Dos Flashcards
What is biodiversity?
Biodiversity describes different combinations of living and nonliving components in varied environmental systems.
What is genetic diversity?
Genetic diversity is the ultimate source of biodiversity on Earth, distinguished by the genetic differences among individuals.
What is the relationship between genetic diversity and species diversity?
Genetic diversity leads to species diversity through changes in genotype over time, resulting in the emergence of new species.
Define phenotype.
Phenotype consists of all anatomical, physiological, and behavioral characteristics of an organism.
Define genotype.
Genotype is an organism’s unique genetic composition and the code for its phenotype.
What are alleles?
Alleles are alternative forms of a gene that contain different instructions for what the gene will produce.
In pea plants, what phenotype does the BB genotype produce?
Purple flowers.
In pea plants, what phenotype does the bb genotype produce?
White flowers.
What causes the production of new alleles?
Mutations caused by errors when genetic material is copied.
How does genetic variation relate to population size?
Large populations usually have more genetic variation than small populations due to a higher likelihood of different alleles.
What is fitness in evolutionary terms?
Fitness is a measure of an organism’s relative viability and fertility.
True or False: The allele for sickle-cell disease can convey resistance to malaria.
True.
What is adaptation?
Adaptation is the process of becoming most fit or suited for a particular environment.
List the key ideas of Darwin’s theory of natural selection.
- Organisms produce more offspring than needed
- Individuals express a range of phenotypes
- Some phenotypes enable better survival
- More fit individuals are more likely to reproduce.
What happens during the bottleneck effect?
A drastic decrease in population size reduces the number of different alleles present.
What is gene flow?
Gene flow occurs when individuals from one population migrate to another, introducing new alleles.
Fill in the blank: The observable characteristics associated with an organism’s genotype is called its _______.
[phenotype]
What is the relationship between genotype and environment in determining phenotype?
Phenotype = genotype + environment.
What is the significance of mutations in evolution?
Mutations can introduce new genetic variations, which may be beneficial, neutral, or harmful.
What is the primary role of natural selection in evolution?
Natural selection favors individuals with traits that enhance survival and reproductive success.
How do physiological responses relate to adaptation?
Physiological responses help organisms tolerate environmental changes without evolving new adaptations.
What is the impact of rapid environmental changes on species?
Rapid changes may exceed a species’ ability to adapt, leading to extinction.
Define nonadaptive evolutionary processes.
Nonadaptive processes, like genetic drift and gene flow, can lead to evolution without the influence of natural selection.
What is genetic drift?
Random changes in genotypes among small populations that can lead to evolution.
What is the consequence of losing the B allele in a population?
The B allele will be lost in just one generation, leading to genetic change and changes in phenotypes over time.
What is the bottleneck effect in genetics?
A drastic decrease in population size due to events like hunting or natural disasters, resulting in reduced genetic diversity.
What correlation has been found regarding low genetic variation in populations?
Low genetic variation is correlated with increased risk of disease and low fertility.
Which animal is a well-known example of low genetic variation due to population decline?
The cheetah.
How does the pace of evolution vary based on environmental change?
Rapid environmental change forces populations to evolve quickly, while slow changes allow for gradual evolution.
What influences the pace of evolution by natural selection?
Three factors: rate of environmental change, amount of genetic variation, and population size.
What happens to a population if it cannot adapt to environmental changes?
The population’s growth rate becomes negative, leading to extinction.
What is the significance of the fossil record?
It provides knowledge about the evolution of life and past species, including extinction events.
What does the geologic time scale represent?
It divides time into intervals marked by significant evolutionary events.
When do mass extinctions occur?
During periods when large numbers of species die in a short time interval.
What was the greatest mass extinction event?
The end of the Paleozoic Era, where 90-95% of marine species went extinct.
What is believed to be causing the current mass extinction?
Human activities leading to habitat destruction.
What is habitat fragmentation?
The process of breaking up large habitats into smaller, isolated sections.
How does habitat fragmentation impact species?
It reduces habitat area, creates barriers for movement, and divides populations, leading to genetic isolation.
What are exotic species?
Species that are introduced to an area by humans, either deliberately or accidentally.
What is a significant consequence of introducing exotic species?
They may thrive in new environments, often outcompeting native species.
What are the three critical factors for an individual organism’s survival in an environment?
Abiotic environmental conditions, availability of resources, and suitable habitat.
What are abiotic environmental conditions?
Chemical or physical factors influencing survival and growth, such as temperature and precipitation.
What role does the fossil record play in understanding extinction?
It provides evidence of species that have gone extinct and insights into past environmental states.
Fill in the blank: The rate of _______ change is a significant factor influencing the pace of evolution.
[environmental]
What are the major conditions that determine which species flourish in terrestrial habitats?
The availability of light, temperature, precipitation, soil type, and nutrient quantity such as nitrogen or phosphorus
These conditions vary with latitude and elevation.
What is the range within which a species can live called?
Range of tolerance
What are resources in the context of ecology?
Aspects of the environment that individuals use to stay alive, such as food, water, light, and oxygen
How do resources differ from environmental conditions?
Resources are consumed and become unavailable to others, while environmental conditions are factors that affect species without being consumed.
What is competitive exclusion?
The principle that if two species compete for the same limiting resource, one will succeed and the other will go extinct.
What is the ecological niche?
The role of an organism within a community—what it does and how it lives.
What occurs during interspecific competition?
Individuals of different species share a limiting resource.
What are the three general ways populations of different species interact?
- Interspecific competition
- Predation
- Mutualism
What is predation?
The use of one species as a resource by another species, including herbivory and parasitism.
What is mutualism?
A type of interaction that increases the survival probability or reproduction of both species involved.
What is the difference between symbiotic mutualism and general mutualistic interactions?
Symbiotic mutualism involves one animal species pollinating only one plant species, while general mutualistic interactions involve multiple species benefiting from each other.
Define a community in ecology.
An assemblage of populations in a particular area or habitat.
What does a food web summarize?
The species that make up a community and the ways they are linked by various predator-prey interactions.
What are trophic levels?
The feeding positions in a food chain or web.
What is a keystone species?
A species that plays a crucial role in its community that is disproportionate to its abundance.
List the three types of keystone species.
- Predators
- Ecosystem engineers
- Mutualists
What is an example of a keystone predator?
Sea otters, which control the population of sea urchins.
What role do ecosystem engineers play?
They create or maintain habitats for other species.
What is an example of a mutualist keystone species?
Mycorrhizal fungi that enhance nutrient extraction for trees.
What are the three important aspects of an ecosystem?
- The ecosystem’s boundary
- The organisms within the ecosystem
- The abiotic components of the environment
What is the definition of an ecosystem?
An ecosystem is a spatially explicit unit of the Earth that includes all organisms and abiotic components within its boundaries.
This definition emphasizes the importance of boundaries, biotic components, and abiotic components.
What are the three important aspects of an ecosystem?
- The ecosystem’s boundary
- The biotic component
- The abiotic component
The abiotic components include temperature, water, salinity, soil structure, and mineral nutrients.
How does an ecosystem differ from individuals, populations, and communities?
An ecosystem contains all living and nonliving parts required for long-term existence, while individuals, populations, and communities depend on other organisms for food and habitat.
What is the major process involving energy flow in ecosystems?
The flow of energy from the Sun through the abiotic and biotic components.
This process is essential for the functioning of ecosystems.
What materials cycle through ecosystems?
- Water
- Carbon
- Nitrogen
- Phosphorus
These cycles are crucial for both global environments and individual ecosystems.
What characterizes the boundary of aquatic ecosystems?
The boundary typically corresponds to the boundary between land and water.
How do scientists estimate the boundary of terrestrial ecosystems?
By the range of the populations that make up the biological community or by particular ecological processes.
What is an energy pyramid?
A model that represents the flow of energy from producers to different levels of consumers, with energy decreasing as one moves up the pyramid.
What is a disturbance in an ecosystem?
A process in which physical, chemical, and biological agents cause rapid injury or death of organisms and damage to the biotic component.
List examples of natural disturbances.
- Hurricanes
- Ice storms
- Natural forest fires
These disturbances can significantly impact ecosystems.
What is the difference between a disturbance and a perturbation?
A disturbance causes rapid changes in an ecosystem, while a perturbation refers to any change to the normal or equilibrium state.
Define resilience in the context of ecosystems.
Resilience is the rate at which an ecosystem returns to its original state after a disturbance.
What are biomes?
Major regions of differing vegetation and wildlife types correlated with mean annual temperature and precipitation.
What biome is known for high plant and animal diversity?
Tropical rainforest.
It is characterized by high productivity but poor soils.
What are key elements of temperate rainforests?
- Tall coniferous trees
- Mild winters
- Heavy rain
- Rich organic matter in soils
What defines boreal coniferous forests?
Forests dominated by conifers with low plant species diversity and large mammal species like moose and bears.
What is the primary vegetation in grasslands?
Grasses, with productivity about one-third of that found in tropical rainforests.
Fill in the blank: The wettest and warmest biome is the _______.
[tropical rainforest]
What are the two major types of aquatic systems?
- Freshwater
- Marine
Aquatic ecosystems include flowing and standing waters.
What is a major limiting factor of marine ecosystems?
The low nutrient content of surface waters despite sufficient light for photosynthesis.
What are wetlands?
Transitional areas between terrestrial and aquatic environments, including salt marshes, bogs, swamps, and intertidal areas.
What are biogeochemical cycles?
Cycles in which elements continually cycle within the biosphere, soils, and water as organisms grow, die, and decompose.
How have human activities altered biogeochemical cycles?
By releasing excess amounts of elements into the atmosphere, soil, or water, affecting ecosystems and landscapes.
What can result from the release of nitrogen and phosphorus from fertilizers?
Over-fertilization of natural ecosystems.
What are biogeochemical cycles?
Cycles that involve the movement of elements between the biosphere, soils, and water as plants and animals grow, die, and decompose.
What human activities can alter biogeochemical cycles?
Activities that release excess amounts of an element into the atmosphere, soil, or water.
What is the primary agent responsible for dissolving and transporting chemical elements necessary for living organisms?
Water.
What is the water cycle?
The movement of water through the atmosphere and over the surface of the Earth.
What are the three possible outcomes when water comes in contact with vegetation or soil?
- Return to the atmosphere by evaporation or transpiration
- Infiltrate the soil and enter the groundwater system
- Move across the land surface in rivers and streams or as runoff.
What is evapotranspiration?
The combination of evaporation and transpiration.
What is the ultimate reservoir of water on Earth?
The ocean.
What processes run the carbon cycle?
- Photosynthesis
- Respiration
- Decomposition
- Combustion.
What is carbon fixation?
The process by which plants convert carbon dioxide into plant material.
What happens to carbon when organisms die?
It becomes part of the dead biomass pool and decomposes in the soil or ocean.
What are fossil fuels?
Compounds such as coal, oil, and natural gas formed from organic matter that gets buried in sediments.
How does combustion affect the carbon cycle?
It releases carbon back into the environment.
What is the primary limiting element for plants in many terrestrial systems?
Nitrogen.
What is nitrogen fixation?
The conversion of atmospheric nitrogen (N2) to a plant-available form, ammonium (NH4+).
What organisms are capable of nitrogen fixation?
- Cyanobacteria
- Certain bacteria and fungi associated with legumes and specific trees.
What is ammonification?
The conversion of organic matter to ammonium driven by microorganisms.
What is nitrification?
The two-step process where ammonium is converted to nitrite and then to nitrate.
What can high accumulation of nitrate in wet soils lead to?
Denitrification.
What is denitrification?
The natural conversion of nitrate to nitrous oxide (N2O), which is emitted to the atmosphere.
What does biodiversity refer to?
The diversity of all the genes, species, and habitats on Earth.
What is genetic diversity?
The variation of genes within a population.
What is the role of alleles in genetic diversity?
Varying combinations of alleles create a pool of genetic diversity within a population.
What is natural selection?
The process by which certain phenotypes better enable individuals to survive and reproduce.
What are keystone species?
Species whose loss can lead to significant damage or extinction of the entire community.
What is community ecology?
The study of how populations interact within a biological community.
What defines an ecosystem?
Specific places on Earth made up of interacting living and nonliving components.
What are the critical cycles that drive ecosystem interactions?
- Water cycle
- Carbon cycle
- Nitrogen cycle.
Fill in the blank: The water cycle is the movement of water through the atmosphere and over the surface of _______.
[the Earth]
Fill in the blank: The carbon cycle is the movement of carbon compounds through the atmosphere, oceans, and _______.
[living organisms]
Fill in the blank: The nitrogen cycle is a set of processes in which nitrogen is converted into different forms as it cycles through the _______.
[environment]
