Thank you for your help.
At first look, I wanted to attempt this question using the concepts of different characteristics of material. However, the answer sheet suggested that this question is from the topic cells.It goes along the line that the plastic sheet gives a shape to the paper bag. I am still trying to understand the solution.


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I will answer B first which will give insight to answer A.

Question B
The structure of animal and plant cells are similar in that both:
- Are eukaryotic, which means they have a defined nucleus which contains chromosomes. It is protected and surrounded by the cytoplasm, which is a watery or gel-like liquid.
- Have a cell membrane that surrounds the cell. This allows for the cell to exert control, in most cases, over what can penetrate the cell, and what cannot.

The are different in three key areas:
- Plant cells have chlorophyll which is required for photosynthesis
- Plants cells have a large, central vacuole, while animal cells may have one or more small vacuoles
- Plant cells have cell walls which are composed of cellulose. This allows high pressure to build inside of it without bursting. As a result a plant cell is able to collect large amounts of liquid through osmosis. In contrast if you fill the animal cell with too much water it will eventually pop.

Question A
One possible reason that the bag surrounded by plastic did not burst is because the plastic bag acted like the cell well of a plant cell. The plastic, "cell wall", allowed for greater pressure inside compared to the paper bag.