Building a few millimeters of soil can take anywhere from a few Blank______ (in healthy grasslands) to a few Blank______ (in a desert or tundra).Multiple choice question.days; monthsmonths; yearsyears; thousand yearsyears; million years

Around the world, about Blank______ of earth's surface is threatened by desertification, or conversion of productive lands to desert.Multiple choice question.one-quarterone-tenthone-thirdone-half

A grassland receives too little rain to support a forest. If the grassland starts to get enough rain to support a sparse tree cover, the grassland may transition into a Blank______ over time.Multiple choice question.deserttaigasavannawet forest

Select the correct answer.In which terrestrial biome would you find precipitation of 300 to 900 millimeters (mm) each year? A. desert B. coniferous forest C. temperate deciduous forest D. rainforest

In a tundra, vegetation includes Blank______, and Blank______ can occur any month of the year.Multiple choice question.pine trees; precipitationmaple trees; raingrasses and lichens; frosttall grasses; thunderstorms

Our current estimates state that the Earth is about Blank______.Multiple choice question.100 billion years old4.5 billion years old4.5 million years old100 million years old