Unit 5-5: Evolution & Genetics

​Science Root of the Day:

DO NOW: Write what you think the example words mean in your lab manual.

Extra Credit: Find three additional words that use this root and write them and their definition in your lab manual (6 Points Max)

Home

Open in new tab

Copy link

Evolution & Genetics

Multiple Choice

True or False? Before cells undergo meiosis they pass through interphase first.

• true

• false

Multiple Choice

In which stage of MEIOSIS does crossing over occur? (The exchange of genetic material between chromosomes)

• Anaphase I

• Metaphase I

• Prophase I

• Telophase I

Multiple Choice

Mendel also observed seed color in pea plants. In a study of several generations, yellow seeds appeared more frequently than green seeds. Which of the following is most likely the reason for this observation?

• Green seeds are dominant to yellow seeds.

• Yellow seeds are recessive to green seeds

• Green seeds are recessive to yellow seeds.

• Green Seeds are just rare random mutations in the population

Multiple Choice

this image is an example of

• codominance
• dominance
• incomplete dominance
• Multiple Genes

Multiple Choice

A breed of chicken shows codominance for feather color. One allele codes for black feathers, another codes for white feathers. The feathers of heterozygous chickens of this breed will be:

• all black
• all white
• all gray
• speckled black and white

Multiple Choice

The dominant trait in this punnett square is

• yellow pea seeds
• green pea seeds
• there is no dominant seed

Multiple Choice

Which of the following is an example of a heterozygous genotype?

• RR
• Rr
• rr

Multiple Choice

What most likely explains why the mouse population changing over time?

• The light mice can reproduce more successfully than the dark mice

• The hawks eat more dark mice than light mice because the dark mice taste better

• The hawks eat more light mice than dark mice because they can see the light mice more easily

• The hawks eat more dark mice than light mice because they can see the dark mice more easily

Multiple Choice

Which organisms are most likely to survive?

• the best adapted

• the fastest

• the strongest

• the most tame

Multiple Choice

This makes an organism more suited to its environment

• species

• lifespan

• adaptation

• mutation

Multiple Choice

Offspring with inherited advantageous traits leave more offspring than organisms with other traits, which causes these advantageous traits to become more common in a population over time. This describes...

• Speciation

• Genetic Drift

• The inheritance of Acquired characteristics

• Natural Selection

Lesson Objectives

• Explain how an understanding of genetics produced insights into the mechanisms of evolution and the origin of genetic variation

• Explain how new Species Form

Allele Frequencies

• Natural selection acts on traits, but traits are not what are passed on to offspring

  • Alleles that produce the traits are what are passed

• Evolution is described as Changes in the allele frequencies of genes over time

• Allele Frequency: how common different alleles are in a population

Allele Frequencies and Natural Selection

• Genetic Variation: Exists when there are multiple alleles

• Natural Selection: An Allele that serves as an adaptation allows an individual with that allele to reproduce more frequently than other organisms

• Evolution: As a result more copies of the advantages allele are passed to the next generation, which increases the allele frequency

  • Note: Natural selection acts on the phenotype, not the allele itself

Multiple Choice

True or False: Natural Selection acts on an individual's genes

• True

• False

Multiple Choice

What term describes how common different alleles are in a population?

• genetic variation
• phenotype distribution
• allele frequency
• chromosome rate

Mechanisms of Evolution

• Natural Selection is the driving force of evolution, but not the only force

• Several other factors play a role

  • Mutation Pressure

  • Genetic Drift

  • Gene Flow

Mutation Pressure

• Mutation Pressure: The change in allele frequencies due to repeated occurrence of the same mutations

  • If the same mutation occurs over and over again, than the allele frequency will change in one directions

Genetic Drift

• Genetic Drift: The evolution of populations due to random chance

  • Imagine two alleles in a population that are neither advantageous nor disadvantageous, so neither allele is selected for

  • Now suppose a storm occurs and randomly kills off individuals, but more individuals with the second allele die than the first

    • The allele frequency has changed, but not due to natural selection

• Genetic drift acts like a coin flip

  • sometimes a random chance forms a pattern

Gene Flow

• A change in allele frequencies that result from a net movement of allels in or out of population

  • Caused by individuals leaving and entering the population

Where Genetic Variation Comes From

• Natural selection requires genetic variation

  • More variation in a population makes it more likely to survive

• Genetic Mutations constantly create new variations in a population

• Sexual Reproduction brings alleles together in new combinations to

Multiple Choice

Genetic drift is change in the allele frequency of a population due to...

• random chance

• natural selection

• non-random mating (sexual selection)

• artificial selection

Multiple Choice

Mutations are important because they bring about...

• death of the organism in which they develop

• genetic variation needed for a population to evolve

• benefits for the individual, not for the population

• equilibrium within a population

Multiple Choice

Which of the following is NOT a mechanism of evolution?

• Biogeography

• Natural Selection

• Gene Flow

• Genetic drift

Multiple Choice

A group of polar bears migrates from the ice floes where they live to the nearby forest, where they interbreed with the brown bears there. This is an example of...

• Genetic drift

• Gene flow

• Natural Selection

• Founder Effect

Multiple Choice

Blue catfish are going extinct. A dam in a lake full of blue catfish bursts due to poor engineering and kills some of the blue catfish. This is an example of:

• Natural Selection

• Gene Flow

• Mutation

• Genetic Drift

Multiple Choice

Which of the following mechanisms of evolution consistently causes populations to become better adapted to environments?

• Genetic drift
• Mutation Pressure

• Natural selection
• Gene flow

How Species Form

• Species: A group of organisms whose members can breed with each other to create fertile offspring

• Speciation: Formation of new species

  • Involve the evolution of reproductive barriers to prevent interbreeding

    • Two types

      • Prezygotic

      • Postzygotic

Prezygotic Barriers

• Fertilization: The joining of an Egg Cell and a Sperm Cell to create a new individual

• Prezygotic Barriers: Reproductive barriers that either prevent individuals from mating or fertilization from occurring when they do mate

  • Examples

    • Breeding seasons and Courtship Rituals may prevent two organisms from breeding with each other

    • Physical Anatomy

Postzygotic Barriers

• Postzygotic Barriers: Reproductive barriers that occur after fertilization that prevent viable offspring from being produced

• Offspring may be weaker/less fit than the parents

• Offspring may be sterile

  • Examples:

    • Horse + Donkey = Mules

    • Lion + Tiger = Liger

Allopatric Speciation

• It takes time and separation for reproductive barriers to evolve

• Allopatric Speciation: New species are formed after a geographic barrier divides a single population into two isolated populations

  • Once Separated, natural selection & genetic drift slowly cause each population to evolve traits independently of one another

Adaptive Radiation

• Adaptive Radiation: An example of allopatric speciation where many new species evolve from a single ancestor

  • Each new species is highly adapted to its environment

    • Example: Darwin's Finches

Sympatric Speciation

• Sympatric Speciation: Occurs without geographic isolation

  • Less common than allopatric speciation

  • Often results from sudden chromosomal changes or hybridization

    • Hybridization: two different species interbreed and produce fertile offspring

  • Most common in plants

Multiple Choice

Which of the following is a term for a group of similar organisms that can reproduce fertile offspring?

• individual
• population
• species
• fossil

Multiple Choice

True or False: The offspring from a cross-species breeding being infertile is an example of a prezygotic barrier

• True

• False

Multiple Choice

After a long time in isolation, Island fruit flies and mainland fruit flies meet. They do not produce viable eggs due to genetic differences. The flies have resulted in two seperate lineages due to:

• Gene Pool

• Genetic Drift

• Gene Frequency

• Speciation

Multiple Choice

Sometimes many new species evolve from a single ancestor, each adapted to a distinct way of life. This is called...

• Adaptive Radiation

• Natural Selection

• Hybridization

• Sympatric Speciation

Open Ended

You are studying a population of beetles that has red and yellow beetles, and know that their color is an inherited trait. You count the number of red and yellow beetles in the population and notice that the number of red beetles is increasing and yellow beetles is decreasing. Name three reasons why this may be occurring.