Answer:
1. reducing soil erosion,
2.Controlling runoff water
Explanation:
Contour farming mitigates the impacts of floods, storms and landslides on the crops by reducing soil erosion up to 50 percent, controlling runoff water, increasing moisture infiltration and retention and thus enhancing soil quality and composition
The crossing over is a process that is essential to human genetic diversity. During the crossing over parts of the homologous chromosomes ( two chromosomes identical by structure, but different in origin, one inherited from the mother and one from the father) randomly exchange parts of their sequences.
If the crossing-over didn't exist, this would greatly decrease the genetic diversity, because the chromosomes would always bee passed o the next generations unchanged.