On the Galapagos Islands, Darwin also saw several different types of finch, a different species on each island. ... Finches that ate small nuts and seeds had beaks for cracking nuts and seeds. Darwin noticed that fruit-eating finches had parrot-like beaks, and that finches that ate insects had narrow, prying beaks.
        
             
        
        
        
It is the nucleus that contains DNA and controls the functions of the cells
        
                    
             
        
        
        
Transverse waves contain crests & troughs
while longitudinal waves contains compressions &rarefactions.
 
        
             
        
        
        
Answer:
The leaf discs only float in bicarbonate solution and in the light environment.
Explanation:
The bicarbonate dissolves in water to produce a source of inorganic CO2 in the reaction:
NaHCO3 + H2O → H2CO3 + OH- + Na+
Then, the HCO3- undergoes fixation through several complex steps in order to form a carbohydrate or sugar. These store the converted solar energy in their bonds as chemical energy to be used in metabolism.
Photosynthesis is a chemical process, essential to plant and other primary producers producing energy. Energy in the form of glucose molecules is derived from solar or light energy, water, and inorganic carbon dioxide, while it releases oxygen (from the light reaction). The leaf discs float as O2 gas is produced, making them buoyant. 
6CO2 + 6H20 + (energy) → C6H12O6 + 6O2
Carbon dioxide + water + energy= glucose + oxygen