Many kinds of disease-causing bacteria are resistant to the standard antibiotics that we use to control them. This is because
A. when bacteria are exposed to antibiotics they mutate.
B. there is genetic variety within the species and those that already have genes for resistance are the ones that reproduce.
C. new species of bacteria have evolved that are resistant to antibiotics.
D. when the size of the population of a species of bacterium is reduced, genetic variety decreases.
B. there is genetic variety within the species and those that already have genes for resistance are the ones that reproduce.
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Which of the following occurs immediately after a haploid spore germinates?
a. A gametophyte is created by mitosis. b. A gametophyte is created by meiosis. c. A sporophyte is created by mitosis. d. A sporophyte is created by meiosis.
As global temperatures increase, Arctic sea ice
becomes thin and breaks up earlier each spring. What potential consequence described in the text might this directly lead to?
a. fewer migratory birds b. polar bears being stranded on ice flows far from land c. further global warming d. a decrease in Arctic sea levels e. an increase in polar bear populations
Deep-diving animals accomplish their dives through ____
a. speeding their heart rate b. swimming vigorously c. storing oxygen in muscles and blood d. binding oxygen to hemocyanin e. going into a deep sleep
Which of the following factors would make the strongest contribution to global climate change?
A. over-harvesting of wild species for consumptive value B. large-scale deforestation C. an increase in soil erosion leading to siltation of rivers and estuaries D. disruption of the waste recycling by decomposers E. drainage of wetlands producing a disruption of water purification