The appearance of banded iron layers in the rock record between 1.08 and 3.8 billion years ago reflect the alteration of oxygen-rich and oxygen-poor conditions in the ocean at that time is True.
<u>Explanation:</u>
Banded rocks have layers of iron oxide and cherts that contain silica. The layer containing iron oxide has a dark color and the chert layer is red in color. Haematite and magnetite are usually the iron oxides that make up the banded rocks.
Banded rocks were formed by the reaction of iron in the oceans with the oxygen produces by photosynthetic bacteria in the ocean. The reaction caused the formation of iron oxides and their precipitation as Banded iron formations.
The presence of free oxygen is crucial for the formation of banded rocks and the formation reduced drastically after 1800 mya period when atmospheric oxygen availability was reduced. Banded rocks represent the oxygen rich and oxygen-poor condition of the ocean at that time.
Genetic variation allows for mutations to occurs where survival of the fittest occurs. This makes sure that the most adapted creatures survive and are able to pass their genes on to offspring. Thus causing evolution.
Options not given but
Clouds at medium altitudes are made of ice crystals.
As the mid-level clouds form ice crystals when the temperature is cold.
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Answer:
They are about 1/10th the size of a typical human cell. Microbes are generally measured in the scale of one millionth of a meter, which is known as a micrometer.
Explanation:
