Alyssa is observing two cells, X and Y. Each cell is from either a plant or an animal. She records some of her observations in a chart.

Based on Alyssa's observations of the two cells, we can deduce the following:

1. Cell X has a cell wall (which is characteristic of plant cells).
2. Cell Y has a round shape and is shaped like a rectangle (suggesting it might be an animal cell).
3. Cell Y has a large nucleus and several organelles, which are typical of eukaryotic cells and could potentially fit both plant and animal cells, but the specific shape suggests it's an animal cell.
4. Cell Y's round shape further indicates it's likely an animal cell, while Cell X's rectangular shape may suggest it's a plant cell.

Considering the additional options presented:

• "Cell X has a cell membrane, and Cell Y does not." This statement is false because both plant and animal cells have cell membranes.
• "Cell Y has a cell membrane, and Cell X does not." This statement is also false for the same reason as above.
• "Cell Y has chloroplasts, and Cell X does not." This is unlikely because chloroplasts are present in plant cells and absent in animal cells.
• "Cell X has chloroplasts, and Cell Y does not." This is likely true, as chloroplasts are characteristic of plant cells (which is likely Cell X) and are not found in animal cells (which is likely Cell Y).

Therefore, the most likely additional observation Alyssa will make is:

Cell X has chloroplasts, and Cell Y does not.