Answer: crossing over, process in genetics by which the two chromosomes of a homologous pair exchange equal segments with each other. Crossing over occurs in the first division of meiosis . At that stage each chromosome has replicated into two strands called sister chromatids.
 
        
                    
             
        
        
        
Answer: C. A brood chamber is made by bees, but comb foundations are built by humans. 
Explanation:
The brood chamber is a natural part of the beehive where the bee workers made cells where these works lay eggs. Here, development of the larvae and pupae takes place. The cells of the brood chamber holds the pollen, nectar and honey which is used to feed to develop the larvae. 
Comb foundations are the artificial creation made by humans is a place made from wax which forms the base of the honeycomb. It is used to give the support to the beehive. 
 
        
             
        
        
        
The scientist that thought he had proven that plants obtain their nutrients from water rather than soil is Van Helmont.
        
             
        
        
        
CO2 molecules can vibrate in ways that simpler nitrogen and oxygen molecules cannot, which allows CO2 molecules to capture the IR photons. Greenhouse gases and the greenhouse effect play an important role in Earth's climate.
        
             
        
        
        
The Hypothalamus
Hope this helped!