The strongest component of the cell wall<span> is a carbohydrate called cellulose, a polymer of glucose. The </span>cell wall gives rigidity<span> and strength to the </span>plant cells<span> which offers protection against mechanical stress. ... The </span>rigidity<span> of primary </span>plant<span> tissues is due to turgor pressure and not from rigid </span>cell walls<span>.</span>
        
                    
             
        
        
        
It’s c Xand Y good luck sweetie
        
             
        
        
        
Mutations are spontaneous and occur at random however there are some mutagenic agents which increase the chance of this happening such as radiation exposure. If it is a point shift mutation then only a few bases on the dna sequence are changed so only changes a few of the amino acids in that chain (such as inversion of a base). If its a frame shift then the base sequence is altered so much so that every amino acid from after that changes (such as deletion of a base) which can create things such as cri-du-chat syndrome which results from a piece of chromosome 5 is missing. Hope this helps:)
        
             
        
        
        
prevents backflow into the left atrium 
 
        
             
        
        
        
Answer:
1. Isabella wanted
2.She read and reviewed
3.She constructed a hypothesis
4.She submitted her proposal
5.Control groups
6.She collected
7.She reached a conclusion
8.she presented
Explanation:
I got it right