Use the graph to answer the questions below At what concentr

Use the graph to answer the questions below: At what concentration of salt was the sweet potato core isotonic to the salt solution? What does a negative weight change mean, in terms of water movement? Name a control variable from the potato core experiment.

Solution

Potato contains water. When kept in a hypertonic NaCl solution, then exosmosis occurs because potato membrane acts as a semi-permeable membrane. This results in loss of water from potato, which further results in weight loss.

a) Isotonic salt solution means the concentration of salt inside and outside the potato is same. So, neither water will go inside potato (endosmosis), nor it will go out (exosmosis).

At 2% NaCl concentration, weight change in sweet potato is zero; as according to the graph.

b) Negative weight change water has started going inside the potato. In other words, the weight of potato has started increasing due to endosmosis, instead of exosmosis.

When, initial weight is x, final weight = x+y; Then weight change will be = (initial- final) = -y = negative

I mean to say that when final weight is more than initial weight, then weight change will be negative.

c) Control variable is boiled potato. In boiled potato, weight change will not be observed; because boiled potato membrane is not a semi-permeable membrane.