Autotrophs are groups of organisms that are capable of manufacturing their own food (organic molecules) through the fixation of carbon dioxide. There are two types of autotrophs:
<em>Photoautotrophs fix carbon dioxide by using light as the energy for driving the process.</em>
<em> </em><em>Chemoautotrophs f</em><em>ix carbon dioxide by using energy from the oxidation of inorganic molecules such as magnesium, or sulfur.</em>
Chemoautotrophs usually inhabit extreme environment such hot vents, deep sea, etc.
In alpha decay, the daughter nucleus is two units less than the parent in atomic number. The mass number also decreases by 4 units. The daughter is thus found two places before the parent in the periodic table.
