C. a toy train is the item that has characteristics similar to a scientific model.
        
                    
             
        
        
        
Answer:
B. a sequence of DNA bases that duplicates a sequence of RNA bases.
Explanation:
Transcription is the first step in gene expression. It involves copying a gene's DNA sequence to make an RNA molecule.
 
        
             
        
        
        
Breaking bonds takes energy, forming bonds releases energy
If you break more bonds than you form it would be an endothermic reaction
        
             
        
        
        
I think the correct answer would be the last option. Monozygotic twins are identical, while dizygotic twins are fraternal. Identical twins involves developing from one zygote where it splits, forming two embryos so that the twins would have more or less the same characteristics. This type of twins can share the same amniotic sac depending on the time the fertilized egg is divided. On the other hand, fraternal twins developed from two eggs wherein they are being fertilized by two different sperm cells resulting to twins which has different characteristics. For this type, the two fertilized eggs would develop separate amniotic sacs.
        
             
        
        
        
The correct answer to this question is this one: a.) bottleneck effect. Increased poaching nearly led to the extinction of the American bison. The kind of effect that does this example represent is called the bottleneck effect. Hope this helps answer your question.