A significant event influencing the rapid evolution of plants on land after their initial appearance was the ____.
A. increase of atmospheric oxygen
B. reduction of ultraviolet radiation penetration through the atmosphere
C. stabilization of global climates
D. increase in soil nutrients
E. merging of land masses
Answer: B
You might also like to view...
When a DNA promoter sequence is methylated, ____
a. it is permanently silenced because the methyl group can never be removed b. it is temporarily silenced because the methyl group can be removed c. it is perpetually transcribed because the methyl group can never be removed d. it is temporarily transcribed because the methyl group can be removed e. the impact on expression depends on the gene being controlled by the promoter
A carbohydrate consists of
a. amino acid units. b. one or more sugar units. c. lipid droplets. d. glycerol.
The main structural component of a plant cell wall is
A) extracellular matrix B) cellulose C) cytoskeleton D) middle lamella E) plasmodesmata
Based on experiments with amphibian embryos, Spemann and Mangold found that
A) transplanted cells always died. B) transplanted cells completely undifferentiated into random masses of tissue. C) transplanted cells always formed a whole new embryo. D) in most cases, transplanted donor cells assumed the developmental fate of the area to which they were transplanted in the host. E) donor cells maintained their original differentiation no matter where in the host they were transplanted.