Answer:
A) A single base pair change.
Explanation:
Point mutation is a change in a single base pair of a nucleotide. This comes as a results of mistakes made during DNA replication, induced by ultravoilet radiations, extreme heat and X-rays. There are three types of point or substitution mutations; change, deletion and insertion. The nucleotide bases are either mistakenly inserted, changed or deleted, thus changing the resulting protein or amino acid being coded for.
 
        
             
        
        
        
<u>Answer:</u>
<em>It is not true to say that common ancestors occurs only within a single species rather two species with similar traits might have a common ancestor. </em>
<u>Explanation:</u>
If the ancestor is same for both the species then it is said that both the species are closely related and share common ancestor with similar evolutionary relationship. 
Phylogenetic tree are drawn and studies are done to understand the ancestor of a species. The evolution has occurred from the ancestor to the new species formed.
 
        
             
        
        
        
Answer:  "photosynthesis" .
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<u>Note</u>:  These small, moving "green disks" seen while observing an <em>Elodea</em> plant cell—under a microscrope— are "chloroplasts".   The "chloroplasts" are organelles that ar responsible for "photosynthesis" .
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Explained in greater detail, each gene resides at a specific locus (location on a chromosome) in two copies, one copy of the gene inherited from each parent. The copies, however, are not necessarily the same. When the copies of a gene differ from each other, they are known as alleles.