IB Biology IA: 60 Examples and Guidance

The International Baccalaureate (IB) program offers a variety of assessments for students, including Internal Assessments (IAs), which are pieces of coursework marked by students’ teachers. The Biology IA is an assessment designed to test students' understanding of the material they have learned in their biology course, their ability to conduct independent research, and their competence in applying their knowledge to real-world biological issues.

What is the IA?

The IA consists of a laboratory report that students must complete during their IB biology course. For assessments before May 2025, the report should be 6 to 12 pages in length, but after May 2025, the length requirement is updated to a maximum of 3,000 words.

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What should the IA contain?

The research question for the internal assessment should be a testable question that is related to the biology curriculum. It's essential that the question is relevant to the biology curriculum, specific and clearly defined. The methodology section should explain how the research was conducted, including the materials and methods used. The methodology should be detailed and well-explained, and should include information on the materials and methods used, as well as any ethical considerations.

Data analysis is an important aspect of the IA. Professional IB Biology tutors recommend that students should present their data in a clear and organized manner, and should use appropriate statistical analysis to interpret their results. They should also make sure to include a discussion of the limitations of their study and the implications of their findings.

The conclusion should summarise the main findings of the study, relate the results back to the research question, and address the relevance of these findings to the broader context of the biological field.

In addition to the laboratory report, students must complete a reflective statement, which is mandatory. This statement should be around 500 words long and must include references to how the student has achieved specific learning objectives outlined in the IB Biology syllabus, and should reflect on the student’s learning during the internal assessment process. The reflective statement should include a description of the student’s personal learning process, including successes and challenges, as well as an evaluation of their performance on the internal assessment and the skills they have gained through the process.

Have a look at our comprehensive set resources for IB Biology developed by expert IB teachers and examiners!

- IB Biology 2024 Study Notes

- IB Biology 2025 Study Notes

- IB Biology 2024 Questions

- IB Biology 2025 Questions

What are some example research questions?

Here are examples with details of potential research questions, written by expert IB Biology tutors and teachers, that could inspire your Biology IA:

1 - Investigating the effect of different types of sugars on the rate of fermentation by yeast.
To investigate the effect of different concentrations of a specific herbicide on the growth rate of a particular plant species, one could set up an experiment in which the plants are grown in soil with varying concentrations of the herbicide. An appropriate range of concentrations and a suitable plant species would need to be chosen, along with control variables such as light, temperature, and watering. The growth rate of the plants could be measured by tracking their height or mass over a set period of time. Comparing the growth rates of the different groups would determine the impact of the herbicide on the plant's growth.

2 - How does the pH of a solution affect the activity of an enzyme?
To investigate the effect of pH on enzyme activity, one could set up an experiment in which the enzyme is exposed to solutions with varying pH levels. The enzyme's activity could be measured by monitoring the rate of a specific reaction catalyzed by the enzyme. Control variables such as temperature, substrate concentration, and enzyme concentration would need to be kept constant. By comparing the activity of the enzyme at different pH levels, the optimal pH range for the enzyme could be determined.

3 - Can the concentration of vitamin C in different types of fruit juice be determined using titration?

To determine the concentration of vitamin C in different types of fruit juice using titration, a standardized solution of a known concentration of potassium permanganate would be prepared. A sample of the fruit juice would be titrated with the potassium permanganate solution until the endpoint is reached, indicating that all the vitamin C has reacted with the potassium permanganate. The concentration of vitamin C in the fruit juice can then be calculated based on the volume and concentration of the potassium permanganate solution used in the titration. This process would need to be repeated for each type of fruit juice being tested.

4 - Investigating the effect of light intensity on the rate of photosynthesis in aquatic plants.

Set up an experiment in which aquatic plants are placed in containers with varying levels of light intensity. The light intensity could be controlled by adjusting the distance between the light source and the plants. The rate of photosynthesis could be measured by tracking the amount of oxygen produced by the plants over a set period of time. Comparing the rates of photosynthesis of the different groups would determine the impact of light intensity on the plant's photosynthetic activity. Control variables such as temperature, water quality, and plant species would need to be kept constant.

5 - How does the concentration of carbon dioxide affect the rate of photosynthesis in terrestrial plants?

Conduct an experiment in which plants are grown under different concentrations of carbon dioxide. The plants would need to be grown in a controlled environment with consistent light, temperature, and watering. The rate of photosynthesis could be measured by monitoring the oxygen production of the plants using a dissolved oxygen probe. The results could then be analyzed to determine how the concentration of carbon dioxide affects the rate of photosynthesis in terrestrial plants.

6 - Can the presence of glucose in urine be determined using Benedict's test?

Collect a urine sample from the individual being tested. Add Benedict's reagent to the sample and heat it in a water bath. If glucose is present in the urine, it will react with the Benedict's reagent and cause a color change. The intensity of the color change can be compared to a color chart to determine the concentration of glucose in the urine. This process would need to be repeated for each urine sample being tested.

7 - Investigating the effect of temperature on the respiration rate of germinating seeds.

Set up an experiment in which germinating seeds are exposed to different temperatures. The respiration rate of the seeds could be measured by monitoring the amount of oxygen consumed or carbon dioxide produced over a set period of time. The experiment would need to control for other variables such as the type of seed, the amount of water and nutrients provided, and the length of time the seeds have been germinating. Comparing the respiration rates of the different groups would determine the effect of temperature on the seeds' respiration rate.

8 - How does the concentration of salt in a solution affect the growth of bacteria?

Prepare a series of solutions with varying concentrations of salt, and inoculate each with a known amount of bacteria. The solutions would need to be incubated at a constant temperature for a set period of time, and the growth of the bacteria could be measured by counting the number of colonies or by using a spectrophotometer to measure the optical density of the solution. Comparing the growth rates of the bacteria in the different salt concentrations would determine the effect of salt on bacterial growth. Control variables such as pH, temperature, and nutrient availability would need to be kept constant.

9 - Can the concentration of nitrogen compounds in soil be determined using colorimetry?

Collect soil samples from different locations and extract the nitrogen compounds using a suitable method such as Kjeldahl digestion. The extracted compounds can then be analyzed using colorimetry, which involves adding a reagent that reacts with the nitrogen compounds and produces a color. The intensity of the color can be measured using a spectrophotometer, and the concentration of nitrogen compounds in the soil can be calculated based on the absorbance of the color. This process would need to be repeated for each soil sample being tested.

10 - Investigating the effect of different types of plant hormones on the growth of seedlings.

Set up an experiment in which seedlings are grown in different concentrations of plant hormones, with control variables such as light, temperature, and watering. The growth rate of the seedlings could be measured by tracking their height or mass over a set period of time. Comparing the growth rates of the different groups would determine the impact of the plant hormones on the seedlings' growth. The experiment could also include observations of other plant characteristics such as leaf size and color, root development, and overall health.

11 - How does the concentration of salt in water affect the hatching rate of brine shrimp?

Set up multiple containers with different concentrations of salt water and add brine shrimp eggs to each container. The containers should be kept at a consistent temperature and light level. After a set period of time, count the number of hatched brine shrimp in each container and calculate the hatching rate. Comparing the hatching rates of the different containers would determine the effect of salt concentration on the hatching rate of brine shrimp.

12 - Can the rate of mitosis be determined using microscopy techniques?

Collect a sample of cells undergoing mitosis and prepare them for microscopy. Using a microscope, observe the cells and record the time it takes for each cell to complete each stage of mitosis. The rate of mitosis can then be calculated by dividing the time taken for each stage by the total time taken for the entire process. This process would need to be repeated for multiple cells to ensure accuracy and reliability of the results.

13 - Investigating the effect of different types of antibiotics on the growth of bacteria.

Culture bacteria in petri dishes with different concentrations of antibiotics. The growth of the bacteria can be observed and measured over a set period of time. The concentration of antibiotic that inhibits the growth of the bacteria can be determined, and the effectiveness of different types of antibiotics can be compared. Control variables such as temperature, humidity, and nutrient availability would need to be kept constant to ensure accurate results.

14 - How does the concentration of oxygen affect the respiration rate of crickets?

Set up a series of chambers with different concentrations of oxygen, ranging from low to high. Place crickets in each chamber and monitor their respiration rate by measuring the amount of oxygen consumed and carbon dioxide produced over a set period of time. The results can be analyzed to determine the effect of oxygen concentration on the respiration rate of crickets. Control variables such as temperature and humidity would need to be kept constant throughout the experiment.

15 - Can the concentration of glucose in blood be determined using glucose oxidase and spectrophotometry?

A sample of blood would be mixed with glucose oxidase, which converts glucose to hydrogen peroxide. The amount of hydrogen peroxide produced is proportional to the amount of glucose in the sample. A spectrophotometer would then be used to measure the absorbance of the sample at a specific wavelength, which is also proportional to the amount of hydrogen peroxide present. The concentration of glucose in the blood sample can then be calculated based on the absorbance reading and a standard curve generated using known concentrations of glucose. This process would need to be repeated for each blood sample being tested.

16 - Investigating the effect of different types of pesticides on the growth of bean plants.

Set up an experiment in which bean plants are grown in soil treated with varying concentrations of different pesticides. An appropriate range of concentrations and a suitable plant species would need to be chosen, along with control variables such as light, temperature, and watering. The growth rate of the plants could be measured by tracking their height or mass over a set period of time. Comparing the growth rates of the different groups would determine the impact of the pesticides on the plant's growth. Additionally, the health of the plants could be assessed by examining their leaves for signs of damage or discoloration.

17 - How does the concentration of light affect the growth of algae?

Set up multiple containers with different concentrations of light, ranging from low to high. In each container, add a sample of algae and monitor their growth over a set period of time. The growth rate of the algae can be measured by tracking their biomass or chlorophyll content. Comparing the growth rates of the different groups would determine the impact of light concentration on the growth of algae. Control variables such as temperature, nutrient availability, and water quality would need to be maintained to ensure accurate results.

18 - Can the presence of starch in leaves be determined using iodine solution?

Obtain a sample of the leaf and grind it into a fine powder. Add a few drops of iodine solution to the powder and observe the color change. If the solution turns blue-black, it indicates the presence of starch in the leaf. This process would need to be repeated for multiple leaves from different plants to ensure accuracy and reliability of the results. Control variables such as the age of the leaf and the time of day the sample is taken should also be considered.

19 - Investigating the effect of different types of plant nutrients on the growth of tomatoes.

Set up an experiment in which tomato plants are grown in soil with varying concentrations of different plant nutrients, such as nitrogen, phosphorus, and potassium. Control variables such as light, temperature, and watering would need to be maintained. The growth rate of the plants could be measured by tracking their height or mass over a set period of time. Comparing the growth rates of the different groups would determine the impact of the plant nutrients on the plant's growth. Additionally, the nutrient content of the tomato plants could be analyzed to determine if there is a correlation between the nutrient concentration in the soil and the nutrient content in the plant.

20 - How does the concentration of carbon dioxide affect the growth of marine plants?

Conduct an experiment in which marine plants are grown in water with varying concentrations of carbon dioxide. The carbon dioxide concentration could be controlled by bubbling different amounts of carbon dioxide gas into the water. The growth rate of the plants could be measured by tracking their height, mass, or chlorophyll content over a set period of time. Comparing the growth rates of the different groups would determine the impact of carbon dioxide concentration on the plant's growth. Other variables such as light, temperature, and nutrient availability would need to be controlled to ensure that any differences in growth rate are due to the carbon dioxide concentration.

21 - Can the concentration of protein in an egg be determined using the Biuret method?

To determine the concentration of protein in an egg using the Biuret method, the egg would need to be homogenized and the protein extracted. A Biuret reagent would then be added to the protein extract, which would cause a color change if protein is present. The intensity of the color change would be proportional to the concentration of protein in the egg. A standard curve could be created using known concentrations of protein to determine the concentration of protein in the egg sample. This process would need to be repeated for each egg being tested.

22 - Investigating the effect of different types of plant hormones on the root growth of seedlings.

Set up an experiment in which seedlings are grown in soil with different concentrations of plant hormones. An appropriate range of concentrations and a suitable plant species would need to be chosen, along with control variables such as light, temperature, and watering. The root growth of the seedlings could be measured by tracking their length or mass over a set period of time. Comparing the root growth of the different groups would determine the impact of the plant hormones on the seedling's root growth.

23 - How does the concentration of oxygen affect the respiration rate of goldfish?

Set up multiple tanks with goldfish and varying levels of oxygen concentration. The respiration rate of the goldfish can be measured by tracking their oxygen consumption or carbon dioxide production. The experiment would need to be conducted over a set period of time with control variables such as temperature and feeding schedules. Comparing the respiration rates of the different groups would determine the effect of oxygen concentration on the goldfish's respiration rate.

24 - Can the concentration of a specific hormone in blood be determined using ELISA?

ELISA (enzyme-linked immunosorbent assay) involves coating a microplate with a specific antibody that binds to the hormone of interest. The sample of blood is then added to the plate, and any hormone present in the sample will bind to the antibody. A secondary antibody that is linked to an enzyme is then added, which will bind to the hormone-antibody complex. The enzyme will then catalyze a reaction that produces a detectable signal, such as a color change. The intensity of the signal is proportional to the amount of hormone present in the sample, allowing for the concentration of the hormone to be determined. A standard curve can be created using known concentrations of the hormone to accurately quantify the concentration in the sample.

25 - Investigating the effect of different types of pollutants on the growth of watercress.

Set up an experiment in which watercress plants are grown in water contaminated with different types and concentrations of pollutants. The growth rate of the plants could be measured by tracking their height or mass over a set period of time. Comparing the growth rates of the different groups would determine the impact of the pollutants on the plant's growth. Control variables such as light, temperature, and watering would need to be kept constant to ensure accurate results. The types and concentrations of pollutants used in the experiment would need to be carefully chosen based on their potential impact on watercress growth and their relevance to real-world pollution scenarios.

26 - How does the concentration of light affect the rate of respiration in germinating seeds?

Set up a series of experiments in which germinating seeds are exposed to different intensities of light. The rate of respiration could be measured by tracking the amount of oxygen consumed or carbon dioxide produced by the seeds over a set period of time. The experiment would need to control for other variables such as temperature and humidity. Comparing the rates of respiration for the different light intensities would determine the impact of light concentration on the rate of respiration in germinating seeds.

27 - Can the concentration of nitrates in water be determined using colorimetry?

Prepare a series of standard solutions of known concentrations of nitrates. A sample of the water would be mixed with a reagent that reacts with nitrates to produce a colored product. The intensity of the color would be measured using a colorimeter, and the concentration of nitrates in the water can be calculated based on the intensity of the color and the concentration of the standard solutions. This process would need to be repeated for each water sample being tested.

28 - Investigating the effect of different types of disinfectants on the growth of bacteria.

Prepare a culture of bacteria and divide it into multiple groups. Each group would be exposed to a different type of disinfectant, while control groups would not be exposed to any disinfectant. The growth rate of the bacteria in each group would be measured over a set period of time, either by counting the number of colonies or by measuring the turbidity of the culture. Comparing the growth rates of the different groups would determine the effectiveness of each disinfectant on inhibiting bacterial growth.

29 - How does the concentration of salt in water affect the growth of duckweed?

Set up multiple containers of water with varying concentrations of salt. Add duckweed to each container and monitor their growth over a set period of time. The growth rate of the duckweed can be measured by tracking their surface area or biomass. Comparing the growth rates of the different groups would determine the impact of salt concentration on the growth of duckweed. Control variables such as light, temperature, and nutrients should be kept constant across all containers.

30 - Can the concentration of ethanol in different types of alcoholic beverages be determined using gas chromatography?

Use gas chromatography to separate the components of the alcoholic beverage sample. The ethanol would be detected and quantified using a detector such as a flame ionization detector. The concentration of ethanol in each sample can then be calculated based on the peak area or height of the ethanol peak in the chromatogram. This process would need to be repeated for each type of alcoholic beverage being tested.

31 - Investigating the effects of different types of exercise on heart rate and blood pressure.

Recruit a group of participants and randomly assign them to different exercise groups (e.g. running, cycling, weightlifting). Measure their heart rate and blood pressure before and after the exercise session. Repeat this process for each exercise group. Analyze the data to determine if there are any significant differences in the effects of the different types of exercise on heart rate and blood pressure. Control variables such as age, gender, and fitness level should be taken into account.

32 - How does the level of noise pollution affect the behavior and communication of animals?

Conduct a field study in which the behavior and communication of animals in areas with varying levels of noise pollution are observed and recorded. Control variables such as time of day, weather conditions, and animal species would need to be taken into account. The observations could include changes in vocalizations, movement patterns, and social interactions. Comparing the behavior and communication of animals in areas with different levels of noise pollution would determine the impact of noise on their behavior. Statistical analysis could be used to establish correlations between noise levels and changes in animal behavior.

33 - Investigating the effects of different types of fertilizers on plant growth and nutrient uptake.

Set up an experiment in which identical plants are grown in soil with different types of fertilizers. The growth rate of the plants could be measured by tracking their height or mass over a set period of time. Nutrient uptake could be measured by analyzing the nutrient content of the plants at the end of the experiment. Comparing the growth rates and nutrient uptake of the different groups would determine the impact of the fertilizers on plant growth and nutrient uptake. Control variables such as light, temperature, and watering would need to be kept constant.

34 - How does exposure to light pollution affect the migration and behavior of nocturnal animals?

Conduct a field study in which nocturnal animals are observed in areas with varying levels of light pollution. The behavior and migration patterns of the animals could be tracked using GPS or radio telemetry. Data on the animals' activity levels, movement patterns, and habitat use could be collected and compared between areas with different levels of light pollution. This would allow for an assessment of the impact of light pollution on nocturnal animals and their ecosystems.

35 - Investigating the effects of different types of water pollution on aquatic ecosystems and organisms.

Set up multiple tanks or containers with different types and levels of water pollution, such as oil spills, chemical runoff, or excess nutrients. Populate each tank with a variety of aquatic organisms, such as fish, algae, and invertebrates. Monitor the health and behavior of the organisms over a set period of time, noting any changes in growth, reproduction, or mortality rates. Comparing the results from each tank would allow for an assessment of the impact of different types of water pollution on aquatic ecosystems and organisms.

36 - How does exposure to electromagnetic radiation affect the growth and development of plants?

Set up an experiment in which plants are exposed to different levels of electromagnetic radiation, such as UV light or radio waves. The plants would need to be grown in a controlled environment with consistent light, temperature, and watering. The growth rate and development of the plants could be measured by tracking their height, leaf size, and overall health over a set period of time. Comparing the growth and development of the plants exposed to different levels of electromagnetic radiation would determine the impact of the radiation on the plants. Control groups of plants not exposed to radiation would also need to be included for comparison.

37 - Investigating the effects of different types of air pollution on respiratory function and lung health.

Recruit a sample of participants who are exposed to different types of air pollution, such as those who live near busy roads or industrial areas. Conduct lung function tests, such as spirometry, on each participant to establish a baseline measurement of their respiratory health. Repeat the tests after a set period of time to determine any changes in lung function. Comparing the results of participants exposed to different types of air pollution would determine the impact of each type on respiratory function and lung health. Other factors, such as age and smoking status, would need to be controlled for in the analysis.

38 - How does the level of acidity affect the growth and survival of aquatic organisms?

Conduct experiments in which aquatic organisms are exposed to different levels of acidity. The organisms could be placed in tanks with varying pH levels, and their survival and growth rates could be monitored over time. Control variables such as temperature, light, and food availability would need to be kept constant. Comparing the survival and growth rates of the different groups would determine the impact of acidity on the organisms. Additionally, other factors such as changes in behavior or reproduction could also be observed and analyzed.

39 - Investigating the effects of different types of food additives on human health and metabolism.

Conduct a literature review to identify the potential health effects of different food additives. Design a study in which participants consume a controlled diet with varying levels of the food additives being tested. Blood and urine samples could be collected at regular intervals to measure changes in metabolism and biomarkers of health. Statistical analysis would be used to determine if there are significant differences in health outcomes between the different groups.

40 - How does the level of UV radiation affect the growth and survival of plants?

Set up an experiment in which plants are grown under different levels of UV radiation. This could be achieved by using UV lamps of varying intensities or by placing the plants at different distances from a natural source of UV radiation, such as the sun. The growth rate, survival rate, and other relevant factors such as leaf size and chlorophyll content could be measured and compared across the different groups. This would help determine the impact of UV radiation on plant growth and survival. Control variables such as temperature, humidity, and watering would need to be carefully monitored and controlled to ensure accurate results.

41 - Investigating the effects of different types of drugs on human physiology and behavior.

Conduct a double-blind, randomized controlled trial with a group of participants who are given different types of drugs. The physiological and behavioral effects of the drugs would be measured through various tests and assessments, such as blood pressure, heart rate, cognitive function, and mood. The results would be analyzed to determine the impact of each drug on the participants' physiology and behavior, and any potential side effects or risks associated with each drug would be identified.

42 - How does the level of carbon dioxide affect the growth and development of plants?

Conduct an experiment in which plants are grown in controlled environments with varying levels of carbon dioxide. The growth rate, height, and biomass of the plants can be measured over a set period of time. The results can be compared to determine the impact of different levels of carbon dioxide on plant growth and development. Other variables such as light, temperature, and watering would need to be controlled to ensure that the results are accurate and reliable.

43 - Investigating the effects of different types of pesticides on non-target organisms and ecosystems.

Conduct a series of experiments in which different non-target organisms are exposed to varying concentrations of the pesticide. The organisms could be chosen based on their ecological importance, such as pollinators or soil microorganisms. The effects of the pesticide on the organisms could be measured by tracking their survival rates, reproductive success, or behavior. Additionally, the impact of the pesticide on the broader ecosystem could be assessed by monitoring changes in the abundance and diversity of other species in the area. Comparing the results of these experiments would provide insight into the potential ecological risks associated with the use of the pesticide.

44 - How does the level of atmospheric pollutants affect the growth and development of plants?

Set up an experiment in which plants are grown in controlled environments with varying levels of atmospheric pollutants, such as nitrogen dioxide or ozone. The growth rate, leaf area, and chlorophyll content of the plants could be measured over a set period of time. Comparing the growth rates and health of the plants exposed to different levels of pollutants would determine the impact of atmospheric pollutants on plant growth and development. Control variables such as light, temperature, and watering would need to be kept constant to ensure accurate results.

45 - Investigating the effects of different types of microorganisms on the digestive system and gut microbiome.

Conduct a study in which different groups of animals are exposed to different types of microorganisms, either through their diet or through direct exposure. The effects on their digestive system and gut microbiome could be measured through various methods such as analyzing fecal samples, measuring changes in gut pH, or monitoring the presence of certain bacteria. Comparing the results from the different groups would determine the impact of the microorganisms on the animals' digestive system and gut microbiome.

46 - How does the level of humidity affect the growth and survival of insects?

Conduct an experiment in which insects are exposed to different levels of humidity in a controlled environment. The survival rate and growth rate of the insects could be measured over a set period of time. The experiment would need to control for other variables such as temperature, food availability, and lighting. Comparing the survival and growth rates of the insects in different humidity levels would determine the impact of humidity on their growth and survival.

47 - Investigating the effects of different types of radiation on the genetic material and DNA replication.

Cultivate a sample of cells in a controlled environment and expose them to different types of radiation, such as gamma rays or UV light. The cells would then be monitored for changes in their genetic material, such as mutations or damage to DNA replication. The results could be compared to a control group that was not exposed to radiation to determine the effects of each type of radiation on the cells. Additional experiments could be conducted to investigate the long-term effects of radiation exposure on the cells.

48 - How does the level of soil salinity affect the growth and survival of plants?

Set up an experiment in which plants are grown in soil with varying levels of salinity. An appropriate range of salinity levels and a suitable plant species would need to be chosen, along with control variables such as light, temperature, and watering. The growth rate and survival rate of the plants could be measured by tracking their height, mass, and number of leaves over a set period of time. Comparing the growth and survival rates of the different groups would determine the impact of soil salinity on the plant's growth and survival. Additionally, the concentration of ions in the soil could be measured to determine the relationship between soil salinity and plant growth.

49 - Investigating the effects of different types of antibiotics on bacterial growth and antibiotic resistance.

Set up a series of petri dishes with agar and bacterial cultures. Each dish would contain a different antibiotic, with varying concentrations. The dishes would be incubated for a set period of time, and the growth of the bacteria would be measured. The results would show which antibiotics were most effective at inhibiting bacterial growth, and whether any resistance had developed. Control variables such as temperature, humidity, and the type of bacteria used would need to be carefully controlled to ensure accurate results.

50 - How does the level of soil pH affect the growth and survival of plants?

Conduct an experiment in which plants are grown in soil with varying pH levels. An appropriate range of pH levels and a suitable plant species would need to be chosen, along with control variables such as light, temperature, and watering. The growth rate of the plants could be measured by tracking their height or mass over a set period of time. Comparing the growth rates of the different groups would determine the impact of soil pH on the plant's growth and survival. Other factors such as nutrient availability and toxicity would also need to be considered and controlled for in the experiment.

51 - Investigating the effects of different types of hormones on animal behavior and physiology.

Conduct experiments with different groups of animals, each exposed to a different hormone. The behavior and physiology of the animals would be monitored and recorded over a set period of time. Control variables such as diet, environment, and age would need to be maintained across all groups. Comparing the results of the different groups would determine the effects of each hormone on the animals' behavior and physiology. Statistical analysis could be used to determine the significance of the results.

52 - How does the level of water availability affect the growth and survival of plants?

Conduct an experiment in which plants are grown in different levels of water availability, ranging from drought conditions to optimal watering. The growth rate, survival rate, and overall health of the plants would be monitored over a set period of time. The data collected would be used to determine the impact of water availability on plant growth and survival. Control variables such as light, temperature, and soil type would need to be kept constant to ensure accurate results.

53 - Investigating the effects of different types of plant extracts on bacterial growth and antibiotic resistance.

Prepare bacterial cultures in petri dishes with different concentrations of the plant extracts. The growth of the bacteria can be observed over a set period of time, and the effectiveness of the plant extracts in inhibiting bacterial growth and antibiotic resistance can be determined by comparing the growth rates of the different groups. Control variables such as temperature and nutrient availability would need to be kept constant to ensure accurate results.

54 - How does the level of nutrients affect the growth and development of microorganisms?

Conduct experiments in which microorganisms are grown in nutrient-rich and nutrient-poor environments. The growth rate and development of the microorganisms could be measured by tracking their population size and observing their morphology under a microscope. Comparing the growth rates and morphology of the microorganisms in the different environments would determine the impact of nutrient levels on their growth and development. Control variables such as temperature, pH, and oxygen levels would need to be kept constant.

55 - Investigating the effects of different types of pollution on the reproductive systems and fertility of animals.

Select a suitable animal species and expose them to different types of pollution, such as air pollution or water pollution. The reproductive systems and fertility of the animals could be monitored over a set period of time, and compared to a control group that was not exposed to pollution. The impact of the pollution on the animals' reproductive systems and fertility could be determined by analyzing factors such as the number of offspring produced, the health of the offspring, and any abnormalities or complications observed during pregnancy or birth.

56 - How does the level of light intensity affect the growth and development of microorganisms?

Set up multiple petri dishes with agar and different levels of light intensity, ranging from complete darkness to bright light. Inoculate each dish with the same strain of microorganisms and incubate them for a set period of time. The growth of the microorganisms can be measured by counting the number of colonies or by measuring the turbidity of the culture. Comparing the growth rates of the different groups would determine the impact of light intensity on the growth and development of the microorganisms. Control variables such as temperature, nutrient availability, and humidity would need to be maintained throughout the experiment.

57 - Investigating the effects of different types of food on the metabolism and energy balance of humans.

Conduct a randomized controlled trial in which participants are assigned to different groups and given different types of food to eat for a set period of time. The participants' energy intake, metabolism, and weight would be measured before and after the intervention to determine the impact of the different types of food on their energy balance. Other factors such as physical activity levels and sleep patterns would also need to be controlled for to ensure accurate results.

58 - How does the level of nutrients affect the growth and development of plants?

Conduct an experiment in which plants are grown in different nutrient solutions with varying levels of nitrogen, phosphorus, and potassium. The growth rate, height, and mass of the plants could be measured over a set period of time to determine the impact of the nutrient levels on their growth and development. Control variables such as light, temperature, and watering would need to be kept constant. The results could be analyzed to determine the optimal nutrient levels for plant growth and development.

59 - Investigating the effects of different types of hormones on plant growth and development.

Set up an experiment in which different groups of plants are treated with different types and concentrations of hormones. The growth rate, height, and mass of the plants could be measured over a set period of time. Control variables such as light, temperature, and watering would need to be kept constant. Comparing the growth rates of the different groups would determine the impact of the hormones on the plant's growth and development. Additional measurements such as leaf size, root length, and flower production could also be taken to further analyze the effects of the hormones.

60 - How does the level of water quality affect the growth and survival of aquatic organisms?

Set up multiple aquariums with varying levels of water quality, such as different levels of pollutants or pH. Introduce the same species of aquatic organism into each aquarium and monitor their growth and survival over a set period of time. The growth rate and survival rate of the organisms can be compared between the different aquariums to determine the impact of water quality on their growth and survival. Control variables such as temperature and feeding schedules should be kept consistent across all aquariums.

Remember to come up with your own original IA topic and check it with your teacher. It should be practical to conduct and relevant to the syllabus. Even A-Level Biology tutors say that this is a great opportunity to develop your personal interests, while advancing your knowledge of the Biology curriculum.

How can I prepare for the IA?

To prepare for the IA, students should ensure that they understand the material covered in their biology course and should practice writing lab reports. They should also seek feedback from their teachers on their writing skills and their understanding of the research process. IB tutors provide personalized guidance and can help students understand complex topics and achieve higher grades as well.

TutorChase's IB resources, including IB Biology Q&A Revision Notes, are perfect for students who want to get a 7 in their IB Biology exams and also prepare for the internal assessment. They are completely free, cover all topics in depth, also have IB Biology past papers and are structured by topic so you can easily keep track of your progress.

How is the IA graded?

The IA is worth 20% of the final grade for the IB biology course, whether you are studying at Higher or at Standard Level. It is graded by the student’s teacher, who is trained and certified by the International Baccalaureate organization. The report is then sent to a moderator, who will check that the report adheres to the IB guidelines and that the grade awarded is appropriate.

Online Biology tutors emphasise that it is important for students to be familiar with the assessment criteria for the biology internal assessment. These criteria are used to grade the laboratory report and reflective statement, and include aspects such as the quality of the research question, the methodology used, the data analysis, and the conclusion. Students should also make sure that their report is well-written and properly formatted, and that it includes all the required sections.

Recent Changes to the IB Biology IA Guidelines

The IB has recently updated the guidelines for the Biology IA to better reflect the evolving nature of biological research and education. These changes include a greater focus on the application of biological principles to real-world situations, a more structured approach to reflective statements, and updated word count and grading criteria. It is important for students to familiarize themselves with these changes to ensure they meet the new expectations.

Source: IB Biology Subject Guide, pre-May 2025

Conclusion

In summary, the IA in the IB is an opportunity for students to demonstrate their understanding of the biology curriculum, as well as their ability to conduct independent research. It consists of a laboratory report and a reflective statement, and is worth 20% of the final grade for the course. To prepare for the assessment, students should ensure that they understand the material covered in their IB Biology.