In a scale model of the solar system, if the sun is represented by a ball with a diameter of about 8 inches, about how large would the earth be?
a the size of a marble
b the size of a popcorn seed
c the size of an apple
d the size of a grapefruit

In 1994, telomerase activity was discovered in human cancer cell lines. although telomerase activity is rarely present in human somatic tissue, this discovery indicated that humans do contain the genes for telomerase proteins and telomerase rna. since inappropriate activation of telomerase may contribute to cancer, why do you think the genes coding for this enzyme have been maintained in the human genome throughout evolution?