Answer: Homeostasis
Explanation: One way that a cell maintains homeostasis is by controlling the movement of substances across the cell membrane. The lipid bilayer is selectively permeable to small, nonpolar substances. Proteins in the cell membrane include cell-surface markers, receptor proteins, enzymes, and transport proteins.
 
        
             
        
        
        
Lithosphere is the correct answer
cause hydrosphere is water
and stratosphere and atmosphere are part of the air
        
             
        
        
        
Answer:
During the gap between DNA synthesis and mitosis, the cell will continue to grow and produce new proteins. At the end of this gap is another control checkpoint (G2 Checkpoint) to determine if the cell can now proceed to enter M (mitosis) and divide.
 
        
                    
             
        
        
        
Answer: D. Hypothesis B is more useful because it suggests a way to test the relationship between heart rate and caffeine intake.
Hypothesis A and B both are suggesting that caffeine intake is related to higher heart rate. But hypothesis B is proving it more certainly by suggesting the affects of caffeine intake on heart rate. As, heart rate of most people will be higher 30 minutes after they drink a cup of coffee is testifying the fact, that higher heart rate is related with caffeine intake. 
Therefore, hypothesis B is more useful because it suggests a way to test the relationship between heart rate and caffeine intake.