Radiometric dating ____
a. is based on the premise that each isotope decays at a constant rate
b. is unpredictable because of changes in temperature and pressure
c. can be used to date sedimentary rock, but not fossils
d. has a substantial error factor
e. can only be used for dating animal fossils
ANSWER: a
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Sodium has one valence electron in its third energy level. To reach a stable energy configuration,
sodium will tend to
a. take up an electron from another atom. b. move its valence electron to the second energy shell. c. give up an electron to another atom. d. share its valence electron with another atom. e. move an electron from the second energy level to the valence shell.
The uptake of water and mineral ions from the soil occurs primarily at the
a. endodermis. b. root cap. c. quiescent center. d. pericycle. e. root hairs.
In which of the following ways does a root
differ from a shoot?
a. a root only has apical meristems -- a shoot could have both b. a root lacks an epidermis- a shoot does not lack an epidermis c. roots lengthen when cells above the apical meristem elongate- in shoots, cell elongation below the apical meristem causes the shoot to lengthen d. in a root the apical meristem at the tip never changes its position- in shoots the apical meristem does change its position as the stem elongates e. all of these are differences between roots and shoots
An earthquake decimates a ground-squirrel population, killing 98% of the squirrels. The surviving population happens to have broader stripes, on average, than the initial population
If broadness of stripes is genetically determined, what effect has the ground-squirrel population experienced during the earthquake? A) directional selection B) disruptive selection C) a founder event D) a genetic bottleneck