Which of these gases was absent in the early Earth atmosphere at the time life first appeared?

A) nitrogen B) oxygen C) carbon dioxide D) water vapor


Answer: B

Biology & Microbiology

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The Crenarchaeota group of archaeons contains which of the following types of organism?

A. hyperthermophiles B. hypothermophiles C. halophiles D. methanogenic organisms E. basophiles

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A seed from a yew tree germinates on the forest floor. During the first few months of its life, the sapling dedicates most of its resources to increasing in height rather than producing the defensive compound taxol

What is this allocation of resources an example of? A. a symbiosis B. a trade-off C. a constitutive defense D. an inducible defense E. a basal response

Biology & Microbiology

What do free radicals do?

a. Improve the efficiency of aerobic respiration. b. Act as coenzymes in glycolysis. c. Damage biological molecules. d. Remove metals that combine with oxygen gas. e. Enhance enzyme activity.

Biology & Microbiology

Achondroplasia Achondroplasia is an autosomal dominant disorder. A newly wedded couple finds after genetic screening that they are both heterozygous for alleles responsible for that genetic disorder. Use this information to answer the following question(s). In the example above, what is the couple's chance to have a heterozygous child?

Biology & Microbiology