Skim coating weak concrete is only a temporary fix. Another option is to lay a thicker overlay and slow-dry the new surface. To slow-dry, cover the driveway with moist, breathable material. Keep the material wet to provide additional moisture for the concrete to absorb.
The two main sources of genetic variation are gene shuffling and  mutations. A mutation is a process wherein the structure of a gene  is altered.Edit. Share to: Blobbert. 37,033 Contributions. Answered.In Genetic Engineering.he 4 types of genetic variation are 1) mutation-is the mutation of a gene. this is really rare, most mutations are in the recessive trait so they are hidden by a dominant t â¦ rait. Most mutations have no effect but some can be harmful and very few have positive effects.
Nature and nurture. Variation is the raw material of evolution. Natural selection and other mechanisms of evolution work on the variation within a population â so without variation, there would be no evolution. However, there are two possible sources of variation: the environment and genes â in other words, nature and nurture. To understand these two components, imagine a field of corn plants with varying heights.