What are the three ways that causes variation of traits

If the birth rate of a population of dolphins is 2.0, the death rate is 0.5, and the population size is 100, what is this dolphin's population growth?

The fruit of a certain plant is sweet and fleshy. the seeds of this plant have a seed coat that is fairly tough. the seeds germinate better if they are exposed to acid, or scarification. what is the most likely type of dispersal for this seed? water animal wind

Dna and rna share a number of similarities,but they also differ in certain aspects of their structure. wich nitrogenous base is found in rna but is not found in dna