Are all the parks on one ground? I'm reading answers and it seems as if you have to use public transportation to visit each park. And are the parks wheel chair accessible ?

Yes it is wheel chair accessible they have an elevator for the second floor

All the parks are not on one ground, most are within ten to fifteen minutes walking distance of at least two other major site/area. They are all wheelchair accessible. Your hotel concierge or even desk staff would be willing to help coordinate your day in advance.

Aquarium and Insectarium are 3 blocks apart. Zoo you will need transportation to. Its uptown. Both are wheelchair accessible.