How do you think scientists use these types of structures to determine how organisms are related?

I think scientists use these types of structures to determine how organisms are related by:

establishing associations between related common ancestors.

Explanation:

The reason behind this answer is that in the first place, scientists can evaluate the source origin of all organisms and find out if they share a common ancestor based on the organization they have. This can be very useful considering certain organisms can share characteristics. So, they might be located near one to the other.