Weathering and erosion are similar in that they both work together to change and shape the Earth's surface. While weathering breaks rock and earth down, erosion is the displacement of the pieces and particles of rock and earth.
Mario sets up an experiment to determine the source of the oxygen gas produced by photosynthesis. To determine this, he uses an isotope of oxygen called O-18. He labels the O-18 oxygen so he can follow its path through photosynthesis. Plant A is given carbon dioxide that contains the O-18 isotope. Plant B is given water that contains the O-18 isotope. When he examines the oxygen from both plants, only plant B produced O-18 oxygen. This indicates that the source of oxygen is water. The photosynthesis involves the transfer of electrons between the photosystem I and II. The water gets split into oxygen, hydrogen ions and electrons in the photosystem I. The electrons move to the photosystem II where the carbon fixation into sugars takes place. The plant A will have O-18 isotope in its synthesised sugar molecule, which gets stored inside it.
Genes organized on
chromosomes carry the information that controls the functions of the cell. Each gene contains a particular set of code for a particular molecule or protein for a specific function.
