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Bio220W Final Exam
Terms in this set (128)
Distinguish between examples of the following hierarchies of living systems: individuals (organisms), populations, communities, ecosystems, landscapes, biomes and the biosphere.
Organisms: one single individual, genetically distinct
Populations: group of individuals
Communities: all populations of different species in an ecosystem
Ecosystems: a community and its environment living and non-living
Landscapes: all visible features of a land
Biomes: a large naturally occurring community occupying a habitat
Biosphere: the regions that surround the earth including the surface
What is a dependent variable?
The dependent variable DEPENDS on the independent variable.
What is an independent variable?
Variable changed by scientist, and observed.
What is a confounding variable?
Any change in an experiment not observed/recorded
What is a controlled variable?
Variables that are held constant
What is the difference between a null hypothesis and an alternative hypothesis?
A null is the hypothesis that states there is no experimental difference between the two variables. Alternative is the hypothesis accepted to be true if the null is disproved
What is the difference between a controlled and comparative experiment?
Comparative experiments are designed to determine the differences between different forms of treatments while a controlled experiment is very similar but has a control group or a group that doesn't get a treatment at all.
Describe the central dogma
A single genes worth of DNA goes through transcription to make a single RNA and then the RNA goes through translation to make a certain polypeptide protein for coding.
Describe the relationship between chromosomes, loci, genes, and alleles
A single gene carries a code. Different genes carry many codes, which are called alleles. DNA contains genes contain alleles. Chromosomes carry the DNA. A loci is the specific location where a sequence of DNA (gene) is responsible for encoding a specific protein with a specific duty.
Describe what it means when an allele becomes "fixed" in a population, and when an allele becomes "lost"
If the initial allele frequency is close to .5 it is more likely to last more generations where as if it is further from .5 it is more likely to be lost in earlier generations. A frequency that is further from .5 or "equilibrium" is usually a result of genetic drift in small populations.
The loss or fixation of an allele usually happens more rapidly in small populations than in large. In a large population the allele frequency is higher even after many generations.
Give 5 mechanisms (evolutionary agents) that could cause a natural population to evolve
Stochastic Events: Random events
Non-random mating: Choosing who to mate with
Mutations: Changing sequence of nitrogenous bases→ New Characteristics
Immigration/Emigration: New alleles introduced to populations
Natural Selection: certain "weak" alleles are rid from a population
Describe the relationship between evolution and natural selection.
Natural selection is the driving force of evolution. Variants that are best suited for the environment are most likely to survive and reproduce, therefore those variants are more likely to survive and thrive in a population and be passed on to future generations.
Explain natural selection and provide an example of a population that evolved as a result of it
Organisms better fit for their environment tend to survive and produce more offspring. Ex: Birds form stronger beaks.
Explain artificial selection and provide an example of a population that evolved as a result of it
Humans directly choose which organisms survive and reproduce based on their characteristics. Ex: Domestic animals.
Explain assortative mating and provide an example of a population that evolved as a result of it
Individuals in a population actively choose who to mate with based on their phenotypes. Ex: Humans
Explain genetic drift and provide an example of a population that evolved as a result of it
Explain mutation and provide an example of a population that evolved as a result of it
Explain migration and provide an example of a population that evolved as a result of it
Describe directional selection
Describe disruptive selection
Describe stabilizing selection
What is positive assortative mating?
What is negative assortative mating?
How does mutation affect genetic diversity in small populations?
It increases diversity
How does genetic drift affect genetic diversity in small populations?
How does migration affect genetic diversity in small populations?
What is spatial pre zygotic isolation?
Animals occupy different habitats
What is temporal pre zygotic isolation?
Animals mate during different time of day, seasons, or years.
What is mechanical pre zygotic isolation?
anatomical incompatibility prevents sperm transfer.
What is behavioral pre zygotic isolation?
species-specific signals & elaborate behaviors to attract mates. (Ex. bird songs & dances, firefly lighting patterns, Ex. chemical pheromones (moths, humans)
What is gamete isolation?
Gametes (sex cells) come in contact but no fertilization takes place
What is low zygote viability as a post zygotic isolation mechanism?
The zygote has a low chance of survival
What is low adult viability as a post zygotic isolation mechanism?
The adult has a low chance of survival
What is adult infertility as a post zygotic isolation mechanism?
The adult cannot produce offspring
What is allopatric speciation?
Populations of the same species become geographically isolated, thus resulting in speciation.
What is sympatric speciation?
A new species develops while inhabiting the same region.
How do loci in Hardy-Weinberg Equilibrium (HWE) differ from loci that are in Non-equilibrium?
HWE loci have no evolutionary agent acting on the population so the loci aren't changing. The frequency for A is constant.
Describe the 5 conditions that need to be met in order for a gene locus in a population to be in Hardy-Weinberg Equilibrium (HWE).
-large population size
- no gene mutation
-no natural selection
Explain the difference between analogous structures and homologous structures.
Analogous- two similar structures are found in organisms but they did NOT come from a common ancestor
Homologous- Come from the same evolutionary ancestor ex. Arm bones in a bird and bat both come from lobe fin fish ancestor
For geometric (discrete) population growth:
describe what it means that growth occurs in discrete, finite periods of time
Growth only occurs at certain intervals
What value does λ takes when N increases?
lambda > 1
What value does λ takes when N decreases?
lambda < 1
What value does λ takes when N stays constant?
lambda = 1
What value does λ takes when N goes extinct?
lambda = 0
For continuous (exponential) population growth
describe what it means that growth is asynchronous, and occurs in infinite periods of time
The population growth is exponential/continuous forever.
What value does r takes when N increases?
r > 0.00
What value does r takes when N decreases?
r < 0.00
What value does r takes when N stays constant?
r = 0.00
What value does r takes when N goes extinct?
r = any negative value
List the animal adaptations
1. Traits to absorb, retain, and release 2. Obtaining nutrients for low-caloric food 3. Obtaining oxygen 4. Obtain/conserve heat 5.Maintain osmotic (water) balance
If there is a high surface area:volume ratio then...
Better absorption, better dissipation
If there is a low surface area:volume ratio then...
Blood flow without a countercurrent heat exchange
The temperature of blood declines continuously as heat is lost to the environment as it flows in and out of the limb.
Blood flow WITH countercurrent heat exchange
The close proximity of the artery and the vein allows heat to be transferred from the warm arterial blood to the colder venous blood as it travels back into the body's interior, conserving heat.
Obtaining nutrients from low calorie foods
1. Long digestive tracts 2. Symbiotic microbial fauna 3. Accessory chambers (Mammals & reptiles)
1. Cutaneous respiration
Heat primarily from the external environment
Generate heat metabolically
Variable and ectothermic
Constant and endothermic
Variable, but ectothermic and endothermic
Behavioral temperature regulation
1. Sunning/shading 2. Sleeping it off
The dropping of body temperature to approximately ambient temperature for a part of each day regardless of the season. DAILY
The dropping of the body the body temperature to a near ambient temperature for a long period of time during the winter.
A period of inactivity/dormancy to avoid physiological stress of heat and drought.
Aquatic organisms that live in freshwater and gain water.
Aquatic organisms that lose water to their surroundings.
Organisms have the same osmotic pressure as seawater.
Processes that counter photosynthesis
1. Respiration 2. Transpiration 3. Photorespiration
Loss of carbon
Loss of water
Loss of carbon and water, Loss of oxygen
Leaf adaptations, Alternate photosynthesis pathways, Low nutrient and moisture, Too much water, Salt water
High specific leaf area characteristics
Thinner leaf, shade, bottom canopy
Low specific leaf area characteristics
Thicker leaf, Sun, top canopy
Nutrient stress in plants results in
slow growth and root allocation
Water stress in plants results in
Ethylene induced changes
Salt stress in plants results in
Solute change, excretion of salt, dilute cells
Gross primary productivity
the total rate of photosynthesis, or the energy assimilated by autotrophs
Net primary productivity
the rate of energy storage as organic matter after respiration (NPP = GPP - R)
the amount of organic matter present at any given time
Most productive aquatic ecosystem
Trophic efficiency (TE)
The ratio of productivity in a given trophic level to the trophic level it feeds on. Only 10 percent of the biomass in a given trophic level is converted to biomass at the next-higher trophic level
The ratio of assimilation to ingestion (A/l)
The ratio of production to assimilation (P/A)
The ratio of production to ingestion (P/I)
Rates of decomposition depend on
Quality, Temperature, Moisture, pH
Microflora involved in decomposition
Bacteria - animal material
Fungi - plant material
Some protists - animal and plant
Excreters involved in decomposition
Decomposed very quickly within the first few days
Proteins, simple sugars, soluble compounds
Decomposed more slowly and were completely broken down in three weeks
Cellulose and hemicellulose
The majority remained intact by day 80-- not easily decomposed
Formation of soil
Litter → Humus → Soil organic matter
Zone of primary production (water)
Zone of decomposition (water)
Nitrogen is available to plants in two forms
Nitrogen gas converted to inorganic nitrogen for assimilation
Ammonium (NH4+) is converted to NH3 as a waste product of microbial activity
Conversion of NH4+ to NO2- and then to NO3-
The chemical reduction of NO3- to N2O and N2
The preservation of biological diversity through the study of organisms and their environments
Direct Use Value
Value of a species that is harvested, used, consumed, or sold directly (entire organism or what it produces)
Indirect Use Value
Value of a species because of its ecological functions, or its importance to a species that has a direct use
Its value due to it NOT BEING HARVESTED
Habitat destruction and degradation
Native species that occur in a single geographic area and no place else
Large landscapes classified by dominant plant types, and have similar temperature and precipitation.
live for only a single year or growing season, then they fall off
Drought-deciduous leaves are lost in response to dry conditions
Winter-deciduous leaves are lost in response to low temperatures
live beyond a year
The broadleaf evergreen leaf is characteristic of environments with no distinct growing season, growth continues year-round
The needle-leaf evergreen leaf is characteristic of environments with a very short growing season or nutrient limitation
Limnetic (pelagic) zone
Open water that extends to the depth of light penetration, habitat of plankton and nekton
Profundal (Aphotic) zone
Beyond the depth of effective light penetration
Feed on the bacteria and fungi growing on coarse particulate organic matter (CPOM) while breaking it down
Filtering or gathering collectors
Feed on fine particulate organic matter (FPOM)
Feed on the algal coating of substrates
Burrow into waterlogged limbs and trunks of fallen trees
Insect larvae feed on the grazers and detrital feeders
High stream velocity adaptations
Flattened and broad
Low stream velocity adaptations
semi-enclosed parts of the coastal ocean where freshwater joins saltwater
Form brackish water
Unidirectional inflow of freshwater interacts with the inflowing/outflowing saltwater tides, setting up a complex of currents
little light, no photosynthesis
Complete darkness below mesopelagic zone
Form when cold seawater flows down through cracks in the basaltic lava floor and the waters react with the hot basalt → water becomes enriched with minerals (e.g., copper, iron, sulfur, zinc)
Rocky shoreline: Supralittoral / Supertidal zone
Lichens, land plants, terrestrial animals
Rocky shoreline: Littoral/ Intertidal zone
exposed part of the day
Oysters, mussels, gastropods, barnacles, brown algae (rockweed)
Rocky shoreline: Infralittoral / Subtidal zone
Brown and red algae "kelp" forests
Sea urchins and other echinoderms, fishes, sea mammals
cover 60 to 75 percent of the coastline of tropical regions
Mangrove forests develop where wave action is absent, sediments accumulate, and the muds are anoxic
Explain how the intrinsic rate of increase (r) is used to predict
-future population size
-change in population size
-population size at a specific time
r = birth rate - death rate
reports growth rate on a per individual level
it's what you multiply the current population size by to find change in population size
Explain how lambda is used to predict:
-future population size
-change in population size
-population size at a specific time
Lambda is the rate of change that the population size goes through. It's what you multiply the current population size by to get the future population size
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