B7 : Seneca Flashcards
What is an ecosystem made up of
An ecosystem is made up of living (biotic) and non-living (abiotic) parts
What are individuals
Individual organisms are the smallest part of an ecosystem.
What are Populations
Populations of individual organisms make up a single species.
What are Communities
Communities are made up of populations of different species.
Competition for resources between animals
Animals often compete for food, mates and territory.
Competition for resources between plants
Plants often compete for water and mineral ions (minerals) from the soil, as well as for light and space.
From which two parts of an ecosystem do organisms need resources to survive and preproduce
Biotic (living)
Abiotic (non-living)
What is interdependence
There is interdependence between different species. This means that one species may rely on another species for services such as food, shelter, pollination, and seed dispersal
What are the factors that species may rely on each other for
Food, Shelter, Pollination, Seed dispersal
What is a stable community
A community is stable when all the species and environmental factors are balanced and population sizes stay more or less constant
When a community is stable, the populations within it are:
Fairly constant
Why may removing one species from an ecosystem make it unstable
There is interdependence between different species.
Removing one species from an ecosystem could remove a key predator or prey. This would either increase or reduce population sizes.
What do food chains show
Food chains show the feeding relationships within a community
What do food chains start with
Food chains nearly always begin with a producer that makes its own food. This is usually a green plant or algae that can photosynthesize
What are producers
Producers are eaten by animals called primary consumers.
What are Primary consumers
Primary consumers are eaten by secondary consumers.
What are Secondary consumers
Secondary consumers are eaten by tertiary consumers.
What are Tertiary consumers
An apex predator is at the top of the food chain.
What is a predator-prey graph
Predator-prey graphs show the cyclical nature of predator and prey populations in stable communities
What word best describes the nature of predator-prey dynamics in stable communities?
Cyclic
How does Environmental Change affect an ecosystem or environment
Environmental change affects the distribution (spread) of species, and in extreme cases, their longevity (how long they survive)
What are examples of environmental changes
. Temperature
. Water
. Atmospheric gases
Temperature
Polar bears hunt seals on floating sea ice.
Increasing temperatures cause this ice to melt. This means that the polar bears are no longer able to hunt their main food source.
Water
Wildebeests migrate annually from the Serengeti plains of Tanzania Northwards into Kenya to track seasonal changes in rainfall patterns.
Atmospheric gases
Carbon dioxide dissolves in water and increases the water acidity.
Acidic water hinders corals’ ability to build a skeleton. This means that the increased carbon dioxide in the atmosphere prevents coral growth.
What are the causes of environmental changes
. Seasons
. Humans
. Geological Activity
Seasons
Many countries have rainy and dry seasons.
The difference in temperature between winter and summer drives birds on worldwide migrations.
Humans
Through the burning of fossil fuels, humans increase the atmospheric concentration of greenhouse gases.
People can change water availability through the building of large dams. The pollution of water sources can make them toxic to wildlife.
Geological Activity
Volcanic eruptions change the composition of atmospheric gases.
Storms and droughts change the availability of water.
Industrial Revolution - Adaptation of Moths
In the industrial revolution (1750 -1850 in the UK), the number of white moths decreased and the number of black moths increased.
The black moths were better adapted to the smoky polluted conditions and were better camouflaged.
What are ways to look at ecosystems and their populations
. Quadrats
. Transects
Quadrats
Quadrats are square frames that can be used to estimate population sizes.
Transects
Transects can be used to investigate the effect of a factor on the distribution of a species.
A transect line is a piece of tape that is stretched across the habitat of interest.
Quadrats are placed at regular intervals along the transect line.
Mean
The arithmetic mean is the average value of a series of numbers.
The mean is calculated by adding up all the values and then dividing by the number of recordings that have been made.
Median
The median is the middle value in a numerically ordered series.
Mode
The mode is the most common value in a series.
How do we use quadrats to estimate a population size
Divide the habitat up into a series of quadrat-sized cells.
Randomly select a given number of cells, then go out into the habitat and place the quadrat in these positions.
To evaluate the quadrat contents, either count the number of individual organisms of interest or record the percentage of the quadrat taken up by an organism (e.g. grass).
Calculate population
How do we calculate a population size using quadrats
population = number counted x (total survey area / area sampled)
Transects can be used to investigate the effect of a ______ on the distribution of a species.
factor
What are the two cycles that are important for living organisms
. The water cycle
. The carbon cycle
The water cycle
This cycle describes how water moves on, above or just below the surface of our planet between different locations, such as rivers, oceans and the atmosphere.
In order for this cycle to be completed, water has to change state.
The carbon cycle
Carbon is present in all living organisms.
When organisms die, the carbon is recycled so that it can be used by future generations.
Carbon cycle
Carbon is removed from the atmosphere by producers (e.g. algae) who use it in photosynthesis.
By consuming plant matter, animals obtain carbon compounds.
Carbon is returned into the atmosphere (as carbon dioxide) because of the respiration that happens in plant and animal cells.
When animals and plants die, decomposers return the carbon locked in their bodies back to the atmosphere via decay.
Combustion of fossil fuels is another source of carbon entry into the atmosphere.
When animals and plants die, what group of organisms returns the carbon locked in their bodies back into the atmosphere?
Decomposers
Water cycle
Water evaporates from the Earth’s surface, before rising up into the atmosphere.
Once in the atmosphere, the water vapour cools and condenses into either rain or snow. This eventually returns to the Earth’s surface.
The rain or snow will either become surface runoff (water flowing off land) or will travel through the earth as ground water.
Plants take up water through their roots.
Carbon is removed from the atmosphere by _________ to be used in photosynthesis to make _______.
producers, glucose
Decay of biological material
Biological material in the form of waste products or dead organisms decays as a result of the activity of decomposers
What is the rate of decay process dependent on
. Oxygen availability
. Moisture availability
. Temperature
Oxygen availability
High oxygen availability is usually best.
Moisture availability
High moisture availability is usually best.
Temperature
High moisture availability is usually best.
Food Decay
Food stored in warm, moist places will decay (rot) faster than food stored in cool, dry places.
Biogas generators
Anaerobic decay happens when the oxygen supply is insufficient (not enough), and results in the production of biogas, which is mainly methane.
Biogas generators produce methane gas, which is used as a fuel. It can also be used to produce slurry which can also be used as a fertilizer.
It is crucial that temperatures are maintained at a suitable level and that oxygen is not allowed to enter the site of fermentation.
Can you suggest potential ways to make sure that the temperatures in biogas generators stay at a suitable level?
Bury the generators underground.
Cover them in insulating jackets.
What are biogas generators
Biogas generators are devices that can produce methane gas as a fuel for purposes such as cooking, heating or refrigeration
Large-scale generators
Large-scale generators take waste from sugar factories or sewage works.
Small-scale generators
Small-scale generators are used by households and farms.
Typical inputs include egested (excreted) material from humans and animals, as well as farm and garden waste.
Which gas do biogas generators produce that can be used as a fuel or slurry
Methane
What is biodiversity
Biodiversity is the variety of all the different species in a given space. Sufficient biodiversity is important for the future of humans
What have been our problems with biodiversity
. Attitude shifts
. Warning signs
. Industrial revolution
Attitude shifts
Attitudes have recently begun to change and measures are being taken to prevent further damage being done and to regain pre-existing biodiversity.
Warning signs
An awareness of the detrimental nature of these activities has existed for several decades.
However, because of the pursuit of economic gain, the warning signs have largely been ignored.
Industrial revolution
For some time, and especially since the industrial revolution, humans have conducted many activities that have caused a severe decline in biodiversity on a global scale.
What has increased waste and pollution afected
.Land
. Water
. Air
Land
Toxic herbicides and pesticides used in farming, buried nuclear waste and household waste in landfill sites are all land pollutants.
Water
Sewage and toxic chemicals, which are produced by industrial practices, as well as excess fertiliser from agriculture, all find their way into the Earth’s water sources.
Air
Smoke and gases are being added into the atmosphere constantly, particularly by power stations and cars.
Peat
Peat is a deposit of partially decayed plant matter, which accumulates in bogs.
Here, carbon remains in the plants instead of being released into the atmosphere.
Peat bog destruction
The destruction of peat bogs has become more common, resulting in the burning or decay of peat.
This releases the stored carbon into the atmosphere in the form of the greenhouse gas, carbon dioxide.
Another negative impact of peat bog destruction is the loss of biodiversity within the habitat.
Reasons for peat bog destruction
Peat bogs are being destroyed for the following reasons:
To free up land for farming, which requires the bogs to be drained.
This draining process stimulates peat decay.
To burn the peat for fuel.
To sell the peat to gardeners as garden compost.
Reducing peat demand
Peat demand can be reduced by gardeners using peat-free compost, such as manure or bark chippings.
What are the negative consequences associated with deforestation
. Loss of biodiversity
. Lack of ecosystem services like erosion prevention, flood control
. Increased carbon dioxide
. Methane (farming)
Carbon dioxide removal
Carbon dioxide is removed from the atmosphere naturally by green plants and algae during photosynthesis.
Other natural stores of carbon include bodies of water and peat bogs.
Carbon dioxide release
Carbon dioxide is released into the atmosphere naturally as the waste product of respiration.
However, many other unnatural processes, such as the burning of fossil fuels, also release carbon dioxide.
What are the consequences of global warming
. Ocean acidification
. Distribution of species e.g. malaria-carrying mosquitos spreading
. Reduction of biodiversity
. Extreme meteorological events
. Ice melting
. Migration patterns
. Sea surface temperatures
How can we maintain biodiversity
. Recycling waste
. Incentivizing farmers
. Breeding programs
. Government - imposed targets
. Protection and regeneration of habitats
What does an organisms trophic level show
An organism’s trophic level describes where it fits into a food chain
Food chain: level 1
At the base of all food chains, there are green plants and algae.
These are called producers and use light energy from the Sun to synthesise (make) their own food.
Food chain: level 2
Herbivores that eat green plants and/or algae are called primary consumers.
Food chain: level 3
Carnivores that eat herbivores are called secondary consumers.
Food chain: level 4
Carnivores that eat other carnivores are called tertiary consumers.
An apex predator is at the highest point in the food chain.
Decomposer
Responsible for recycling organic matter within an ecosystem and represents the final stop for all food chains.
Apex
predator
Occupies the top of the food chain and is not preyed upon.
How do decomposers break down food
Decomposers break down dead material by secreting (producing) enzymes.
Enzymes partly digest the waste products, producing small and soluble food molecules.
These small soluble molecules can then diffuse into the decomposer.
Two examples of decomposers
. Bacteria
. Fungi
What is biomass
Biomass is the total mass of living material in an organism multiplied by the number of organisms.
What is a biomass pyramid
A pyramid of biomass can be constructed to represent the relative amount of biomass at each trophic level in a food chain.
Pyramids of biomass are almost universally pyramid-shaped.
What is the general rule for transfer efficiency between trophic levels
A general rule for transfer efficiency between all trophic levels is that 10% of energy from a given trophic level will be available to the next trophic level.
Producers energy
Producers only manage to trap approximately 1% of light energy from the sun.
Inefficiency of biomass transfer
Energy is wasted at each trophic level in a food chain, meaning less biomass and energy is passed on to the next organism in the food chain.
This progressive loss of energy usually means that there are fewer individuals at higher trophic levels.
Reasons for Inefficient Transfer of Biomass
. Excretion
. Body temperature
. Movement
. Digestion
What are the obstacles to food security
. Costs of agricultural inputs
. Diet shifts
. Extreme meteorological events
. Conflicts
. Birth rates
. New pests and pathogens
What is food security
This is achieved when the whole global human population has access to enough safe and nutritious food to stay healthy.
What is biotechnology
Biotechnology is the use of biological processes to develop or make products
Modern biotechnology techniques include
. Genetic modification
. Growing microorganisms for food
Genetic modification
Genetically modified crops have the potential to provide more food, including more nutritious food.
Growing microorganisms for food
Genetically modified crops have the potential to provide more food, including more nutritious food.
What are farming techniques that help increase food production
. Livestock
. High protein foods
. Food chains
Livestock
Energy will always be transferred from livestock to the environment due to essential processes, like moving or maintaining body temperature.
Limiting the amount of energy wasted in this way helps improve food production efficiency.
High protein foods
Feeding animals foods that are high in protein helps boost their growth rates.
Food chains
Only about 10% of energy passes from each trophic level to the next.
Therefore, shortening food chains will greatly increase efficiency.
What are the consequences of declining fish stock
. Food security is threatened
. Financial struggle
. Populations at risk
. Food chains affected
How can we achieve sustainable fishing
. Fishing quotas
. Net size
Fishing quotas
By restricting the number and size of fish that can be legally caught, the risk of overfishing is greatly reduced.
Net size
Controlling the net (holes) size allows the smaller, younger fish to slip through the net so that they can survive at least until maturity.
How do you know if animals are from the same species
Individuals are members of the same species if they can interbreed (breed amongst themselves) to produce fertile offspring
How did Alfred Wallace propose the development of a new species occurs
. Geographical isolation -
Two populations of the same species become geographically isolated (separated).
. Genetic variation -
The populations exhibit (show) genetic variation.
. Natural selection -
Due to differing environments and selection pressures, natural selection (survival of the fittest) operates differently on the populations.
. Genetic divergence -
This eventually leads to genetic divergence until the populations are unable to interbreed to produce fertile offspring.
At this point, they have become two different species.
Darwin was not the only scientist to think of natural selection. What did Darwin and Wallace have in common?
. Joint writings
. Island research
What year did Alfred Wallace write to Darwin
1858
What are the two main sources of evidence for evolution
. Antibiotic resistant bacteria
. Fossils
Antibiotic resistant bacteria
Natural selection neatly explains this phenomenon:
Bacteria reproduce rapidly.
Mutations occur during reproduction.
If a mutated bacterium is resistant to antibiotics, it will survive exposure to antibiotics and go on to reproduce.
This bacterium will represent the original ancestor of a new resistant strain.
Fossils
Fossils show the gradual changes in organisms over vast periods of time.
What are the three different ways of forming fossils
. Hardening soft materials
. Mineral replacement
. Preservation when decay is not possible
Hardening soft materials
The hardening of soft materials can produce casts or impressions, such as footprints.
For example, clay hardens around an organism that is buried within it. This organism then decays, leaving behind a cast of itself.
Mineral replacement
Hard parts of organisms are gradually replaced by minerals as they decay slowly, creating a rock-like substance.
When the surrounding sediment turns to rock, the teeth-shaped mineral structure remains distinct (different).
Preservation when decay is not possible
Where decomposers cannot act, preservation is possible.
Decomposers cannot operate in glaciers (extreme, low temperatures) and peat bogs (extreme acidity).
Resistant strain of bacteria
If a mutated bacterial pathogen is resistant to antibiotics, when a person is treated with antibiotics, the bacteria will survive and go on to reproduce.
This bacteria is the original ancestor of a new resistant strain.
This bacteria will spread, as there will be no treatment for it, and people are not immune to it (as they were previously treated with antibiotics).
Anitbiotics
The development of new antibiotics is a slow and costly process.
It struggles to keep up with the emergence of new strains.
Reducing new resistant strains
Measures must be taken to reduce the emergence of new antibiotic resistance strains:
Doctors should avoid prescribing antibiotics unnecessarily, for example for treating non-serious or viral infections.
Patients must finish a course of antibiotics to make sure that all of the bacteria are killed.
The use of antibiotics in agriculture (for example, cattle feed), should be restricted.
What is an example of antibiotic resistant bacteria
MRSA
Apart from genes, what are the two main sources of evidence for evolution?
. Fossils
. Antibiotic resistant bacteria
Apart from genes, what are the two main sources of evidence for evolution?
Acidity
Mid-19th century understanding of genetics
Gregor Mendel, an Austrian monk, performed breeding experiments on pea plants.
This work showed that characteristics were determined by inherited “units” passed from parents.
Late-19th century
The first observation of how chromosomes behave during cell division.
Early-20th century
The similarity between the behaviour of chromosomes and Mendel’s ‘units’ was recognised.
Consequently, it was decided that the ‘units’ were located on chromosomes.
Additionally, the ‘units’ were renamed genes.
Mid-20th century
Technological advancements allowed scientists to work out the structure of DNA.
The mechanism by which genes operate was also unearthed at this time.
Extinction
Extinction happens when there are no individuals of a species left in the world. A change in abiotic (physical) or biotic (relating to organisms) factors can cause an extinction if a species cannot adapt or move to another environment
Slow extinctions
Geological and atmospheric changes happening over a longer period of time can also cause slower extinctions.
Rapid extinctions
Sometimes abiotic (physical) factors can change rapidly to cause extinctions.
Large volcanic eruptions can change the carbon dioxide levels in the atmosphere, block light and cause pH changes in soils.
A meteorite or asteroid impact (like the one around the time of the dinosaurs) would have a similar (but larger) effect to a large volcanic eruption.
Large volcanic eruptions can cause changes in the levels of
. Light
. pH
. Carbon dioxide
What are the different modes of natural selection
Stabilising selection is a type of natural selection that favours the average phenotype.
Directional selection is a type of natural selection that favours an extreme phenotype.
