What is a mutation? Are mutations always harmful? Always helpful? Explain

According to the cladogram, which organisms have roundworms as a common ancestor?

Plz ! for many generations farmers in north america have been choosing to cross corn plants with large ears of corn each year this results in the new generation of plants also growing large ears of corn. what is the technique called? a. selective breeding. b. natural selection. c. mitosis. d. asexual budding.

"your temperature analysis reveals a pattern with coldest temperatures located to the portion of the map."