When were the oldest stromatolites formed?
a. about 2.1 billion years ago
b. about 3.5 billion years ago
c. about 3.9 billion years ago
d. about 4.2 billion years ago
Answer: b. about 3.5 billion years ago
You might also like to view...
Because of the _____________________, traits carried by early settlers are found in a large fraction of the descendent population
Fill in the blank(s) with correct word
How long is a typical C-C bond?
a. 0.580 nm b. 0.107 nm c. 0.154 nm d. 0.214 nm
Refer to Figure 5-1. Which of the following statements about the red blood cells in Figure B is true?
a. These red blood cells have been placed in an isotonic solution.
b. These red blood cells have swollen in response to a hypertonic external solution.
c. These red blood cells have swollen in response to a hypotonic external solution.
d. These red blood cells have shrunken in response to a hypertonic external solution.
e. These red blood cells have shrunken in response to a hypotonic external solution
A danger associated with the use of specially developed plants in agriculture is that they
A. are likely to escape and become pests. B. often show great genetic diversity. C. often have little genetic diversity. D. typically cannot reproduce.