IB MYP Integrated Sciences e-Assessment : Digestion Exam Style Practice Questions - New Syllabus
Question a (3 marks)
Many pain relief tablets are enteric coated, meaning they are coated with a substance that delays the tablet from dissolving until it has passed through the stomach into the small intestine. Suggest why it is an advantage for a tablet to dissolve in the small intestine rather than the stomach.
▶️Answer/Explanation
Advantage:
The stomach has a highly acidic environment (pH ~2), which can degrade certain medications before they are absorbed. The small intestine has a more neutral pH (~6-7), which is better suited for the absorption of many drugs. Additionally, the small intestine has a larger surface area for absorption, ensuring that the medication is effectively delivered into the bloodstream.
Question b (4 marks)
A student is carrying out an investigation to see which type of enteric coating is best for the delivery of a particular medication. This medication needs to dissolve as soon as possible when it reaches the small intestine.
The student has three different types of enteric coating. Inside each coating is a sample of blue dye. The student places these tablets into liquids with different pH and records the time it takes for the liquids to turn blue.
Data Table:
| Coating | pH 1 | pH 4 | pH 7 |
|---|---|---|---|
| A | 8.00 h | 1.50 h | 0.75 h |
| B | 4.00 h | 3.00 h | 0.25 h |
| C | 6.00 h | 4.00 h | 0.20 h |
Use the information in the table provided to state which coating would be the most suitable for this medication. Justify your choice using scientific reasoning.
▶️Answer/Explanation
Most Suitable Coating: Coating C
Justification:
– The small intestine has a slightly alkaline pH (around 7-8). The medication needs to dissolve as soon as possible when it reaches the small intestine.
– Coating C dissolves the fastest at pH 7 (0.20 hours), which is the pH of the small intestine.
– Coating B also dissolves quickly at pH 7 (0.25 hours), but Coating C is slightly faster.
– Coating A takes much longer to dissolve at pH 7 (0.75 hours), making it less suitable.
– Therefore, Coating C is the most suitable because it dissolves the fastest in the pH conditions of the small intestine.
Question c (2 marks)
The student is also investigating the effect of temperature on the dissolution time of the enteric coating. The student places the tablets in liquids at different temperatures and records the time it takes for the liquids to turn blue.
State two control variables that the student must keep constant during this investigation.
▶️Answer/Explanation
Control Variable 1: pH of the liquid
– The pH must be kept constant to ensure that the dissolution time is only affected by temperature and not by changes in pH.
Control Variable 2: Volume of the liquid
– The volume of the liquid must be kept constant to ensure that the dissolution time is not affected by the amount of liquid used.
Question d (3 marks)
The student records the following data for the dissolution time of the enteric coating at different temperatures:
| Temperature (°C) | Dissolution Time (h) |
|---|---|
| 20 | 2.50 |
| 30 | 1.75 |
| 40 | 1.00 |
| 50 | 0.50 |
Describe the relationship between temperature and dissolution time.
▶️Answer/Explanation
Relationship:
– As the temperature increases, the dissolution time decreases.
– At 20°C, the dissolution time is 2.50 hours, but at 50°C, the dissolution time is only 0.50 hours.
– This shows that higher temperatures speed up the dissolution process of the enteric coating.
Explanation:
– Higher temperatures increase the kinetic energy of the molecules, causing the coating to dissolve faster. This is a common trend in chemical reactions, where increasing temperature generally increases reaction rates.
Question e (2 marks)
The student concludes that the enteric coating dissolves faster at higher temperatures. Suggest one practical application of this finding in the pharmaceutical industry.
▶️Answer/Explanation
Practical Application:
– This finding can be used to design medications that release their active ingredients more quickly in the body, especially in cases where rapid drug delivery is needed (e.g., pain relief medications).
– It can also help in the development of enteric coatings that are more effective in different environmental conditions, such as in warmer climates or during fever when body temperature is elevated.