Knowledge Check: Unit 4 — Chapters 18–20 – Biology

Knowledge Check: Unit 4 — Chapters 18–20

Test yourself on Unit 4: Evolutionary Processes (Chapters 18–20). Every question below was written from the chapters’ own text — their summaries, key terms, explanations, and tables — and none repeats a question from the section pages. There are no hints: treat it like a test. Questions are grouped by the section they come from, so a miss tells you exactly which section to review.

Chapter 18: Evolution and the Origin of Species

18.1 Understanding Evolution

From 1848 to 1852, where did the naturalist Alfred Russel Wallace travel to collect insects?

A mutation that has no effect on an organism’s phenotype’s fitness is called a ________ mutation.

How does the geographic distribution of the plant family Proteaceae across Australia, southern Africa, and South America support evolution’s account of the supercontinent Gondwana breaking apart?

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Broad groups that evolved before the supercontinent Pangaea broke up are distributed worldwide, while groups that evolved since the breakup appear uniquely in regions of the planet. The presence of members of the plant family Proteaceae in Australia, southern Africa, and South America indicates that their ancestors were predominant on the supercontinent Gondwana prior to its breaking up.

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broad groups that evolved before the supercontinent Pangaea broke up are distributed worldwide
groups that evolved since the breakup appear uniquely in regions of the planet
the presence of members of the plant family Proteaceae in Australia, southern Africa, and South America indicates that their ancestors were predominant on the supercontinent Gondwana

18.2 Formation of New Species

For a genetic change to pass to the next generation through sexual reproduction, which type of cell must possess the changed trait?

Polyploidy formed by the reproduction of individuals from two different species, producing a viable offspring, is called a(n) ________.

How does habitat isolation, illustrated by a cricket population divided by a flood, differ from behavioral isolation, illustrated by fireflies, as forms of reproductive isolation?

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Habitat isolation occurs when populations of a species move or are moved to a new habitat and take up residence in a place that no longer overlaps with the same species’ other populations, as when a cricket population that was divided after a flood could no longer interact with each other. Behavioral isolation occurs when the presence or absence of a specific behavior prevents reproduction, as when a male firefly’s light pattern is not recognized by a female of a different species, so she would not mate with the male.

Did your answer mention:

habitat isolation occurs when populations of a species move or are moved to a new habitat and take up residence in a place that no longer overlaps with the same species' other populations
a cricket population that was divided after a flood could no longer interact with each other
behavioral isolation occurs when the presence or absence of a specific behavior prevents reproduction
a female would not recognize the light pattern and would not mate with the male

18.3 Reconnection and Speciation Rates

Immediately after a new species arises through speciation, what describes the stretch of time during which the closely related species continue to interact?

If hybrids in a hybrid zone remain fit and reproductive so that hybridization between the two species continues indefinitely with no net change taking place, biologists classify this outcome as ________.

A sudden drop in water level separates a species of snails into one large population and one tiny population. Why does new genetic variation spread quickly through the tiny population afterward?

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The tiny population faces new environmental conditions, and because its gene pool quickly became so small, any variation that surfaces and that aids in surviving the new conditions becomes the predominant form.

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the tiny population faces new environmental conditions
because its gene pool quickly became so small
any variation that surfaces and that aids in surviving the new conditions becomes the predominant form

Chapter 19: The Evolution of Populations

19.1 Population Evolution

The coherent understanding of the relationship between natural selection and genetics that took shape by the 1940s is known as:

The sum of all the alleles that the individuals in a population carry is called the population’s ________.

What conditions does the Hardy-Weinberg principle assume are true of a population it describes?

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The Hardy-Weinberg principle assumes an infinitely large population and conditions with no mutations, migration, emigration, or selective pressure for or against genotype.

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an infinitely large population
no mutations
no migration or emigration
no selective pressure for or against genotype

19.2 Population Genetics

The diversity of alleles and genotypes within a population is called:

An environmental factor that causes one phenotype to fare better than another is called a ________.

Some turtles and other reptiles show temperature-dependent sex determination (TSD). What is TSD, and why do the sex differences it produces not lead to evolution?

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Some turtles and other reptiles have temperature-dependent sex determination (TSD). TSD means that individuals develop into males if their eggs are incubated within a certain temperature range, or females at a different temperature range. Because these phenotypic differences are due to environmental variation instead of genetic differences, they cannot be inherited and do not lead to evolution.

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individuals develop into males if their eggs are incubated within a certain temperature range, or females at a different temperature range
these phenotypic differences are due to environmental variation instead of genetic differences
they cannot be inherited and do not lead to evolution

19.3 Adaptive Evolution

The result of directional selection is:

Scientists call an organism’s ability to survive and to contribute offspring to the next generation’s gene pool its evolutionary, or ________, fitness.

Why can natural selection never produce the perfect organism?

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Natural selection cannot produce the perfect organism. Natural selection can only select on existing variation in the population. It does not create anything from scratch. Thus, it is limited by a population’s existing genetic variability and whatever new alleles arise through mutation and gene flow.

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natural selection can only select on existing variation in the population
it does not create anything from scratch
it is limited by a population's existing genetic variability and whatever new alleles arise through mutation and gene flow

Chapter 20: Phylogenies and the History of Life

20.1 Organizing Life on Earth

In the taxonomic classification system’s example for the dog, which level does the taxon Canis name?

The point where a single lineage on a phylogenetic tree splits into two distinct new lineages is called a ________.

Why might two closely related lineages end up looking more different from each other than either does from a more distantly related lineage?

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If two closely related lineages evolved under significantly varied surroundings, it is possible for the two groups to appear more different than other groups that are not as closely related.

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if two closely related lineages evolved under significantly varied surroundings
it is possible for the two groups to appear more different
than other groups that are not as closely related

20.2 Determining Evolutionary Relationships

Which of the following pairs of structures is analogous rather than homologous?

Why can DNA sequence comparisons sometimes make two very closely related organisms appear unrelated?

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Two very closely related organisms can appear unrelated if a mutation occurred that caused a shift in the genetic code. Inserting or deleting a mutation would move each nucleotide base over one place, causing two similar codes to appear unrelated.

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a mutation occurred that caused a shift in the genetic code
inserting or deleting a mutation would move each nucleotide base over one place
causing two similar codes to appear unrelated

In a DNA comparison, why can two distantly related organisms sometimes appear closely related?

20.3 Perspectives on the Phylogenetic Tree

According to the classic tree model, how were prokaryotic species thought to evolve?

How do fungal species that feed on yew trees illustrate horizontal gene transfer in eukaryotes?

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Fungal species feeding on yew trees, from which the anti-cancer drug TAXOL is derived from the bark, have acquired the ability to make taxol themselves, a clear example of gene transfer.

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fungal species feeding on yew trees
have acquired the ability to make taxol themselves
a clear example of gene transfer

Using DNA analysis and a new mathematical algorithm, abbreviated CR, James Lake’s laboratory proposed that eukaryotic cells developed from an endosymbiotic gene fusion between an archaeal and a bacterial species. The algorithm is called ________.

This knowledge check is written for Unit 4 (Chapters 18–20) of Biology 2e by Mary Ann Clark, Jung Choi, Matthew Douglas, and OpenStax, © OpenStax, licensed under CC BY-NC-SA 4.0. Access the original for free at openstax.org. Changes: every question is locally written from the pinned text of the chapters’ own modules — their section summaries, glossary definitions, body passages, and comparison tables — and none is transcribed from the book’s exercise sets, which the section pages already carry; no question carries a hint, and every self-check carries a rubric that decomposes a model answer made of the module’s own sentences.

Perspectives on the Phylogenetic Tree Viruses