Units 1-4 Study Set Flashcards
Scientific method
- Make Observations
- Background research/Ask a question
- Form a hypothesis
- Design an Experiment
- Gather/Present Data
- Analyze Data/Draw Conclusions
Independent variable
- A variable that stands alone and isn’t changed by the other variables you are trying to measure
- The cause of the experiment
- X-axis
Dependent variable
- What you measure in the experiment and what is affected during the experiment
- The effect of the experiment
- Y-axis
Energy
The ability to do work or transfer heat
Joule
The amount of energy used when a 1-watt electrical device is turned on for 1 second
Energy conversions
- energy = power × time
- power = energy ÷ time
Electromagnetic radiation
A form of energy emitted by the Sun that includes, but is not limited to, visible light, ultraviolet light, and infrared energy
Photon
A massless packet of energy that carries electromagnetic radiation at the speed of light
Potential energy
Energy that is stored
Chemical energy
Potential energy stored in chemical bonds
Kinetic energy
Energy of motion
Temperature
The measure of the average kinetic energy of a substance
1st Law of Thermodynamics
Energy is neither created nor destroyed, but may be converted from one form to another
2nd Law of Thermodynamics
When energy is changed from one form to another, some useful energy is always degraded to lower quality energy
Entropy
The amount of disorganization present in a system
Open system
A system in which exchanges of matter or energy occur across system boundaries
Closed system
A system in which matter and energy exchanges do not occur across boundaries
Input
An addition to the system
Output
A loss from the system
Steady state
A state in which inputs equal outputs, so that the system is not changing over time
Negative feedback loop
A system responds to a change by returning to its original state, or by decreasing the rate at which the change is occurring
- Helpful
Positive feedback loop
Change in a system is amplified
- Undesirable
Ecosystem
○ Some have well-defined boundaries, while others do not
* The biotic and abiotic components of
an ecosystem provide the boundaries
that distinguish one ecosystem from
another
* Some ecosystems are very small
* Each ecosystems interact with each
other through the exchange of
energy and matter
Biosphere
The region on our planet where life resides
Predator
Eats other organisms
Prey
Organisms eaten by other organisms
Symbiosis
a close, long-term interaction between two species in an ecosystem
Mutualism
Both organisms benefit
Commensalism
One organism benefits, one organism neither benefits nor is harmed
Parasitism
One organism benefits and one is harmed
Competition
Organisms compete when they seek the same limited resource
Interspecific competition
Members of a different species compete for the same resource
Intaspecific competition
Members of the same species compete for resources
Producers/autotrophs
Organisms that use the Sun to produce usable energy
Photosynthesis
The use of solar energy to convert carbon dioxide and water into glucose and oxygen
Cellular respiration
A process by which cells unlock the energy of chemical compounds
Aerobic respiration
The opposite of photosynthesis, where oxygen and glucose are converted into energy, carbon dioxide, and water
Anaerobic respiration
- Cells convert glucose into energy in the absence of oxygen
- does not provide as much energy
Consumers/heterotrophs
Organisms incapable of photosynthesis who must obtain their energy by consuming other organisms
Herbivores/primary consumers
Consumers that eat producers
Carnivores
Consumers that eat other consumers
Secondary consumers
Carnivores that eat primary consumers
Tertiary consumers
Carnivores that eat secondary consumers
Trophic levels
The success of organisms consuming one another
Food chain
The sequence of consumption from producers through tertiary consumers
Food web
- A complex model of how energy and matter move through trophic levels
- All species in an ecosystem are connected to one another
Omnivores
Organisms that operate at several trophic levels
Scavengers
Organisms that consume dead animals
Detritivores
Organisms that break down dead tissues and waste products into smaller particles
Decomposers
The fungi and bacteria that complete the breakdown process by converting organic matter into small elements and molecules that can be recycled back into the ecosystem
Gross primary productivity (GPP)
- A measure of the total amount of solar energy that producers in an ecosystem capture via photosynthesis over a given amount of time
- Indicates the total amount of energy captured by producers
Net primary productivity (NPP)
- The energy captured minus the energy respired by producers
- The greater productivity of an ecosystem, the more primary consumers can be supported
Biomass
The total mass of all living matter in a specific area
Standing crop
- The amount of biomass present in an ecosystem at a particular time
- not the same as productivity
Ecological efficiency
- The proportion of consumed energy that can be passed from one trophic level to another
- 10% average across all ecosystems
10% rule
Only 10% of energy from one trophic level is able to move up to the next
Trophic pyramid
A method of representing the distribution of biomass among trophic levels
Biogeochemical cycles
The movements of matter within and between ecosystems
Hydrologic cycle
The movement of water through the biosphere
Evapotranspiration
- The combined process of evaporation from land surfaces and transpiration from plants
- An important component of the hydrologic cycle as it returns water vapor back into the atmosphere
Transpiration
The process by which plants release water vapor into the atmosphere through their leaves
Steps of the hydrologic cycle
- Water evaporates from the Earth and into the atmosphere: Heat from the sun causes water to turn into water vapor and rise into the atmosphere, while plants can release water from their leaves.
- Once the water has evaporated into the atmosphere, it comes back down to the Earth in the form of precipitation (rain, snow, hail/sleet, etc)
What happens to water when it returns to Earth?
- Surface runoff
- Percolation
- Photosynthesis
Surface runoff
- Water that flows over the land surface rather than infiltrating into the ground
- Occurs when rainfall or snowmelt exceeds the soil’s ability to absorb it or when the ground is already saturated
Percolation
- The process of water seeping through soil or rock layers and moving downward into the ground
- The water will be absorbed by the ground and will become part of the Earth’s groundwater stores
Human impacts on the hydrologic cycle
- Clear-cutting forests can lead to soil erosion and flooding
- Erosion and heat waves can become extreme and cause harm to humans and other ecosystems
- Pollution of water and climate change caused by human presence on Earth depletes and dirties water supply
Carbon cycle
The movement of carbon around the biosphere
Photosynthesis and the carbon cycle
- When photosynthesis occurs, CO2 from human activity and other natural processes is regulated and converted to oxygen, essential for the Earth’s health and human survival
- Since CO2 is a greenhouse gas, preventing its overabundance is important so as to mitigate the effects of climate change
- The CO2 that plants retain is kept in their plant tissue, which eventually dies
- Decomposers will process that matter, leaving all carbon in the soil or nearby surroundings
Carbon sinks
Natural or artificial reservoirs that absorb and store carbon dioxide from the atmosphere, helping to mitigate climate change
Carbon exchange
The ocean absorbs some CO2 from the atmosphere, and it releases roughly the same amount of CO2 back into the atmosphere
Sedimentation
- The process by which particles settle out of a fluid (such as water) and accumulate at the bottom, forming layers of sediment over time
- The CO2 combines with calcium ions in the water to form calcium carbonate, which sinks to the bottom of the ocean and accumulates
- If left undisturbed, it can cause accumulation of carbon, but upon disturbance that carbon is reintroduced to the atmosphere and continues its journey through the carbon cycle
Fossil fuels
Natural resources formed from the remains of ancient plants and animals that have been buried and subjected to heat and pressure over millions of years
Macronutrients
One of six key elements that organisms need in relatively large amounts; nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur
Nitrogen cycle
The movement of nitrogen around the biosphere
Nitrogen fixation
Allows nitrogen gas to be converted into a form that can be used by plants and animals, such as ammonia (NH3) or nitrate (NO3)
Nitrification
The process by which ammonia (NH3) is converted into nitrite (NO2-) and then into nitrate (NO3-), primarily carried out by bacteria
Assimilation
- The process in which plants and animals take up nutrients from their environment and incorporate them into their own tissues for growth and development
- This nitrogen can be synthesized by consumers, or it can run into the ocean, providing aquatic ecosystems with enough nitrogen
- When these organisms die, decomposition occurs and organic nitrogen present in these organisms through the nitrogen cycle reverts back into ammonium
Mineralization
- The process by which organic matter, such as dead plants and animals, is broken down into inorganic substances like minerals
- This releases nutrients back into the soil or water for use by other organisms
- Last step before nitrification can begin again
Denitrification
The process by which nitrate is converted back into nitrogen gas
Ammonification
The conversion of organic nitrogen compounds into ammonia (NH3) by decomposer bacteria
Phosphorus cycle
The movement of phosphorus around the biosphere
Steps of the phosphorus cycle
- When materials like rock are weathered, organic phosphorus is released into surrounding environments
- It is then transported between land and water through aquatic functions like rain or excess runoff
- After phosphorus has been transported between groundwater and soil, living organisms can absorb it and use it for production of DNA and other important biomolecules
- These absorbers will eventually die, and their decomposition will release phosphorus back into the environment to restart the cycle
Eutrophication
Excessive richness of nutrients in a lake or other body of water, frequently due to runoff from the land, which causes a dense growth of plant life and death of animal life from lack of oxygen
Geologic uplift
The process by which Earth’s crust is raised, resulting in the elevation of landforms such as mountains and plateaus
Terrestrial biomes
Geographical regions that each have a particular combination of average annual temperature and precipitation and contain distinctive plant growth forms that are adapted to that climate
Aquatic biomes
Biomes categorized by particular combinations of salinity, depth, and water flow
Habitat
An area where a particular species lives in nature
Oligotrophic
A lake with a low level of productivity
Mesotrophic
A lake with a moderate level of productivity
Eutrophic
A lake with a high level of productivity
Ecosystem services
The process by which life-supporting resources, such as clean water, timber, fisheries, and agricultural crops are produced
Environmental indicators
An indicator that describes the current state of an environmental system
Five global-scale environmental indicators
○ Biodiversity
○ Food production
○ Average global surface temperature and carbon dioxide concentration in the atmosphere
○ Human population
○ Resource depletion
Biodiversity
The diversity of life forms in an environment
3 scales of biodiversity
- Ecosystem
- Species
- Genetic
Genetic diversity
- A measure of the genetic variation among individuals in a population
○ Populations with a high genetic diversity are better suited to respond to environmental change
Species diversity
- The number of species in a region or in a particular ecosystem
○ Higher species diversity causes more resilience to environmental changes and are more productive
○ Critical environmental indicator
Speciation
The evolution of a new species
Background extinction rate
The average rate at which species become extinct over the long term
Ecosystem diversity
- A measure of the diversity of ecosystems that exist in a given region
○ A greater number of healthy and productive ecosystems results in a healthier environment overall
Species’ richness
- The number of species in a given area
○ Used to measure biodiversity in a given area
Species’ evenness
- The relative proportion of individuals within the different species in a given area
○ Tells us whether a particular ecosystem is numerically dominated by one species or whether all of its species have similar abundances
Microevolution
Evolution below the species level
Macroevolution
Evolution that gives rise to new species, genera, families, classes, or phyla
Mutation
- A random change in the genetic code produced by a mistake in the copying process
○ Mutations can affect an organism’s survival and make their chances better or worse
Recombination
- The genetic process by which one chromosome breaks off and attaches to another chromosome during reproductive cell division
○ Does not create new genes but brings together new combination of alleles on a chromosome and therefore can produce novel traits
Artificial selection
The process in which humans determine which individuals breed, typically with a preconceived set of traits in mind
Natural selection
The process by which the environment determines which individuals survive and reproduce
Gene flow
- The process by which individuals move from one population to another and thereby alter the genetic composition of both populations
○ Alters the frequency of alleles in populations
○ Can bring in genetic diversity to a population that lacks it
Genetic drift
A change in the genetic composition of a population over time as a result of random mating
Bottleneck effect
- A reduction in the genetic diversity of a population caused by reduction in its size
○ When a population is reduced, its genetic diversity reduces as well
○ Can causes individuals to be less equipped to face environmental problems, disease, or low fertility
Founder effect
A change in the genetic composition of a population as a result of descending from a small number of colonizing individuals
Regulating services
Natural ecosystems help to regulate environmental conditions
Support systems
- Natural ecosystems provide several support systems that would be very costly for humans to generate
○ Ex: The pollination of food crops and natural pest control services
Resilience
- Ensures an ecosystem will continue to exist in its current state
○ Depends greatly on species diversity
Cultural services
Ecosystems provide beauty that many people are willing pay for
Theory of island biogeography
- A theory that demonstrates the dual importance of habitat size and distance in determining species richness
○ Depends on habitat size and distance from mainland
Range of tolerance
The limits to the abiotic conditions that a species can tolerate
Fundamental niche
The suite of abiotic conditions under which a species can survive, grow, and reproduce
Realized niche
The range of biotic and abiotic conditions under which a species actually lives
Distribution
- Areas of the world in which a species lives
○ Realized niche helps us understand the distribution of a species
Mass extinction
- A large extinction of a species in a relatively short amount of time
○ 5 mass extinctions have occurred over Earth’s history
6th mass extinction
During the last 2 decades, scientists have stated that we are currently experiencing a sixth mass extinction of a magnitude within the range of the previous 5 mass extinctions due to human activities
Geographic isolation
Physical separation of a group of individuals from others of the same species
Allopatric speciation
The process of speciation that occurs with geographic isolation
Sympatric speciation
The evolution of one species into two, without geographic isolation
Reproductive isolation
The result of two populations within a species evolving separately to the point that they can no longer interbreed and produce viable offspring
Polyploidy
The heritable condition of possessing more than two complete sets of chromosomes
Primary succession
Succession that starts with an essentially lifeless area where there is no soil or bottom sediment in an aquatic area
Pioneer species
The first organisms to colonize a barren or disturbed area
Secondary succession
The process of ecological change that occurs after a disturbance, such as a fire or clear-cutting, where an existing community is destroyed but the soil remains intact
Keystone species
A plant or animal that plays a critical role in maintaining the structure and function of an ecosystem
Indicator species
Organisms whose presence, absence, or abundance can provide information about certain environmental conditions or changes
Invasive species
animals or plants from another region of the world that don’t belong in their new environment
Species adaptation
The process by which a species changes over time in response to its environment, allowing it to survive and reproduce successfully
Selective pressures
Environmental factors that influence which individuals within a population are more likely to survive and reproduce
Trophic cascade
Occurs when predators limit the density and/or behavior of their prey and thereby enhance survival of the next lower trophic level
Niche generalist
- A species that can live under a wide range of abiotic or biotic conditions
○ Fare better under changing conditions
Niche specialist
- A species that is specialized to live in a specific habitat or to feed on a small group of species
○ More vulnerable to extinction from habitat changes
K-selected species
- A species with a low intrinsic growth rate that causes the population to increase slowly until it reaches carrying capacity
○ Large mammals and most birds are K-selected species
r-selected species
- A species that has a high intrinsic growth rate, which often leads to population overshoots and die-offs
○ These species reproduce often and produce many offspring
○ Small organisms are r-selected species
Survivorship curves
Graphs that represent the distinct patterns of species survival as a function of age
Type I survivorship curve
A pattern of survival over time in which there is a high survival throughout most of the life span, but then individuals start to die in large numbers as they approach old age
Type II survivorship curves
A pattern of survival over time in which there is a relatively constant decline in the survivorship throughout most of the life span
Type III survivorship curve
A pattern of survival over time in which there is low survivorship early in life with few individuals reaching adulthood
Carrying capacity (K)
The maximum population of a particular species that a given habitat can support over a given period
Density-independent factors
A factor that has the same effect on the individual’s probability of survival and the amount of reproduction at any population size
Density-dependent factors
A factor that influences an individual’s probability of survival and reproduction in a manner that depends on the size of the population
Limiting resource
A resource that a population can’t live without and that occurs in quantities lower that the population would require to increase in size
Population growth rate
The number of offspring an individual can produce in a given time period, minus the deaths of the individual or its offspring during the same period
Instrinsic growth rate (r)
The maximum potential for growth of a population under ideal conditions with unlimited resources
Exponential growth model
- A growth model that estimates a populations future size after a period of time based on the intrinsic growth rate and the number of reproducing individuals currently in the population, without considering limiting factors
□ This model produces a J-shaped curve
□ Exponential growth is a density-independent factor
Logistic growth model
- A growth model that describes a population whose growth is initially exponential, but slows as the population approaches the carrying capacity of the environment
□ This model produces a S-shaped curve
□ Logistic growth is a density-dependent factor
Overshoot
When a population becomes larger than the environment’s carrying capacity
Die-off
A rapid decline in a population due to death
Total fertility rate (TFR)
Average number of children each woman will have
Replacement fertility rate
- The total fertility rate for a nation that would keep its population stable
○ For most nations, this number is 2.1%
□ Greater number = increase ; lesser number = decrease
Crude birth rate
births per 1,000 individuals/year
Crude death rate
deaths per 1,000 individuals/year
Global population growth rate
(CBR - CDR)/10
National growth rate
[(CBR + immigration) - (CDR + emigration)]/10
Doubling time
- When a population grows exponentially and the number of years it takes for it to double
○ 70 / % growth rate
Rule of 70
- n = 70/R
○ R = growth rate
Factors that influence human population
- Population size
- Birth/death rates
- Fertility
- Life expectancy
- Migration
Population growth characterisitics of developing countries
○ Higher fertility, infant mortality, and death rates
○ Lower life expectancy
○ Low per capita resource use
Population growth characteristics of developed countries
○ Lower fertility, infant mortality, and death rates
○ Higher life expectancy
○ High per capita resource use
Factors affecting life expectancy, infant mortality and child mortality
- Available health care/prenatal care
- Adequate food supply
- Portable drinking water
- Good sanitation
- Moderate to low levels of pollution
Factors affecting life spans (gender)
- Gender-specific diseases
- Hazardous lifestyle choices
- Wars
- Dangerous jobs
Theory of demographic transition
The theory that as a country moves from a subsistence economy to industrialization and increased affluence, it undergoes a predictable shift in population growth
Stage 1 of demographic transition
○ CBR = CDR
○ Short life expectancy, high infant mortality
○ US/Europe = before 18th century
○ No countries in stage 1 now
Stage 2 of demographic transition
○ Death rates decline
○ Fertility rates remain high -> imbalance
○ US = early 19th century ; India = now
Stage 3 of demographic transition
○ # of births decline -> more birth control available
○ CBR = CDR again
○ Economy/education improves
Stage 4 of demographic transition
○ CBR < CDR
○ High affluence/economic development
○ More elderly
○ Government may encourage immigration or gives incentives to have more children
Three stages of age structure
○ Pre-reproductive
○ Reproductive
○ Post-reproductive
Theory of plate tectonics
The theory that pieces of Earth’s lithosphere are in constant motion, driven by convection currents in the mantle
Convergent plates
- Two tectonic plates collide or come together
- Causes mountains, volcanic activity, and earthquakes
- Ex: Mariana Trench
Subduction
One tectonic plate moves beneath another plate at a convergent boundary, resulting in the recycling of old crust back into the Earth’s mantle
Divergent plates
- Two tectonic plates move away from each other, resulting in the creation of new crust as magma rises to fill the gap
- Causes visible fault lines, rift valleys, seafloor spreading, volcanoes, and earthquakes
- Ex: Mid-Atlantic Ridge
Transform plates
- Two tectonic plates slide past each other horizontally
- Causes earthquakes
- Ex: San Andreas Fault
Soil horizons
- Distinct layers of soil that form as a result of various processes such as weathering, organic matter accumulation, and leaching
- Each horizon has unique characteristics that influence the movement of water, nutrients, and organisms within the soil
The process of soil formation
- Starts with parent material
- Over time, weathering occurs and the parent material is broken down into smaller and smaller particles
- Particles from other places might be introduced through the deposition
- Once a small layer of soil has been formed, moss and other small vegetation begin to grow
- With the presence of small vegetation and organisms, more soil horizons form and nutrients are added to the soil
- From here, the soil continues to develop as more plants and organisms interact with it
Soil erosion
- Often, soil can be washed away or eroded away by wind and water
- This happens when no plants or vegetation are available to hold the soil in place
Water quality and soil erosion
- Erosion can negatively impact water quality
- No soil or vegetation means that water won’t be filtered which might result in unclean water with higher amounts of pollutants
Water-holding capacity of soil
- The ability of a soil to retain water for plant use
- Particle size and amount of organic matter are significant factors in water-holding capacity
Porosity
- The measure of how much empty space, or pores, there is in a material such as soil or rock
- Indicates the ability of a substance to hold and transmit fluids
Permeability
- How easily fluids can flow through a material such as soil or rock
- Measures how well interconnected the pores are within a substance
Fertility
- How well-suited soil or land is for supporting plant growth
- Depends on the presence of essential nutrients, organic matter, and other factors that promote healthy plant development
Chemical properties of soil
- Soil pH
- Cation exchange
Soil pH
The measurement of acidity or alkalinity in soil
Physical properties of soil
- Aeration
- Soil compaction
- Permeability
- Particle size
Aeration
The ability of soil to take in essentials like nutrients, water, and oxygen
Soil compaction
- How compacted the soil particles are
- This can affect porosity, permeability, and aeration given space between individual particles
Biological properties of soil
Determined by the organisms and plants that live in it
Soil texture triangle
- A graphical tool used to classify different types of soils based on their proportions of sand, silt, and clay particles
- Follow the lines of each particle based on percent
- The point where the lines intersect is the type of soil it is
