OSMOSIS LAB WRITE-UP ASSIGNMENT
1. According to your best fit line, did potatoes placed in lower or higher salt concentration tend to lose
the least weight? Use your understanding of osmosis to explain whether or not you expected those
results. For example, why should different salt concentrations cause potatoes to lose or gain weight?
2. Which solutions were hypertonic to your potatoes? Explain how you know the answer to this
question.
3. Which solutions were hypotonic to your potatoes? Explain how you know the answer to this
question.
Before answering questions 4 and 5, review the instructions for using a best-fit line. But write your
answers in your own words! Answers with phrasing copied from the handout will receive no points.
4. Determine the osmolarity of the real potato:
a) Explain (in your own words) how you can use your best-fit line to estimate the osmolarity of the
potato. (Give a step-by-step explanation, just as if you were giving instructions to a friend.)
b) According to your best-fit line, what is the % of dissolved particles in the potato?
5. Determine the osmolarity of the “unknown” solution:
a) Explain (in your own words) how you can use your best-fit line to estimate the % salt
concentration in the unknown solution. (Give a step-by-step explanation, just as if you were
giving instructions to a friend.)
b) According to your best-fit line, what is the % of salt in the unknown solution?
6. How did plant (potato) cells respond to being placed in a hypotonic solution? Why do plant and
animal cells behave differently when placed in the hypotonic solution?
7. How did animal (blood) cells respond to being placed in a hypotonic solution? Why was the response
in a hypotonic different to the response of the animal cells placed in isotonic and hypertonic
solutions?
