The continuing addition of large amounts of nitrogen and phosphorus to aquatic ecosystems may exceed planetary boundaries and create a tipping point in which
A) nitrogen and phosphorus are depleted from soils.
B) high nitrogen and phosphorus levels cause aquatic ecosystems to change in ways difficult to reverse and that are damaging to human food production.
C) these ecosystems produce far more human food than ever before.
D) water is lost from these systems, and they become deserts.
Question 2
From the end of the Cold War through 2013, Russian nuclear warheads have been
A) stored widely in the former Soviet Union where they remain today with minimal protection.
B) dismantled, but their nuclear waste remains in Russian facilities with minimal security.
C) dismantled, with the nuclear fuel purchased by the United States for its nuclear power plants.
D) concentrated in two centralized Russian locations with high levels of security, awaiting long-term storage.
Water and salt regulation by isosmotic, hyperosmotic, and hypoosmotic aquatic organisms.
Large size can provide a refuge from predators. While young African elephants may be vulnerable to p
Large intestine.
The carbon-nitrogen-oxygen cycle of The Sun
Large white butterfly egg