Need help with the eye on earth questions I understand the whole section but don

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Need help with the eye on earth questions I understand the whole section but don't know where to find there answers in the book A. B. and ammonia, both of which were plentiful in Earth's primitive atmosphere. Some scientists suggest that these bacteria called prokaryotes, which material (DNA) is not separated trom gases could have been easily reorganized into useful organic molecules by ultraviolet light. Others consider by a nucleus. Because oxygen was larg Earth's early atmosphere and oceans, lightning to have been the impetus, as the well-known isms employed anaerobie (without oxy experiments conducted by biochemists Stanley Miller extract energy from "food." Their food organic molecules in their surrounding Still other researchers suggest that amino acids arrived ply was very limited. Later, bacteria evo ly-made," delivered by asteroids or comets that collided solar energy to synthesize organic comp and Harold Urey attempted to demonstrate with a young Earth. Evidence for this hypothesis comes This event was an important turning poir evolution: For the first time, organisms ha drites, which contain amino acid-like organic compounds. produce food for themselves as well as for Recall that photosynthesis by ancient c material needed for life came from the methane and atpe of prokaryote, contributed to the grac ogen sulfide that spews from deep-sea hydrothermal level of oxygen, first in the ocean and later in simokers) (see Figure S.22, page 257). It is sphere. It was these early organisms, which b that life originated in hot springs similar to Earth 3.5 billion years ago, that dramatically et another hypothesis proposes that the organic also possible those found in Yellowstone National Park Earth's First Life: Prokaryotes 22.20). The first known organisms were si our planet. Fossil evidence for the existence of scopic bacteria includes distinctively layered m stromatolites, composed of slimy material sec organisms, akong with trapped sediments (Figur. of where or how life originated, it is clear that What is known about these to "now involhved change (Figure from the studly hange ( ure from the study of modern stromatolites like thoe Shark Bay, Australia (Figure 22.218) Today's stro like stubby pillars built as microbes slowly move mple sinl EYE ON EARTH 22.2 he rocks shown here are Cambrian-age stromatolites of the Hoyt Limestone, exposed at Lester Park, near Saratoga Springs, New York. QUESTION 1 Using Figure 22.3, determine approximately how many years ago these rocks were deposited QUESTION 2 What is the name of the group of organisms that likely produced these limestone deposits? QUESTION 3 What was the environment like in this part of New York when these rocks were deposited?

Explanation / Answer

1.As shown in the figure that these rocks are of cambrian age so the rocks were formed 540-490 million years ago .As we know in geological time scale cambrian period is 540-490 million years ago.

2.Stromatolites are cyanobacterias which secrete calcareous sedimets from them and we know limestone has composition of calcium carbonate so stromatolites are the group of orgamisms who made the rock.

3.As we know limestone formed under shallow marine environment so may be in past the new york was in shallow marine condition with little more warmth.

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