Graduating from high school this year makes me feel a bit sad. Biology was such a fun but crazy class.
Enough of my sentiments; I'm here to help, :-).
This answer is dependent upon what ecosystem you choose your project over. 
So, abiotic factors are nonliving things in an ecosystem. Biotic factors are living organisms and anything alive. 
For instance, if you choose a pond for your ecosystem then the water, soil, maybe trash would be abiotic factors. Some could argue there is living material within the water and soil but those abiotic factors are not alive. I mean water is not alive but it could be a home to biotic factors like microorganisms such as protozoans and worms. The grass and trees and animals around a pond would be biotic factors. 
Hope you get the idea. if there's any questions then leave a comment and I'll help. Good luck!
        
                    
             
        
        
        
Keratin
Protecting the skin is one of its main responsibilities as a protein in epidermis. 
I Hope this helped you!!!
        
                    
             
        
        
        
The cell membrane folds upon itself easily, which facilitates cellular reproduction by mitosis. 
<span>The membrane is a flexible, fluid mosaic and changes shape easily to create holes for substances to move in and out of the cell. </span>
<span>The outer layer of the membrane is hydrophilic, which allows water to flow in and out of the cell easily to eliminate waste. </span>
<span>The proteins that are embedded in the cell membrane act as channels to transport substances in and out of the cell.</span>
        
             
        
        
        
Ribosome- both
endo reticulum- both
golgi apparatus- both
cell wall- plant only
vacuoles- plant only 
lysosomes- animal only 
mitochondria- both
cell membrane- both 
cytoplasm- both
chloroplasts- plant only
        
             
        
        
        
Missing choices: 
a) Calcium entry into the sarcoplasm, calcium binds to troponin, muscle contracts, closing of calcium channels, calcium released from troponin, muscle relaxes
b) Calcium entry into the sarcoplasm, muscle contracts, calcium binds to troponin, closing of calcium channels, calcium released from troponin, muscle relaxes
c) Calcium entry into the sarcoplasm, calcium released from troponin, muscle contracts, closing of calcium channels, calcium binds to troponin, muscle relaxes
d) Calcium entry into the sarcoplasm, closing of calcium channels, calcium binds to troponin, muscle contracts, calcium released from troponin, muscle relaxes
My answer: d) Calcium entry into the sarcoplasm, closing of calcium channels, calcium binds to troponin, muscle contracts, calcium released from troponin, muscle relaxes