In 1630 at the beginning of European settlement, about 425,000,000 hectares of the US were forested. By 2017, the area of forested land has declined to 300,000,000 hectares. What is the percent decrease of forested land between 1630 and 2017? Show your work!

Which of the following statements is true about the relationship between genetic variation and natural selection? a. genetic variation must be present in a population before natural selection can act on it. b. genetic variation arises in a population as a result of natural selection. c. natural selection can act on a population whether there is genetic variation within the population or not. d. after natural selection acts on a population, the amount of genetic variation in the population always increases.

Which genetic disorders, caused by an extra x chromosome (xxy), is characterized by a lack of testicular development in males, effeminate features, possible mental impairment, and a thin stature?

Which of the following is not a benefit of genetically modified foods? a. pest-resistant crops b. herbicide-resistant crops c. plants that do not require water?