Science Section II Flashcards
Science
What is evolution and biodiversity?
genetic variation resulting in environmentally adaptive traits has resulted in a diverse number and types of species
What is community ecology?
how populations of species grow, disperse, and interact with other populations
What are ecosystems?
the integration of living and nonliving system components in specific geographic areas
What are biomes?
variation in global patterns of temperature, sunlight, and rainfall create geographic regions distinguished by different dominant forms of plants and animals
What are global energy and matter cycles?
global biogeochemical cycles on which all ecosystems depend on
What is the most common measure of biological diversity?
the number of different species in a certain area
What is Earth’s large number of species a result of?
a large amount of genetic diversity in species
What is genetic diversity?
the variety of genes
What are genes?
the chemical building blocks that provide the blueprint for how every individual organism grows
About how many different genes do all humans have combined? (referring to types of genes)
30,000
What is the exception to the fact that no 2 people will have the exact same combination of genes?
identical twins
What are species distinguished by at the most basic level?
how different their genes are
What is the ultimate source of biodiversity on Earth?
genetic diversity
The genetic differences between individuals in the same species can lead to what?
physical variety, such as in eye color, lead arrangement, or beak size
What are changes in the blueprint of a species over time?
evolution
Why do bears today have little resemblance to their ultimate ancestor?
this is due to evolution
What do you need to understand to learn how genetic diversity leads to species diversity?
the basic principles of genetic diversity
Where do all organisms inherit their genes from?
their parent(s)
Genes contain most/all of the instructions for which types of traits?
relatively simple traits
What do more complex traits require to produce?
the interaction of more than one gene
What is a phenotype?
the trait that is the result of a genotype
What is a genotype?
the genetic code for an organism
What is an organism’s genotype comprised of?
all of an organism’s genes
What are genes chemically made up of?
DNA
Genes are arranged within an organism’s cells on structures called ________________.
chromosomes
Genes have alternate forms that have different instructions for what the phenotype will be, the alternate forms are called _________.
alleles
If a gene in a population has 2 alleles, how many potential combinations are there for the genotype?
3
If an individual has 2 copies of a gene (B and b) what are the potential gene combinations?
BB, Bb, and bb
What is the dominant allele for Bb?
B is the dominant allele
What is the dominant allele for BB?
both are dominant
What is the dominant allele for bb?
there is no dominant allele
Is it possible to measure all the different alleles for a particular trait that occurs in a population?
No, it is impossible
What is Canis familliaris?
the domestic dog
Why do people breed certain breeds of the domestic dog?
to produce desired traits
What causes variations in size, shape, coat texture, color, and more in the domestic dog?
different combinations of alleles in different dog breeds
What is the only way a new allele can be produced?
through a mutation
What is a genetic mutation?
an error when genetic material is copied, and can permanently alter the genotype of an organism and its descendants
When do mutations occur?
randomly and spontaneously
When are mutations more likely to occur?
when an organism is exposed to anthropogenic chemicals, ex: those in tobacco smoke or radiation
Where does the mutation have to occur to be passed down to an organism’s offspring?
its sex cells
If there are many different alleles for a particular trait, will there be a small or large amount of genetic variation in the population?
a large amount
Do large or small populations usually have more genetic variation?
large populations usually have more
Why do larger populations have more genetic variation?
because there is a higher likelihood that the population has more alleles due to its size
In simple cases, what is a phenotype?
an expression of the genotype
In complex cases, what is a phenotype?
the result of the interaction between the genotype and its environment
What is the formula for phenotype? (complex)
Phenotype = Genotype + Environment
What 2 types of processes does species diversity result from?
adaptive and nonadaptive processes
How do most new species arise?
when the genotypes and phenotypes of two or more populations diverge through processes at the population level
How will a frog with longer legs compare with a frog with normal legs?
the frog with longer legs will be able to jump farther, allowing it to catch food more easily, thus increasing its fitness
What is fitness?
a measure of the relative viability and fertility of an organism
What is viability?
the ability to survive
What is fertility?
reproductive success
Harmful alleles tend to what?
die out with the individuals that carry them
Sickle–cell disease is an example of what?
harmful alleles
What is sickle–cell disease?
a disease that reduces the oxygen capacity of blood
What effects does sickle–cell disease have on humans?
it results in many severe mental and physical impairments, usually death
Sickle–cell disease occurs in people of __________ descent.
African
What is a benefit of sickle–cell disease?
it provides resistance to malaria
In Africa, there are many deadly diseases, but the most deadly disease is __________.
malaria
How many copies of the allele are necessary to produce sickle–cell disease?
2
What will happen if an organism has one allele for sickle–cell disease?
it will not develop the disease but will have some natural resistance against malaria
Who synthesized the concept of evolution through natural selection into a unifying theory?
Charles Darwin
When did Darwin make his observations about natural selection?
when he was aboard the HMS Beagle
What was the name of Darwin’s natural selection theory when he published it?
The Origin of Species by Means of Natural Selection”
When did Darwin publish his natural selection theory?
in 1859
What are the key ideas of Darwin’s theory of natural selection?
- Organisms produce more offspring than needed to replace parents
- Individuals will express a range of phenotypes
- Some phenotypes will allow an organism to be more fit than others in their environment
- The more fit individuals will have a better chance of reproducing, they will be selected and well–established
What does Darwin’s theory mainly explain?
why do individuals with certain traits survive and reproduce
What is an adaptation?
a trait that helps an organism become more fit for a particular environment
Will a species with more genetic variation adapt faster or slower than one with little genetic variation?
it will be able to adapt faster
What are the fastest ways to adapt to an environment?
changes in behavioral or physiological responses
Panting of a dog or a human sweating are adaptations that allow the organism to do what?
cool off
Plants dropping their leaves at the beginning of a dry season allows them to do what?
conserve water
When do short–term responses fail?
when an environment changes too much
As environments undergo major changes, what will happen to the species?
they will either die out or adapt through natural selection
Thick, fleshy leaves with thick, waxy surfaces allow a plant to do what?
conserve more water
The ability of a species to adapt to environmental changes depends on what?
how much and how fast that change occurs
Much of the current environmental change caused by humans is ____________ and _____________.
dramatic and sudden
What occurs when organisms from one population migrate to and mate with another population?
gene flow
In which species do high rates of gene flow occur?
species with much dispersal of individuals
Most populations are relatively ____________.
isolated
Genetic isolation in most species is an issue in what?
the maintenance of biodiversity
What type of adaptive process is genetic drift?
a nonadaptive process
What is genetic drift?
random changes in genotypes among small populations
The bottleneck effect is a type of __________ ________.
genetic drift
What is the bottleneck effect?
when a population is drastically decreased
What are the causes of the bottleneck effect?
hunting, habitat loss, a natural disaster, or changes in the environment
Increased disease and low fertility are problems linked with what?
low genetic variation
Why have cheetah populations decreased so much?
because of hunting and habitat loss
The cheetah population is so small, all cheetahs are basically what?
identical twins
Cheetahs tend to have _____ fertility and _____ rates of disease.
low, high
What percent of male cheetahs have abnormal sperm cells?
70%
The only reliable studies have been conducted with which cheetahs?
zoo cheetahs
Do we know if cheetahs in the wild have reduced fitness?
No, because there haven’t been any reliable studies on them
How long can a significant change in a species genotype take?
hundreds to thousands of years
Smaller scale evolutionary changes can occur over a much ___________ time scale.
shorter
How many factors are important influences on the pace of evolution by natural selection?
3
What is the first factor that influences the pace of evolution by natural selection?
the rate of environmental change to which a species must adapt
What is the second factor that influences the pace of evolution by natural selection?
the genetic variation of a population, more genetic variation usually results in less time but the accumulation of mutations takes a lot longer
What is the third factor that influences the pace of evolution by natural selection?
adaptive traits can spread faster in small populations than in larger ones
Small populations are likely to undergo rapid evolution by which processes?
nonadaptive processes, such as genetic drift and bottlenecks
Do we know the actual number of species on Earth?
No
What does the total number of species in the world today equal?
the species that evolved over time minus the species that no longer exist
What happens when the environment changes so that a population is no longer adapted to it?
its growth rate becomes negative and will eventually reach zero
How can a population save itself when the environment changes?
it can either adapt or migrate to an environment it can succeed in
Is there always a favorable environment for a population?
No
Organisms that can’t adapt to environmental change will eventually go __________.
extinct
What is most of what we know about the evolution of life, based on?
fossils
What are fossils?
the remains of dead plants and animals that have been preserved in rock
What parts of an organism are usually fossilized?
typically the hard parts of an organism, and sometimes softer organic material
How can soft organic material get fossilized?
it is buried and protected by mud and sediment, over time it will harden
Where are the oldest fossils found?
at the deepest layers of Earth and the fossil record
What is the basis of the geologic time scale?
the fossil record
What does the geologic time scale divide time into?
various intervals from the formation of the Earth to the present
What characterizes the intervals in the geologic time scale?
distinctive events
When did bacteria appear in the fossil record?
3.5 billion years ago
When did multicellular and shelled organisms appear in the fossil record?
540 million years ago
From when can we trace identifiable species?
1–10 million years of the fossil record
When were mammalian species found in the fossil record?
1 million years ago
When were clams and marine species found in the fossil record?
10 million years ago
Do organisms found in the fossil records usually exist today?
No
What is the example given in the book for a species that was found in the fossil record and still exists today?
the ginkgo tree
Where is the ginkgo tree found?
in China and some parts of the US (in the US it is commonly used as an ornamental tree)
When did the ginkgo tree appear in the fossil record?
roughly 60 million years ago
How did the Dodo become extinct?
through overexploitation by European settlers and invasive species competing with them for food
Why were the Dodo hunted so much?
because they were large, flightless birds, basically an easy source of meat
What are Dodo birds?
large, flightless birds
When did European settlers start overhunting the Dodo bird?
during the 17th century or 1600s
Where was the Dodo bird hunted?
the Indian Ocean Island of Mauritius
What is habitat fragmentation?
the splitting up of habitats into smaller pieces
The construction of roads housing development, or shopping/industrial centers is an example of what?
habitat fragmentation caused by humans
Habitat fragmentation reduces the area of what?
contiguous habitat
What are the effects of reducing the area of contiguous habitat?
it creates barriers to the normal movement of a species
The mountain lion, wolf, and tiger all require what type of land?
large tracts of relatively uninhabited undisturbed land
Fragmentation creates more habitat that is along a(n) ________.
edge
What does increased edge habitat cause?
a change in the species composition of the habitat overall
Since there is more edge created, the inner portions of something like a forest are now closer to the outside, causing what?
causing organisms to penetrate into the forest more easily, resulting in them eating organisms that would have been safer without the edge
How does habitat fragmentation affect the size of the population?
it can divide the population into several smaller populations
How will the gene flow of the smaller populations caused by habitat fragmentation be affected?
it will be greatly reduced as the population will become genetically isolated and may lose genetic variation through genetic drift
What are exotic species? (we call them invasive species)
organisms that are introduced by people to an area they are not native to
While moving things from place to place, what have humans brought to new continents and areas?
diseases and new species
The zebra mussel is an example of what?
an exotic species
Where is the zebra mussel native?
the Caspian Sea in Asia
Where did the zebra mussel first enter the US?
through the Great Lakes
How was the zebra mussel brought to the US?
through a ship
When was the zebra mussel brought to the US?
the 1980s
Does the zebra mussel have any known predators in North America?
no
How has the zebra mussel population grown in North America?
exponentially
Where in North America has the zebra mussel population grown?
the Eastern US and Canada
What has the zebra mussel done to its environment?
depleted food supplies, clogged water intake valves, and caused many other problems
When an exotic species enters a new area, what might it encounter?
an unexploited resource they can rapidly utilize
What happens to the populations of exotic species due to the fact that they have no natural predators in this new environment?
they grow rapidly and there is usually nothing to stop it
What do we need to know to fully explore the patterns of biodiversity?
how species distribution and abundance is limited by its environmental conditions
What is ecology?
the study of the relationship between organisms and their environment
What do relationships include in this context?
the adaptation of an individual’s physiology to environmental extremes, the killing and eating of prey, and the flow of carbon through an environment
To study such a diversity of natural phenomena, ecologists have divided the science into what?
a hierarchy from individuals to large–scale ecological systems
Different processes have what kind of effects on biodiversity?
different effects
What 3 things are critical to an organism’s survival in an environment?
its abiotic environmental conditions. the availability of resources, and a habitat for it to live in
What are conditions?
the chemical or physical factors in the environment that influence survival and growth
What do conditions determine?
which species and communities flourish in some habitats compared to others
For terrestrial systems, what determines the absence or presence of certain species?
the availability of light from solar radiation, temperature of air and soil, soil type, and amount of nutrients
Conditions for terrestrial systems vary depending on what?
location, or latitude and elevation
In aquatic systems, what determines the absence or presence of certain species?
temperature, available light from solar radiation, gradients in the amount of oxygen dissolved in the water, salinity, acidity
Conditions for aquatic systems vary depending on what?
depth of the water, the location in a stream, latitude, elevation, and more
What are the main locations in a stream?
upstream, midstream, and downstream
Under optimal environmental conditions, how will the species live?
they will thrive, or survive, grow, and reproduce
What happens as conditions become less optimal?
they will grow and survive, but might not reproduce
What happens when conditions become so bad they can barely live?
they will barely survive and will not reproduce but might grow
What is the range at which a species can exist?
its range of tolerance
Food, water, light, and oxygen are all examples of __________.
resources
What are resources?
aspects of the environment used to stay alive
The amount of available resources is important to which levels of ecology?
all levels of ecology
Can a habitat with a large amount of resources support a lot of species or just a few?
they can support a lot of species
What is the direct correlation between the amount of resources and the number of species?
suprisingly, there is very little correlation between the two
Where does the explanation of the little correlation between the amount of resources and the number of species lie?
the varied abilities of individual organisms to use resources under various abiotic environmental conditions
If a habitat has a large amount of resources but very extreme abiotic environmental conditions, will there be a lot of organisms that live there?
No, only the ones that are adapted to withstand these conditions can survive there
The large salt marshes that extend along the easter coast of the US from Georgia to Cape Cod are an example of what?
areas with a large amount of resources but very harsh environmental conditions
Salt marshes act like a ____________ _______ for large amounts of nutrients caught from the flow of rivers.
storage tanks
Do salt marshes produce high or low levels of biomass?
high levels
Is the vegetation within salt marshes diverse?
No
Is the vegetation within salt marshes abundant?
Yes
A few grass species make up what percent of salt marsh biomass?
over 95%
Why do only certain grasses dominate salt marshes?
because of only those species can process the nutrient–rich resources under the extreme environmental conditions
What causes the extreme environmental conditions in salt marshes?
fluctuation in salt concentrations throughout the year, low oxygen levels in the soil, and large amounts of toxins
How do salt concentrations increase in salt marshes?
through rapid evaporation
How do salt concentrations decrease in salt marshes?
through rapid flooding and heavy rains
What causes the low oxygen levels in the soil of salt marshes?
a high level of microbial decomposition that takes place, which uses lots of oxygen
What is another side effect of high microbial decomposition in salt marshes? (other than low oxygen)
it also produces large amounts of toxins
