Mountain systems are collections of similar mountain ranges across continents. Himalayas extend across five countries, including India and China. Mount Everest is the tallest mountain on Earth. Andes are the longest mountain range in South America
Skin cysts form beneath skin, filled with fluid or air, common in over 18s. Skin abscesses are pus-filled pockets caused by bacterial infections. Pimples are oil-filled skin eruptions appearing during puberty. Blackheads form when hair follicles become clogged with oil
Two internationally significant waterways connecting Aegean and Mediterranean to Black Sea. Located in northwest Turkey, dividing Europe and Asia. Governed by Montreux Convention since 1936