1nucleic acids
2protein
3carbohydrates
4 Carbohydrates
5 covalent bonds
6hydrogen bond
7hydrogen bond
8ionic bond
9covalent bond
I hope this somewhat helps you
(Density dependent is the answer)
A. external
These types of signals are observed when there is a cut on the body. The epidermal cells lose contact with one another and divide faster until they are in contact once again. After they come into contact, division slows down again.