Autotrophic nutrition falls on two levels. Light energy used in photosynthesis and chemical energy for processes involving chemosynthesis. Essentially plants survive on the products of photosynthesis and depend upon the power of the sun to help produce these foods. There are a number of physiological functions in plants, which also help the process of photosynthesis. In order for these organisms to achieve Autotrophic nutrition, they must gather together many raw materials from its environment for photosynthesis to occur. Plants require a source of carbon dioxide and water, chlorophyll to collect absorb the light. Oxygen, in plants is a waste product. Many specialised functions help plants and autotrophs survive. Phototropism is an adaptation given by plants as the shoots grow up towards the light and have a rapid elongation of the shoots to get light as fast as it can, known as etiolation.
As for Hetrophic nutrition, there are many forms. Holozoic nutrition, is concerned with taking food into their bodies and digest it into smaller molecules. Saprobiontic nutrition involves feeding off the bodies of decaying organisms. Some forms of bacteria and fungi feed in this way. Parasitism is concerned with feeding off other living organisms.
All humans feed in holozoic conditions, either carnivore, herbivore or omnivores. We, unlike plants take food into our bodies and digest and absorb them making use of them in such processes as for growth and repair as proteins do, for example.
With Holozoic nutrition, movement of the animal to the food source is essential, whether that be catching prey or walking from the living room to the dining room table, we don’t live on the surface area of our foods like some organisms (called symbiosis’).
We mechanically digest our food with various physiological structures such as out teeth and our mouths. The teeth grind the food down so that it is ready for mechanical digestion by enzymes and other chemicals in the stomach and along the alimentary canal. As with autotrophic nutrition, there is excretion. However the products are much different. In plants the waste product is oxygen whereas in animals and hetrotrophs the products, especially in humans, are carbon dioxide and urea. However, humans also have the added process of egesting the food waste, which is not used and cannot be digested. This process is defecation.
Overall, there are many differences and similarities between autotrophic and hetrophic nutrition. The key difference is how food is obtained, whether it is produced inside the organism or if it is obtained by consumption of other organisms.
