Answer:
Mealybugs will commonly leave a white residue on a plant's leaves that resembles cotton. You will find this residue mostly on the stems and leaves. ... You may also find that the plant has a sticky residue on it. This is honeydew and is secreted by the mealybugs.
Explanation:
 
        
             
        
        
        
Adaptations are physical or behavioral traits that make an organism better suited to its environment. Heritable variation comes from random mutations. Random mutations are the initial cause of new heritable traits. For example, a rabbit can't choose to have a different fur color.
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DNA code is transffered to mRNA in the nucleus through a process called transcription. 
Nucleus, the control center of the cell is the organelle which intiates, enables, and manages the various simplex. compound and complex cellular activities. It also stores the DNA of the cell which is then replicated and recopied over a hundredth and thousandth times over through cell division processes. In the nucleoplasm -nucleolus, the inner part of nucleus of a cell is where the DNA to mRNA and to protein; vice-versa happens.   
        
             
        
        
        
Answer:
<em>The correct option is A) an increase in oxygen levels, which led to the extinction of many anaerobic organisms.</em>
Explanation:
Photosynthesis can be described as a process in which food (glucose) is produced by photosynthetic organisms by using carbon dioxide, water along with light energy from the sun. Oxygen is released as a by-product of this reaction. The process of photosynthesis initially allowed for oxygen gas to get accumulated in the air. This caused the rise of aerobic organisms who required oxygen for respiration. Before the photosynthesis organisms evolved, there was not enough oxygen gas on earth to support the life of aerobic organisms.