I believe the answer is 2: multiple ecosystems in a biome
        
             
        
        
        
1.
C. Genus and species
Binominal nomenclature: a formal system of naming species of living things, such as humans which are <em>homo sapiens.</em>
2.
A. carbohydrates
any of a large group of organic compounds occurring in foods and living tissues and including sugars, starch, and cellulose.
3.
C. work with other cells
one unicellular organism would quickly die if was not within a colony of very similar unicellular organisms.
4.
C. Bacteria
bacteria are able to cause contagious diseases seeing as a virus, (which can be a contagious disease) is a form of bacteria.
 
        
             
        
        
        
Down syndrome is an example of a condition caused by trisomy<span>. People with Down syndrome typically have three copies of chromosome 21 in each </span>cell<span>, for a total of 47 chromosomes per </span>cell<span>. Monosomy, or the loss of one chromosome in </span>cells<span>, is another kind of aneuploidy</span>