Answer:
One type of control that occurs at the DNA level is the regulator genes. The regulator genes synthesize a repressor molecule that binds to the operator and stops transcription of the structural genes. Whenever there is enough amount of structural genes made, a repressor molecule will bind to the operator region and stop further transcription.
One type of control that occurs at the RNA level is RNA splicing. By this method, different proteins can be made by a single RNA transcript. 
 
        
             
        
        
        
There are five major types of infectious agents: bacteria, viruses, fungi, protozoa, and helminths. In addition, a new class of infectious agents, the prions, has recently been recognized
        
                    
             
        
        
        
Di = 2
Tri = 3
C. Since there are only 2 Phosphates, the molecule shown is ADP.
        
             
        
        
        
Sample Response: The main reason for the decrease in trillium is the large number of deer in the forest that are eating the trillium. The author cites a research study performed by scientists as evidence to support her claim. In this study, researchers planted two fields, each containing garlic mustard and trillium. One was left open to deer, and the other was fenced off. Scientists kept track of the fields for several years. They found that trillium was able to regain much of its original space in the protected field. In the unprotected field, there was still more garlic mustard because the deer ate the trillium. The author also states that similar research studies have been conducted in many forests across the United States, and they all reveal similar results.
 
        
             
        
        
        
Answer:
Long life span
Explanation:
A model organism is a non  human specie that is used for study in order to understand a particular biological phenomena. 
One of the qualities of a model organism is that; It should have a short life span this will make it more amenable to experimental manipulation due to short generational time. Therefor Long life span will not be a desirable characteristic.
Other desirable characteristic includes ease of growth and production of many offsprings. 
Also common genetic mechanism with other organisms, they should share some degree relatedness.