Answer:
The microorganisms present metabolic wastes that serve as the primary source of food for other living things.
Bacteria that live free in the soil or in symbiosis with plants are essential to fix nitrogen, both nitrates and ammonia. These bacteria take nitrogen directly from the air, originating compounds that can be incorporated into the composition of the soil or living beings.
This property is restricted only to prokaryotes and is widely distributed among different groups of bacteria and some archaeobacteria. It is a process that consumes a lot of energy that occurs with the mediation of the enzyme nitrogenase, which the rest of the living organisms that cannot do or comply with this process is because they lack said enzyme.
Dunaliella is a genus of microscopic algae of the Chlorophyceae class and of the order Volvocales. All are unicellular, although with very varied morphologies.
Morphologically, its main characteristic is that they lack a rigid polysaccharide cell wall.
The ecology of this genus of green algae is characterized by its high tolerance to salinity, with eukaryotic organisms having greater tolerance to salt. They are euryhaline, adapted to salt concentrations from 50 mM NaCl to almost 5.5 M NaCl.
Explanation:
By nitrogen fixation is meant the combination of molecular nitrogen or dinitrogen with oxygen or hydrogen to give oxides or ammonia that can be incorporated into the biosphere. Molecular nitrogen, which is the majority component of the atmosphere, is inert and not directly usable by most living things. Nitrogen fixation can occur abiotic (without the intervention of living beings) or by the action of microorganisms (biological nitrogen fixation). Fixation in general involves the incorporation into the biosphere of a significant amount of nitrogen, which globally can reach about 250 million tons per year, of which 150 correspond to biological fixation.
<u>Answer:</u>
Recent evidence suggest that feathers evolved from scales and suggest that 'feathers and pycnofibers' could be homologous.
<u>Explanation:</u>
- One of the major difficult issue related to bird evolution is the evolution of feathers.
- Feathers are considered as the most 'complex integumentary structures' which are found in vertebrates.
- Evolutionary developmental biology suggests that the 'planar scale structure' is been modified for developing into feathers by 'splitting' to form web like structures.
- Scales and Feathers consist of 'two distinct form of keratin' so it was thought that 'each type was exclusive skin structure' but recent study suggests that they are developmental expressions of same skin structures.
Background extinction refers to the normal extinction rate. These are species that go extinct simply because not all life can be sustained on Earth and some species simply cannot survive. Mass extinction is a widespread event that wipes out the majority (over 50%) of living plants and animals.