6. this diagram shows two groups of plant cells, one with rhizome and one without the bacteria. label which is which, and explain the obvious size difference, using observations from part c of the lab in your answer.

I would say the bacteria containing rhizobium is the bigger one and the one without the bacteria is the smaller one. In the document, in section C, you observed the two. You can clearly see that rhizobium has bigger chunks than the one without it. The smaller one contains regular bacteria which makes it really small compared to the other

Here's some context I got from this website, it should help :)
"This is because when the bacteria enters the cells and begins to reproduce, the cells expand to make room for the growth of the Rhizobium colony and, therefore, become larger than their neighboring cells that do not have Rhizobium." (https://docslide.us/documents/biosem2516.html)

Hope this makes sense, good luck
-K12 student ;)