Science Section 2 - Part 2 Flashcards
What field focuses on interactions between biotic and abiotic factors of a specific location?
ecosystems
Scientists calculate the number of species in an area PRIMARILY to understand the
degree of biological diversity
Roughly how many genes do humans have?
30,000 genes
What type of value assessment focuses on the benefit species give to humans?
instrumental value
Biodiversity primarily originates from
genetic variation
Traits such as body size and eye color contribute to an organism’s
phenotype
Genes are structurally organized in
chromosomes
A cross between a red snapdragon and a white snapdragon produces snapdragons with
pink petals
Info: Snapdragons with red petals have the AA genotype, and snapdragons with white petals have the BB genotype. A cross between these two flowers will result in progeny with an AB genotype that corresponds to pink petals.
Alleles of different dogs combine to cause variations in all of the following categories
color, size, temperament, shape
Not in species
New alleles arise through
mutations
Mendel conducted his genetic studies using
pea plants
Which of the following phenotypic distributions BEST describes the expected phenotypes of the F2 generation of a cross between smooth pea plants and wrinkled pea plants?
a. all pea plants have smooth peas
b. one wrinkled pea plant for every smooth pea plant
c. three wrinkled pea plants for every smooth pea plant
d. all pea plants have wrinkled peas
e. three smooth pea plants for every wrinkled pea plant
three smooth pea plants for every wrinkled pea plant
All of the following types of variation are types of genotypic diversity
within individual organisms, among species, among individuals within a population, among populations
Speciation through genetic divergence typically occurs through mechanisms at the level of a(n)
population
What term describes an organism’s ability to survive and reproduce?
fitness
Sickle-cell disease has a disproportionate effect on individuals from
Africa
To which disease does the sickle-cell disease allele confer resistance?
malaria
Charles Darwin worked as a naturalist for the HMS
HMS Beagle
Charles Darwin made all of the following observations EXCEPT
a. many species displayed phenotypic variation
b. all members within a species had the same fitness
c. very few offspring survived
d. more progeny were produced than the number of parents
e. there was evidence that some species had died out
all members within a species had the same fitness
In 1859, Charles Darwin published
The Origin of Species by Means of Natural Selection
The field of evolution defines adaptation as
optimization for a specific environment
Which response would an environmental scientist consider an adaptation?
a. A plant has waxy leaves to present water loss.
b. A dog pants to cool off.
c. A person puts on sunscreen to prevent skin cancer.
d. A bee flies towards a meadow to find food.
e. A tree drops some leaves to conserve water.
A plant has waxy leaves to present water loss.
Rapid environmental change such as that caused by humans MOST often causes species to
struggle to adapt
What evolutionary term BEST describes migration between populations?
gene flow
Which of the following examples leads to genetic drift?
a. A population of snakes decreases to twenty because of disease.
b. Increased selection pressure from hawks means only the fastest mice survive.
c. Geographic isolation leads one species to diverge into two.
d. An abundance of water allows more elephants to survive and reproduce.
e. Two populations of birds meet, and some birds from each population decide to mate.
Two populations of birds meet, and some birds from each population decide to mate.
The bottleneck effect in cheetahs resulted in cheetahs with the genetic similarity of
identical twins
What percentage of sperm from cheetahs have an irregularity?
70 percent
About how many years passed between the evolution of prokaryotes and eukaryotes?
1.8 billion years
Which of the following populations would evolve MOST quickly?
a. small, genetically consistent population under slow environmental change
b. large, genetically diverse population under rapid environmental change
c. small, genetically diverse population under rapid environmental change
d. large, genetically consistent population under slow environmental change
e. large, genetically consistent population under rapid environmental change
small, genetically diverse population under rapid environmental change
By definition, a fossil has been
buried
The deepest layer of the fossil record contains the
oldest fossils
What did scientists use to organize the geologic time scale?
fossil record
The first instance of bacteria in the fossil record occurred
3.5 billion years ago
What organisms exists in both the fossil record and the present day?
ginkgo tree
What volcanic eruption contributed to the largest known mass extinction in Earth’s history?
Siberian Traps erupted at the end of the Paleozoic Era
The mass extinction responsible for the end of the dinosaurs occurred in the
K-T boundary, which delineates the transition from the Cretaceous Period to the Tertiary Period, saw the extinction of the dinosaurs.
What concepts describes the positive relationship between available habitat and number of species supported?
species-area relationship
Species richness describes the
economic impact of a species
How many mass extinctions happened in the past 450 million years, not including the current mass extinction?
five
How many years passed before biodiversity recovered in previous mass extinctions?
ten million to 100 million years
What term BEST describes how humans contributed to the extinction of the dodo?
overexploitation
Fragmentation has all of the following effects EXCEPT
a. reducing genetic drift in populations
b. increasing habitat on an edge
c. reducing continuous habitat space
d. inhibiting movement for feeding and mating
e. reducing gene flow between populations
reducing genetic drift in populations
What organisms gains the GREATEST benefit from habitat fragmentation? small mammals, mountain lions, raccoons, skunks, plants, birds
Raccoons and skunks tend to live on forest edges, which increase in number with habitat fragmentation
In which decade did the zebra mussel arrive at the Great Lakes?
1980s
The field of ecology consists of the study of how
organisms interact with the environment
An individual organism’s survival in a certain environment depends most on the
abiotic conditions of the habitat
Ecologists define conditions as
chemical and physical determinants of survival and growth
What condition affects terrestrial systems to a large extent?
phosphorus levels, solar radiation, temperature, precipitation, and nutrient availability
What conditions have a large impact on aquatic environments?
oxygen gradients, salinity, temperature, and light from the sun
How are organisms distributed across environmental conditions?
Every environmental condition supports at least some organisms.
The baobab tree originates from
East Africa
To describe the two abiotic conditions most responsible for species distribution, scientists created the index of
evapotranspiration
A species’s range of tolerance describes the
environmental conditions where a species can survive
How do resources differ from conditions?
Organisms use up resources, while conditions do not become unavailable
Large salt marshes exist in the
eastern coast of the United States
Which percentage of salt marsh biomass consists of only a few species?
95 percent
A graph of population size over a range of environmental conditions most resembles a
bell curve
What factor of a salt marsh would scientists classify as a resource for the grasses?
oxygen, so the grasses can conduct photosynthesis
Which factor MOST strongly predicts the extinction of a species?
a. abundance of food resources
b. small population size
c. increased human activity
d. limited genetic diversity
e. habitat loss
small population size
An intraspecific interaction consists of interactions between
individuals in the same population
What organism did Georgy Gause use to study density-dependent growth?
Paramecia
Georgy Gause studied the growth of organisms with
sufficient resources, optimum environment, and limited space
Limits on factors influencing density-dependent growth cause populations to grow following a(n)
logistic growth model
The logistic growth model does NOT operate under the assumption that
a. populations receive unlimited space and resources
b. population density and growth rate have a linear relationship
c. population density measurements use appropriate units
d. the distribution of ages stays the same across population sizes
e. population growth rate changes immediately in response to changes in population density
populations receive unlimited space and resources
How many years pass in each cycle of the whooping crane growth curve?
10 years
The manager of a commercial fishery seeks to produce the
maximum sustainable yield
Which biologist created a logistic growth model to establish limits on fishing in 1935?
M. Graham
What location held the fishery with the highest yield until 1972?
Peru, an anchovy fishery with estimated sustainable yield of 10 million anchovies per year
What event caused environmental changes that disrupted anchovy populations?
El Niño
What factors are density independent?
hurricanes, fires, floods, volcanic activity
Davidson and Andrewartha studied the effect of plant availability on the population size of
Thrips imaginis
What term describes a population with geography-based subgroups?
metapopulation
What factors contributes to extinction in a deterministic way?
limitations on space
What species of Paramecium served as the subjects of Georgy Gause’s 1934 study?
P. caudatum and P. aurelia
Gause’s isolated cultures of Paramecium grew to a high density in
10 days
All of the following factors can become a limiting resource EXCEPT; temperature, space, food, oxygen, soil nutrients
temperature
What principle outlines the concept that two species cannot share a limiting resource?
competitive exclusion
Info: Competitive exclusion states that competition between species for a limiting resource will result in the extinction of one species
What plant naturally outcompetes barley crops in the Great Plains?
wild oats
Ecologists define a niche as
a species’ job in a community
How do ecologists generally define predation?
using another species as a resource
All of the following warblers use niche partitioning to survive off of spruce trees EXCEPT
a. Blackburnian warbler
b. black-throated green warbler
c. willow warbler
d. myrtle warbler
e. Cape May warbler
willow warbler
Which adjective BEST describes predation?
a. intraspecific
b. mutualistic
c. density-independent
d. density-dependent
e. commensalistic
density-dependent
What aspect of ecology can scientists study MOST easily in a laboratory environment?
predator-prey cycles
How long must scientists collect data to study natural predator-prey cycles?
several decades
The direct relationship between prey and predator densities contributes to
the numerical response, describes the tendency of predator density to relate directly to prey density.
Which of the following scenarios exemplifies the functional response?
a. Bird populations decrease because insect population densities decrease.
b. A tree sheds its leaves to prevent water loss during the dry season.
c. A population of honeybees only pollinates one species of wildflower.
d. As beetle populations decrease, birds start to eat crickets instead of beetles.
e. Hummingbirds evolve longer beaks to reach the nectar in a flower.
As beetle populations decrease, birds start to eat crickets instead of beetles.
What do ecologists call mutualism?
reciprocal exploitation
How many species of fig trees exist?
900
Info: Each fig tree species has a mutualistic relationship with a separate type of fig wasp
Communities consist of
several populations coexisting in one habitat
Food webs do NOT
typically collapse with the loss of any species in the food web
Which description BEST defines keystone species?
a. native species in a community
b. species with low relative abundance but high community impact
c. the most abundant species in a community
d. species with the greatest level of genetic diversity in a community
e. key energy producers in the community
species with low relative abundance but high community impact
What organism controlled Mytilus populations in the Pacific Coast intertidal community?
Pisaster, a sea star
Info: The sea star Pisaster maintained populations of Mytilus mussels in the Pacific Coast intertidal, making Pisaster a keystone species. Without Pisaster, eight additional species died out because of competition with the mussels.
In the Greater Yellowstone food web, pine martens consume
pika, Pacific tree frongs, and Douglas’s squirrels
Scientists classify species with high proportions of biomass and a large impact on a community as
dominant species
What animals are keystone pollinators of the South Pacific islands?
Old World fruit bats, also called flying foxes
What keystone species affects the community through mutualism with another species?
mycorrhizal fungi, grow on the roots of trees, promoting tree growth by improving how trees obtain nutrients.
Species replace others in a community over time in the process of
succession
What event leads to primary succession?
glacial scouring or volcanic eruption, which causes the land to lose its soil surface
Scientists once described the last stage of succession in a forest with the obsolete term
climax forest
To which state would an ecologist travel to study Organ Cave?
West Virginia
What organism lives part-time in Organ Cave?
bats, they sleep in Organ Cave
Crayfish, isopods, and amphipods inhabit the cave all of the time
Ecologists study Organ Cave as a(n)
input-output system for water and energy
In ecology, the First Law of Thermodynamics indicates that
the energy within carnivores cannot exceed the energy within herbivores
What equations describes the overall process of photosynthesis?
CO2 + H2O + Sun energy → CH2O + O2
Primary productivity consists of
the rate of biomass production
Net primary productivity accounts for
energy used for respiration
Primary producers typically have an energy efficiency of
1 percent
The term “trophic level” comes from the Greek word for
nourishment
If the grass in a field with ten percent transfer efficiency has a biomass of 1,000 g/m2, the secondary consumers in the field will have a biomass of
10 g/m2
What diagram BEST shows how much energy moves between trophic levels?
ecological pyramid
Who co-founded a project to research the Hubbard Brook ecosystem?
Gene Likens
In a grassland ecosystem, frogs are a
secondary consumer
Ecosystems differ from populations and communities in that ecosystems
are self-contained
Why can scientists identify aquatic ecosystems more easily than terrestrial ecosystems?
Aquatic ecosystems have a clearer boundary between land and water.
Scientists consider all of the following events disturbances
clearing land for agriculture, a large hurricane, natural forest fires, sudden ice storms
Ecologists define resilience as
an ecosystem’s ability to recover
Ecosystems with no disturbances are MOST likely to
have one dominant species
Ecologists define biomes as
regions with distinct types of species
What drives the circulation of water and air around the planet?
solar energy flux
Why do certain regions of the Earth receive more solar energy than others?
Sunlight hits different locations at different angles, so energy distribution over a certain surface area varies
What term describes the cycle of air from the equator to 30 degrees north or south of the equator?
Hadley cell
Scientists describe atmospheric circulation in the west-east direction with the term
Coriolis effect
In what direction do oceanic currents of the Northern Hemisphere move?
clockwise
What biome exists at the lowest levels of precipitation and coldest annual temperatures?
tundra
The majority of vegetation found in tropical dry forests consists of
deciduous trees
Scientists have identified temperate broadleaf forests in all of the following regions
southern Canada, Europe, eastern United States, and eastern Asia
BUT NOT in southern Africa
The common name for a grassland in central Asia is
steppe
What percentage represents the highest typical level of desert productivity relative to tropical rainforests?
5 percent
What organism produces MOST of the energy available to freshwater communities?
phytoplankton
What percentage of the Earth consists of ocean?
71 percent
At what depth does the ocean contain the most biodiversity?
2,000 to 3,000 meters
Scientists classify all of the following regions as freshwater wetlands
marshes, peatlands, bogs, and swamps
Of an organism’s dry weight, macronutrients typically make up at least
0.1%
Micronutrients include all of the following elements
boron, manganese, iron, and molybdenum
What phenomenon consists of the movement of elements throughout the biosphere?
biogeochemical cycles
What elements has the GREATEST effect on plant productivity?
nitrogen and carbon
Plants lose water through their leaves in the process of
transpiration
What energy source drives the hydrologic cycle?
solar energy
What time period BEST represents the mean residence time of water on land?
403 years
Info: Terrestrial water, found on land and in animals, has a mean residence time of 403 years. [
What process DOES NOT drive the carbon cycle?
evapotranspiration
Info: Photosynthesis, respiration, decomposition, and combustion drive the carbon cycle.
What process describes the use of carbon dioxide to create plant tissues?
carbon fixation
How does respiration differ from combustion?
Combustion is abiotic, while respiration is biotic.
How has human activity affected the carbon cycle?
Human activity moved the carbon cycle out of a steady state.
What human practice negatively affects the carbon cycle?
slash-and-burn agriculture
Organisms need nitrogen because of its importance for
amino acids
What percentage of the Earth’s atmosphere consists of nitrogen?
78%
What process follows ammonification in the nitrogen cycle?
nitrification
Info: The process of nitrification uses ammonium from ammonification to create nitrite, then nitrate. Plants rely on nitrate as a crucial nutrient.
All biodiversity ultimately derives from
genetic diversity
What MOST commonly explains why individuals often fail to express a certain trait despite carrying the allele for that trait?
Some alleles are dominant over others.
All of the following processes are evolutionary mechanisms EXCEPT
a. natural selection
b. succession
c. gene flow
d. genetic drift
e. adaptation
succession
How many “known” species exist today?
1.8 million known species
How do scientists typically measure the current extinction rate?
by estimating habitat loss
Population ecology is the study of the
abundance and distribution of species
What population regulators is density-independent?
extreme weather
What role do green plants and algae play in a food web?
producers
Why would the extinction of a single species most likely NOT affect the long-term health of the entire community?
Other species in the same trophic level can fulfill the role of the extinct species.
Which two factors play the MOST important role in controlling the formation of biomes?
temperature and moisture
How many major types of terrestrial biomes exist?
10
Wetlands, lakes, and rivers are all examples of
freshwater environments
Why is nitrogen important for life on Earth?
It is a critical component of DNA and proteins.
