Biological soil crusts<span> are communities of living organisms on the </span>soil<span> surface in arid and semi-arid ecosystems. They are found throughout the world with varying species composition and cover depending on topography, </span>soil<span> characteristics, climate, plant community, microhabitats, and disturbance regimes.</span>
Explanation:The genotype for some with attached earlobes would be ee because unattached earlobes are dominant(EE or Ee) which means attached would be recessive(ee).