1. Y10 Triple Scientists Biology ISA
Context: Investigating how Concentration affects the rate of diffusion

2. What is a transdermal patch?
A transdermal patch is a medicated adhesive patch that is placed on the skin to deliver a specific dose of medication through the skin and into the bloodstream.
The medication enters the body, through the skin, by diffusion.

3. Diffusion
Diffusion is the movement of molecules from a region of high concentration to a region of lower concentration down the concentration gradient.
It happens because of the kinetic energy of the particles and their rapid random movement.
It stops when equilibrium is reached and the concentration is uniform (there is no diffusion gradient).

4. Diffusion in Biology Why is diffusion important in biology?
Gases and substances in solution enter and leave cells by diffusion.
Substances enter our cells from the blood.
Substances enter the blood by diffusion.
Diffusion is used as method to deliver medicines through the skin eg hormone patches. It is also used in dialysis machines when people have kidney failure.

5. Drug Patches
Scientists have developed ways to administer drugs by using patches adhering to the skin. These include: Nicotine patches to help smokers stop smoking Morphine patches for pain control Hormone patches for hormone replacement therapy

6. What is the advantage of transdermal patch?
An advantage of a transdermal drug delivery route over other types of medication delivery such as oral, topical, intravenous, intramuscular, etc. is that the patch provides a controlled release of the medication into the patient, usually through either a porous membrane covering a reservoir of medication or through body heat melting thin layers of medication embedded in the adhesive.

7. A wide variety of pharmaceuticals are now available in transdermal patch form.
Link to “How to apply a nicotine patch” video

8. Context
Nicotine patches come in different strengths that deliver different amounts of nicotine to the body over the time period that the patient wears them for.
Manufacturers need to be able to make patches that deliver nicotine at different rates to patients, depending of the strength of patch they use.

9. Context: Investigating how Concentration affects the rate of diffusion
Doctors wish to have patients receiving the right dose of a drug and for it to last a lengthy period of time.
Getting the right concentration so the drug diffuses through the skin into the body to provide the right dose is crucial if the drug is to be effective.

10. Hypothesis
Increasing the concentration will increase the rate of diffusion.
This is because as concentration increases the difference in concentrations will increase causing a greater concentration gradient.
Higher concentration = greater number of particles therefore will collide and diffuse more rapidly.

11. Method Planning Independant Variable = concentration
Dependant variable = time taken for indicator to be changed totally in centre of block.
Control variables: -
temperature of the acid must be the same
size of the jelly blocks must be the same
shape of the jelly blocks must be the same
volume of acid used

12. Method

13. Method Risk assessment
Using dilute hydrochloric acid – corrosive – causes burns.
Likelihood of harm low if careful
Wear goggles to protect eyes and if any spillage on skin, wash under tap.