What is a gene?
a. the different forms of a trait
b. a segment of dna that is the basic unit of heredity
c. the appearance or characteristics that are seen in an organism
d. an organisms allele combination

he forelimbs below belong to four species that descended in a direct line from the ancestral mammal shown above. of the four descendants shown, which species most likely appeared earliest in evolutionary history?

answer; synapse;