Autotrophs obtain energy by the process of photosynthesis. Any living organism need energy to survive and autotrophs are no different. Two types of autotrophs are present and they are Photoautotrophs and Chemoautotrophs. The Photoautotrophs rely on the energy produced during the process of photosynthesis and the Chemoautotrophs get their energy from most of the inorganic substances. Phtoautotrophs actually get their energy from the sunlight and then convert it into reusable form. In case of Chemoautotrophs ammonia is an important source of energy for them.
Well, autotrophs are living things that produce their own food like plants. While heterotrophs get their food from other sources like the autotrophs e.g man Autotrophs obtain their food from a process called photosynthesis. Energy is gotten from the sun, which helps them to manufacture their food. Well, according to the word photosynthesis, photo means light, and synthesis means combining or putting together. We all know that plants need light, water, air and nutrients to survive. This light needed is gotten through the process of photosynthesis. Energy is gotten from the light of the sun. Photosynthesis takes place in the leaves. It is also responsible for the green color. Hydrogen and carbon dioxide in the air are used to form food. Chlorophyll and some other pigments absorb energy from sunlight. All these can be proven by the reaction between water and carbon dioxide. They produce glucose and oxygen. Glucose is the food; carbon dioxide + water→glucose+ oxygen This reaction takes place in the presence of sunlight. Hope i helped.
Crossing over. At the chiasmata during prophase I of meiosis, breakage may occur and exchange of genetic information may take place. New gene combinations which result in variations.
Independent assortment. The arrangement of homologous chromosomes at the equator of the spindle during metaphase of the first meiotic division is random. These homologous chromosomes segregate into different daughter cells which contain different genetic combinations which brings about variation
Fertilisation permits parental genes to be brought together in different combinations. This is the cause of variations in members of the same family.
Mutation is the spontaneous change in the genetic makeup of an organism. These changes may be inherited by the offspring therefore beginning variation.
