New cartilage continuously divides, mature and is ossified. what replaces this ossified cartilage cells

Which element forms the basis of all organic organisms a carbon b oxygen c hydrogen d nitrogen

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

What would be the result if crossing over did not happen during meiosis in humans? a. there would be less genetic variation in humans. b. parents would be more likely to look like their children. c. the human population could not reproduce. d. children would have more chromosomes.