Why do most premature babies have breathing troubles?

What is the next step in muscle contraction after the actin changes shape? (apex)

Hey everybody i need with a biology question. all the gametes of isogamous organisms are genetically identical. true false

At what point on a roller coaster is the gravitational potential energy (gpe) the lowest? question 7 options: at the top of the highest drop at the lowest point of the roller coaster while on the decline while on the incline