Molecular clocks that are used to estimate the time when organisms diverged from a common ancestor are only effective when
A) the rate of base substitution mutation is known.
B) the protein cytochrome c of both the species is identical.
C) fossil evidence is absent or unreliable.
D) the species being compared are very closely related.
A) the rate of base substitution mutation is known.
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Who provided X-ray diffraction photographs of purified DNA fibers that suggested a helical structure with a consistent diameter of about 2 nm and a complete helical turn every 3.4 nm?
A. Hershey and Chase B. Chargaff C. Franklin D. Watson and Crick
Why is the ocean off the coast of Florida warmer than it is off the coast of Western Mexico?
A) Florida is closer to the equator. B) Mean precipitation is higher in Mexico. C) Wind patterns are clockwise in the Atlantic. D) Ocean currents are coming from the tropics rather than the poles.
ATP- __________ _____________ remodeling uses the energy of ATP hydrolysis to change the position or composition of nucleosomes.
Fill in the blank(s) with the appropriate word(s).
The amphibian heart has
Select one: a. two separate atria and two separate ventricles that partition oxygen-rich and oxygen-poor blood. b. two separate atria and one shared ventricle that allow oxygen-rich and oxygen-poor blood to mix. c. two separate ventricles and one shared atrium that allow oxygen-rich and oxygen-poor blood to mix. d. one atrium and one ventricle similar to the fish. e. one atrium and one ventricle but reroutes the blood through the heart after passing through the gills.