Question

1. the organisms responsible for producing much of earths atmospheric oxygen are

a. ammolites
b. cyanobacterium
c. strata
d. stromatolites

1. evidence of an oxygen - rich atmosphere is the presence of

a. cyanobacteria
b. trace fossils
c. banded iron formations
d. stromatolites

1. decide whether each statement is true (t) or false (f). place your answer in the blank space given.

a. fossils of coastal organisms have been found along the eastern edge of the rocky mountains.
b. cyanobacteria were the dominant form of life on earth for about two billion years.
c. archaea are found living near deep - sea thermal vents.
d. the absence of red and grey bands in sedimentary rock from 1.8 billion years ago to the present indicates a lack of oxygen in the atmosphere.

1. match each description with the appropriate term listed. place your answer in the blank space given.

i. stromatolites ii. sedimentary iii. trace fossil
iv. strata v. fossil vi. cyanobacteria
a. evidence or remains of ancient life preserved in earths crust
b. rock formed from compressed layers of sediment or organic matter
c. single - celled, photosynthetic bacteria
d. layered bands within sedimentary rock
e. albertas oldest fossils
f. indirect fossilized evidence left by ancient organisms

Explanation:

1. Cyanobacteria are photosynthetic organisms that have been crucial in producing Earth's atmospheric oxygen through photosynthesis over billions of years.
2. Banded iron formations are formed when iron reacts with oxygen in the water. Their presence indicates the existence of an oxygen - rich atmosphere in the past.

12.

• a. Fossils of coastal organisms have been found in non - coastal areas due to geological processes like plate tectonics and sea - level changes. The Rocky Mountains were once under water in some parts, so this is true.
• b. Cyanobacteria were dominant life forms for about two billion years and played a major role in oxygenating the Earth's atmosphere.
• c. Archaea are known to inhabit extreme environments, including near deep - sea thermal vents.
• d. The presence of red and grey bands in sedimentary rocks is related to oxygen levels in the past. The absence of such bands does not necessarily mean a lack of oxygen throughout that time period.

13.

• a. Fossils are the evidence or remains of ancient life preserved in Earth's crust.
• b. Sedimentary rock is formed from compressed layers of sediment or organic matter.
• c. Cyanobacteria are single - celled, photosynthetic bacteria.
• d. Strata are the layered bands within sedimentary rock.
• e. Stromatolites are among Alberta's oldest fossils.
• f. Trace fossils are the indirect fossilized evidence left by ancient organisms.

Answer:

1. B. cyanobacterium
2. C. banded iron formations

12.

• a. T
• b. T
• c. T
• d. F

13.

• a. v. fossil
• b. ii. sedimentary
• c. vi. cyanobacteria
• d. iv. strata
• e. i. stromatolites
• f. iii. trace fossil