Answer:
The presence of an additional chromosome
Explanation:
Look at "pair" 21. See how there are THREE chromosomes instead of TWO? Normally, there would only be two chromosomes in each pair but this karyotype shows a trisomy (see def. below) of the 21st pair. This was caused by a nondisjunction mutation of the 21st pair. The is also the karyotype of a person with Down's Syndrome.
Definition of Trisomy:
A condition of the presence of three chromosomes in a pair instead of two. This normally causes developmental irregularity.
 
        
             
        
        
        
These sorts of studies can help researchers determine the relative importance of nurture and nature in determining a trait. Nature here would refer to genetics passed down to an individual from its parents, whereas nurture refers to the environment the individual is exposed to.
        
             
        
        
        
Answer:
3 ways to understand the differences between compounds and mixtures are described below in explanation.
Explanation:
1. In a mixture, no new product is formed. It is a simple tacking of two molecules without any chemical reaction occurring. For example water and sand. Compound is a new substance formed by chemical reactions occurring between various molecules. For example, carbon and oxygen combine to form carbon dioxide.
2. A compound is always homogeneous whereas a mixture can be homogeneous or heterogeneous.
3. Compounds have a fixed boiling and melting temperature. Whereas, mixtures do not have a definite melting and boiling temperature. 
 
 
        
             
        
        
        
Answer:
Some organisms have a tremendous amount of noncoding DNA, like repetitive sequences.
Explanation:
DNA is the genetic material in almost all the living organisms but except in case of viruses that has RNA as their genetic material. DNA consists of the four nitrogenous bases, pentose sugar and phosphate group.
Prokaryotes have simple body organization and structure because of the sall amount of DNA. Eukaryotes have complex body organization because they have large amount of the transposons, repetitive sequences and non repetitive DNA sequences.
Thus, the correct answer is option (b).
 
        
             
        
        
        
Answer:
D Butterfly, coral and amoeba came from pre existing  cells  
Explanation: