The molecule shown above is the purine ____
a. thymine
b. adenine
c. uracil
d. guanine
e. cytosine
B
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Which of the following contributed to the growth in human population that began about 11,000 years ago?
a. sidestepping limiting factors b. increased carrying capacity c. all of the choices d. geographic expansion
If you completely girdle a deciduous tree’s trunk in mid-summer, why could the tree potentially retain
leaves throughout some or all of the rest of the growing season, but eventually die?
What will be an ideal response?Your book lists several ways to live a more sustainable lifestyle (using alternative energy sources and natural fertilizers, rotating crops, and preventing soil erosion). What other sustainable activities can you list?
What will be an ideal response?
Which of these is not a common concern about genetically modified food crops?
A) They may have unintended negative effects on surrounding organisms. B) They may cause the evolution of pesticide-resistant crop pests. C) They may cause a reduction of genetic diversity among food crops. D) They may increase the number of human infections by transgenic E. coli. E) They may cause unforeseen allergies in those who consume the genetically modified food.