In the picture below ions, or charged particles, are being pumped through the cell membrane. Why do they require energy to transport across the membrane?

1. the is the thinnest part of the earth. 2. the is the thickest part of the earth. 3. what metals are mentioned in the text?

The seed coat's most important function is to provide a) a nonstressful environment for the megasporangium. b) the means for dispersal. c) dormancy. d) a nutrient supply for the embryo. e) desiccation resistance.

Which statements describe resources? one of the factors people use when deciding where they will live is the availability of resources. renewable resources have little value for people. resources are unevenly distributed throughout the world. energy is the world resource which has the highest use. the use of nonrenewable resources has decreased in recent history. the use of resources is evenly distributed throughout the world. the world's oil supply will last for the next forty years if its use continues as expected.