Answer:
more train cars
Explanation:
because if I had more train cars I could put both the cooler and the heater on the train.
Hope this helps :)
The second membrane protects e.coli (Gram-negative bacteria) against a harsh environment.
The outer membrane indirectly helps stabilize the inner membrane as peptidoglycan layer in Gram-negative bacteria is relatively thin than gram positive bacteria ( they have multilayer pepdtidoglycan )