Nephrons
Nephrons are the basic structural
and functional units of the kidneys. Each
of the kidneys contains over a million nephrons. Nephrons function by filtering
blood and then removing needed substances from the filtrate before eliminating
the remaining fluid that contains water, metabolic waste, and toxins.as urine. This process occurs through three stages which
are ultrafiltration, selective reabsorption and osmoregulation.
Rhizobium bacteria fix nitrogen after becoming established inside the root nodules of plants(such as legumes)
C. The question is hinting at the similarities between how single cellular organisms maintain homeostasis by regulating water levels the same way the kidney does for multi cellular humans.
The threat to biodiversity is human impact