Approximately Two Billion Years Ago, ________ Were Primarily Responsible for Initially

question 15

Multiple Choice

Approximately two billion years ago, ________ were primarily responsible for initially oxygenating Earth.

• A) algae
• B) Archaea
• C) cyanobacteria
• D) purple sulfur bacteria

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Definitions:

Fear

Fear is an emotional response to perceived threats or danger, characterized by feelings of anxiety, apprehension, and a heightened state of alertness.

Anxiety

A feeling of worry, nervousness, or unease, often about an imminent event or something with an uncertain outcome.

Stimulus Generalization

is the process in which a response is elicited by stimuli that are similar but not identical to the conditioned stimulus in a conditioning paradigm, demonstrating the ability to generalize learning to new stimuli.

Conditioned Response

A learned reaction to a previously neutral stimulus that has become associated with an unconditioned stimulus.