Question

Describe an investigation into the effect of bile on fat digestion. You are given some cloudy fat suspension, which turns clear when all of the fat in it has been digested. You are also given some bile and some lipase solution. Be sure to make your investigation valid and reliable.

Answer 1

Because bile contains salts and digestive compounds and lipase is a digestive enzyme, you might create a simple qualitative experiment to test the action of bile and lipase. Bile is first used to emulsify and break down food entering the small intestine, and lipase is used afterwards by the pancreas to break down fats. With this information, I suggest this experiment:
1) Label 4 test tubes A, B, C, and D. Divide the fat solution equally into the 4 tubes.
2) In tube B, add an x amount (but not the whole volume) of the bile solution.
3) in tube C, add a y amount (but not the whole volume) of lipase solution.
4) in tube D, add the x amount of bile and the y amount of lipase solution. 
5) Swirl/mix until everything looks homogenized/settled.
6) tube A is your control. Compare the 3 other tubes to it and write observations. You should be able to make conclusions about the role of bile in digesting a fatty solution, and the extent of digestion with and without the additional lipase. 
Hope this is helpful!~ There are certainly many other possible experiments.

Answer 2

Same volume  of fat suspension into each of two boiling

tubes. Place in water bath with thermometer, and wait

until balanced . Add equal volumes  of lipase solution

to each, and bile to only one . Time how long it takes each

tube to clear.