I'll give a few, Plants, animals, meteors or bones.
 
        
             
        
        
        
Answer:
To carry out life processes like breathing, respiration, digestion, excretion etc.
Explanation:
 
        
             
        
        
        
Answer:
Control group
Explanation:
In an experiment, the group which receives the treatment (in this case injection of actual drug)  is known as experimental group because the experiment is being conducted on it. While on the other hand the group which do not receive the treatment is known as control group. The results obtained from the experimental group are compared with the control group to determine the effectiveness of the treatment. 
 
        
             
        
        
        
Answer:
Explanation:
Urea is the cellular waste product that the kidneys remove from the blood.Kidneys are the two bean shaped organs that has several functions to keep the body healthy. It not only removes urea from the blood, but also helps in the formation of urine and maintaining the fluid level of the body. The two kidneys are placed on the two sides of the spinal cord. The blood enters the kidney through the renal artery. The nephron within the kidneys mainly take out the waste products and the excess water from the blood and purifies it.If the kidneys of a person fail to work properly then it becomes important to perform dialysis for taking out the waste materials from the blood.