U6 Terms Flashcards
Differences in early Earth compared to modern Earth: (5)
1) No plants or animals
2) Tons of volcanic activity
3) Intense UV rays
4) Constant debris raining down
5) No free O2 in the atmosphere or oceans
First life forms on Earth were…
Unicellular, anaerobic
Great Oxidation Event
O2 began accumulating in the atmosphere and the SURFACE of the ocean for the first time
Impacts of the great oxidation event
Created the conditions for the evolution of AEROBIC respiration
Oxygenic photosynthesis first arose in…
cyanobacteria
Stromatolites
Fossilized microbes
–> Layered sedimentary formations created by several species of ancient microbes layered upon one another
Although oxygenic photosynthesis first arose in cyanobacteria, they DID NOT…
Cyanobacteria did not INVENT photosynthesis
–> It evolved many many more years prior
First development of photosynthesis was…
ANOXYGENIC –> Did not produce oxygen
What organisms did/still do anoxygenic photosynthesis?
Green and purple sulfur bacteria
Anoxygenic Photosynthesis Products
1) Large High Energy Molecules (NOT GLUCOSE) –> Typically formaldehyde
2) Elemental Sulfur (in many cases)
3) H2O
Oxygenic Photosynthesis Products
1) Large, high energy molecules (GLUCOSE)
2) O2
3) H2O
On early Earth, oxygen was actually…
TOXIC to most life forms
Oxygenic photosynthesis evolved due to…
Random mutations in certain genes that turned out to be beneficial to the organism doing the photosynthesizing
Main benefit of oxygenic photosynthesis
A new carbon source: Glucose
–> Provided more energy than inorganic carbon sources like formaldehyde
Development of oxygenic photosynthesis led to 3 main patterns of change on Earth:
1) Initial oxygenation of the biosphere
2) Production of ORGANIC carbons (sugars)
3) Increased nutrient availability to other organisms
How did oxygenic photosynthesis increase nutrient availability to other organisms?
An increase in oxygen conc. led to increase in OXIDATION which produced SULFURIC ACID
–> Sulfuric acid broke down rocks causing the leaching of minerals necessary for life into rivers and oceans
Aerobic Respiration
A much more efficient form of respiration due to higher ATP output
–> Requires oxygen input
Aerobic respiration advantage
Provided greater energy to microbes that had evolved to do aerobic respiration
Aerobic cellular respiration allowed for the development of…
Eukaryotes
Nitrogen Fixation
A process invented and performed by bacteria that converts unusable nitrogen into a form useable by living organisms
Bacteria in plant roots role in nitrogen fixation
The bacteria take in atmospheric nitrogen and converts it to ammonium (NH4+) which can be used by plants
What prevented biological nitrogen fixation from becoming widespread before oxygen became abundant?
–> Nitrogen fixation requires ANOXIC conditions so it wasn’t the lack of oxygen that prevented it
–> Nitrogen fixation requires certain minerals that were inaccessible on early Earth
–> Oxygenation cause increased oxidation which released these minerals from rocks allowing for them to be utilized in nitrogen fixation
How did microbes change the Earth? (3 ways)
1) Development of oxygenic photosynthesis
2) Development of aerobic cellular respiration
3) Increased nitrogen availability (needed for life)
3 methods of nitrogen fixation:
1) Atmospheric fixation
2) Biological fixation
3) Industrial fixation (“Haber-Bosch” method)
Atmospheric Nitrogen Fixation
1) Lightning breaks N2 bonds
2) Free N atoms are able to then combine with other atmospheric atoms
–> Most commonly forming NO3-
3) Rain brings this NO3- to Earth where it undergoes the nitrogen cycle
Biological Fixation
Accounts for most of nitrogen fixation (90%)
–> Produced by microorganisms on land and in the sea
Industrial Fixation
Haber-Bosch Process
–> Combine nitrogen and hydrogen over an iron catalyst to make ammonia: NH4+
–> NH4+ then gets oxidized to form NO3- and NO2- which are used to fertilize crops
Fertilizers
Contain synthetically made nitrites and nitrates to help with plant growth
Overuse of fertilizers caused:
Excess nitrogen to enter marine and aquatic environments through RUN OFF
–> Led to harmful algal blooms
Effects of algal blooms
“Choke” the water: Uses up all the free oxygen in the water
–> Creates a dead zone
Dead Zone
Areas with hypoxia: reduced levels of oxygen in the water that causes plants and animals to die
Eutrophication
Excessive richness of nutrients in a lake of other body of water
Dead zones lead to…
Many decaying organisms which causes organic buildup on the floors of water environments
Excessive organic buildup on aquatic/sea floors causes…
Whatever little oxygen is left to NOT BE ABLE TO REACH LOWER SEDIMENT LEVELS
–> Causes denitrifying bacteria to thrive
Denitrifying Bacteria
Convert nitrates and nitrites into nitrogen gas (N2) and nitrous oxide (N2O)
–> Do NOT need O2 (anoxic conditions)
When denitrifying bacteria thrive too much…
Lots of N2O gas is produced which leads to greater greenhouse effect and contributes to climate change
Nitrifying Bacteria
Converts ammonia into nitrates and nitrites
–>Requires oxygen!
Decomposition of human waste produces:
NH4+
NH4+ from human waste gets into water ways by (3)
1) Combined sewage overflows
2) Incomplete sewage treatment
3) Leaching from septic tank systems
Use of fertilizers has increased the production of _________ in soils
N2O
Which is more potent green house gas? CO2 or N2O
N2O
Land plants evolved from
Aquatic algae
What character adaptations were needed for the evolution of algae to land plants?
1) Structures preventing desiccation and protection from UV
2) Reproduction without water
3) Structural support on land
4) Moving materials against gravity (being able to get substances to different areas of a plant)
2 key character adaptations needed for the evolution of algae to moss:
1) Development of the cuticle
2) Development of the stoma
Cuticle
A “skin” layer
–> Prevents water loss and desiccation while also helping with UV protection
What was a drawback to the cuticle and what development fixed the problem?
Cuticle didn’t allow for gas exchange
–> Development of the stoma allowed for gas exchange through the cuticle
Stoma
A hole that can open and close in the cuticle which allows for gas exchange
What adaptation led to the development of larger plants?
Vascular Tissue/System
Vascular Tissue
Allows for movement of liquids against gravity and across plant tissues
Vascular Tissue is made of:
2 cell types:
1) Xylem
2) Phloem
Xylem
Transports water (ONE WAY system; roots to leaves)
Phloem
Transports sugars (TWO way, TWO tube system)
Impacts of plant size on the atmospheric content
Greater plant size = >carbon sequestering = > CO2 removed and > O2 produced
GAS HAS MASS: Air is just less _____________ but this does not mean that it does not have ___________
1) Air is less dense
2) But this does not mean that it doesn’t have mass
Why did increase in atmospheric oxygen lead to the development of massive insects?
Because insects cannot control breathing rate –> It occurs through diffusion SO
> O2 = > respiration (that they can’t control == > growth
Mosses, Ferns, and relatives require ____________ for reproduction
WATER –> They have swimming sperm
How did swimming sperm hinder movement to land?
Limited the when and the where of reproduction
–> Limited dispersal to new habitats (stuck to the water)
Mosses evolved ____________ which aided a bit in dispersal by __________ but still…
1) SPORES
–> Aided in dispersal by WIND
BUT, wind still limited dispersal as it could only take the spores so far
Spore
Haploid reproductive unit
What reproductive elements did gymnosperms and angiosperms have?
1) POLLEN
2) SEEDS
Pollen
Male gametophyte of plants
Pollination
Movement of pollen to plant female structure = fertilization
Gymnosperms
WIND moves pollen
–> Have cones
Angiosperms
Flowering plants –> Flowers attract animals
–> ANIMALS move the pollen
–> Have fruit
Advantage of angiosperms
Animals moving the pollen allowed for greater dispersal over a wider range
Seeds
Baby plants/embryos inside a protective sheath
Gymnosperms hold their seeds in
CONES
Angiosperms hold their seeds in
FRUIT
Fruit
Structure derived from flowers that holds seeds
–> Provides an advantage for dispersal as fruit attracts consumption by animals
Synapomorphy
Derived character state uniquely shared by a group of taxa
Photoautotrophs
1) Inorganic carbon as matter source
2) Sun as energy source
Photoheterotrophs
1) Organic carbon as matter source
2) Sun as energy source
Chemoautotrophs
1) Inorganic carbon as matter source
2) Bonds of inorganic and organic molecules (food)
Chemoheterotrophs
1) Organic carbon as matter source
2) Bonds of inorganic and organic molecules (food)
Food
Large, carbon rich molecules that are sources of energy and matter
What is/is not food for an organisms depends on…
the organism’s ability to get BOTH energy and matter from the substance
For some organisms, energy in their food does NOT trace back to the sun but instead:
Hydrothermal Vents
Which organisms get their energy from hydrothermal vents?
Chemoautotrophs get their energy from H2 gas pumping out of the hydrothermal vents
What happens to indigestible and dead tissues? (3 processes)
1) Decomposition
2) Combustion
3) Fossilization
Decomposition
Dead/Indigestible things undergo chemical reactions that create new molecules (Broken down by other organisms)
Decomposers
Organisms that rearrange molecules of dead tissue to create new molecules that they can use for energy, tissue building, and storage
–> Invertebrates, bacteria, and fungi
Fungi are more similar to _________ than ___________
More similar to animals than plants
Absorptive Heterotrophy
Feeding more of fungi
–> Secrete digestive enzymes OUTSIDE of body and then ABSORB the digestion products into their cells
Saprobes
Organisms that absorb nutrients from DEAD organic molecules (what fungi are)
Fungi disperse via
Haploid spores
Fruiting
Building reproductive structures that will produce more spores
Fungi are the primary decomposers of (3 molecules)
1) Cellulose
2) Lignin
3) Keratin
Without fungus, the ____________ would fail
Carbon cycle
What is the body of a fungus called
Mycelium
Mycelium
Root like structure of a fungus consisting of a mass of branching tubular filaments (hyphae)
Hyphae
Tubular filaments that make up mycelium
Septate Hyphae
Hyphae with incomplete cells walls (septa)
Purpose of septa
Separates cells while still allowing for the passage of materials between them
Hyphae cell walls are made of
Chitin
Why do hyphae need septa?
Because chitin is not permeable (need some way to connect cells)
Coencytic Hyphae
Hyphae without septa
Septa
Incomplete cell walls
Rhizoids
Modified hyphae for anchoring
Fruiting Body
Structure that releases spores (only around for short period of time)
Ex: Mushroom
Fungi impacts on the biosphere
Made soils suitable for first land plants
How did fungi prepare the land for the first land plants
Released digestive enzymes that could break down rock AND organic substances which generated nutrient rich soils
Protaxities
That scary tall as hell fungus that is one of the more important ancient fungi
–> may have provided shelter to arthropods
Combustion
AKA Burning
–> Process that breaks down dead tissues and releases energy in the form of heat while also releasing CO2
Most of the mass of something that is combusted goes where
Into the air as CO2
Fossilization
Alternative for dead/indigestible tissues: Don’t get broken down
–> Under the right pressure and heat, ancient plants become fossilized into COAL
Coal
Dead matter that has not rotted or burned, but has been compressed under great amounts of pressure
Fossilized tissues are NOT…
Easily broken down
Coal is made up of ____________________ so when we burn it we are ____________________
1) Ancient carbon
2) Releasing a lot of carbon into the environment that hasn’t been around for a very long time
–> For this reason, burning coal is more like ADDING carbon to the environment rather than cycling it
Ancestral eukaryotes reproduced via
Mitosis only
2 methods of reproduction:
(Characterize them)
1) Asexual –> Produces identical offspring
–> Mitosis and fission
2) Sexual –> Produces unique offspring
–> Involves meiosis and mating
Asexual reproduction benefits
1) Faster reproduction
2) Easier
3) Takes fewer resources
4) Duplicates SUCCESSFUL individuals
Asexual reproduction disadvantages
Lack of variation
1) Changes to environment/unpredictable environment = death
2) Predators and parasites specialize in most common prey type = (all are the same so…) death
3) Infectious disease = death
Sexual selection benefits
1) Generates variable offspring + novel variants
–> Ensures some would survive in changing environments or would be resistant to a pathogen, able to escape predator, etc.
2) Recombination helps to generate chromosomes without harmful alleles
3) Recombination helps to generate chromosomes with beneficial alleles
Sexual selection disadvantages
1) Slower reproduction (only females produce offspring)
2) Finding mates requires greater energy and resources
3) Finding mates can be risky (increased vulnerability to predators and STDs)
4) Many new variants may not survive as well as the parents did
–> Recombination can also break up favorable allele combos
What is the difference in rate between sexual and asexual reproduction?
Sexual reproduction rate = 50% the rate of asexual reproduction
–> Because only females can produce the offspring
Sporophyte
A diploid multicellular phase in which cells undergo meiosis to produce haploid spores
What occurs to spores?
Undergo mitosis to produce the gametophyte
Gametophyte
A haploid multicellular stage in which gametes produced from this stage (by mitosis) undergo fertilization
Fertilization of the gametes from the gametophyte produces…
An embryo (zygote) which undergoes mitosis to turn into a sporophyte (multicellular diploid state)
Double Fertilization
Occurs only in angiosperms:
Two fertilization events take place
1) 1 sperm combines with an egg = zygote
2) 1 sperm combines with 2 haploid nuclei from female gametophyte = ENDOSPERM
A zygote has n =
n = 2 (diploid)
Endosperm
Large mass of cells that stores nutritious molecules for the zygote as it develops
–> The zygote’s food
Endosperm has n =
3 (triploid)
Cnidarians
A group of marine invertebrates which includes corals, jellyfish, and anemones
2 mature forms of cnidarians
1) Polyp
2) Medusa
Corals only have one mature form:
Polyp
Jellyfish only have one mature form:
Medusa
Hydrozoans
Organisms with both polyp and medusa forms
Polyp
Tube shaped and attached to a surface
Medusa
Bell shaped and free moving
Coral sperm and eggs combine to form (fertilize)
Planula (larvae)
What happens once planula are formed?
They drift in the water until they settle on a hard surface in which they begin developing into a polyp
Mature polyps undergo…
Budding (asexual reproduction)
Coral growth methods:
1) Budding
2) Fragmentation
Fragmentation
1) Fragment of coral breaks off
2) Drifts away and then settles somewhere
3) Undergoes asexual reproduction
4) New colony forms
Tetrapods
4 legged vertebrates
Includes: Mammals, reptiles, amphibians, birds
What reproductive trait evolved in tetrapods?
Amniote Egg
Amniote Egg
Egg that contains an aquatic environment INSIDE of it for the embryo that is then protected by an outer hard shell that allows for gas exchange
Amnion
A fluid filled sac that cushions the embryo
Yolk
Nutrient bearing portion of the egg whose primary function is to provide food to the developing embryo
What did the amniote egg allow for?
1) Allowed for animals to lay eggs on land where there were less predators (increased survival and dispersal)
2) Opened access to new terrestrial habitats away from the water
Pseudogenes
AKA “Dead genes”
–> Gene sequences that have been made inactive due to accumulated mutations
Why don’t humans have yolks?
The genes for yolk proteins are still within our genome but they are knocked out (dead genes)
Placenta
An organ that forms in the womb to provide nutrients and oxygen to the embryo
What did the placenta develop from?
Viral proteins: Syncytin-1 and Syncytin-2
What did syncytin-1 and syncytin-2 allow for?
The fusing of placental cells
What did the placenta lead to?
Development of internal pregnancy
Symbiosis
Species living very closely together
ENDO-symbiosis
A species living WITHIN another species (within the body or even a cell)
Organism Interactions:
Both are HARMED
Competition
Organism Interactions:
Both are BENEFITTED
Mutualism
Organism Interactions:
Ones benefits + one is harmed (4)
1) Predation
2) Herbivory
3) Parasitism
4) Infectious Disease
Mutualism
A symbiosis or endosymbiosis in which BOTH specie benefit from the interaction
Mutualism = symbiosis BUT…
Not all symbiosis events are mutualisms
Endosymbiotic Theory
Mitochondria and chloroplast were once bacteria that became integrated into our cells
Mitochondrial Endosymbiosis
Mitochondria are descendant from aerobic endosymbiotic bacteria living within cells of another species which became the ancestor of all eukaryotes
Overtime, the mitochondrial genome… (2)
1) was greatly reduced
2) moved partly via insertion mutations into the host cell’s genome
Chloroplast Endosymbiosis
In a descendant lineage of eukaryotes (with mitochondria) an endosymbiotic CYANOBACTERIA evolved into the original “primary” chloroplast
Mitochondrial/chloroplast endosymbiosis led to
the evolution of eukaryotes
Mycorrhizal Fungi
A group of fungi closely associated with the roots of plants that increase WATER and NUTRIENT uptake for the plants
–> They get sugars in return from the plants
Many plants wont grow without…
Mycorrhizae
Symbiont of coral
Zooxanthelle algae (a photosynthetic algae)
–> Lives inside the body of the coral and provides it with 95% of its food
What does coral provide to the algae?
1) CO2
2) Protection (place to live)
3) Nutrients from the coral waste
Human Gut Microbiome
Microbes aid in digestion and produce nutrients that we cannot ourselves
Most of the genes in our body come from…
Bacteria (specifically due to the gut microbiome)
Medical implications of fungus
Led to the discovery of the first antibiotic
–> Continues to be a source of new antibiotics in an age where bacterial resistance is rising
Alfatoxins
Fungal toxin
–> 25% of the world’s food crops are affected by alfatoxins
What does alfatoxin consumption lead to?
Connected to liver cancer –> 26,000 deaths per year due to it
Yeast
Unicellular, free-living fungus
Why is yeast evolution special?
Yeast evolved from multicellular organism (became simpler through evolution)
Yeast are NOT
Monophyletic –> Because they have evolved multiple times from different ancestors
Fungal Parasites in Plants: How do they invade?
Invade plant tissues through the stomata
Haustoria
Projections of fungal parasites that press into plant cells and absorb nutrients (don’t penetrate the cells)
Fungal parasites can cause detrimental __________________ ___________________ BUT they also are important for controlling ________________
1) Detrimental population decline
2) Control population size of abundant species
How much of our food is reliant upon pollinators?
1 in every 3 bites of food
Pollinators are threatened by (4)
1) Habitat loss
2) Climate change
3) Pesticide use
4) Diseases + pathogens
Ecosystem Services:
1) Provisioning services (what they provide us with)
2) Regulating services (water filtration, etc.)
3) Cultural services
Each kernel of corn is produced by a ________________ which means each kernel represents…
1) Produced by a separate fertilization event
2) Each kernel represents a genetically different individual
Order of plant species evolution to land plants
Algae –> Mosses –> Ferns –> Gymnosperms/angiosperms
Algae evolved into
Moss
What trait did moss gain that caused it to evolve from algae?
1) Stomata
2) Cuticle
Mosses evolved into
Ferns
What trait did ferns gain that caused them to evolve from moss?
Vascular Tissue
Ferns evolved into
Angiosperms and gymnosperms
What traits did angio/gymo-sperms gain that caused them to evolve from ferns?
1) Seeds
2) Sex without water (POLLEN)
Differences between angiosperms and gymnosperms
Angiosperms:
1) Seed dispersal through FRUIT
2) Pollination by ANIMALS
3) ENDOSPERM
Gymnosperms:
1) Seeds stored in CONES
2) Pollination by WIND
2 synapomorphies of fungi:
1) Chitin in cell walls
2) Absorptive heterotrophy
