The early Earth atmosphere is thought to have lacked which of the following gasses?

A human cell contains 23 pairs of chromosomes for a total of 46. If it divides by meiosis, the result will be

When we use the Shannon diversity index to calculate the effective number of species, we are determining how many species would provide that same diversity value:

The effect of inbreeding is __________.

A cause of extinction that has been caused, at least in part, by humans is

A tropical deciduous forest, a hot desert, and the tundra are examples of

A nonprofit conservation organization receives a sizeable donation and decides to purchase several thousand acres of “high desert” in southern California. This particular type of desert has an intermediate level of species diversity and few unique species. However, much of the original areas of high desert have been converted to suburban housing and shopping. The decision by the nonprofit to preserve this area was most likely based upon what conservation strategy?

A human cell contains 23 pairs of chromosomes for a total of 46. If it divides by meiosis, the result will be

The Northern leopard frog (  Rana pipiens) and Southern leopard frog (  Rana utricularia) are morphologically similar, but their mating calls sound very different. Based on this, what is the best explanation for why these frogs are considered separate  species?

What shape park is preferable for minimizing edge effects?