(D)an atom can join with other kinds of atoms.
Basically he explained what a molecule is. 
 
        
        
        
The word is scientifically termed as Peristalsis.
        
             
        
        
        
Answer:
The ventricles of the heart have thicker muscular walls than the atria. This is because blood is pumped out of the heart at greater pressure from these chambers compared to the atria.
Explanation:
hope this helps
 
        
             
        
        
        
Answer:
The correct answer is d. photorespiration
Explanation:
In the C3 plant, the Rubisco enzyme is important that fix CO2 into organic molecule by binding with CO2. Rubisco can also bind to oxygen when the oxygen concentration increases in cells which leads to the loss of fixed CO2  and waste of energy which is called photorespiration.
So when stomata are open CO2 comes in and O2 goes out of the cell which maintains the high CO2 concentration in the cell but during hot days C3 plants close stomata to prevent water loss.  
So closing of stomata decrease the intake of CO2 and increase the oxygen concentration inside the cell. So in increased temperature and high oxygen concentration, the rubisco enzymes bind to O2 and promote photorespiration.
 
        
             
        
        
        
Answer:
I think its cell membranes
Please correct me if I am wrong thank you
Explanation: