Answer:
down syndrome
Explanation:
people with down syndrome have an extra chromosome in the twenty-first pair
 
        
                    
             
        
        
        
Answer:
The pressure of a given amount of gas is directly proportional to the temperature at a given amount of volume. When the temperature of a system goes up, the pressure also goes up, and vice versa. 
Explanation:
This occurs because of the pressure temperature law. (or also known as the Gay-Lussac's law)
 
        
             
        
        
        
Answer: C
Explanation:
 For example, in trp-operon, an abundance of tryptophan. coli inhibits the expression trp-operon genes.
Trp operon is a negative repressible feedback mechanism
trpR gene is expressed continually at a low level
 
        
             
        
        
        
Roots and stems
Explanation: the cork of mature roots and woody stems is perforatedby nonsuberized pores called lenticels.
        
             
        
        
        
Answer:The bodies of different species are similar.
The development of different species are similar.
The DNA of different species are similar.
Experiments can form the molecules of life out of chemicals.
Fossils show a history of life that gets more complex.
Fossils show different stages of evolution in a species.
The fossil record is backed up by the geological record.
Explanation: their all true, i did the lesson