The embryo develops<span> inside an organ called the uterus (womb). It sinks into the soft lining of the uterus and absorbs food from the mother through an organ called the placenta, which </span>develops<span> from the </span>embryo<span>. The uterus has a very stretchy wall so that it can expand as the baby grows.</span>
Answer:
There is a precise compatibility between the active site and the lactose molecule.
Explanation:
An enzyme's active site has a specific shape, where only the substrate it is designed for can fit. It's much like a puzzle, where you must have the right pieces join together or else you wont get a coherent picture.
I would say cartilage because that is the unusual material they are made of
Hope this helps :)