Evolutionary Biology Quiz

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Questions and Answers

What is the founder effect?

A small group separating from a larger group.

Which of the following are key points of Darwin's theory of evolution? (Select all that apply)

  • Organisms have a drive to become more complex
  • Species living today have remained unchanged from their ancestral species.
  • Species living today have descended from ancestral species with modifications. (correct)
  • Natural Selection is a mechanism for evolution. (correct)

What was Wallace's theory of evolution?

Over generations, natural selection of inherited traits could give rise to new species.

What is the fossil record?

<p>A chronological collection of life's remains in sedimentary rock layers.</p> Signup and view all the answers

What is biogeography?

<p>The study of past and present distribution of organisms.</p> Signup and view all the answers

Define convergent evolution.

<p>Process by which unrelated organisms independently evolve similarities when adapting to similar environments.</p> Signup and view all the answers

What are direct observations?

<p>Observing phenomena using the five senses; capturing information by watching participants.</p> Signup and view all the answers

Define natural selection.

<p>A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.</p> Signup and view all the answers

What is artificial selection?

<p>Breeding organisms with specific traits in order to produce offspring with identical traits.</p> Signup and view all the answers

Define homologies.

<p>Similarities between organisms based on descent from a common ancestor.</p> Signup and view all the answers

Explain the mechanism of natural selection.

<p>Mutations create genetic diversity in a population, and individuals with traits that make them better adapted to their environment are more likely to survive and reproduce. This process leads to the accumulation of favorable traits over generations, resulting in adaptation and evolution. It is a process of descent with modification.</p> Signup and view all the answers

What is descent with modification?

<p>The principle that each living species has descended, with changes, from other species over time.</p> Signup and view all the answers

What is a homologous structure?

<p>A body part that is similar in structure on different organisms but performs different functions.</p> Signup and view all the answers

Define analogous structure.

<p>Body parts that share a common function, but not structure.</p> Signup and view all the answers

What is a fossil?

<p>A trace of an ancient organism that has been preserved in rock.</p> Signup and view all the answers

Define vestigial structure.

<p>Remnant of a structure that may have had an important function in a species' ancestors, but has no clear function in the modern species.</p> Signup and view all the answers

What is an evolutionary tree?

<p>A branching diagram that reflects a hypothesis about evolutionary relationships among groups of organisms.</p> Signup and view all the answers

Define adaptation.

<p>A trait that helps an organism survive and reproduce in its environment</p> Signup and view all the answers

What is evolution?

<p>The gradual change in a species over time.</p> Signup and view all the answers

Why is the smallest unit of evolution a population?

<p>Evolutionary changes occur through shifts in allele frequencies within a group of interbreeding individuals over generations.</p> Signup and view all the answers

How does genetic variation arise in populations?

<p>Shifts in allele frequencies.</p> Signup and view all the answers

Why is genetic variation necessary for natural selection?

<p>It provides diversity of traits to be selected.</p> Signup and view all the answers

What are the Hardy-Weinberg equilibrium equations?

<p>p^2 + 2pq + q^2 = 1 p + q = 1</p> Signup and view all the answers

What are the five conditions needed for Hardy-Weinberg equilibrium? (Select all that apply)

<p>Random mating (A), No migration (B), Large population (D), No selection (F), No mutations (G)</p> Signup and view all the answers

What is directional selection?

<p>Occurs when natural selection favors one of the extreme variations of a trait.</p> Signup and view all the answers

What is disruptive selection?

<p>Favors individuals at both extremes of the phenotypic range.</p> Signup and view all the answers

What is stabilizing selection?

<p>Natural selection that favors intermediate variants by acting against extreme phenotypes.</p> Signup and view all the answers

What is balancing selection?

<p>Natural selection that maintains two or more phenotypic forms in a population.</p> Signup and view all the answers

Natural selection is goal-oriented and can produce perfect organisms.

<p>False (B)</p> Signup and view all the answers

Why does genetic drift have a greater effect on smaller populations?

<p>It has a greater effect because it works faster in smaller populations.</p> Signup and view all the answers

What is a gene pool?

<p>Combined genetic information of all the members of a particular population.</p> Signup and view all the answers

Define bottleneck effect.

<p>A reduction in the genetic diversity of a population caused by a reduction in its size usually due to random environmental events killing its members.</p> Signup and view all the answers

What is genetic drift?

<p>Random change in allele frequencies that occurs in small populations.</p> Signup and view all the answers

Define gene flow.

<p>Movement of alleles from one population to another.</p> Signup and view all the answers

What is fitness?

<p>Ability of an organism to survive and reproduce in its environment.</p> Signup and view all the answers

What is horizontal gene transfer (HGT)?

<p>The transfer of genes from one genome to another through mechanisms such as transposable elements, plasmid exchange, viral activity, and perhaps fusions of different organisms.</p> Signup and view all the answers

Define biological species?

<p>Species is a group of populations whose members have the potential to produce fertile offspring.</p> Signup and view all the answers

What is the morphological species concept?

<p>Characterizes a species by body shape and other structural features.</p> Signup and view all the answers

How does a single species become two species?

<p>Reproductive isolation</p> Signup and view all the answers

Why is reproductive isolation necessary for divergence in populations?

<p>It prevents gene fow between populations, allowing them to accumulate genetic differences and evolve independently.</p> Signup and view all the answers

What are the eight mechanisms of reproductive isolation? (Select all that apply)

<p>Behavioral isolation (A), Hybrid breakdown (B), Temporal isolation (C), Reduced hybrid viability (D), Gametic isolation (E), Habitat isolation (F), Reduced hybrid fertility (H), Mechanical isolation (I)</p> Signup and view all the answers

How does sympatric speciation occur?

<p>Polyploidy, habitat differentiation, sexual selection</p> Signup and view all the answers

What is allopatric speciation?

<p>Members of a species become geographically separated. This is the most common way new species arise.</p> Signup and view all the answers

What is reproductive isolation?

<p>Separation of species or populations so that they cannot interbreed and produce fertile offspring.</p> Signup and view all the answers

Define hybrid zone.

<p>A geographic region in which members of different species meet and mate, producing at least some offspring of mixed ancestry.</p> Signup and view all the answers

What is polyploidy?

<p>Condition in which an organism has extra sets of chromosomes.</p> Signup and view all the answers

Define intraspecific.

<p>Variations within a single species.</p> Signup and view all the answers

What is adaptive radiation?

<p>Single species evolves into an array of descendants.</p> Signup and view all the answers

How did eukaryotic cells evolve from prokaryotic cells?

<p>Endosymbiosis, where one prokaryotic cell engulfed another, forming a symbiotic relationship that eventually led to the evolution of organelles like mitochondria and chloroplasts.</p> Signup and view all the answers

What are the main steps for the evolution of life on Earth?

<ol> <li>Nucleotides and amino acids produced prior to the existence of cells.</li> <li>Polymerization into larger molecules.</li> <li>Polymers became enclosed in membranes, forming protocells.</li> <li>Origin of self-replicating molecules</li> </ol> Signup and view all the answers

What is the age of Earth?

<p>4.6 billion years.</p> Signup and view all the answers

When did prokaryotes appear?

<p>3.5 Billion years ago.</p> Signup and view all the answers

When did multicellular eukaryotes appear?

<p>1 billion years ago</p> Signup and view all the answers

When did animals appear?

<p>0.8 Billion years ago</p> Signup and view all the answers

When did land plants appear?

<p>0.5 Billion years ago.</p> Signup and view all the answers

How has Earth's environment changed over history and affected living organisms?

<p>Earth's environment has undergone significant changes over time, including shifts in climate, atmosphere, land masses, and the occurrence of events like floods, glaciation, volcanic eruptions, and meteorite impacts. These changes have driven the evolution of life, shaping adaptations, creating new environments, and sometimes leading to mass extinctions.</p> Signup and view all the answers

What is radiometric dating?

<p>The process of measuring the absolute age of geologic material by measuring the concentrations of radioactive isotopes and their decay products.</p> Signup and view all the answers

How does the depth of a fossil help us understand its relative age?

<p>The deeper the strata found in, the older the fossil.</p> Signup and view all the answers

Where did the first living cells evolve?

<p>Oceans.</p> Signup and view all the answers

How does spatial expression of genes affect pattern formation?

<p>It affects phenotypes.</p> Signup and view all the answers

How does early development of an organism help us understand evolutionary relationships?

<p>By revealing shared embryonic features and developmental processes that reflect common ancestry, highlighting similarities between species that may not be apparent in their adult forms.</p> Signup and view all the answers

What are protocells?

<p>Simple vesicle-like structures that harbor nucleic acids.</p> Signup and view all the answers

Define hydrothermal vents.

<p>An opening in the seafloor out of which heated mineral-rich water flows.</p> Signup and view all the answers

Define alkaline vents.

<p>Deep-sea vents that release water that has a high pH (9-11) and is warm (40-90ºC) rather than hot.</p> Signup and view all the answers

What are ribozymes?

<p>Catalytic RNA molecules that function as enzymes and can splice RNA.</p> Signup and view all the answers

Define endosymbiont.

<p>A cell that lives within a host cell.</p> Signup and view all the answers

What is the Cambrian explosion?

<p>Earliest part of the Paleozoic era, when a huge diversity of animal species evolved</p> Signup and view all the answers

Define unicellular.

<p>One cell</p> Signup and view all the answers

What is a prokaryote?

<p>A cell without a nucleus.</p> Signup and view all the answers

Define eukaryote.

<p>A cell that contains a nucleus and membrane-bound organelles.</p> Signup and view all the answers

What is half-life?

<p>The time required for one half of the atoms of a radioisotope to emit radiation and decay products.</p> Signup and view all the answers

Define a monophyletic group.

<p>A group that consists of a single ancestral species and all its descendants and excludes any organisms that are not descended from that common ancestor.</p> Signup and view all the answers

How can neutral mutations spread through populations?

<p>Genetic drift, where random changes in allele frequencies occur over generations, allowing these mutations to become more common even though they don't affect an organism's fitness.</p> Signup and view all the answers

What is the principle of parsimony?

<p>Favors the hypothesis that requires the fewest assumptions.</p> Signup and view all the answers

What is a molecular clock?

<p>Model that uses DNA comparisons to estimate the length of time that two species have been evolving independently.</p> Signup and view all the answers

How can horizontal gene transfer and convergent evolution complicate drawing phylogenetic trees?

<p>Horizontal gene transfer can transfer genes between different species, confusing true evolutionary relationships and convergent evolution can make it difficult to distinguish homologous traits from analogous traits.</p> Signup and view all the answers

What is binomial nomenclature?

<p>Classification system in which each species is assigned a two-part scientific name.</p> Signup and view all the answers

What is the hierarchy of taxonomic grouping?

<p>Kingdom, Phylum, Class, Order, Family, Genus, Species</p> Signup and view all the answers

Define taxon.

<p>A group of organisms in a classification system.</p> Signup and view all the answers

What are sister taxa?

<p>Groups of organisms that share an immediate common ancestor and hence are each other's closest relatives.</p> Signup and view all the answers

What is a clade?

<p>A group of species that includes an ancestral species and all its descendants.</p> Signup and view all the answers

Define paraphyletic.

<p>Pertaining to a group of taxa that consists of a common ancestor and some, but not all, of its descendants.</p> Signup and view all the answers

Flashcards

Founder effect

Small group separating from a larger group.

Darwin theory of evolution

Species descend from ancestors through natural selection.

Natural selection

Process where individuals with certain traits survive better.

Fossil Record

Collection of life’s remains in sedimentary layers.

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Biogeography

Study of organism distribution over time.

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Evolutionary tree

Diagram showing evolutionary relationships.

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Adaptation

Trait that enhances survival and reproduction.

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Gene pool

Combined genetic information in a population.

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Genetic drift

Random changes in allele frequencies in small populations.

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Speciation

Formation of new species.

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Reproductive isolation

Separation preventing gene flow between species.

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Bottleneck effect

Loss of genetic diversity due to population reduction.

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Hardy-Weinberg equilibrium

Model for understanding allele frequencies.

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Directional selection

Natural selection favors one extreme of a trait.

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Artificial selection

Breeding for specific traits by humans.

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Homologous structure

Body parts similar in structure but different in function.

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Analogous structure

Body parts that share a function but not a structure.

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Molecular clock

Uses DNA comparisons to estimate evolutionary time.

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Biological species concept

Species capable of interbreeding to produce fertile offspring.

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Adaptive radiation

Single species evolves into many forms.

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Endosymbiont

A cell living within another cell.

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Cambrian explosion

Rapid diversification of life forms.

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Half-life

Time for half of a radioisotope to decay.

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Gene flow

Movement of alleles between populations.

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Evolution

Gradual change in a species over time.

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Study Notes

Founder Effect

  • Small group separates from larger group

Darwin's Theory of Evolution

  • Species today descended from ancestral species ("descent with modification")
  • Natural selection is a mechanism for evolution

Wallace's Theory of Evolution

  • Natural selection of inherited traits leads to new species over generations

Fossil Record

  • Chronological collection of life's remains in sedimentary rock layers

Biogeography

  • Study of past and present organism distribution

Convergent Evolution

  • Unrelated organisms evolve similar traits adapting to similar environments

Direct Observations

  • Observing phenomena using the five senses

Natural Selection

  • Individuals with favorable inherited traits survive and reproduce at higher rates

Artificial Selection

  • Breeding organisms with specific traits to produce offspring with identical traits

Homologies

  • Similarities due to common ancestry

Mechanism of Natural Selection

  • Mutations create genetic diversity
  • Certain organisms have higher fitness
  • Descent with modification leads to adaptation

Descent with Modification

  • Living species have changed over time from ancestral species

Homology

  • Similarity from common ancestry

Homologous Structures

  • Similar structure, different function in different organisms

Analogous Structures

  • Similar function, different structure in different organisms

Fossil

  • Trace of ancient organism preserved in rock

Vestigial Structure

  • Remnants of structures with function in ancestors, but no clear function today

Evolutionary Tree

  • Diagram reflecting evolutionary relationships among organisms

Adaptation

  • Trait that helps an organism survive and reproduce

Evolution

  • Gradual change in a species over time

Population as Unit of Evolution

  • Evolutionary changes are due to shifts in allele frequencies in populations

Genetic Variation in Populations

  • Shifts in allele frequencies

Genetic Variation and Natural Selection

  • Provides traits for selection

Hardy-Weinberg Equilibrium (Allele and Genotype Frequency)

  • p² + 2pq + q² = 1
  • p + q = 1

Hardy-Weinberg Equilibrium Conditions

  • No selection
  • No mutations
  • No migration
  • Large population
  • Random mating

Directional Selection

  • Natural selection favors one extreme trait variation

Disruptive Selection

  • Favors both extreme phenotypic variations

Stabilizing Selection

  • Favors intermediate phenotypes against extreme variations

Balancing Selection

  • Natural selection maintains multiple phenotypic forms

Natural Selection: Non-Goal-Oriented

  • Natural selection cannot produce perfect organisms

Genetic Drift in Small Populations

  • Genetic drift (random fluctuation) is faster in small populations

Gene Pool

  • Combined genetic information of a population

Population

  • Group of individuals of the same species in the same area

Microevolution

  • Evolutionary change within a species over a short period

Macroevolution

  • Large-scale evolutionary changes over long periods

Bottleneck Effect

  • Reduction in genetic diversity from a population size reduction due to random environmental event

Genetic Drift

  • Random allele frequency change in small populations

Gene Flow

  • Movement of alleles between populations

Migration

  • Permanent relocation

Fitness

  • An organism's ability to survive and reproduce

Mutation

  • Change in DNA sequence

Horizontal Gene Transfer

  • Gene transfer between genomes; e.g., transposons, plasmids, viruses

Biological Species Concept

  • Species as populations able to interbreed and produce fertile offspring

Morphological Species Concept

  • Species characterized by body shape and structure; difficulty in defining degree of dissimilarity.

Ecological Species Concept

  • Species defined by its ecological niche; difficulty with overlapping niches

Speciation: Formation of Two Species from One

  • Reproductive isolation

Reproductive Isolation and Divergence

  • Prevents gene flow, allowing independent evolution

Reproductive Isolation Mechanisms

  • Habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, gametic isolation, reduced hybrid viability, reduced hybrid fertility, hybrid breakdown

Sympatric Speciation

  • Speciation within the same geographic area; involves polyploidy, habitat differentiation, and sexual selection

Allopatric Speciation

  • Speciation by geographic isolation; most common

Speciation

  • Formation of new species

Reproductive Isolation

  • Separation preventing interbreeding and fertile offspring production

Biological Species Concept

  • Species as interbreeding populations

Hybrid Zone

  • Area where different species meet and interbreed

Polyploidy

  • Extra sets of chromosomes

Hybrid

  • Offspring of crosses between different traits

Intraspecific

  • Variations within a single species

Interspecific

  • Competition between different species

Adaptive Radiation

  • Single species evolving into many descendants

Eukaryotic Evolution from Prokaryotes

  • Endosymbiosis (one prokaryote engulfs another) forming organelles like mitochondria/chloroplasts

Fossil Record Biases

  • Information limited by preservation conditions

Main Steps in the Evolution of Life on Earth

  • Nucleotide/amino acid production, polymerization, protocell formation, self-replicating molecules

Age of Earth

  • 4.6 billion years

Appearance of Prokaryotes

  • 3.5 billion years ago

Appearance of Eukaryotes

  • 1.8 billion years ago

Appearance of Multicellular Eukaryotes

  • 1 billion years ago

Appearance of Animals

  • 600 million years ago

Appearance of Humans

  • 2.5 million years ago

Appearance of Land Plants

  • 500 million years ago

Environmental Change and Organisms

  • Environmental changes (climate, landmasses, floods, glaciation, volcanism) affect organisms genetically.

Radiometric Dating

  • Measuring absolute age of geological material using radioactive isotopes and decay products

Fossil Relative Age

  • Deeper strata = older fossils

Origin of First Living Cells

  • Oceans

Spatial Gene Expression and Pattern Formation

  • Affects phenotypes

Early Development and Evolutionary Relationships

  • Embryonic features and developmental processes reflect common ancestry

Protocells

  • Simple vesicle-like structures

Hydrothermal Vents

  • Openings releasing heated mineral-rich water

Alkaline Vents

  • Deep-sea vents releasing high pH, warm water

Ribozymes

  • Catalytic RNA molecules

Endosymbiont

  • Cell living within a host cell

Cambrian Explosion

  • Diverse animal evolution in the Paleozoic era

Unicellular

  • One cell

Multicellular

  • Many cells

Prokaryote

  • Cell without a nucleus

Eukaryote

  • Cell with nucleus and organelles

Half-Life

  • Time for half of a radioisotope to decay

Monophyletic Group

  • Group with single ancestor and all descendants, excluding others

Neutral Mutations and Spread

  • Spread by genetic drift (random allele changes)

Principle of Parsimony

  • Favors hypothesis with fewest assumptions

Molecular Clock

  • Estimates evolutionary time from DNA comparisons

Horizontal Gene Transfer and Phylogenetic Trees

  • Complications due to gene transfer between species / convergent evolution

Binomial Nomenclature

  • Two-part scientific name for species

Taxonomic Hierarchy

  • Kingdom, Phylum, Class, Order, Family, Genus, Species

Taxon

  • Group of organisms in a classification system

Sister Taxa

  • Groups sharing immediate common ancestor

Analogy

  • Similarity due to environment, not ancestry

Homology

  • Similarity due to common ancestry

Clade

  • Group of species with common ancestor and all descendants

Paraphyletic Group

  • Group of common ancestor but not all descendants

Polyphyletic Group

  • Taxa from multiple unrelated ancestors

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