Biology Final Exam

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If many human genes differ in about 10% of their bases from another species' same genes and substitutions occur at an estimated rate of 2% per one million years, approximately how many years have passed since the two species diverged?

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Explanation

Combining fossil data with molecular data allows us to time the divergence of different groups of organisms. Please see section 13.6 for more information.

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If many genes from two species differ in about 5% of their bases and substitutions occur at an estimated rate of 5% per one million years, approximately how many years have passed since the two species diverged?

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Explanation

Putting timing on the separation of species based, in part, on gene sequence data, is known as using a molecular clock. Please see section 13.6 for more information.

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Why do different mutations accumulate in two species once they diverge?

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Explanation

Two non-mixing gene pools cannot homogenize by mating and remain similar--they diverge in the sequence of their genes. Please see section 13.6 for more information.

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Evolution occurs in

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Explanation

While there is a role for alleles, individuals, and other things in evolution, evolution itseld is about the divergence of one species from another. Please see section 13.6 for more information.

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Dinosaurs lived essentially during the Paleozoic era.

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Explanation

Dinosaurs lived during the Mesozoic. Please see section 13.1 for more information.

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If you were looking for a time line of Earth's history, you would need one spanning about 4.6 billion years.

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Explanation

Earth has existed for billions of years, but life has been on land for only a small fraction of that time. Please see section 13.1 for more information.

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The abundant presence of ammonite fossils in a large area indicates that the area was once part of an ocean.

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Explanation

Ammonites are oceanic creatures, so their presence in a place indicates the former existence of an ocean there. Please see section 13.1 for more information.

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The fossil record is often incomplete, in part because scientists will never be able to discover some of the fossils that are buried deep in the earth and in part because some living things fossilize more readily than others.

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Explanation

The fossil record is very valuable, but its incompleteness requires caution from scientists. Please see section 13.2 for more information.

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When ocean levels dropped about 70 million years ago, marsupial mammals moved into North America and displaced many of the placental mammal species.

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Explanation

The movement of marsupials into North America occured millions, not tens of millions, of years ago. Please see section 13.3 for more information.

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Placental mammals give birth to more fully developed offspring than marsupial mammals and therefore have a greater chance of survival. This helps to explain why placental mammals from North America displaced many native South American marsupial mammals when a land bridge formed between the two continents.

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Explanation

More advanced young at birth have a phenotype which is promoted by natural selection over the less advanced young of marsupials selected. Please see section 13.3 for more information.

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The techniques used to study molecular evolution are based on the comparison of nucleotide and amino acid sequences among species.

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Explanation

Sequences diverge over time in different species, giving some idea of just how distantly related species are. Please see section 13.6 for more information.

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In the section "Investigating Life: Evolving Backwards," how did the scientists test the hypothesis?

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Explanation

Fossils can be a great help in seeing connections between ancestors and current animals, using the anatomy of each for comparison. Please see section 13.6 for more information.

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In the section "Investigating Life: Evolving Backwards," what is the significance of Najash rionegrina, an extinct, land-dwelling species of snake with functional legs, pelvis, and sacrum?

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Explanation

Najash represents a key transitional fossil in the evolution of snakes. Please see section 13.6 for more information.

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Biology Final Exam

Question 1 of 1

Time Left

If many human genes differ in about 10% of their bases from another species' same genes and substitutions occur at an estimated rate of 2% per one million years, approximately how many years have passed since the two species diverged?

Select the correct answer(s).

(0/0)

Explanation

If many genes from two species differ in about 5% of their bases and substitutions occur at an estimated rate of 5% per one million years, approximately how many years have passed since the two species diverged?

Select the correct answer(s).

(0/0)

Explanation

Why do different mutations accumulate in two species once they diverge?

Select the correct answer(s).

(0/0)

Explanation

Evolution occurs in

Select the correct answer(s).

(0/0)

Explanation

Dinosaurs lived essentially during the Paleozoic era.

Select the correct answer(s).

(0/0)

Explanation

If you were looking for a time line of Earth's history, you would need one spanning about 4.6 billion years.

Select the correct answer(s).

(0/0)

Explanation

The abundant presence of ammonite fossils in a large area indicates that the area was once part of an ocean.

Select the correct answer(s).

(0/0)

Explanation

The fossil record is often incomplete, in part because scientists will never be able to discover some of the fossils that are buried deep in the earth and in part because some living things fossilize more readily than others.

Select the correct answer(s).

(0/0)

Explanation

When ocean levels dropped about 70 million years ago, marsupial mammals moved into North America and displaced many of the placental mammal species.

Select the correct answer(s).

(0/0)

Explanation

Select the correct answer(s).

(0/0)

Explanation

The techniques used to study molecular evolution are based on the comparison of nucleotide and amino acid sequences among species.

Select the correct answer(s).

(0/0)

Explanation

In the section "Investigating Life: Evolving Backwards," how did the scientists test the hypothesis?

Select the correct answer(s).

(0/0)

Explanation

In the section "Investigating Life: Evolving Backwards," what is the significance of Najash rionegrina, an extinct, land-dwelling species of snake with functional legs, pelvis, and sacrum?

Select the correct answer(s).

(0/0)

Explanation

In the section "Investigating Life: Evolving Backwards," what is the significance of the marine fossil snakes (highlighted in the figure)?

Select the correct answer(s).

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What structures were examined between species of snakes?

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Explanation

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