A paleontologist estimates that when a particular rock formed, it contained 12 mg of the radioactive
isotope potassium-40, which has a half-life of 1.3 billion years. The rock now contains 3 mg of the
isotope. About how old is the rock?
a. 2.6 billion years
b. 5.2 billion years
c. 1.3 billion years
d. 0.3 billion years
e. 0.4 billion years
B
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Which of the following statements is correct?
A. Global warming is the same as global climate change. B. Global climate change includes changes in patterns of rainfall, but not in patterns of temperature. C. Global climate change includes global warming, but also increased fires, changes habitats, and changes patterns of temperature and rainfall. D. Global climate change has no effects of human populations.
Recall that the age structure histogram (for humans) of India is shaped like a pyramid (Figure 46.8). What does this tell you about India's population?
A. It is shrinking. B. It is growing. C. It is relatively constant. D. It is currently shrinking, but will increase over the next few years. E. It is currently growing, but will decrease over the next few years.
There is no change in population size when the instantaneous per capita rate of growth (r) is equal to ________
Fill in the blank(s) with correct word
PhyB may inhibit flowering in:
a. day-neutral plants. b. vernalized plants. c. long-day plants. d. senescing plants. e. short-day plants.