Changes to populations and the environment Flashcards
What is succession?
A directional change in a community over time.
What is meant by primary succession?
Where an area previously devoid of life is colonized by pioneer species.
What is a pioneer species?
Species that can survive in hostile environments and colonies bare rock or sand. Ex. lichen.
Summarize the process of succession
Pioneer species colonies the area. They die, decompose and add nutrients to the ground. Over time, this allows more complex organisms to survive.
What are seres?
Various intermediate stages in succession in an ecosystem progressing towards a climax community.
Define secondary succesion
A type of succession in which a habitat is re-colonised after a disturbance.
What is the climax community and how is it reached?
The final stage of succession, where the ecosystem is balanced and stable. It’s reached when the soil is rich enough to support large trees or shrubs and the environment is no longer changing.
How does succession affect species diversity and the stability of a community?
It increases it.
Describe four pieces of evidence for climate change.
-Increasing levels of CO2, a greenhouse gas
-Changing patterns in t° records
-Analysis of pollen grains from peat bogs indicates which plant species were present when the peat formed
-Dendrochronology
What is dendrochronology?
Measurement of tree ring width to analyze the temperature and moisture of the year in which the ring was added.
What is anthropogenic climate change?
Climate change caused by human activity like deforestation, burning of fossil fuels, intensive agriculture.
What is the greenhouse effect?
Greenhouse gases CO2 and methane absorb infrared radiation from the sun. Warms the earth’s surface and atmosphere.
Suggest two controversial scientific debates surrounding climate change
What should be done to reduce climate change? To what extent are human actions responsible for climate change?
Why might scientific conclusions on controversial issues differ?
They may require suggestions rather than empirical fact, and it depends on the intention of the researcher (subconscious bias or pressure from an institution)
How can knowledge of the carbon cycle be used to reduce atmospheric carbon dioxide levels?
Increase photosynthetic absorption of CO2=reforestation
Reduce CO2 release= burn fewer fossil fuels
How can models of future climate change be generated?
By extrapolating data
Why do climate change models have limitations?
Models assume the pattern continues and don’t consider factors that may change later, like reduction in greenhouse gas emissions.
State two geological effects of climate change
Rainfall patterns change, seasonal cycles change
How can climate change affect plants and animals?
Distribution of species and migratory patterns change. This increases interspecific competition. Selection pressures change and disruption to life cycles and development (e.g. sex in reptiles)
Explain how increasing t° above the optimum affects the rate of an enzyme-controlled reaction
Increased vibrations break hydrogen and ionic bonds in tertiary structure, active site changes shape, enzyme is denatured, no more enzyme-substrate complexes can form and the rate of reaction decreases.
What is Q10?
Temperature coefficient. Measures the rate of change of a reaction when the t° is increased by 10 °C.
How can increased t° due to climate change affect organisms on a molecular scale?
Organisms typically have proteins adapted to work optimally in their natural climate. If the t° increases, the proteins may denature and will be unable to function correctly.
What is evolution?
Change in allele frequency in gene pool of a population. Results in development of new dominant characteristics.
What is natural selection?
The process by which organisms that are better adapted to their environment are able to survive and reproduce. This contributes to evolution over time.
How does natural selection lead to evolution?
Random mutations result in new alleles. Some of these provide an advantage, making the individual more likely to survive and reproduce. Offspring receive the allele and frequency increases over many generations.
Why does natural selection occur?
Predation, competition, disease.
What is speciation?
The formation of a new species due to the evolution of two reproductively separated populations.
What are the two different types of speciation?
Allopatric speciation and sympatric speciation.
What is meant by sympatric speciation?
Speciation resulting from a non physical barrier, like a mutation that no longer allows two organisms to produce fertile offspring, changes in anatomy or behavior.
What is reforestation?
The replanting of trees to replenish forests that have been destroyed.
What are biofuels?
Fuels which have been made from biomass (plant and animal matter). They can be a carbon-neutral and renewable alternative to fossil fuels.
What is sustainability?
The ability to maintain a process or supply over time. Supplying the present generation without depriving the future generations of the resource.
