Answer:
I have a straight back and sharp teeth to cut objects.
What is easy to get into, but hard to get out of?
I am a way to say goodbye to your sweetheart
I am not alive but I grow I don't have lungs but I need air I don't have a mouth but water kills me. What am I?
I go through a door but never go in and never come out.
A little house full of meat, no door to go in and eat.