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Questions and Answers
During meiosis, at what stage does recombination (crossing over) occur, and what is the significance of this process?
During meiosis, at what stage does recombination (crossing over) occur, and what is the significance of this process?
- Anaphase I; it separates homologous chromosomes.
- Prophase I; it creates new combinations of alleles on the same chromosome. (correct)
- Telophase II; it restores the diploid number of chromosomes in daughter cells.
- Metaphase II; it ensures the independent assortment of chromosomes.
How does independent assortment during meiosis contribute to genetic variation?
How does independent assortment during meiosis contribute to genetic variation?
- By aligning homologous tetrads in a specific, predetermined order on the metaphase plate.
- By preventing the fusion of gametes during fertilization.
- By ensuring that sister chromatids are identical.
- By randomly aligning homologous tetrads on the metaphase plate, leading to different combinations of maternal and paternal chromosomes in each gamete. (correct)
Within the context of population genetics, what does the term 'heterozygosity' (H) represent, and how is it calculated?
Within the context of population genetics, what does the term 'heterozygosity' (H) represent, and how is it calculated?
- The proportion of homozygous individuals in a population; calculated as $p^2 + q^2$.
- The measure of population variation at a single locus; calculated as $2pq$. (correct)
- The total number of different alleles present in a population; calculated by summing the frequencies of all alleles.
- The rate of mutation within a population; calculated as the number of new mutations divided by the population size.
What does the Hardy-Weinberg Equilibrium principle state about allele frequencies in a population, and under what conditions does this principle hold true?
What does the Hardy-Weinberg Equilibrium principle state about allele frequencies in a population, and under what conditions does this principle hold true?
Which of the following factors can disrupt the Hardy-Weinberg Equilibrium and lead to microevolutionary change in a population?
Which of the following factors can disrupt the Hardy-Weinberg Equilibrium and lead to microevolutionary change in a population?
How does gene flow affect allele frequencies in different populations, and what is the cause of this phenomenon?
How does gene flow affect allele frequencies in different populations, and what is the cause of this phenomenon?
How does genetic drift impact allele frequencies, especially in small populations, and what is the primary cause of this effect?
How does genetic drift impact allele frequencies, especially in small populations, and what is the primary cause of this effect?
In the context of chromosomal changes during meiosis, how does a translocation differ from an inversion?
In the context of chromosomal changes during meiosis, how does a translocation differ from an inversion?
Which of the following best explains how artificial selection contributed to Darwin's development of the theory of natural selection?
Which of the following best explains how artificial selection contributed to Darwin's development of the theory of natural selection?
How does the concept of 'descent with modification' explain the diversity of life on Earth?
How does the concept of 'descent with modification' explain the diversity of life on Earth?
A population of insects is exposed to a new pesticide. Initially, most of the insects are susceptible, but over several generations, the population develops resistance. Which of the following best describes the mechanism behind this change?
A population of insects is exposed to a new pesticide. Initially, most of the insects are susceptible, but over several generations, the population develops resistance. Which of the following best describes the mechanism behind this change?
Which of the following evolutionary changes is most directly associated with alterations in the timing of developmental events?
Which of the following evolutionary changes is most directly associated with alterations in the timing of developmental events?
Which of the following represents a challenge Darwin faced when formulating his theory of evolution by natural selection?
Which of the following represents a challenge Darwin faced when formulating his theory of evolution by natural selection?
How do vestigial structures provide evidence for evolution?
How do vestigial structures provide evidence for evolution?
Paedomorphosis, a type of heterochrony, is characterized by which of the following?
Paedomorphosis, a type of heterochrony, is characterized by which of the following?
Hox genes play a crucial role in development by:
Hox genes play a crucial role in development by:
What is the significance of transitional fossils like Tiktaalik in understanding evolution?
What is the significance of transitional fossils like Tiktaalik in understanding evolution?
Considering that, on average, 1 in 100,000 to 1 in 1,000,000 sperm cells carries a mutation at a given locus, why isn't the rate of genetic disorders in offspring higher?
Considering that, on average, 1 in 100,000 to 1 in 1,000,000 sperm cells carries a mutation at a given locus, why isn't the rate of genetic disorders in offspring higher?
How does a paraphyletic group differ from a monophyletic group in phylogenetic classification?
How does a paraphyletic group differ from a monophyletic group in phylogenetic classification?
A scientist discovers a new species of beetle on an isolated island. After analyzing its DNA, they find that the beetle has a unique set of genes not found in any other known insect. Which evolutionary process is most likely responsible for this genetic uniqueness?
A scientist discovers a new species of beetle on an isolated island. After analyzing its DNA, they find that the beetle has a unique set of genes not found in any other known insect. Which evolutionary process is most likely responsible for this genetic uniqueness?
In the context of phylogenetic trees, what distinguishes a phylogram from a cladogram?
In the context of phylogenetic trees, what distinguishes a phylogram from a cladogram?
The principle of maximum parsimony suggests that the most accurate phylogenetic tree is the one that:
The principle of maximum parsimony suggests that the most accurate phylogenetic tree is the one that:
Which of the following is the correct order of taxonomic classification from the broadest to most specific?
Which of the following is the correct order of taxonomic classification from the broadest to most specific?
What is the primary difference between homology and analogy in the context of evolutionary relationships?
What is the primary difference between homology and analogy in the context of evolutionary relationships?
Which evolutionary challenge primarily drove the development of waxy cuticles in early land plants?
Which evolutionary challenge primarily drove the development of waxy cuticles in early land plants?
During which geological period did the first forests and seed-bearing plants appear?
During which geological period did the first forests and seed-bearing plants appear?
Which of the following scenarios exemplifies the bottleneck effect?
Which of the following scenarios exemplifies the bottleneck effect?
The Permian-Triassic extinction event was primarily triggered by which of the following factors?
The Permian-Triassic extinction event was primarily triggered by which of the following factors?
Which of the following consequences of the Permian-Triassic extinction directly led to coral reef collapse?
Which of the following consequences of the Permian-Triassic extinction directly led to coral reef collapse?
In a population of butterflies, individuals with brightly colored wings are more visible to predators but also more attractive to mates. If both extreme phenotypes (bright and dull wings) become more common over time, which type of selection is likely occurring?
In a population of butterflies, individuals with brightly colored wings are more visible to predators but also more attractive to mates. If both extreme phenotypes (bright and dull wings) become more common over time, which type of selection is likely occurring?
Why is the assumption that all genotypes have equal fitness often incorrect in the context of natural selection?
Why is the assumption that all genotypes have equal fitness often incorrect in the context of natural selection?
During the Mesozoic Era, which group of marine reptiles included ichthyosaurs, plesiosaurs, and mosasaurs?
During the Mesozoic Era, which group of marine reptiles included ichthyosaurs, plesiosaurs, and mosasaurs?
Which evolutionary innovation allowed angiosperms to thrive and co-evolve during the Mesozoic Era?
Which evolutionary innovation allowed angiosperms to thrive and co-evolve during the Mesozoic Era?
A small group of lizards colonizes a remote island. The allele frequencies in this new lizard population are different from the allele frequencies in the original population on the mainland. Which evolutionary mechanism is at play here?
A small group of lizards colonizes a remote island. The allele frequencies in this new lizard population are different from the allele frequencies in the original population on the mainland. Which evolutionary mechanism is at play here?
What is the primary role of chance in the process of evolution by natural selection?
What is the primary role of chance in the process of evolution by natural selection?
The rapid diversification of mammals during the Paleogene period was primarily due to what factor?
The rapid diversification of mammals during the Paleogene period was primarily due to what factor?
The emergence of modern mammal and bird families, along with the spread of grasses, characterized which period of the Cenozoic Era?
The emergence of modern mammal and bird families, along with the spread of grasses, characterized which period of the Cenozoic Era?
In a bird population, larger beaks are favored during drought years when only large, hard seeds are available. However, smaller beaks are favored during wet years when smaller, softer seeds are abundant. What type of selection is most likely occurring in this bird population over many generations?
In a bird population, larger beaks are favored during drought years when only large, hard seeds are available. However, smaller beaks are favored during wet years when smaller, softer seeds are abundant. What type of selection is most likely occurring in this bird population over many generations?
How does heterozygote advantage help to maintain genetic diversity in a population?
How does heterozygote advantage help to maintain genetic diversity in a population?
How did the formation of Pangea contribute to the Permian-Triassic extinction event?
How did the formation of Pangea contribute to the Permian-Triassic extinction event?
Why is natural selection considered a non-random process?
Why is natural selection considered a non-random process?
What can be inferred about organisms with large morphological differences that arise from altered growth rates?
What can be inferred about organisms with large morphological differences that arise from altered growth rates?
During which eon did the Earth's layer differentiation, leading to the formation of the core, mantle, and crust, primarily occur?
During which eon did the Earth's layer differentiation, leading to the formation of the core, mantle, and crust, primarily occur?
What significant atmospheric change marked the Proterozoic eon, leading to major climate and environmental shifts?
What significant atmospheric change marked the Proterozoic eon, leading to major climate and environmental shifts?
The Great Oxygenation Event, which began approximately 2.7 billion years ago, is characterized by what primary process?
The Great Oxygenation Event, which began approximately 2.7 billion years ago, is characterized by what primary process?
Which of the following is the correct order of events in the early Earth's history?
Which of the following is the correct order of events in the early Earth's history?
During which period of the Paleozoic Era did a rapid diversification of complex organisms, known as the Cambrian explosion, occur?
During which period of the Paleozoic Era did a rapid diversification of complex organisms, known as the Cambrian explosion, occur?
Why was a reducing atmosphere crucial for the synthesis of organic molecules during the Archean eon?
Why was a reducing atmosphere crucial for the synthesis of organic molecules during the Archean eon?
What key development during the Proterozoic eon led to the formation of complex cellular structures in eukaryotes?
What key development during the Proterozoic eon led to the formation of complex cellular structures in eukaryotes?
How did the development of hard body parts, such as shells and exoskeletons, during the Cambrian period influence ecological dynamics?
How did the development of hard body parts, such as shells and exoskeletons, during the Cambrian period influence ecological dynamics?
What evidence suggests the presence of liquid water on Earth during the Hadean eon, despite the high surface temperature?
What evidence suggests the presence of liquid water on Earth during the Hadean eon, despite the high surface temperature?
What was the primary consequence of the accumulation of oxygen in the oceans during the Great Oxygenation Event?
What was the primary consequence of the accumulation of oxygen in the oceans during the Great Oxygenation Event?
What is the significance of the Ediacaran biota, which appeared during the late Proterozoic eon?
What is the significance of the Ediacaran biota, which appeared during the late Proterozoic eon?
Why did the Ediacaran species decline at the end of the Proterozoic eon?
Why did the Ediacaran species decline at the end of the Proterozoic eon?
The Huronian glaciation, one of the first major glaciations in Earth's history, occurred during which eon?
The Huronian glaciation, one of the first major glaciations in Earth's history, occurred during which eon?
The emergence of bilateral symmetry, segmented bodies, and limbs during the Cambrian period is most directly related to:
The emergence of bilateral symmetry, segmented bodies, and limbs during the Cambrian period is most directly related to:
During the Archean eon, the Earth's magnetic field was weak and unstable. What was a direct consequence of this?
During the Archean eon, the Earth's magnetic field was weak and unstable. What was a direct consequence of this?
Flashcards
Chromosomal Changes
Chromosomal Changes
Alterations in chromosome structure, including translocation, deletion, duplication, inversion, isochromosome, and fusion.
Recombination/Crossing Over
Recombination/Crossing Over
Exchange of genetic material between homologous chromosomes during Prophase I, creating genetic diversity.
Independent Assortment
Independent Assortment
Random alignment of tetrads during Metaphase I, leading to multiple chromosome combinations in gametes.
Fertilization Variation
Fertilization Variation
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Heterozygosity (H)
Heterozygosity (H)
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Hardy-Weinberg Equilibrium
Hardy-Weinberg Equilibrium
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Disrupting Factors of Hardy-Weinberg
Disrupting Factors of Hardy-Weinberg
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Microevolution
Microevolution
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Evolutionary Theory
Evolutionary Theory
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Descent with Modification
Descent with Modification
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Natural Selection
Natural Selection
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Artificial Selection
Artificial Selection
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Homology
Homology
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Fossil Record
Fossil Record
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Biogeography
Biogeography
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Mutation
Mutation
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Genetic Drift
Genetic Drift
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Bottleneck Effect
Bottleneck Effect
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Founder Effect
Founder Effect
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Adaptive Evolution
Adaptive Evolution
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Directional Selection
Directional Selection
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Heterozygote Advantage
Heterozygote Advantage
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Frequency-Dependent Selection
Frequency-Dependent Selection
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Desiccation
Desiccation
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UV Radiation
UV Radiation
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Gas Exchange
Gas Exchange
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Structural Support
Structural Support
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Nutrient Acquisition
Nutrient Acquisition
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Pangaea Formation
Pangaea Formation
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Mass Extinction
Mass Extinction
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Mesozoic Era
Mesozoic Era
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Cenozoic Era
Cenozoic Era
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Allometric Growth
Allometric Growth
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Heterochrony
Heterochrony
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Paedomorphosis
Paedomorphosis
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Hox genes
Hox genes
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Binomial nomenclature
Binomial nomenclature
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Paraphyletic group
Paraphyletic group
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Monophyletic group
Monophyletic group
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Cladogram
Cladogram
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Maximum Parsimony
Maximum Parsimony
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Hadean Eon
Hadean Eon
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Earth's Layer Differentiation
Earth's Layer Differentiation
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Archean Eon
Archean Eon
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Abiogenesis
Abiogenesis
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Great Oxygenation Event
Great Oxygenation Event
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Proterozoic Eon
Proterozoic Eon
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Endosymbiosis
Endosymbiosis
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Eukaryotic Cells
Eukaryotic Cells
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Paleozoic Era
Paleozoic Era
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Cambrian Period
Cambrian Period
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Colonization of Land
Colonization of Land
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Banded Iron Formations (BIFs)
Banded Iron Formations (BIFs)
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Study Notes
Evolution
- Evolution is a theory explaining how life changes after its origin, not how life began
- Abiogenesis: Processes that led to life's origin
- Key steps in evolution (scientific hypothesis):
- Prebiotic synthesis of small organic molecules (sugars, lipids, nucleobases, peptides)
- Molecular self-replication (e.g., RNA)
- Self-assembly (e.g., protocells)
- Evolution is not a climb up a ladder of progress; it's about reproductive fitness, not progress
- Natural selection eliminates individuals with lower reproductive success in a given environment
- Many taxa have changed little over long periods (e.g., mosses, fungi, corals, crayfish) and are examples of little change over time (e.g., stromatolites ~3.5 billion years old)
- Evolution is partially random; random mutations are the ultimate source of genetic variation, but evolutionary change is limited by environmental conditions. Only heritable variations that improve population fitness persist.
- Natural selection is not about organisms trying to adapt; it's about which individuals with heritable variations survive and reproduce more successfully in given environments
- The inheritance of acquired characteristics is inaccurate, as traits are passed down through genes, not acquired characteristics. Vestigial structures show long-term evolutionary processes
Darwin and Descent with Modification
- Life has existed for billions of years and changed over time by natural selection
- Historical roots leading to Darwin's Proposal:
- Variation within populations
- Artificial selection practiced
- Time: Enormous amounts (Hutton, Lyell)
- Species change (Lamarck)
- Species extinction (Cuvier)
- Observations matter (Vesalius)
- Species growth limitations (Malthus)
Evolution of Populations (Microevolution)
- Mutation: Random changes in DNA sequence:
- 3.5 mL @ 300 M/mL approximately equals 1 B sperm.
- 1 gamete mutated in 100,000 to 1 M.
- Protein-coding genes have a relative low mutation rate for most mutations.
- Mutation effects range from neutral to harmful or helpful (lethal, advantageous).
- Sexual Reproduction:
- Recombination/Crossing Over in Prophase I: Homologous chromosomes align and exchange genetic material, creating unique combinations
- Independent Assortment in Metaphase I & Anaphase I: Homologous chromosomes separate randomly, resulting in various combinations of alleles.
- Fertilization: Random fusion of gametes adds further variation
- Heterozygosity (H) : a measure of population variation at a single locus. It can be helpful to know average heterozygosity across multiple loci to understand a more comprehensive picture of variation.
- Hardy-Weinberg Equilibrium: Allele frequencies remain constant across generations, suggesting no evolution.
Factors Disrupting Hardy-Weinberg Equilibrium
- Gene Flow: Allele frequencies change by immigration (introducing alleles from different populations).
- Population Size: Small populations lead to random fluctuations in allele frequencies (genetic drift).
- Natural Selection: Traits impacting reproductive success alter allele frequencies.
- Nonrandom Mating/Inbreeding: Alters allele frequencies
Speciation
- Biological Species Concept: Species are groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups.
- Prezygotic Barriers: Prevent mating or fertilization:
- Habitat isolation
- Temporal isolation
- Behavioral isolation
- Mechanical isolation
- Gametic isolation
- Postzygotic Barriers: Prevent viable or fertile offspring:
- Reduced hybrid viability
- Reduced hybrid fertility
- Hybrid breakdown
- Speciation can be slow (millions of years) or rapid (one generation); involves multiple genes or a single gene and occurs in macroevolution (large-scale changes above the species level).
- Allopatric speciation: Speciation due to geographic isolation.
- Parapatric speciation: Speciation in geographically continuous but ecologically distinct areas.
- Sympatric speciation: Speciation without geographic isolation (common in plants)
History of Earth
- Hadean (4.6-4.0 billion years ago): Formation of Earth and the Moon. Early Earth with high heat flow, reducing atmosphere.
- Archean (4.0-2.5 billion years ago): Oldest known rock formations, volcanic activity, and possible RNA synthesis.
- Proterozoic (2.5-541 million years ago): Great Oxidation Event, first major glaciations, and evolution of early eukaryotic cells (endosymbiosis).
- Phanerozoic (541 million years ago-present): Rise of complex organisms, colonization of land, multiple extinction events.
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Description
Explore the stages of meiosis, including recombination and independent assortment. Learn about heterozygosity, Hardy-Weinberg Equilibrium, and factors disrupting it. Understand gene flow, genetic drift, and chromosomal changes like translocation and inversion.
