Answer:
81.64
Explanation:
pie x diameter = circumference
Most people in the world get our water from rivers and lakes, including the vast majority of the world’s poorest people.
But half of the world’s 500 most important rivers – water sources for hundreds of millions of people – are being seriously depleted or polluted.* Approximately 40 percent of the rivers in the U.S. are too polluted for fishing and swimming.**
Water shortages will likely be a fact of life for most people on the planet within the next ten years.*** We can’t afford to pollute and destroy our drinking water sources. But that’s exactly what we’re doing – often without knowing it.
Forests, grasslands and wetlands are nature’s water filters. They help keep erosion and pollution from flowing into our waters and they slow rainwater down, sending more water into underground supplies. But every year we lose 32 million acres of forest – that's a lot of water filters, gone, every year.
We are facing dirtier, unsafe water and more risk of water shortages and scarcity. This crisis is real, it’s happening now and it’s getting worse fast.
The Nature Conservancy partners with people communities in all 50 states and 30 countries to protect water sources. We work on the ground to:
<span><span>Prevent deforestation and destruction of grasslands – nature’s water filters</span><span>Restore forests and grasslands that have already been lost or damaged and sending erosion into our waters</span><span>Equip farmers with practical ways to keep harmful run-off out of our waters</span><span>Restore floodplains that act as sponges and send water down into groundwater supplies and filter pollution out of rivers</span><span>Create new science that helps pinpoint the greatest threats to our waters and the most effective ways to combat them</span></span>
But we understand that nature won’t solve everything, so we’re finding new ways to reduce water use. More than 70 percent of water withdrawn from nature goes to agriculture, so we’re helping farmers access new technologies and practices that use less water while continuing to produce the food we need.
Answer:
Cell surface receptors (membrane receptors, transmembrane receptors) are receptors that are embedded in the plasma membrane of cells. They act in cell signaling by receiving (binding to) extracellular molecules. They are specialized integral membrane proteins that allow communication between the cell and the extracellular space.
Explanation:
