Practice Test Ch 15

Stromatolite fossils that formed 3.5 billion years ago indicate that _____

• life must have arisen earlier, perhaps 3.9 billion years ago

• the first life-forms were photosynthetic

• the first organisms were eukaryotes

• life originated 3.5 billion years ago

Which of the following choices has the correct sequence of stages by which life is likely to have arisen? Here are the stages: A. origin of self-replication molecules B. abiotic synthesis of small organic molecules C. packaging of molecules into "protocells" D. joining of small organize molecules into polymers

• A, B, C, D

• D, B, C, A

• B, D, C, A

• C, D, B, A

The pioneering experiments of Miller and Urey were designed to demonstrate ___

• that organic molecules can be made from inorganic building blocks in the absence of living organism

• that functional proteins could be built from inorganic molecules

• the moleccular composition of the atmosphere on the early Earth

• how the first functional cells originated

What is one hypothesis about the formation of the first polymers?

• abiotically generate enzymes catalyzed dehydration synthesis of the first polypeptides and nucleic acids

• Very High concentrations of salt are thought to have spurred abiotic dehydration synthesis, forming the first polypeptides and other polymers

• extreme heat from volcanic vents on teh seafloor caused monomers to spontaneously from complex

• amino acids, or RNA, in solution could have splashed on hot rocks, and, or clay, causing them to bond together in chains

The first "genes" were probasbly ___

• present in protocells

• short strands of DNA that could form complementary chains

• short strands of DNA in prokaryotes

• short strands of RNA that could form complementary chains and replicagte themselves

protocells are ___

• the first life-forms

• organelles within the earliest cells

• self-replicating strands of RNA

• small vesicles formed abiotically that can grow and divide

evidence indicates that the first prokaryotes arose at least ___ years ago; the first eukaryotes arose about ___ years ago; and the first large organisms that colonized land arose about ___ years ago. Our species arose about ___ years ago.

• 3.5 billion years; 1.8 billion; 200 million; 300,000

• 3.5 billion years; 1.8 billion; 500 million; 195,000

• 3.5 billion years; 3.0 billion; 500 million; 100 million

• 6,000; 6,000; 6,000; 6,000

you have found a fossil of a soft-bodied animal. you suspect it is from the late Proterozoic eon. which isotope would be the best choice to approximate the actual age of the fossil?

• carbon-14

• a combination of radioactive tracers

• carbon-12

• potassium-40

which pair of organisms, if found together in the same well-defined fossil layer, would cause a major rethinking of our current understanding of the fossil record?

• prokaryotes and bony fish

• marine algae and bony fish

• dinosaurs and gymnosperms

• dinosaurs and primates

in the geologic record, what events or developments separate geologic eras?

• the transition point for each era is marked by a mass extinction or significant species radiation

• the transition point for each era is marked by a catastrophic geologic event

• the estimated time of life on Earth was divided by four, each unit represents one era

• each time a new phylum emerged, it marked the beginning of a new era