Nitrogenous waste of the body are excreted by organisms of different species differently. Others, such as the mammals excrete it in a form of urea while other in a form of ammonia. Still others, excretes it in a form of uric acid. The latter group of organisms being referred to are the BIRDS and REPTILES.
This organisms found to excrete the nitrogen as urea are called as uricothelic organisms and excrete white powder or paste. The process of conversion of ammonia to uric acid needs a lot of energy or energy intensive, however; it is less toxic and reduces need for water.
Sends signals between the brain and body - Nervous Tissue
Protects the skin from bacteria and particles - Epethelial Tissue
Allows shivering to produce ear and maintain body temperature - Muscle Tissue
Provides structural support for the organs - Connective Tissue
Answer is c. If one essential nutrient within an ecosystem runs out, primary productivity will be limited
According to Vitousek et al., 2010, nutrient limitation defined as meaningful additions of an essential element in biologically available forms which increases the rate of primary productivity or increase in the biomass in an ecosystem. Alternately, nutrient limitation may also explained as when the supply of one essential nutrient of the ecosystem runs out the primary productivity of the plants will be limited.