Germination experiments and simple osmosis labs are seen all too often by moderators. If you want to show real personal engagement then your investigation has to have a 'twist' that shows you have really thought about some biology. These ideas provide suggestions for this sort of enhancement of some simple lab ideas to help you show your personal engagement.

Spring, summer or autumn germination of seeds? Does light affect seeds differently according to their normal season of germination?

The effect of abiotic factors on the germination of seeds is a bit of a standard lab, the methods are very easy and doesn't show much personal engagement unless students can put an interesting spin on the investigation. This idea is one way to do just that.  Research is necessary on the choice of seeds for the experiment. Students find out about the normal germination time of the seeds, the method the seeds use to control this germination time and then test testing the specific effect of light on germination. The colour of light (red / far-red, etc.), the intensity of light, or the day/night length could all be interesting factors, as could other abiotic factors appropriate to the season.  Biodynamics agricultural ideas could be a rich source of possible hypotheses to test too.

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 freezing or winter cold on germination of perennial seeds.

Some seeds (perennials) require a period of moist cold before they germinate. They get this naturally in the wild over winter but plants relying on natural cold stratification usually make many seeds, because the process in nature results in the death of many seeds. Gardeners have developed ways of creating these conditions to promote germination more safely, called cold moist stratification. Any of the following methods would make interesting investigations: How long should this freezing treatment last?  What minimum temperature is required to have the 'freezing effect'?

• Cold water soaking: Put seeds into a jar in the fridge and change the water frequently. This is supposed to be like snowmelt,  it is supposed to wash away germination inhibitors from the seeds.

• Refrigeration: Mix seeds into a little clean sand, sterile soil or paper towels. Put this into a resealable plastic bag in the fridge.  Three months is a good time, but sometimes you can get away with less, even 3 weeks.

• Autumn / fall planting: Plant the seeds in pots before it gets too cold and cover the pot with something which will allow a little water to get in but not too much and also insulate them from extremes of cold.

• Winter solstice sowing: (December 21 in northern hemisphere) Planting in the middle of winter or even later, up to February. The harder your winter the later you can plant. This takes advantage of the natural swings between cold and warm that occur in late winter. Europeans have been winter sowing for decades--I've seen a mosaic from Roman times depicting Frenchmen winter sowing beans.
• Outdoor treatment: "Plant" seeds as in the refrigeration method, but instead of putting the ziplock bags in the fridge, put them outside in a shed during winter. This gives the seeds a fluctuation in temperatures instead of steady cold of the fridge. Keep the seeds away from direct light (and hungry mice!).

Any of these would be an improvement on the all too common 'factors which affect germination' experiments.  Deliberately investigating a specific biological mechanism is better than simply describing an observed effect, without an understanding of why this happens.

This book, Norman Deno "Seed Germination Theory and Practice" (1993) is well known by gardeners in the USA. It describes many reasons and mechanisms for delaying germination used by seeds.  Well worth looking at.

The effect of water temperature, or some other aquarium conditions on the gender distribution of livebearer offspring.

It is known that egg incubation temperatures can influence the proportion of male and female chicks which hatch, but could this same factor influence the gender of guppies, or other fish which can be easily kept and bread in an aquarium. Guppies are ideal because the male and female fish are so distinct and they readily breed. This experiment would need to be carefully carried out to comply with the guidelines on animal experimentation, but so lond as the conditions were within the natural ranges of the fish this would be fine.

The biggest challenge would be the length of time the fish take to breed, and also managing the conditions so the fish actually do reproduce. Predation of the fry might also be a challenge if there are other fish in the tank, although plenty of vegetation can reduce this.  This is perhaps an investigation idea for a student who already keeps tropical fish, or who is in a school with a lab aquarium.

Does your blood group affect the frequency which you get insect bites, or the severity of the skin's reaction?

This is another investigation idea with which students must be careful to comply with the IB animal experiment guidelines. You must not plan to deliberately cause discomfort to participants, or mosquitoes. But I could imagine that the data might be collected after a evening event where mosquitoes were an irritation and where many of the participants knew their blood groups already.  That means that it's not an idea for everyone.  The principal of the methodology is interesting, although it may be that students with some means of access to a group of medical professionals in an after work barbeque could be the only ones who might try.
  It could be a data-base type investigation if the right data cold be found. There is much research on malaria which may prove useful. Remember too that a hybrid study is also possible, where a small sample of experimental can be supplemented with some secondary data.

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.

Data analysis of body temperature in different groups of people.

If you can find a good data base which provides enough data so that you can choose a part of it (and thus control some variables) it could make a good IA.  A hybrid IA could compare experimental data with a data set published in the biological literature.  Here is a nice example of a set of data, Body temperature data and there are many more suggestions of data sets here: Temperature of a Healthy Human. An interesting option might be to test whether temperatures of a group of people in your school community measured in an experiment are the same as data selected from one of these data sets. Notice that there are interesting differences in 'oral' and 'tympanic' measurements as well as young and old people, males and females, and who knows more. There are plenty of options to investigate; BMI and temperature, mealtimes, time of day, etc.

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 permitted to use body fluids in IAs, testing your own hair would be acceptable. To meet the animal experimentation guidelines the hair would have to be collected ethically, without causing pain!  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.

Are the limits of manufacturer's instructions reliable? E;g. the IKEA Växer hydroponic growing system.

Testing the manufacturer's instructions for a growing system could make an interesting IA.  Why does it advise specific types of LED lights? What is the ideal daily light duration? Does changing the chemicals dissolved in the water for the hydrponic system affect plant growth. The challenge of this investigation would be to find a biological reason for a changed variable to have the effect predicted. Obvious one might be light intensity affecting photosynthesis, temperature affeting transpiration or enzymes, or location, fertilizer, type of water used.

What happens after the sell-by date on yoghurt, and other dairy foods?

A simple question in appearance but quite a complex problem. The first aspect to decide would be for which reason are the products past their best.  It could be growth of spoilage bacteria, release of enzymes naturally part of a ripening process, chemical changes from another cause. Of course a specific research question would be needed, but this would probably arise out the choice of food and the background research quite naturally.