internal assessment
Rubrics below come from the IB Biology subject guide online.
Click for a printable summary of IB Biology internal assessment requirements.
Click for a printable summary of IB Biology internal assessment requirements.
Click here for IB Internal Assessment Student Guide
Click here for the IB Internal Assessment Lab Template
Click here for the IB Internal Assessment 6 Part Deadline Guide
IA Overview
The internal assessment requirements are the same for biology, chemistry and physics. The internal
assessment, worth 20% of the final assessment, consists of one scientific investigation. The individual
investigation should cover a topic that is commensurate with the level of the course of study.
Student work is internally assessed by the teacher and externally moderated by the IB. The performance in
internal assessment at both SL and HL is marked against common assessment criteria, with a total mark out
of 24.
The internal assessment requirements are the same for biology, chemistry and physics. The internal
assessment, worth 20% of the final assessment, consists of one scientific investigation. The individual
investigation should cover a topic that is commensurate with the level of the course of study.
Student work is internally assessed by the teacher and externally moderated by the IB. The performance in
internal assessment at both SL and HL is marked against common assessment criteria, with a total mark out
of 24.
IA component
- Duration: 10 hours
- Weighting: 20%
- Individual investigation.
- This investigation covers assessment objectives 1, 2, 3 and 4.
IA criteria
The new assessment model uses five criteria to assess the final report of the individual investigation with the following raw marks and weightings assigned:
The new assessment model uses five criteria to assess the final report of the individual investigation with the following raw marks and weightings assigned:
Personal Engagement
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Exploration
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Analysis
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Evaluation
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Communication
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Click on the links above to get more detailed information about the assessment
Levels of performance are described using multiple indicators per level. In many cases the indicators occur together in a specific level, but not always. Also, not all indicators are always present. This means that a candidate can demonstrate performances that fit into different levels. To accommodate this, the IB assessment models use mark bands and advise examiners and teachers to use a best-fit approach in deciding the appropriate mark for a particular criterion.
Teachers should read the guidance on using mark bands shown above in the section called “Using assessment criteria for internal assessment” before starting to mark. It is also essential to be fully acquainted with the marking of the exemplars in the teacher support material. The precise meaning of the command terms used in the criteria can be found in the glossary of the subject guides.
Teachers should read the guidance on using mark bands shown above in the section called “Using assessment criteria for internal assessment” before starting to mark. It is also essential to be fully acquainted with the marking of the exemplars in the teacher support material. The precise meaning of the command terms used in the criteria can be found in the glossary of the subject guides.
Ideas for Internal Assessment
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 will 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 high 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.
he 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 affect 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
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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.H
ere 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 / hydrophilic 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 mild stress, e.g. answering questions, on a physiological feature of the body.
In this investigation the connection between mild stress and physiological features 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 must be harmless.
Investigation of a method of scarification on the germination of seeds.
Scarification involves weakening, opening, or otherwise altering the coat of a seed to encourage germination. Scarification is often done mechanically, thermally, or chemically. Some mechanical methods involve nicking, sanding, or clipping off part of the seed's shell so water can get to the inside part to activate germination. Chemical methods can use sulfuric acid, hydrogen peroxide or alcohol. Thermal scarification is covered in detail in the next idea. You can search YouTube to see a selection of videos on this topic.
The effect of body position on heart rate and blood pressure.
The baroreceptor reflex helps to maintain blood pressure at nearly constant levels. The baroreflex uses negative feedback, an increase in blood pressure causes the heart rate to decrease and also causes blood pressure to decrease. Could the position of the body affect blood pressure and thus heart rate? This might make an interesting investigation. Of course controlling other factors which are well known to affect heart rate will be one of the challenges of an investigation into this topic.
Testing the effectiveness of a shampoo, anti-tangle product or conditioner on a property of hair.
There are many claims made from producers of hair products which could be tested in an IA. Does conditioner really make your hair stronger, does a tangle easing product really prevent knots, or reduce friction between hairs. While it is not allowed to use body fluids testing your own hair would be acceptable. So long as it was collected ethically! Research into the structure of hair and use of a microscope to study changes in the hairs might also be a useful part of this experiment.
The affect of temperature on non-enzyme controlled reactions or processes.
This is an interesting twist on an classic enzyme reaction. What is the effect of temperature on the absorbance of light by photosynthetic pigments? Is there a difference in the stretchiness of a ring of artery at different temperatures. Of course the control of all the other variables which may affect the reaction will be important and may not be easy. You have to collect sufficient data and repeats of each value a,d it would be good to be able to suggest a possible biological mechanism, although this isn't essential.
Ripeness of fruit and vitamin C content.
Does ascorbic acid get converted to sugar as part of the ripening process of a fruit. The challenge of this IA would be to accurately, or quantitatively estimate the ripeness of the fruit. This could be helped if the fruit can actually be collected as it falls off the tree. Perhaps the color of the fruit can suggest ripeness, and remember that many plant parts contain vitamin C, not just oranges. DCPIP will be useful as an indicator of the concentration of vit C but a calibration curve might be useful.
Effects of light on vitamin C.
This investigation is interesting as it relates to the shelf life of food and also the quality of food after the processing. If a bottle of juice is stored in direct sunlight does the vitamin C get damaged. Using DCPIP and a simple titration an experiment can be planned to estimate the concentration of vitamin C in a juice drink after a range of different light treatments. Artificial bulbs or sunlight screens could be used to get a range of the independent variable, and of course it will be important to control other variables.
[There are many possible variations on this experiment: such as looking at storage temperature, or interactions with other chemicals, preservatives, colourings, or perhaps even other fruit juices which may cause oxidation or decomposition of Vitamin C., Even simple contact with the air may have an effect. It might also be possible to compare the stability of different sources of vitamin C at different temperatures. Why limit yourself to vitamin C, any nutrient which can be tested would lend itself to this type of study. It would be possible to estimate the concentration of enzymes like catalase in samples of fruit, for example.]
Methods of preventing decay in vegetables
This is an applied study of inhibition of enzyme reactions, or the prevention of the growth of spoiling bacteria. It is vital to decide which one of these is the focus of the research question, at the beginning. The way in which bacteria might spoil food could be influenced by the origins of the food, it's cultivation, organic or not, and any treatment after harvesting, or during transport. Controlling these factors will be a challenge but might be possible by washing in diluted antiseptic solution. Of cause all the normal problems of control of temperature and other factors during the experiment will be important too. There are lots of possible research questions, and using a single type of vegetable will be more focused than comparing several.
If enzyme reactions are thought to cause the decay this will make for another research pathway. Of course reactions will happen more slowly at cold temperatures, but there may be inhibitors or catalysts in the environment such as plant hormones, acids or oxygen. Perhaps the enzymes of one fruit (like bananas) will have an effect on another, we all know that storage of bananas and unripe Kiwis can speed up ripening but do they speed up spoiling?
Investigation of a factor which might affect skin temperature.
This seems like an easy investigation but it certainly has challenges. Careful organize for the collection of meaningful data and controlling variables other than the IV will be required. Consent forms for participants are essential and some biological reasoning for the possibility of a correlation will be important. Possible specific research questions could address temperatures of different parts of the skin, related to hair, or muscle, or blood circulation. alternatively differences between different people, some have cold hands and feet for example.
Investigation to avoid - probably.
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.
Online Labs - Ideas and links. This is a list of possible sites for students to use as online labs.
You can access these here http://www.sciencecourseware.org/biologylabsonline (Thanks to Sarah Kelley for the link)
- FlyLab - genetics of inheritance
- Evolution Lab - adaptation by natural selection
- Translation Lab - the genetic code
- Demography Lab - human population growth
- Hemoglobin Lab - mutations, protein structure/function
- Pedigree Lab - human genetics and RFLP probes
- Mitochondria Lab - electron transport
- Leaf Lab - plant physiology/photosynthesis
- Cardio Lab - cardiovascular homeostasis
- Enzyme Lab - biochemistry of the enzyme invertase
- Population Genetics Lab - principles of population genetics
- Population Ecology Lab - dynamics of population growth
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..
More online virtual labs here: (Biology, 6/e, Author Dr. George B. Johnson, Washington University,Author Dr. Peter H. Raven, Missouri Botanical Gardens & Washington University,)
- Part I Virtual Lab - The Origin of Living Things
- Part II Virtual Lab - Biology of the Cell
- Part III Virtual Lab - Energetics
- Part IV Virtual Lab - Reproduction and Heredity
- Part V Virtual Lab - Molecular Genetics
- Part VI Virtual Lab - Evolution
- Part VII Virtual Lab - Ecology and Behavior
- Part VIII Virtual Lab - The Global Environment
- Part IX Virtual Lab - Viruses and Simple Organisms
- Part X Virtual Lab - Plant Form and Function
- Part XI Virtual Lab - Plant Growth and Reproduction
- Part XII Virtual Lab - Animal Diversity
- Part XIII Virtual Lab - Animal Form and Function
- Part XIV Virtual Lab - Regulating the Animal Body
- Human benchmark lab - Quite a nice small set of tests, including reaction times
- Mean arterial pressure calculator online - a useful little calculator
- Science lab Chemical data sheets MSDS (Materials Safety data sheets) - useful for risk assessments
Below, are several exemplar IA's to help you with writing your own.
I would recommend starting with the investigation 1. Next read the annotated copy then the moderator comments
I would recommend starting with the investigation 1. Next read the annotated copy then the moderator comments
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