Plant and animal cells. Cytoplasm. Jelly-like substance, where chemical reactions happen. In plant cells there's a thin lining, whereas in animal cells most of the cell is cytoplasm. Plant and animal cells. Nucleus. Controls what happens inside the cell.Carries genetic information. In exams don't call the nucleus the 'brain' of the cell.ytoplasm. Jelly-like substance, where chemical reactions happen. In plant cells there's a thin lining, whereas in animal cells most of the cell is cytoplasm. Plant and animal cells. Nucleus. Controls what happens inside the cell. Carries genetic information. In exams don't call the nucleus the 'brain' of the cell.
Iron is rarely found in its pure form on the surface of the earth; as it tends to get oxidized when it comes in contact with atmospheric oxygen. For this reason, most of its ores are in the form of iron oxides.
For example, it is an iron atom in haemoglobin that is responsible for carrying oxygen around the blood stream. Iron is not found as the free metal in nature. The most common ore is haematite (iron oxide, Fe203). Iron is found in other minerals such as magnetite, which is seen as black sands along beaches. The core of the earth, more than 2000 in radius, is composed largely of iron.