Chapters 15-17 Flashcards
when did earth form
about 4.6 billion years ago
how first life may have evolved
- abiotic synthesis of small organic molecules, such as amino acids and nitrogenous bases
- joining of these small molecules into polymers, such as proteins and nucleic acids
- packaging of these molecules into “protocells”
- origin of self-replicating molecules that eventually made inheritance possible
what does O2 tend to do?
As a strong oxidizing agent, O2 tends to disrupt chemical bonds.
next 3 stages of life
- Abiotic synthesis of polymers
- Formation of protocells
- Self-replicating RNA
macroevolution
evolutionary change above the species level. encompasses…
- the origin of a new group of organisms through a series of speciation events and
- the impact of mass extinctions on the diversity of life and its subsequent recovery.
radiometric dating
- is based on the decay of radioactive isotopes (unstable forms of an element)
- can date rocks and fossils.
- carbon-14 decays to another element
plate tectonics
the theory that Earth’s crust is divided into giant, irregularly shaped plates that essentially float on the underlying mantle.
permian extinction
linked to the effects of extreme volcanic activity.
cretaceous extinction
included most dinosaurs. may have been caused by the impact of an asteroid.
adaptive radiations
periods of evolutionary change in which many new species evolve from a common ancestor.
“evo-devo”
combines evolutionary and developmental biology.
taxonomy
branch of biology concerned with identifying, naming, and classifying species.
binomial
two-part scientific name
phylogeny
The evolutionary history of a species or group of species
systematics
a discipline of biology that focuses on
- classifying organisms
- determining their evolutionary relationships.
phylogenetic tree
a hypothesis of evolutionary relationships.
analogy
Similarity due to convergent evolution
cladistics
groups organisms by common ancestry.
clade
monophyletic group that consists of an ancestral species and all its evolutionary descendants—a distinct branch in the tree of life.
Cladistics two main types of characters
- A shared ancestral character
2. A shared derived character
shared ancestral character
common to members of a particular clade, but originated in an ancestor that is not a member of the clade.
shared derived character
common to members of a particular clade and is not found in its ancestors.
parsimony
the adoption of the simplest explanation for observed phenomena.
molecular systematics
uses DNA or other molecules to infer relatedness.
molecular clock
a method that estimates the time required for a given amount of evolutionary change.
Earliest form of life
prokaryotes about 3.5 to 2 billion years ago
origin of single-celled eukaryotes
1.8 billion years ago. originated when prokaryotic cells became capable of aerobic respiration or photosynthesis
origin multicellular eukaryotes
1.2 billion years ago. larger organisms 600 million years ago.
earth’s eon history
hadean, archaean, Proterozoic, and Phanerozoic
paedomorphosis
the retention in the adult body of structures that were juvenile features in an ancestral species
hierarchical classification of an animal
species -> genus -> family => orders => classes => phyla => kingdoms => domains
taxon
each taxonomic unit at any level
convergent evolution
occurs when similar environments and natural selection produce similar adaptations in organisms from different evolutionary lineages
outgroup
a species from a lineage that is closely related to but not part of the group of species we are studying
horizontal gene transfer
a process in which genes are transferred from one genome to another through mechanisms such as plasmid exchange and viral infection.
metagenomics
researchers collect samples from a particular environment, and isolate and sequence the DNA they contain
microbiome
genomes of individual species
microbiota
the community of microorganisms that live in and on our bodies
pathogens
disease-causing agents
cocci
spherical prokaryotic cells.
streptococci
cocci that occur in chains
bacilli
rod-shaped prokaryotes
3 most common prokaryote cell shapes
- cocci
- bacilli
- spiral shape
a. Relatively short and rigid cells called spirilla and
b. Longer and more flexible cells called spirochetes.
purpose of a cell wall
- provides physical protection
- prevents the cell from bursting in a hypotonic environment
Gram-positive bacteria
have simpler walls with a relatively thick layer of peptidoglycan
peptidoglycan
a polymer of sugars cross-linked by short polypeptides
gram-negative bacteria
less peptidoglycan and are more complex, with an outer membrane that contains lipids bonded to carbohydrates.
-often more toxic and more threatening
fimbriae
hairlike projections that enable some prokaryotes to stick to a surface or to one another.
endospore
a specialized resistant cell
prokaryotic phototrophs
capture energy from sunlight
chemotrophs
prokaryotes that harness the energy stored in chemicals, either organic or inorganic chemicals
autotrophic
when organisms make their own organic compounds
autotrophs
prokaryotes that obtain their carbon atoms from carbon dioxide
photoautotrophs
prokaryotes that harness sunlight for energy and use C0(2) for carbon
photoheterotrophs
prokaryotes that obtain energy from sunlight but get their carbon atoms from organic sources
chemoautotrophs
prokaryotes that harvest energy from inorganic chemicals and use carbon from C0(2) to make organic molecules.
chemoheterotrophs
prokaryotes that acquire both energy and carbon from organic molecules
biofilms
highly organized colonies of prokaryotes
bioremediation
use of organisms to remove pollutants from the soil, air, or water.
extreme halophiles
archaea that thrive in very salty places
extreme thermophiles
archaea that thrive in very hot water
methanogens
archaea that live in anaerobic environments and give of methane as a waste product.
proteobacteria
bacteria all gram-negative and share a particular rRNA sequence.
symbiosis
a close association between organisms of two or more species
cyanobacteria
the only group of prokaryotes with plantlike, oxygen-generating photosynthesis.
chlamydias
live inside eukaryotic host cells.
five groups bacteria
-proteobacteria
-gram-positive bacteria
cyanobacteria
-chlamydias
-spirochetes
spirochetes
helical bacteria that spiral through their environment by means of rotating, internal filaments. include notorious pathogens
exotoxins
proteins that bacterial cells secrete into their environment
endotoxins
lipid components of the outer membrane of gram-negative bacteria that are released when the cell dies or is digested by a defensive cell.
protists
diverse collection of mostly unicellular eukaryotes
SAR
largest and most diverse supergroup of eukaryotes. Protist clades Stramenopila, Alveolata, and Rhizaria.
diatoms
unicellular algae that are one of the most important photosynthetic organisms on Earth
charophytes
photosynthetic eukaryotes. plants and green algae
how do plants maintain moisture?
C0(2) and O(2) diffuse across leaf surfaces through stomata (tiny pores)
apical meristems
growth-producing regions of cell division
vascular tissue
a network of thick-walled cells joined into narrow tubes that extend throughout the plant body.
two types of vascular tissue
xylem and phloem
xylem
include dead cells that form microscopic pipes conveying water and minerals up from the roots
phloem
consists entirely of living cells. distributes sugars throughout the plants
lignin
thickens and reinforces the cell walls of some plant tissues
gametangia
gametes in male and female structures
pollen grains
structures that contain the sperm-producing cells
seed
consists of an embryo packaged with a food supply within a protective covering
alternation of generations
the diploid and haploid stages are distinct, multicellular bodies
gametophyte
haploid generation of a plant produces gametes
sporophyte
diploid generation produces spores
pollination
when a pollen grain lands on a compatible female structure, it undergoes mitosis to produce a sperm
fruit
ripened ovary of a flower
hyphae
feeding structures of a fungus that are a network of threadlike filaments
mycorrhiza
symbiosis between fungi and plant roots
mold
any rapidly growing fungus that reproduces asexually by producing spores
yeast
any single-celled fungus
lichens
symbiotic associations of millions of microscopic green algae or cyanobacteria held in a mass of fungal hyphae
what opportunities did life on land offer adaptations?
- bright and abundant sunlight,
- abundant atmospheric CO2,
- initially, few pathogens or plant-eating animals.
disadvantages that life on land had
- maintain moisture inside their cells,
- support the body in a nonbuoyant medium,
- reproduce and disperse offspring without water,
- anchor their bodies in soil
- obtain resources from soil and air.
Three key events occurred in the history of the plant kingdom.
- Origin of land plants
- Origin of vascular plants
- Origin of seed plants
bryophytes
include mosses, hornworts, and liverworts
