Which of the following structures is formed by cartilage?
a. cheeks
b. ears
c. hair
d. teeth

clumped distribution, because you'de have all of the population gathered in a relatively small are.

it's the most common because it provides protection and a mate for reproduction

example: humans, seeweed, cattles, etc.

a- all cells come from pre-existing cells

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).

its b. greenhouse gasses trap uv rays for heat so that the plants stay alive.