Large amounts of oxygen gas appeared in Earth's atmosphere about ________ years ago
A) 200 million
B) 1.7 billion
C) 2.7 billion
D) 4.5 billion
C
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Aluminum is toxic to many aquatic species
Indicate whether the statement is true or false
According to scientific evidence, what is the best prevention method known for reducing the chance of contracting a common cold?
What will be an ideal response?
In meiosis, genes that are found close together on a chromosome
A) are usually inherited together. B) usually exhibit crossing over. C) are usually assorted independently. D) are usually in trans.
If the population age structure of a country resembles a pyramid, with the pre-reproductive age group the largest proportion of the population, and the post-reproductive age group the smallest, this country can most likely be classified as one of the
A) stable populations. B) least developed countries. C) most developed countries. D) steady-state populations. E) expanding populations.