Only about 3 percent of the worlds water is fresh, and even less than that is usable, because most of it is locked up in glaciers or in permanent snow fields.
The correct answer is D.
1.each of several hierarchical levels in an ecosystem, comprising organisms that share the same function in the food chain and the same nutritional relationship to the primary sources of energy.
A scavenger is an organism that mostly consumes decaying biomass, such as meat or rotting plant material. Many scavengers are a type of carnivore, which is an organism that eats meat. While most carnivores hunt and kill their prey, scavengers usually consume animals that have either died of natural causes or been killed by another carnivore.
Scavengers are a part of the food web, a description of which organisms eat which other organisms in the wild. Organisms in the food web are grouped into trophic, or nutritional, levels. There are three trophic levels. Autotrophs, organisms that produce their own food, are the first trophic level. These include plants and algae. Herbivores, or organisms that consume plants and other autotrophs, are the second trophic level. Scavengers, other carnivores, and omnivores, organisms that consume both plants and animals, are the third trophic level.
Nitrogen is converted from atmospheric nitrogen (N2) into usable forms, such as NO2-, in a process known as fixation. The majority of nitrogen is fixed by bacteria, most of which are symbiotic with plants. Recently fixed ammonia is then converted to biologically useful forms by specialized bacteria.
An established population that is accustomed to change.
Answer:
If you're on EDGE 2021, it's NOT D.
I think it's A.
<span>In a balanced ecosystem, the number of secondary consumers must be fewer than the number of primary consumers.
In a balanced ecosystem, the number of producers is ALWAYS the largest. As the trophic levels increase, the number of organism decrease, so primary consumers are less than producers, secondary consumers are less than primary consumers, and so on.</span>
