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Answer:
Seafloor spreading at the mid-ocean ridge provides the mechanism for tectonic plate movement. The Earth's mantle moves through convection, showing that tectonic plates are able to glide. The location of the plates was determined by locating their boundaries, using data on the Earth's magnetic field.
 
        
             
        
        
        
Answer:
The answer is C.
Explanation:
At first, an enzymes called Helicase unwind the double helix in a DNA .
 
        
             
        
        
        
Answer: There is presence of tumor.
Explanation: The adhesion of cells to extracellular matrix (EMC) through integrins ( cell-EMC binding molecules, which are collagens, laminins and fibronectin) causes the activation of kinases in the cytoplasm.
 
However, kinanes helps in controlling the epithelial cell differentiation and upholding the epithelial tissues. This is done by the addition of phosphate groups to a substrate protein which is termed Protein phosporylation. Then, the kinases direct the affairs of the cell and it's activities. For example, it determines the cell division, anabolic and catabolic activities of the cell, movement of ions between the cell and it's environment (signal transduction), protein functions and etc. 
Conclusively, since the activities of the cell like cell division and protein functions is dictated by the kinase, reduction in cell division that gave rise to rapid growth is put on hold. Hence, the tumor is been suppressed. 
Note: the binding of cell-EMC is regulated by Transforming Growth Factor (TGF) β.
 
        
             
        
        
        
Answer:
A. Biodiversity will decrease .
Explanation:
- The loss of a keystone species can cause extinction  or mass destruction of other species that are dependent on it because keystone species are those species which significantly influence the existence and survival of other species in an ecosystem
- Since, beavers are considered as the keystone species, their removal  from the ecosystem will cause loss of many other species in the ecosystem resulting in Decrease in the biodiversity of that ecosystem.