An animal cell containing 15% sucrose is placed into a solution containing 70% sucrase. assuming that sucrose cannot readily cross the cell membrane, what will likely happen to the cell over the course of a 24 – 48 hour period

Sucrose cannot pass the cell membrane, but water molecules can.

By the given percentages, we can conclude that the animal cell has a higher water potential, because it has a lower sucrose concentration. Meanwhile the solution has a lower water potential, since it has a higher sucrose concentration.

In this way, water molecules will move from the cell to the solution, due to osmosis.

Osmosis is always the water molecules, moving from a region of higher water potential to a region of lower water potential, through a semi permeable membrane, which is the cell membrane.

So what would happen is that the cell will shrink, because it lose so much water.