Axillary buds are found at the insertion point of leaves and lateral branches in the nodes and give rise to lateral branches and flowers. Internodes are the stem regions between nodes. They lack lateral organs. It can be said that the stem is made up of nodes, internodes and axillary buds tidily arranged.
So they can say the number quicker.
Darwin's theory of evolution by natural selection can explain how antibiotics are becoming defective because the bacteria that is trying to be fought off might have had a mutation making it more likely to survive. Once that surviving bacteria makes offspring most of the first generation will die from the antibiotic but soon all of their offspring will produce a resistance to that antibiotic.