I understand that you should use 'is' for singular and 'are' for plural, but in this sentence I am not sure which applies.
Take the sentence
Bees are an important part of our ecosystem.
Let's say I wanted to reword it so that the subject is at the end of the sentence. Which of these two is correct?
An important part of our ecosystem are bees.
An important part of our ecosystem is bees.
To me they both sound wrong, so I want to know how I can determine correct grammar in these cases.