The code in the image is: cellsmatter
This is the first line of the image, which is a poster that says "Cells Matter." The code is all lowercase, without spaces, and alphabetical, which meets all of the requirements.
The image also contains the following text:
Found this written down. I wonder what it means...
A6 B15 B37 C20 C29 C35 D1 D7 D14 D26
This text suggests that the code is a way of encoding the message "Cells Matter." The letters A, B, C, and D seem to correspond to the lines A, B, C, and D of the text.
The numbers 6, 15, 37, 20, 29, 35, 1, 7, 14, and 26 could be the positions of the letters in the message, but it is not clear how this encoding works.
Another possibility is that the code is a way of representing the structure of a cell. The letters A, B, C, and D could represent different parts of the cell, such as the nucleus, the cell membrane, the cytoplasm, and the mitochondria.
The numbers 6, 15, 37, 20, 29, 35, 1, 7, 14, and 26 could represent the positions of these parts of the cell within the cell.