The basic shape of a DNA molecule is the _____.
A) base pair
B) sugar-phosphate backbone
C) single helix
D) double helix
Ans: D) double helix
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Studies have shown that in the flowering plant Arabidopsis whether or not a root epidermal cell develops a root hair is
determined ____.
a. by the distance of the cell from the root tip b. from the timing of cell division c. by positional information from cells of the root cortex d. shortly after the eight-cell embryo stage e. by the direction of cell division
In bacteriophage T4, all rIIA mutants are found to complement all rIIB mutants. However, rIIA mutants fail to complement other rIIA mutants, and rIIB mutants fail to complement other rIIB mutants
Furthermore, mutants with deletions that span both rIIA and rIIB complementation groups do not complement either A or B mutants. What do these data mean, and what do the complementation groups represent?
The formation of ions involves the
A) gain or loss of electrons. B) sharing of electrons. C) gain or loss of neutrons. D) sharing of protons. E) gain or loss of protons.
Evolutionary adaptations for survival on land produced tetrapods, which later evolved into
A) amphibians only. B) amphibians, reptiles, and mammals. C) reptiles only. D) birds only.