Scientists estimate that there may be up to species alive today.
a. 30 billion
b. 30 million
c. 1.9 million
d. 1.9 billion

What links the two strands in a dna helix together in the middle? a. phosphate groups b. sugar rings bonded together c. proteins d. bases with hydrogen bonds

Based on anatomical similarities, to which modern animal is dr. digger’s creature most closely related?

What makes a dominant allele different from a recessive allele