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.
When focusing a specimen you should always start with the SCANNING objective. Scanning objective is used to put the object you want to examine in focus. After proper focusing on the object, you can now switch to power objective.
The water is able to leave in and out of the cells because there is a cell membrane splits the bilayer of tissue and then the water start leaving and coming back in again from the stage of osmosis.