Most of the world's iron ore, including that found in northern Minnesota, formed during the middle Precambrian period, ranging in age from 1.8 to 2.5 billion years old. They are composed of alternating layers of iron-rich material, most often magnetite or hematite, and silica. These iron oxide minerals formed on the ocean floor, creating the banded iron deposits you see here. What was the source of the oxygen that helped to produce these deposits?

A) The oxygen that was released into the atmosphere as a by-product of
photosynthesis caused iron deposits to oxidize creating the iron oxide minerals.

B)Photosynthetic organisms making oxygen as a by-product of photosynthesis and the oxygen reacted with the iron dissolved in seawater
to form iron oxide minerals.

C)The decomposition of carbon-based life forms in the oceans released oxygen and carbon dioxide. These gases reacted with the iron deposits
forming the minerals mentioned.

D)In Earth's early biosphere, there were not organisms that underwent aerobic cellular respiration and an excess of oxygen built up in the
atmosphere. This oxygen reacted with iron deposits to form iron oxide
minerals.

Interpret the model. a three-part model with black right-arrows between the parts. left part: a large green apple-shaped component with a w-shaped indentation centered on top. a small blue apple-slice shape sits above the left indentation and an arrow points from the shape to the indentation. a small purple apple-slice shape and arrow sit above the right indentation and an arrow points from the shape to the indentation. middle part: a large green apple-shaped component with a square indentation centered on top. sitting in the left side of the indentation is a blue apple-slice shape with a flat bottom, fused to a purple apple-slice shape with a flat bottom on the right side of the indentation. right part: a large green apple-shaped component with a w-shaped indentation centered on top. an up-arrow is centered above the indentation pointing to a fused blue and purple apple-slice-shaped flat-bottom component sitting above the indentation. assigne "true" or "false" to the end of each statement. the model shows a shape change occurring in the enzyme after the substrate is bound in the active site. t/fthere are two products in this model. t? f there are three substrates in this model. t/f the model shows two different enzymes. t/f

One of the purposes of transcription is to produce a sequence of bases that

Which of the following typically characterizes a tropical rainforests