Why do materials move across a membrane?

Which of the following are causes of coastal erosion? check all that apply. beach grasses and other plants trap windblown sand. wave action carves away the coastline. groundwater under pressure is forced to earth’s surface. artificial structures stop the natural flow of sand along the coast. underground caves collapse as bedrock is dissolved.

In general, characteristics that an organism survive and reproduce become more common in a population over time. what mechanism of evolution cause this change?

The part of the eye that closes and opens to let light in is .