the process by which species gradually change over time.
an English naturalis. He studied the plants and animals of South America and the Pacific islands, and in his book On the Origin of Species by Means of Natural Selection (1859) set forth his theory of evolution.
the ship Darwin sailed on a 5 year trip around the world. He studied fossils (preserved remains of organisms) in Argentina and Brazil and zoology (types of animals) in the Galapagos Islands.
a statement that has been backed up by experimentation. It is not a fact. It is only as strong as its evidence!
diversity (how Darwin's trip changed his thinking)
an infinite number of animals and plants, each with adaptations suited to their environment.
older bones were similar but different to newer bones.
animals from the same species appeared to develop traits to survive in new environments.
On the Origin of Species
Darwin's most famous book which contained observations from his trip.
theory of evolution
species gradually change over time to adapt better to their environment.
theory of natural selection
organisms better adapted to their environment will survive and reproduce-"Survival of the Fittest".
what causes natural selection to happen?
overproduction, variation, and competition. Changes to environment can affect an organisms ability to survive and can lead to selection.
species that produce more offspring survive better.
offspring differ from each other in many ways.
a limited supply of food and other resources and presence of predators leads to competition between species.
evidence supporting theory of evolution
fossils, similarities in early development, DNA comparisons
the preserved remains of an organism
adaptations that organisms inherited from a common ancestor.
adaptations that are similar because of a common environment.
early development: organisms at birth
comparing animal fetuses shows similarities not obvious in adult form.
comparing animal DNA and gene makeup shows similarities not obvious in adult form.
a diagram that identifies time points where new species are made. Shows how different organisms evolved from each other. Less levels of shared classification = bigger differences in appearance.
when do new species form?
when a group of individuals remains isolated from the rest of its species long enough to evolve different trait.
how do fossils form?
1) Animal dies and is buried under layers of sediments (particles of soil and rock)
2) Sediments harden to become rock and animal is preserved as a fossil
3) Rock erodes and fossil is exposed
types of fossils
petrified, molds/casts, preserved
minerals soak into bones, turning them into rocks.
bones dissolve, leaving gaps.
full animal stored in ice or other minerals.
Fossils found higher on rock are younger than fossils found lower on rock.
Used to compare fossils.
Does not tell scientists actual age.
Compare amount of radioactive element in fossil to amount of other elements in which it breaks down
Work backwards from present to calculate age.
unstable elements that decay (break down) into different elements.
time it takes for half the atoms in a sample to decay.
the millions of fossils scientists have collected over time.
geologic time scale
calendar of Earth's History, created using radioactive dating from fossils.
Calendar goes backwards-starts millions of years ago, ends at present time.
unanswered questions about evolution
what causes mass extinctions?
do species evolve by gradualism or punctuated equilbria?
scientists hypothesize (make an educated guess) that major climate change is responsible.
evolution occurs slowly but steadily over time, which is how Darwin thought evolution occurred.
the theory that species evolve by rapid changes separated by long periods of little or no change, which accounts for gaps in the fossil record.
a living thing.
made of one cell, such as bacteria.
made of many cells, such as animals.
characteristics that all living things share
have a cellular organization, contain similar chemicals (water, proteins, carbohydrates, lipids/fats, and DNA), use energy, respond to their surroundings, grow and develop, reproduce.
a change in an organism's surroundings that causes the organism to react.
a reaction or change in behavior.
organisms use energy to get bigger
the process of change that occurs during an organism's life to produce a more complex organism.
produce offspring through seeds, eggs, or clones.
theory of spontaneous generation
the mistaken idea that living things can arise from non-living things. Scientists found this by observing flies growing from dead meat.
the process of grouping things together based on their similarities.
why do scientists classify?
to make organisms easier to study.
the classification of living things by similar traits.
a pioneer of Taxonomy who developed organism naming system that is used today Each organism has 2 names: genus and species. 1st: Genus - Group of organisms that are closely related. 2nd: Species - Distinct feature of the species. Capitalize genus but not species.
are used to determine the identity of an organism. They use traits to classify organisms.
levels of classification
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species (Didn't King Philip Come Over For Green Soup)
more levels two organisms share = more similar they are.
evolution and classification
species with similar ancestors and similar cell structure are classified more closely together.
1st step on the classification ladder. Based on: cell type, make food/eat food, and number of cells in body.
get food from sunlight/other chemicals.
get food from other organisms.
an organism without a nucleus in their cells.
an organism with a nucleus in their cells.
prokaryote, unicellular, autotrophs and heterotrophs.
prokaryote, unicellular, autotrophs and heterotrophs.
Difference from bacteria: found in extreme conditions, heat, acid, salty, sewage.
organisms have cells with a nucleus.
Divided into 4 kingdoms, protists, fungi, plants, animals.
eukaryote, unicellular and multi-cellular (algae), autotroph and heterotroph.
eukaryote, multi-cellular (except for yeast) heterotrophs that digest food outside their body & then absorb it.
eukaryote, multi-cellular autotrophs that absorb sunlight to make glucose.
eukaryote, multi-cellular heterotrophs that capture and eat their food.
cilia and flagella
shape and size of bacteria
spherical shape, rod shape, and spiral shape.
size ranges from 1/1,000th of a meter to 1/1,000,000th of a meter.
reproduction of bacteria
asexual: binary fission
one cell divides to form two identical cells.
1) Chromosome unwinds
2) Bacteria makes copy of chromosome
3) Chromosome moves to edge of cell
4) Cytokinesis-cell splits into two.
sexual reproduction of bacteria.
2 cells share DNA to make new bacteria.
bacteria protects DNA from harsh environment by surrounding with spore wall. Once the desired environment is reached, the bacteria will reproduce.