is really how to control the temperature of the fruit (or the light) for a long period of time, perhaps 2 weeks. Another difficulty will be to devise a way to measure the extent of fruit ripening, or softness. Bananas lend themselves to this because their skin changes colour. Of course the underlying processes are controlled by enzymes, or the fruit ripening hormone ether.

What is the difference in the CO₂ levels in exhaled air before and after exercise?

This investigation might sound simple at a first glance but there are many difficulties to overcome in terms of controlled variables and the method of measuring the CO₂. This might involve the use of a data logger, or perhaps a titration using bromothymol blue.  The release of CO2 by the body in the lungs is not simple either, factors to consider include the relative amounts of aerobic and anaerobic respiration, as well as the position of the muscles being exercised.  Perhaps the muscles with a greater blood flow will cause a different effect to those in the bodies extremities, and what effect could warming up have on the process?

How does a specific abiotic factor affect biodiversity in a habitat?

This is nice project if there is a specific environmental gradient in the site being investigated.  The use of a transect of transects will be useful for the sampling. The challenge is to explain why there might be a change using biology and then to test it using some type of ecological sampling.  Ensuring that there is enough data will also be important as there are likely to be quite a few other factors which will need controlling or considering at least.

The effect of a short burst of exercise on blood pressure or two groups of people.

This is a simple experiment to carry out, but a difficult experiment to get good controlled data for.  There needs to be some clear links to the biology of blood pressure and how exercise affects it. A clear RQ is essential and there are quite a few possibilities.  Controlling factors which can affect blood pressure could be an investigation in itself!  Of course the IB guidelines on experimentation needs to be followed and written consent sought for participants.

The effect of a warm up on the maximum heart rate (or maximum speed) achieved in a standard test

The role of a warm up in sport is clear. Athletes perform better if they warm up properly before an event.  Is there an optimum intensity of warm up to achieve best performance?  Can the max performance be measured best using max heart rate or maximum speed? These are just some of the questions which will need answering.

The effect of isotonic drinks on rehydration and recovery after exercise

The problem of this investigation is that it is difficult to measure rehydration or salinity.  At the end of a long endurance event cramps and muscle fatigue will be evident but this is not possible to recreate in the lab in school.  Perhaps some form of experiment using isotonic solutions on slightly dehydrated muscle tissue from a chicken leg, or liver would work. This would be a challenge and it would require some research before beginning.  Avoid any investigation where you are getting friends to drink Gatorade and measuring some unrelated but easy to measure factor, like pulse rate.

The effect of different colours of light on the growth of seedlings

This is an interesting study and it links to the role of auxin as well as photosynthesis so there is theory to discuss.  Practical procedures and controls will be the challenge, but data should be easy to record if the seedlings grow.  Some preparation time will be required to germinate and plant the seeds.

The effect of salt on the germination of seeds.

This is an interesting topic of investigation which relates to osmosis and ecology.  Some plants grow well in coastal soils with igh salt concentrations but others don't. The practical methods to germinate seeds and select appropriate salt concentrations will present definite challenges but this is an interesting study for students living near the coast, or in places where salt is applied to the roads in winter.

Examining the effect of plants on the solutes in the runoff from soils

While there is a considerable challenge in designing apparatus and growing plants the idea of using plants to filter the water in 'ecological' swimming pools is quite well established. There may be a combination of roles for plant roots and bacteria in the substrate and both of these link to the nitrogen cycle and so would allow for a detailed hypothesis and a focused research question.

Examining the glucose concentration in something

using potassium permanganate and heating, from a protocol from Science & plants for schools. This is an interesting quantitative method to estimate glucose concentration.  It could be used in a wide range of labs.  Lots of plant ideas in the questions and answers  It is also possible to use this method to study glucose levels in ripening fruit, lactase activity in milk producing glucose or maltase activity in germinating seeds.

Examining a factor which affects vital capacity, or tidal capacity of the lungs.

The greatest challenge in this investigation is getting a large enough data set which takes into consideration enough of the factors which need to be controlled. Comparing boys and girls for example will be impossible, unless the sample size is very large.  One possible solution is to measure another (or some other) factors about the body and look for a correlation. One nice idea might be to see if the growth in the lungs' vital capacity correlates better with the circumference of the skull or the length of the legs in children of different ages.  Biological explanations could look at the way we grow, and if the brain changes size at the same rate as the lungs. It may even be possible to find a database of measurements of children of different ages. There are some ethical questions involved too, and parental consent will be essential for any experiments on children.

The effect of soil pH on the germination of seeds

This is a simple idea, but the explanation is more complex, and this might be the challenge of this particular investigation.  Would soil pH effect the enzymes in the seed responsible for germination, is there another explanation?  Controlling other factors which affect germination and collecting a large enough data set will also be good challenges for a Biology student to work out.

Investigation of the functioning of the eyes when using paper or different electronic screens

First is to ensure that there is some biology to explain any hypothesis, and that the RQ is firmly focused in the Biology. Then is is going to be a challenge to design a method of data collection which controls all the possible variables. Some independent variables will be easier to test than others, for example size of text and distance wt which it can be read, would be better than measuring reading speed which can be affected by many other variables.

Examining the effect of household cleaning products on the growth of house plants

This could be a difficult investigation to do quantitatively unless there was a longer time period available to observe growth.  There could be some biology theory applied to the plants leaves, or roots.  Processes such as diffusion and osmosis as well as the effect of chemicals on components of cell membranes, or on enzymes could be included in the theory. Some of the challenges of this type of investigation will be controlling other factors which affect the growth of plants. One option might be to test the chemicals on small aquatic plants, or germinating seedlings, but there are challenges to overcome here too.

Using published epidemiological data to examine a link between an illness and a specific factor.

Here the challenge is the exploration section. You have to show that the data has been carefully selected, and that measures have been taken to ensure that other factors which might affect the data have been controlled, by careful selection of the data used. Some assessment of the reliability of the sources will be needed and some discussion of ethics of using someone's data, with their consent, hopefully.  The best investigations will have a biological reason why there might be a correlation between the IV and the DV.  The data must be analysed by the student and tables / graphs etc. should include all the normal conventions of d.p. and uncertainties.

Investigation of the effects of natural selection related to colour markings of a single species of animal or plant

This is a great idea, but it could be complex and time consuming depending on the lab.  There are some online simulations but these can only be used in conjunction with some other analysis; never just present the online lab as an investigation on it's own. Other possibilities are paper simulations, e.g. with peppered moth types.  Practical work could look at the density of aphids on leaves of different shades, or bumble bee feeding on flowers of different shapes or predator prey interactions etc.  Lots of scope but not an easy investigation to complete in the time, in 12 pages.

Investigation into the effect of regular exercise on the increase in pulse rate after a short period of exercise.

This is a bit more complex than a simple pulse rate investigation, but the challenge to control variables is equally great.  If a person exercises regularly they should have a better level of fitness, this might mean that their heart rate increases by less in the short burst of exercise than someone who does no regular exercise.

Investigation of the properties of photosynthetic pigments using different solvent mixes and rf values.

This investigation is a bit biochemical and the answer to simple research questions about the hydrophobic / hydrophyllic properties of photosynthetic pigments themselves would be a little bit obvious, so the challenge is to thing of a research question that could be answered by mixing petroleum ether (a nonpolar solvent) and propanone (a polar solvent) in different proportions and calculating retention factors.  Some suggestions of research questions may be; Is there a difference in the composition of photosynthetic pigments in the leaves of a plant found in the sun or the shade? Which pigments are made first in a growing leaf, or are all the pigments made at the same time? How does the shade of a leaf relate to the composition of photosynthetic pigments it contains?

Investigation of the behaviour of two groups of animals, or several groups of animals in a range of conditions.

This investigation is going to require a very precise research question and some careful methodology to ensure that the data collected can be used to answer the RQ.  However it could be really interesting to compare simple behaviour in animals.  Does the behaviour of an animal change as the population increases? Do individuals of different types all behave in the same way to a stimulus.

Investigation of SA:vol on the rate of diffusion

This is a standard lab and the challenge will be to ensure that it is put into an interesting biological context. Starting with a process which requires diffusion in living cells will help the topic to be interesting and will show some personal engagement. The analysis of the results and the design of the method is another place where PE can be demonstrated, try to take the standard lab and adapt it so show something which is not 'standard'. 

Investigating the effect of sucrose concentration of the rate of respiration in yeast.

This is interesting because the higher concentrations will cause outward osmosis in the yeast and perhaps slow down respiration, or even kill the yeast. Lower concentrations will slow respiration because of a lack of substrate.  The challenge will be in deciding which concentrations to test and in explaining the results.

The effect of exam conditions on a physiological feature of the body.

In this investigation a change in a physiological feature is explored. There are plenty of factors to control which makes this investigation difficult and if there isn't enough data or the controls are not in place this could lead to a low mark after much work.  The choice of physiological features of the body could include heart rate, or pupil size, or skin redness. Measuring theses factors might be tricky and will involve some testing, although using a phone camera or a video camera could help. It is possible to establish a theoretical link between mild stress and adrenaline (epinephrine) which will affect features in the body including pupil size but it is not possible to directly measure the level of any hormones in the body.  Remember any participants will need to give written consent before any experimenting, and the mild stress of exam conditions must be harmless.

total = 30

Investigations to avoid !

Every year the examiners' report mentions problematic Investigations, those which are unethical, or standard labs which are not applied to any specific interest.  The following examples are not unethical, but just not very good, because the data is rarely enough for a good analysis and difficult to control.

Investigation of the effect of music on the heart rate.

Don't do it! This sounds like an easy investigation but it is tricky because first there needs to be some biological reason why the heart should speed up in the presence of music and this is impossible to explain with IB Biology. Perhaps another research question will be better, something linked to hormones, or to physical activity.  If you insist on trying this then be sure to cover the control of variables, there are a lot which can affect the heart. Perhaps one of these other variables will be a better variable to investigate instead of music. If you are still not dissuaded then be sure to collect enough data and try to be analytical, don't mix types of music and tempos of music and try to keep the investigation to some biological cause or effect. The IB advise student and teachers, each year, to avoid this sort of lab.

The effect of reading different genres of literature on blood pressure and pulse rate.

Avoid this type of investigation, .  While it is an interesting idea, like the example above there are many factors to control in this investigation, which is an interesting modification of a standard lab looking at exercise.  The difficulty begins with identifying the genres in a scientific way. The biological explanation of why blood pressure might change when reading may be tenuous. This could be compared to listening to music where research has been done to establish that pulse rate can be affected by music.

External Online Labs - Ideas and links

This is a list of possible sites for students to use as online labs. 

Sometimes sites go ofline or change their address.

Pease comment on broken links and suggest alternative ideas in the comments.

Biology Labs Online have the potential for making biology education more interactive, effective, and fun!
Biology Labs Online is a collaboration between the California State University system and Pearson, Inc.
You can access these here https://sciencecourseware.org/BiologyLabsOnline/  (Thanks to Sarah Kelley for the link)

Lab bench fly breeding lab Breeding Drosophila, fruit flies

Natural selection - lab bench  Which type of water fleas escape predators best?

Human benchmark lab - Quite a nice small set of tests, including reaction times

Mean arterial pressure calculator online - a useful little calculator

Sciencelab Chemical data sheets MSDS (Materials Safety data sheets) - useful for risk assessments