Evidence from proxies indicate eight major oscillations in global temperatures over the past 800,000 years, most likely the result of
A) rising and falling sea levels that greatly impact photosynthetic activity.
B) variations in solar activity that produce different levels of radiation.
C) Milankovitch cycles of periodic variations in Earth's orbits around the sun.
D) lunar cycles in which the moon orbits at different distances from the Earth.
Question 2
Only about 30 species have recovered significantly enough to be removed from the Endangered Species List. Recovery to this extent is limited because
A) the regulations protecting the species do not extend to private landowners.
B) hunting of protected species often continues even after the organisms are listed.
C) populations are already low and at high risk by the time they are listed.
D) protecting the habitat of an endangered species is not as critical as once assumed.
Major components and functions of the nervous system.
The absorption of cerebrospinal fluid from the subarachnoid space (blue) into a major sinus. Note ...
Major Wind Systems: Monsoons
Industry is responsible for 21% of global greenhouse gas emissions
The origin and spread of modern H. sapiens, reconstructed from genetic and fossil evidence.
Some of the major nerves of the human nervous system