Evolution and Genetics Overview

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Questions and Answers

Which of the following theories did Darwin and Wallace primarily rely on to explain natural selection?

  • Blending inheritance (correct)
  • Modern synthesis
  • Lamarckism
  • Particulate inheritance

What was the major obstacle to understanding the mechanisms of evolution before the integration of genetics?

  • Lack of knowledge about DNA structure
  • Absence of experimental data on natural selection
  • Limited understanding of inheritance patterns (correct)
  • The prevailing theory of spontaneous generation

What was the significance of Mendel's work in the context of evolution?

  • It disproved Darwin's theory of natural selection
  • It directly led to the development of the modern synthesis
  • It laid the foundation for understanding the particulate nature of genes (correct)
  • It provided evidence for the blending inheritance theory

How did the rediscovery of Mendel's work in the early 20th century impact evolutionary science?

<p>It initially created confusion about the mechanism of gradual evolution (A)</p> Signup and view all the answers

What is the central principle of the modern synthesis?

<p>Natural selection acts on genetic variation, leading to gradual evolution. (C)</p> Signup and view all the answers

Which of the following is NOT a connection between evolution and the annual flu vaccine?

<p>Determining the exact genetic makeup of each individual's immune system (A)</p> Signup and view all the answers

How does our knowledge of evolution contribute to the development of flu vaccines?

<p>It allows scientists to study the genetic variation of flu strains over time. (B)</p> Signup and view all the answers

Which of the following provides the best explanation for the need for a new flu vaccine each year?

<p>Flu viruses mutate rapidly. (D)</p> Signup and view all the answers

What is the frequency of homozygous dominant (YY) individuals in a population with allele frequencies p=0.7 and q=0.3?

<p>0.49 (A)</p> Signup and view all the answers

If p = 0.8 and q = 0.2, what is the predicted frequency of heterozygous (Vv) individuals?

<p>0.48 (A)</p> Signup and view all the answers

How many individuals are expected to be homozygous recessive (yy) in a population of 500 if the frequency of q is 0.3?

<p>90 (A)</p> Signup and view all the answers

Which statement accurately reflects the Hardy-Weinberg principle?

<p>Allelic frequencies can remain stable if no evolutionary forces act. (B)</p> Signup and view all the answers

In a gene pool where p represents the allele frequency of a dominant trait, what does the value of q represent?

<p>Frequency of the recessive allele (B)</p> Signup and view all the answers

If the predicted frequency of homozygous recessive individuals is 0.09, what percentage of the population exhibits this genotype?

<p>9% (D)</p> Signup and view all the answers

Which equation is used to calculate the expected frequencies of genotypes in a population at Hardy-Weinberg equilibrium?

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

What does a deviation from predicted allelic frequencies suggest about a population?

<p>It is likely evolving. (D)</p> Signup and view all the answers

What is the total number of alleles contributed to the gene pool by 500 individuals, each contributing two alleles?

<p>1000 (B)</p> Signup and view all the answers

If the frequency of individuals producing yellow peas is higher than expected, what could be a potential reason?

<p>Selection pressure favoring yellow phenotype (C)</p> Signup and view all the answers

What challenge do scientists face in developing effective vaccines for rapidly evolving viruses?

<p>Vaccines for past strains may not be effective against new strains. (D)</p> Signup and view all the answers

Which statement accurately describes allele frequency in a population?

<p>It is the rate at which a specific allele appears in the population. (D)</p> Signup and view all the answers

What is the Hardy-Weinberg principle of equilibrium primarily used for?

<p>To describe stable allele and genotype frequencies without evolutionary forces. (C)</p> Signup and view all the answers

What does genetic drift involve?

<p>Random changes in allele frequencies with no significant advantage. (D)</p> Signup and view all the answers

Which factor can lead to allele frequency changes in a population due to non-typical conditions?

<p>The founder effect. (D)</p> Signup and view all the answers

How is allele frequency calculated in a specific population?

<p>By dividing the number of copies of an allele by the total number of alleles in the population. (A)</p> Signup and view all the answers

What is one outcome of natural selection on allele frequencies?

<p>Beneficial alleles can spread throughout the population. (D)</p> Signup and view all the answers

In the ABO blood type system, how do the frequencies of the alleles IA, IB, and I0 add up?

<p>They total 100 percent. (B)</p> Signup and view all the answers

Which factor is NOT a requirement for Hardy-Weinberg equilibrium?

<p>Active gene flow from neighboring populations. (C)</p> Signup and view all the answers

Which is a characteristic of a diploid organism concerning alleles?

<p>It can carry two alleles for a particular gene. (D)</p> Signup and view all the answers

What is meant by an allele becoming fixed in a population?

<p>All individuals in the population carry that allele. (A)</p> Signup and view all the answers

What evolutionary process is often difficult to distinguish from natural selection in populations?

<p>Genetic drift. (C)</p> Signup and view all the answers

In population genetics, what does the term 'gene pool' refer to?

<p>The sum of all alleles in the population. (C)</p> Signup and view all the answers

What effect do environmental factors have on allele frequency?

<p>They cause some alleles to become less prevalent. (A)</p> Signup and view all the answers

Which of the following statements is accurate regarding phenotypic observation in genetics?

<p>Only the homozygous recessive genotype can be determined from phenotype. (C)</p> Signup and view all the answers

Flashcards

Natural Selection

The process where organisms better adapted to their environment tend to survive and produce more offspring.

Blending Inheritance

An incorrect theory that offspring are a smooth blend of parental traits.

Gregor Mendel

An Austrian monk known as the father of genetics for his work on plant hybridization.

Modern Synthesis

A comprehensive theory that integrates genetics with natural selection to explain evolution.

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Microevolution

Small changes in a population's genetic makeup over time.

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Macroevolution

Major evolutionary changes that result in the emergence of new species.

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Flu Vaccines

Vaccines developed to protect against evolving flu strains each year.

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Evolutionary Predictions

Forecasts about how organisms, like flu viruses, will change over time.

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Vaccine Development

Process of creating vaccines to fight specific virus strains.

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Virus Mutation Rate

The speed at which viruses undergo genetic changes.

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Allele

A variant form of a gene that determines a trait.

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Allele Frequency

The rate at which a specific allele appears in a population.

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Population Genetics

The study of genetic variation within populations.

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Genetic Drift

Random changes in allele frequencies in a population.

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Founder Effect

When allele frequencies change due to a small group starting a new population.

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Hardy-Weinberg Principle

Theory stating allele and genotype frequencies remain stable without evolutionary forces.

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Gene Pool

The total collection of genes and alleles in a population.

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Phenotypic Change

Observable changes in characteristics of a population.

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Selection Pressure

Factors that influence reproductive success and survival in a population.

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Homozygous Recessive

An individual with two identical recessive alleles for a trait.

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Genotype Frequency

Proportion of different genotypes in a population.

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Alleles in ABO Blood Type

Three alleles (IA, IB, I0) determine human blood types.

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p and q

Symbols representing the frequencies of alleles in a trait (p for dominant, q for recessive).

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Genotypic Ratio

The ratio of different genotype combinations in offspring.

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Homozygous Dominant

An individual with two dominant alleles (e.g., YY).

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Heterozygous

An individual with one dominant and one recessive allele (e.g., Yy).

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Hardy-Weinberg Equation

p² + 2pq + q² = 1; predicts genotype frequencies in a population.

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Evolutionary Forces

Factors like mutation, migration, and selection that influence allele frequencies.

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Study Notes

Understanding Evolution and Genetics

  • Darwin and Wallace lacked understanding of inheritance mechanisms, hindering their understanding of evolution.
  • The prevailing "blending inheritance" theory was inaccurate, impacting comprehension of natural selection.
  • Gregor Mendel's work on plant hybridization, published in 1866, wasn't known to Darwin and Wallace initially.
  • Rediscovery of Mendel's work in the early 20th century led to a synthesis of genetics and evolution.
  • Initial difficulty integrating genetics and gradual evolution was overcome by the modern synthesis.

Modern Synthesis

  • The modern synthesis (1940s) is the accepted understanding of the relationship between natural selection and genetics.
  • It elucidates how evolutionary processes like natural selection modify populations' genetic makeup.
  • It links microevolution (small-scale changes in populations) with macroevolution (changes leading to new species).

Flu Vaccines and Evolution

  • Annual flu vaccination is a response to the evolution of influenza viruses.
  • Rapid viral evolution necessitates predicting predominant strains annually.
  • Effectiveness of vaccines is challenged by the continuous adaptation of flu strains.

Population Genetics

  • Alleles are variants of a gene for a specific trait (e.g., ABO blood types).
  • Individuals have two alleles for a particular gene, but multiple alleles can exist within a population.
  • Allele frequency is the proportion of a specific allele within a population.
  • Allele frequency changes lead to population evolution.

Factors Affecting Allele Frequency

  • Environmental factors influence allele frequencies.
  • Beneficial alleles increase in frequency through natural selection and offspring inheritance.
  • Genetic drift is the random change in allele frequencies without selective advantage.
  • Natural selection and genetic drift often coincide.
  • The founder effect is the allele frequency change in a population’s isolated part, deviating from its original one.

Hardy-Weinberg Equilibrium

  • The Hardy-Weinberg principle describes a non-evolving population.
  • Allele and genotype frequencies in such populations remain stable.
  • The principle assumes large population size, no mutations, no migration, and no selection.
  • It serves as a baseline to study evolving populations.

Hardy-Weinberg Equations

  • The equations (p + q = 1, p² + 2pq + q² = 1) predict genotype frequencies.
  • The observed deviations from these calculated frequencies indicate evolving populations.
  • Useful for predicting offspring genotype distributions in specific situations (e.g., pea color in plants).

Illustrative Example

  • The Hardy-Weinberg principle was used to determine the expected distribution of genotypes (and phenotypes) in a plant population.
  • If alleles or genotypes deviate from those expected by Hardy-Weinberg Equation; therefore, the population is evolving.

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