Ljósavirkni

Ljósavirkni is an Icelandic term that translates to "photosynthesis" in English. It is the fundamental biological process by which green plants, algae, and cyanobacteria use sunlight, water, and carbon dioxide to create their own food in the form of glucose (a sugar) and oxygen. This process is vital for life on Earth as it forms the base of most food chains and is responsible for producing the oxygen that most organisms, including humans, breathe.

The process of ljósavirkni occurs primarily in specialized organelles within plant cells called chloroplasts. These chloroplasts contain chlorophyll, a pigment that absorbs light energy from the sun, particularly in the red and blue wavelengths. This absorbed light energy is then used to split water molecules into hydrogen and oxygen. The hydrogen is then combined with carbon dioxide from the atmosphere to produce glucose. The oxygen is released as a byproduct into the atmosphere.

Ljósavirkni can be broadly divided into two main stages: the light-dependent reactions and the light-independent reactions (also known as the Calvin cycle). The light-dependent reactions capture light energy and convert it into chemical energy in the form of ATP and NADPH. These energy-carrying molecules are then used in the light-independent reactions to fix carbon dioxide and synthesize glucose. The efficiency and rate of ljósavirkni are influenced by various environmental factors such as light intensity, carbon dioxide concentration, temperature, and water availability. It is a cornerstone of ecological systems, enabling the production of biomass and the sustenance of biodiversity.