Lecture Exam 4 Flashcards
(157 cards)
1
Q
What is an ecosystem?
A
The species present in a region, along with abiotic components such as sol, climate, water and atmosphere
2
Q
What is the biosphere?
A
The thin zone of life surrounding the earth
3
Q
What is the proposed new gelogical timescale epoch called?
A
The anthropocene – the new human epoch
4
Q
How does energy enter ecosystems?
A
Through primary producers
5
Q
What are primary producers?
A
Autotrophs – organisms that can synthesize their own food from inorganic sources.
In most ecosystems, primary producers use solar energy + photosynthesis to manufacture food. In deep-sea hydrothermal vents, primary producers use methane and hydrogen sulfide.
6
Q
Do primary producers create energy?
A
No. They transform the energy from sunlight or inorganic compounds into the chemical energy stored in sugars.
7
Q
What is gross primary productivity (GPP?)
A
The total amount of chemical energy produced in a given area and time period
8
Q
How do primary producers use chemical energy?
A
1) Cellular respiration (or in anaerobic microbes, fermentation) produces ATP. ATP fuels metabolic processes.
2) Growth and reproduction. Energy invested in building new tissue or offspring is called Net Primary Productivity
9
Q
Describe the relationshi pbetween primary producer productivity and respiration/lost energy
A
NPP = GPP - R
10
Q
What is net primary productivity?
A
The total amount of chemical potential energy stored in organic material, or biomass.
11
Q
How much of the available sunlight energy is harnessed in photosynthesis? Why so little?
A
0.8%; Why so inefficient
- The pigments in photosynthesis absorb only a fraction of the light wavelengths.
- Plants absorb way less in winter
- If it gets dry in the summer, plants close their stomata to conserve water, stalling photosynthesis due to lack of CO2
- Enzymes are temperature-dependent
12
Q
How much of GPP goes to production of new biomass?
A
45% of GPP goes to NPP. The rest goes to respiration or is lost.
13
Q
Describe the energy flow model for ecosystems.
A
Energy flows from autotrophs to other organisms in the form of biomass.
-
Consumers eat living organisms.
- Primary consumers eat primary producers
- Secondary consumers eat primary consumers
- Tertiary consumers eat secondary consumers
-
Decomposers (detritivores) get energy by feeding on the remains of other organisms or waste products
- Detritus - dead animals and dead plant tissues. Many fungi are decomposers.
- Energy flows when one organism eats another
14
Q
What is a trophic level?
A
A “feeding” level. Organisms that get energy from the same type of source occupy the same trophic level.
15
Q
What is a food chain?
A
A food chain is one possible pathway of energy flow among trophic levels.
16
Q
What are food webs?
A
Food chains overlap and consumers often feed at multiple trophic levels, so food webs are a way to summarize energy flows.
17
Q
Is more biomass eaten dead or alive?
A
On earth, 95% is eaten dead. In marine environments, only 65% is eaten dead. Important:
- Makes decomposers very important to the study of forest energy flow
- Decomposer food chain is “leaky” – that is, forest detrius easily washes into streams, releasing energy.
18
Q
Describe the pattern of biomass production according to trophic levels?
A
Each year, the total biomass produced declines from lower trophic levels to higher trophic levels.
Ex: there is less hawk biomass than chipmunk biomass, and so on up the food chain.
19
Q
What is the 10 percent rule?
A
On average, only 10% of energy in one trophic level makes it to the next one.
20
Q
Describe variation in the 10 percent rule
A
large mammals are more efficient at producing biomass because they lose less heat and have a smaller surface area to volume ratio.
Ectotherms are more efficient than endotherms because they rely on environmental heat and do not oxidize sugars to keep warm.
21
Q
What is biomagification and why does it happen?
A
Pollutants like Mercury and POPs undergo a process called biomagniciation where they increase in concentration at higher levels in a food chain.
22
Q
What happens in biomagnification?
A
Persistent atoms or molecules are taken from air/water by primary producers.
Consumers eat the producers and ingest lots of the pollutant but don’t filter it out. (Consumers at 10 times their body mass)
Pollutant gets more concentrated as it moves up food chain.
23
Q
What is a famous example of a POP?
A
DDT. Birds were dying in areas sprayed with the mosquito pesticide; egg shells became thin and got crushed.
24
Q
- How do top predators affect the food web? Give an example.
A
Top-down control and trophic cascades.
- Top-down control
- When a consumer limits a prey population, like the sea star vs. mussels in the Pacific Coast
- Greater Yellowstone Wolves in the 20th century
- Trophic cascade
- When top-down control changes cause conspicious effects two or three links away in food web
- Greater Yellowstone Wolves
25
Describe the effects of Greater Yellowstone Wolf dwindling. What is this an example of?
**Trophic cascade**
* Wolves fed on elk;
* when wolves were reintroduced, elk numbers declined and so more elk food (aspen, cottonwood, willow) is around;
* Changes in plant species triggered increase in beavers, which comete with elk for plants
* beavers dam streams, forming ponds that are a habitat for frogs, etc.
* Wolves hate coyotes, and fewer coyotes means more mice, which means more hawks that prey on mice.
26
is productivity higher on land or sea? why?
land, probably because light is more available to drive photosynthesis
27
Which terrestrial ecosystems are most productive?
wet tropics.
productvitiy declines going from equator to poles (except for Sahara) due to less sunlight and colder temperature
28
What factors determine global productivity of terrestrial ecosystems?
sunlight, location, water, nutrient availability, temperature
29
30
Which marine ecosystems are most productive?
Along the coastlines. Shallow water receives more nutrients from rivers, etc.
31
Which biomes are most produtive?
* Tropical wet forests and tropical seasonal forests cover \<5% of earth's surface but account for over 30% of total NPP
* Aquatic: Algal beds and coral reefs, wetlands, estuaries
* NPP per square meter is low in open ocean, but biome is so extensive that total NPP is still high.
*
32
Of total NPP on earth, how much are humans using?
About a quarter of the planet's biomass
33
What is the biogeochemical cycle?
the path an element takes as it moves from abiotic systems through producers, consumers, and decomposers.
34
What happens to detritus as it decomposes?
Microscopic decomposers form **soil organic matter** until the detritus is *totally* decayed and becomes **humus**.
Eventually, decomposition converts nutrients in soil organic matter to an **inorganic form**, and then the nutrients can be taken up by plants again.
35
What factors control the rate of nutrient cycling?
* Biggest limiting factor is often decomposition of detritus
* decomp is influenced by
* abiotic conditions like oxygen availability, temperature, precipitation
* quality of detritus as nutrient source for fungi/bacteria/archaea
* abundance and diversity of detritivores present
36
Describe how abiotic conditions could affect detritus decomposition rate
tropical areas have consistently warm temperature,optimal for detritivores; boreal forests get cold, which is bad for them
37
How can detritus quality influence growth of decomposers and the decomp rate?
decomposition is inhibited if detritus is low in nitogen or high in lingin. Additionally, oxygen must be present.
38
How can nutrients exit an ecosystem?
* eaten by organism which then leaves
* wind or water carries particles or inorganic ions and deposits them somewhere else
* man-made acccelerated nutrient export: farming/logging; soil erosion; runoff
39
How can nutrients be replaced in an ecosystem for normal functioning?
1. ions that act as nutrients are released as rocks weather
2. nutrients can blow in on soil particles or arrive dissolved in streams
3. nitrogen is added when nitrogen-fixing bacteria convert N2 into ammonium or nitrate ions
40
Scientists did an experiment where they devegtated one of two similar stream areas in the same watershed; what was the lesson?
Once soil is lost, it is difficult to regain. Soil takes a very long time to form.
41
What are the three main questions in the study of the global biogeochemical cycle?
1. **What are the reservoirs? **What are the size and nature of the reservoirs -- areas or "compartments" where elements are stored for a period of time?
1. ex: Carbon can be in biomass, coal, soil etc.
2. **How and how fast are reservoir switches? **How fast How fast does the element move between reservoirs, and what processes move elements from one reservoir to another?
1. ex: Photosynthetic rate tells us how fast carbon moves from CO2 to biomass carbon
3. **How do cycles interact? **How does one biogeochemical cycle interact with another biogeochemical cycle?
1. ex: How do changes in nitrogen cycle affect the carbon cycle?
42
Summarize the water cycle
* Water evaporates out of ocean
* water precipitates back into ocean, but slightly less
* water vapor moves over continents and is joined by evap from lakes and is transpired by plants; rain falls
* water moves from land back to oceans via streams and groundwater
43
Where is most groundwater stored?
aquifiers, layers of porous rock, sand, or gravel that are saturated with water
44
What effects do humans have on the water cycle?
* asphalt/concrete stop water from percolating down to deep soil
* grassland --\> agricultural fields destroy root systems that hold water
* irrigated agriculture removes massive amounts of groundwater and brings it to the top
45
What is the water table?
The level where soil is saturated with stored water. It's dropping on every continent.
46
Summarize the global nitrogen cycle
* N2 gas comes mainly from atmosphere. must be "fixed" into ammonium or nitrate.
* Reduced/fixed nitrogen builds up slowly in soils and water
* Reduced/fixed nitrogen cycles among animals, soil, fungi, plants, etc.
* bacteria digest nitrogen-containing molecules and return N2 to atmosphere
47
How does nitrogen fixation happen?
lightning-driven reactions
bacterial reactions
48
How have humans modified the nitrogen fixation cycle?
human sources of N2 fixation almost equal natural sources.
1. industrial fertilizers
2. crops that harbor N2 fixing bacteria
3. fossil fuel burning
49
Adding N2 to terrestrial ecosystems usually makes them more productive. But why is overfertilization with nitrogen bad?
N2-laced runoff causes algae blooms, and when all the algae die and are decomposed by microbes, all the oxygen is depleted, creating oxygen-free dead zones.
Productivity increases but species diversity decreases
50
Describe the global carbon cycle
* movement of carbon among terrestrial, ocean, and atmosphere
* ocean largest; atmosphere fastest
* photosynthesis takes C out of atmosphere and incorporates it into tissue in terrestrial/aquatic ecosystems
* Cell resp releases carbon back as CO2
51
How have humans changed the carbon cycle?
* deforesting land for agriculture and settlements
* fossil fuel burning
* current CO2 levels are 30% higher than the highest level measured in the last 800,000 years
52
What are the three main drivers of environmental change?
* changes in land use
* massive loss of species
* global climate change (global warming)
53
What alarms scientists about climate change?
not that it is happening, but its rate
54
What is a greenhouse gas?
A gas that traps heat radiated from earth and keeps it from being lost into space
55
A major study on climate change took place in Mauna Loha, HI. Its findings:
* rate of increase of CO2 is not slowing
* temp fluctuates but there is a clear increase in average
* no net increase in solar energy over time
56
Why are atmospheric CO2 and temp rising so fast?
1. human population explosion
2. per-person fossil fuel use increase
57
How much will the climate change?
average global temperature will increase another 1-7 degrees celsius (2-12 degrees F) by 2100
58
Describe positive feedback in climate change and cite examples
changes due to GW accelerate GW
* warmer/drier climate increases forest fires, which release CO2
* Tundra sequesters carbon in soil, but warm summers release carbon stores into atmosphere
* polar ice caps melt, leaving open water darker and absorbing more solar heat/energy
59
What negative feedback happens with regard to GW?
* plants grow faster, which should reduce atmospheric CO2
60
What climate factors other than temperature are affected by climate change?
* temperature affect the water cycle, increasing precipitation in some areas and drying other areas
* variability in extreme weather conditions/events
* sea level rise due to melting glaciers/ice caps
* ocean currents change due to ice caps
61
what is phenology?
timing of seasonal events (i.e. arrival of spring)
62
What are the effects of climate change on organisms?
* **Phenology shifts** (timing of seasonal events --\> changes in hatching, flowering, feeding, etc.)
* **Geographic range shifts** (species redistribute as climate changes)
* **Evolutionary adaptaiton** to new environment
* **Extinction**
* **Acidification **(ocean absorbs CO2 into bicarbonate and then deprotonates to form carbonic acid). Bad for corals, mollusks, etc.
63
How is net primary productivity (NPP) changing on land?
Global terrestrial NPP has declined. Droughts in the southern hemisphere have actually DECREASED the amount of photosynthesis!
64
How is net primary productivity changing in the oceans?
Overall, NPP is decreasing in the oceans. Seawater stratifies because its density depends on temperature, and currents are modified.
65
What are the five main levels of ecological study? Give an example of each.
1. **Organismal ecology**
How do individuals interact with each other and their physical environment?
*Salmon migrate from saltwater to freshwater to breed*
2. **Population ecology**
How and why does population size change over space and time?
*Each female almon produces thousands of eggs; only a few offspring will survive to return to breed*
3. **Community ecology**
How do species interact, and what are the consequences?
*Salmon are prey as well as predator*
4. **Ecosystem ecology**
How do energy and nutrients cycle through the local environment?
*Salmon die young and then decompose, releasing nutrients used by other organisms*
5. **Global ecology**
How is the biosphere affected by global changes in nutrient cycling and climate?
66
What is a biome?
regions characterized by distinct abiotic characteristics and dominant types of vegatation
67
What abiotic conditions are determined by climate?
* temperature -- crucial for enzyme efficiency
* moisture -- required for life
* sunlight -- for photosynthesis
* wind -- exacerbates effects of temperature and moisture. also, birds/insects.
68
How do we estimate net primary productivity?
by measuring aboveground biomass (total mass of living plants, excluding roots)
69
BIOME ID: Identify the temperature, precipitation, and notes on
## Footnote
**Tropical Wet Forest**
* also called tropical rainforests
* equatorial regions
* plants with broad leaves and are evergreen with lots of growth, extremely high productivity, and diversity
* temp: no seasonal variation in temp
* precip: very very wet
70
BIOME ID: Identify the temperature, precipitation, and notes on
## Footnote
**Subtropical Deserts**
* 30 degrees latitude north and south
* temp: temperature variation; sometimes very cold
* precip: low precipitation
71
BIOME ID: Identify the temperature, precipitation, and notes on
## Footnote
**Temperate Grasslands**
* grasses are dominant life form
* too dry for tree growth
* prairie fires burn encroaching trees
* temp: temperate zone
* precip: too hot and dry for forests, but moderate precip
72
BIOME ID: Identify the temperature, precipitation, and notes on
## Footnote
**Temperate Forests**
* North America and Europe
* Deciduous species and some evergreens
* lower productivity than rainforest but more than trassland
* temp: moderate fluctuation
* precip: moderate
73
BIOME ID: Identify the temperature, precipitation, and notes on
## Footnote
**Boreal Forests**
* Canada, Alaska, northern Europe. Cold-tolerant conifers, etc.
* Low NPP, but high aboveground biomass because the slow-growing trees are old and large.
* temp: very cold winters and short summers
* precip: low precip
74
BIOME ID: Identify the temperature, precipitation, and notes on
## Footnote
**Arctic tundra**
* low species diversity, low productivity, low aboveground biomass
* treeless
* permafrost
* temp: short growing season. other than that, freezing
* precip: low precip
75
What does population size depend on?
* birth
* death
* immigration
* emigration
76
What is a population's structure?
How many individuals of each age are alive
77
What is a generation?
the average time between a mother's first offspring and her daughter's first offspring.
78
What is a life table?
a table that summarizes the probability that an individual will survive and reproduce in any given time interval over the course of its lifetime.
79
What comprises an organism's environment
abiotic factors and biotic factors
80
How do you calculate R for a population?
population growth R = (birth - death) + (immigration - emigration)
81
How does population grow when there are no limits?
Exponential at first.
82
How does population grow when there are limiting factors?
Logistic growth: exponentially at first but slows as it reaches its carrying capacity.
83
What are factors that limit population growth?
density-independent factors that impact a population regardless of size -- weather conditions, seasonal cycles, natural disasters
density-dependent factors that impact a population according to size -- predators, disease, resource scarcity
84
What is the current fertility rate and replacement rate?
2.7, 2.1
85
Define suvivorship
the proportion of offspring produced that survive to a particular age.
86
Describe the types of survivorship rates
Type 1 - lots live til old, then die
Type 2 - steady dying off
Type 3 - lage initial dying off, then strong survivotrs
87
What is fecundity?
the number of female offspring produced by each female in the population.
88
What is r? rmax?
r = change in population over time
rmax is the species-specific rate of increase under optimal conditions
89
What are two measures of species diversity?
species richness - number of species present
species evenness - relative abundance or how common a species is compared to others in community
90
Describe metapopulations and extinction
Populations within a metapopulation can go extinct and be reestablished by migration. Each population in a metapop is expected to go extinct at some point.
91
describe the increase of the human population
* reached 1 billion in 1804
* only 123 years to reach 2 billion
* 12 years to add 1 billion to reach 7 billion total
*
92
Describe the relationship between Malthus and Darwin. What was Malthus's idea?
Malthus was a source of inspiration for Darwin as he was coming up with evolution by natural selection.
Malthus warned that the population cannot continue to increase unchecked; competition for resources will eventually slow population growth, whether by famine, war, or voluntary reduction of family size.
93
Describe human population growth.
growing fast, but the rate itself has begun to decline. highest in 1965-70; current growth rate is 1.2% annually. Projected to be 11 billion in 2050 unless something changes.
94
What is a community
all species in a particular area
95
How can species interact?
1. commensalism (+/0)
2. Competition (-/-)
3. Consumption (+/-)
4. Mutualism/Symbiosis (+/+)
96
What are the key themes of species interactions?
1. Species interactions can affect distribution and abundance of a species
2. species act as agents of natural selection when they interact
3. The outcome of interactions among species is dynamic and conditional
97
Give an example of commensalism
Antbirds and their ants. As the ants march, they hunt; the birds pick off anything that jumps out of the way
98
What effect does compeition have on fitness?
-/-. Lowers fitness in both because competitors using resources mean those resources cannot help other individuals
99
define intraspecific and interspecific competition
intraspecific = within species
interspecific = between species
100
When does interspecific competitoin occur?
When niches of two species overlap
101
what happens when one species is a better competitor?
asymmetric competition occurs.
two species occupying the same niche cannot coexist. The competitive exclusion principle.
102
What happens if two species in asmmetric competition have niches that don't completely overlap?
weaker species should retreat to the area of non-overlap. Then distinguish between fundamental niche and realized niche
103
What are fundamental niche and realized niche?
* fundamental - total theoretical range of environments a species can tolerate
* realized - the portion of the fundamental niche that a species actually occupies
104
What are the two responses to interspecific competition?
competitive exclusion (ecological response) or niche differentiation (evolutionary response)
105
Describe the key mechanism of coexistence
Niche differentiation. An evolutionary change in resource used to avoid competition. The change that enables this is called character displacement.
106
Give an example of niche differentiation
beak depth in the galapagos islands.
107
What are the three types of consumption?
herbivory
parasitism
predation
108
What are constitutive defenses?
defenses that are present even in the absence of predators -- hiding, fleeing, poison, armor, confusion, etc.
109
What are some types of constitutive defenses?
* cryptic coloration
* escape behavior
* toxins
* schooling/flocking
* defense and armor weapons
110
What is batesian mimicry?
harmless species imitates harmful one
111
what is mullerian mimicry?
different harmful species with the same predator evolve to look similar because it helps them scare off prey more frequently.
112
What are inducible defenses and what is their advantage?
don't require as much energy to maintain as constitutive defenses
defenses that are induced in the prey in response to a predator's presence
113
What are the three types of symbiosis?
mutualism (+/+)
commensalism (+/0)
parasitism (+/-)
114
what is coevolution?
the interdependent evolution of two interacting species
115
What are abiotic factors that affect an ecosystem?
energy flow
carbon cycling
biomes
116
What are the differences between prokaryotic and eukaryotic cells?
* E DNA enclosed in nuclear membrane
* E have membrane bound organelles
117
What is the abiotic to bioitic transition hypothesis?
* Key properties of life:
* accurate replication
* metabolism
* Protobiont formation in ancient seas
* aggregates of abiotic molecules
* form spontaneously
* enzymes are trapped within
* Were able to take in substances across the lipid bilayer
118
How do we distinguish between bacteria and archaea?
Bacteria split off from A and E first
* Bacteria have peptidoglycan in their cell walls
* Archaea have unique phospholipids in their plasma membrane -- hydrocarbon tails from isoprene
119
Describe bacteria, archaea, and eukarya in terms of:
* DNA in nuclear envelope
* Plasmid DNA
* Membrane-bound Organelles
* Rotating flagella
* Multicellular species
* Cell walls with peptidoglycan
* RNA polymeras has \>10 units
* Translation initiated with methionine
Describe bacteria, archaea, and eukarya in terms of:
* DNA in nuclear envelope (BN, AN, EY)
* Plasmid DNA (BY, AY, EY)
* Membrane-bound Organelles (BN, AN, EY)
* Rotating flagella (BY, AY, EN)
* Multicellular species (BN mostly, AN, EY)
* C
ell walls with peptidoglycan (BY, AN, EN)
* RNA polymerase has \>10 units (BN (5), AY, EY)
* Translation initiated with methionine (BN, AY, EY)
120
What were the first organisms on earth and when did they form?
Prokaryotes - 3500 mya
from stromatolites
121
What replaced protobionts, autotrophs or heterotrophs?
probably autotrophs, some of which could use light
heterotrophs emerge secondarily, dependent upon autotrophs
122
What effect did bacteria have on earth's atmosphere?
Caused O2 to accumulate; was likely toxic to most organisms present at the time
123
Describe the diversity of prokaryotes at a broad level
most are unicellular; some are colonial
innumerable species
5e30 individuals exist on the earth
124
How many bacterial cells are ther ein your body?
10e14 (compared to 10e13 human cells in your body)
125
Describe extremophiles
bacteria or archaea that thrive in extreme environments
* high salt, high, temp, low temp, high pressure
* hydrothermal vents at the bottom of the ocean
* halophiles - highly saline
* thermophiles - high temp environments
* psychrophiles - low temp environments
126
What are koch's posulates?
criteria that must be met to establish causality between a microbe and a disease
1. microbe must present in patients and absent in healthy
2. organism must be isolated and grown in a pure culture
3. pure culture organisms injected into healthy must lead to disease
4. organism should be isolated in diseased experimental animal, grown again, and shown to be same as original organism
127
What is the germ theory of disease?
* pattern: certain diseases are infectious
* process: caused by transmission and growth of certain bacteria and viruses
128
What are flagella and fimbriae/pili?
* flagella are for motility. long whips
* fimbriae/pili are short, hairlike, and not used for motility; more for adhesion and conjugation
129
Describe archaea vs. bacteria cell wall structure
archaea - variable
bacteria - cell wall contains peptidoglycan
130
Distinguish between gram positive and gram-negative bacteria?
gram-positive: purple, thick layer of peptidoglycan
gram-negative: pink, thin layer of peptidoglycan surrounded by outer membrane
131
Describe the evolution of the bacterial cell wall
gram positive bacteria
* firmicutes
* streptococcus, stphyloccoccus
* endospore formers
*
132
How are organisms categorized metabolically?
* energy source
* phototrophs - light energy
* chemotrophs - chemical energy
* carbon source
* autotrophs - carbonfixing (co2)
* heterotrophs - ingest organic nutrients
133
give examples of the four metabolic categories
* photoautotrophs - photosynthetic organisms - cyanobacteria
* photoheterotrophs - photosynthetic and conume other organisms - only prokaryotes
* chemoautotrophs - only prokaryotes. Use H2S, NH3, etc.
* chemoheterotrophs - humans
134
How are organisms categorized based on oxygen usage?
* obligate anaerobes are poisoned by oxygen
* facultative anaerobes will use Oxy if present but can grow without
* obligate aerobes need oxygen
135
what are the size, shape, and motility categories for bacteria?
* size - from .15 cubic micrometers to 200e6 micrometers
* filaments, spheres, chains, spirals
* swimming with flagella - tumbling - gliding
136
Bacteria and archaea can do cell respiration in many ways
Strip electrons from an organic molecule, transfer these high-energy electrons to the electron carriers NADH and FADH2 and then move down the electron transport chain.
glucose is oxidized to CO2, which is given off as a byproduct. oxygen is final electron acceptor (at bottom of chain)
137
What are other possible electron donors other than sugars and acceptors other than oxygen?
donors: H, H2S, NH3, CH4
acceptors: SO42-, nitrate, etc.
138
what is fermentation?
ATP production strategy not involving electron transport chains
139
How do nitrates pollute the oceans?
nitrate runoff stimulates algal blooms
those algae die off eventually
decomposers have a feeding frenzy and consume all the oxygen in an area of water
everything in that area dies - dead zone
140
How do bacteria reproduce?
binary fission: mitosis. can have lateral gene transfer (transformation, transduction, conjugation)
141
What ecological roles do bacteria play?
decomposers
primary producers
nitrogen fixation
142
When did greater genetic complexity evolve?
after bacteria, after archaea, before eukaria
143
Does genome size correlate to genotype?
no, amount of base pairs does not necesarily correspond to total number of genes
144
what are dark matter regions?
non-coding regions of DNA.
145
When did more complex cytoskeleton evolve?
after bacteria, after archaea, before eukarya
146
What are the elements of the cytoskeleton?
* provide the structural framework for the cell
* microtubules (load bearing)
* microfilaments (pulling forces)
* intermediate filaments (pulling forces)
147
do any prokaryotes possess cycoskeleton?
possibly, some
148
when did the endomembrane system evolve?
after bacteria, after archaea, before eukarya
149
What is the endomembrane system?
infolding of plasma membrane leading to nuclear envelope and endoplasmic reticulum
150
when did mitochondria evolve and how?
before eukarya; endosymbiosis
151
What are 4 key traits that evolved after bacteria and after archaea but before eukarya
* more complex cytoskeleton
* greater genetic complexity
* endomembrane system
* evolution of mitochondria
152
what are the key evolutionary events within eukarya?
evolution of sexual reproduction
evolution of multicellularity
evolution of chloroplasts and secondary endosymbiosis
153
Summarize wolves in yellowstone
10 years after reintroduction to yellowstone, wolves are abundant
initiated trophic cascade, scaring elk to high ground
elk numbers dropped
so vegetation affected -- willow thickets and cottonwoods bounced back
those plants stabilize stream banks and provide shade, lowering water temp and making better for trout. bigger fish.
songbirds like the new vegetation
other carnivores take over wolf carcasses
154
Explain deer in rock creek park
* we killed all mountain lions and timber wolves, so deer have no predator
* we control via birth control agents, controlled hunts
155
Describe human population growth: environmental impacts, social impacts, and solutions
* environmental impacts
* resource scarcity
* climate change
* social impacts
* conflict over natural resources
* economic system changes
156
Describe ocean acidification
* progressive increase in the acidity of the oceans, caused by uptake in atmospheric co2
* force marine organisms to spend more energy regulating ph rather than growing/reproducing
* won't kill all ocean life but we will see changes in abundance and number of marine organisms
* tens to hundreds of millennia to recover
*
157
describe the biodiversity article
* three global megatrends: urbanization, loss of biodiversity, prevalence of allegies
* cement and such reduce exposure to microbes, correlated with allergies
* biodiversity on human skin may be tied tot his
