The existence of land bridges was used to dispute continental drift
Proteins are made up of a chain of 20 amino acids
I believe the answer is that the CFCs cause low ozone concentrations in the atmosphere.
Sorry if I'm wrong, hope this helps.
A group of similar (accoding to function) types of cells, when comes together to perform a specific function, then it forms a tissues.
When a group of similarly working tissues come together then they form an organ.
And this relation could be written as
cell > tissue > organ
So, organ is a collection of tissues and tissues are collection of cells.
