• Natural selection: nature “selects” for organisms that are better suited for their environment

• Examples: Giraffes have long necks, allowing them to feed on leaves from tall trees that other organisms cannot reach.

• Artificial selection: breeders select for the best organisms

• Examples: Cows that produce the most milk.

• Adaptation: feature that an organism has that allows it to survive in the wild

• Examples: Camels have thick eyelashes, preventing them from eye infections due to potential sandstorms.

• Fitness: the ability of an individual to survive and reproduce in its specific environment

• Examples: Polar bears with thicker fur are more likely to survive freezing temperatures than polar bears with thinner fur.

• Speciation: formation of a new species from an already existing species

• Examples: Finches evolved into other finches with different abilities.

• Convergent evolution: species are unrelated but look alike because they live in similar environments

• Examples: Beavers, otters, and capybara

• Divergent evolution: species are related but look different because of the environments in which they live

• Examples: Koala, bear, chimpanzee

• Coevolution: when species of organisms have a close relationship they evolve in response to each other

• Examples: Flowers have evolved to produce more pollen so that bees, or other pollinators, can collect the pollen.

• Extinction: elimination of a species

- There are two types of evolution:

- gradual extinction: slow process of extinction

Examples: Pandas are slowly going extinct.

- mass extinction: catastrophic event

Examples: Dinosaurs were killed by asteroids

• Gradualism: slow evolution

• Examples: Peppered moths have evolved to be a certain color to survive in the wild.

• Punctuated equilibrium: sudden burst of evolution

• Examples: Lizards, turtles, and other mammals of dinosaurs were able to develop new adaptations now that dinosaurs are gone

• Sexual selection: female chooses the best male

• Examples: A female peacock will choose the male with the brightest feathers.

• Homologous structures: structurally similar but serve different purposes

• Examples: human, cat, horse, bat, dolphin

• Vestigial structures: remains of a once-used structure

• Examples: Tailbone

• Fossils: remnants of an ancient species

• Phylogeny: evolutionary history of an organism

• Taxonomy: how we classify organisms scientifically

• Phylogenetic tree: diagram used to predict evolutionary relationships among groups of organisms

• Reproductivity determines a new species.

• Factors that lead to genetic diversity in a population:

  • Meiosis (crossing over)

  • Random mutations

  • Migration (gene flow)

• Examples of evolution: Wolves → dogs

The 4 Principles of Evolution

• Overproduction of offspring: multiple offspring, only a few survive

• Variation: allows for species’ survival in case of catastrophic events (genetic diversity)

• Adaptation: feature that allows an organism to better survive

• Descent with modification: beneficial adaptations can be passed to the offspring. Over time, these adaptations become more common in the population, causing the population to change “modification”.

  Modes of Natural Selection

Most traits cover a wide range. Sometimes, nature selects for a very specific phenotype.

• Directional selection: nature selects for one of the extreme phenotypes

• Examples: the peppered moth was commonly white, whereas black moths were uncommon, since they were easily spotted by predators. During the industrial era, buildings darkened, causing black peppered moths to become more common.

• Disruptive selection: nature selects for the two extreme phenotypes

• Examples: Gray snakes that live on rocks will survive, and green snakes that live on grass will survive. Intermediate coloring would be disadvantaged because they are more visible to predators.

• Stabilizing selection: nature selects for the average phenotypes

• Examples: Babies with low birth weight have weak immune systems, while babies with high birth weight can cause damage to the birth canal. Babies with an average birth weight are more likely to survive.

• Organisms that are well adapted to their environment will survive and produce more offspring.

• Being fit for an environment means being able to survive and reproduce.

• Individuals don’t survive, populations do

DOMAIN
KINGDOM
PHYLUM
CLASS
ORDER
FAMILY
GENUS
SPECIES

• Mitosis produces two genetically identical daughter cells from a single parent cell.

• Meiosis produces cells that are genetically unique and only contain half as much DNA.

Types of Prokaryotic Cells

• Bacteria

• Archaea

Scientific Experiments

• Independent variable: what is being changed in the experiment

• Dependent variable: what is being changed in response to the independent variable in an experiment

• Control group: the group used in comparison to the experimental group

• Constant: Aspects in an experiment that are held consistent

Amino Acids

• AUG is the start codon

• UAG, UAA, and UGA are the stop codons