Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

25 Cards in this Set

  • Front
  • Back


The crossing of two different species that share common genes
Directional Selection
Natural selection that changes the distribution of a trait to favor one extreme phenotype
Stabilizing Selection
Intermediate phenotype becomes more common in a population
Normal Distribution
A population that is not undergoing natural selection


A random change in the DNA of a gene which can cause genetic variation
Founder Effect
loss of genetic variation that occurs when a new population is established
Intrasextual Selection
Competition among the males to mate

Bottleneck Effect

Genetic variation is lost - Disaster
Distributive Selection
Intermediate phenotypes or selected against both extreme phenotypes
Genetic Drift
Changes in allele frequencies within a population

Allele Frequency

A measure of how commonly a particular allele occurs in a population
Is the divergence of two or more species from an existing one
Behavioral isolation
A difference of chemical scents between two populations.

Genetic Mutations

Are random


Increase the rate of chemical reactions
Divergent Evolution
Evolution towards different traits and closely related species

Mutations and Recombination

Two main sources of genetic variation


Species evolve in response to changes in each other
Collisions with asteroids in meteorites
Contributed to the intense heat of the Hadean eon

Lipid membrane hypothesis / Liposomes

Act as barriers between organic molecules and the environment
The discovery that RNA can self-replicate
Supports the hypothesis THATRNA was the genetic material in the earliest organisms
Through the process of Endosymbiosis
Bacteria may have evolved into mitochondria

The Miller-Urey

Demonstrated the energy from lightning might have help create earth's first organic molecules


Changed the earth by adding oxygen to the atmosphere
Cell walls
Found in plant cells, but not in animal cells