Its is to remove liquid waste from the blood in the form of urine, and keep a stable balance of salts and other substances in the blood and produce erythropoietin, hormone that is the formation of ref blood cells. The kidney remove ursa from the blood through this filtering units called nephrons
        
             
        
        
        
There are several specific characteristics for procaryote and eucaryote:
- Procaryotes has a cell wall, in addition to the cell membrane.
- procaryotes has chromatin in the cytoplasm, they do not have a nucleus.
- Procaryotes are small cells visible only at the microscope with x100 objective.
About the eucaryotic cells:
- Eucaryotes have mitochondria, 
- Eucaryotes have endoplasmic reticulum
- Eucaryotes have a nucleus with DNA chromatin and nucleoli inside it.
- Eucaryotes are visible in the microscope x40
        
             
        
        
        
Answer:
Aspects of evolution are constantly being challenged and explored in light of new evidence
Explanation:
The whole idea of evolution has to do with the fact that organisms developed into their present form from simpler life forms. According to Oxford dictionary, evolution is; ''the process by which different kinds of living organism are believed to have developed from earlier forms during the history of the earth.''
Evolution depends on evidence from fossil records. Evidences that support the theory of evolution continue to be amassed as science advances. Hence, aspects of evolution are constantly being challenged and explored in light of new evidence.
For this reason, the evolutionary history and development of whales is being hotly debated and there has recently been a major shift in our understanding of the processes used to detail whale evolution.