Which of the following mass extinctions was the worst in earth's history?
a. ordovician-silurian extinction
b. late devonian extinction
c. permian-triassic extinction
d. end triassic extinction
e. cretaceous-tertiary extinction
Ans: c. permian-triassic extinction
You might also like to view...
In bacteria, a unique RNA that binds the A site of the ribosome and directs the addition of approximately 12 amino acids to the nascent peptide when no stop codon is present is called the ________.
Fill in the blank(s) with the appropriate word(s).
The movement of water and dissolved solutes
from the soil to the vascular cylinder is driven by
a. active transport. b. osmosis. c. endocytosis. d. simple diffusion. e. more than one of these
Specific heat capacity
What will be an ideal response?
Which of the following statements is true of proteins?
a. Proteins lose some or all of their normal activity if their three-dimensional structure is disrupted. b. Proteins are composed of ribose, phosphate, and a nitrogen-containing base. c. The activity of proteins is independent of temperature and pH. d. Denaturation is usually reversible. e. All proteins are enzymes.