Ecology Flashcards
(176 cards)
1
Q
What is EcoLOgy?
A
The interaction of Living Organisms in their Environment with the Biotic and Abiotic Factors.
2
Q
examples of biotic factors: living
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availability of food, predators, prey, micro-organisms
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Q
examples of abiotic factors: non-living
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oxygen level, oxygen content, (g), CO2 content, temperature, light intensity, water/moisture, iron content in soil, H20 content.
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Q
Habitat
A
area/ region/place where an organism lives
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Q
PopulAtiON
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a species of one, same type eg: red squirrels
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Q
coMMuniTy
A
species of diFFerent types of organisms interacting eg: red squirrels, grey squirrels
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Q
Ecosystem
A
a specific habitat eg: land, water in which living organisms interact with each other (biotic, abiotic factors)
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Q
competition
A
plants and animals eg: living organisms compete for light, space, territory, water, mineral ions, food (chemical energy).
9
Q
interdependence
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within a habitat plants and animals rely on each other and on the biotic and abiotic factors for their survival
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Q
species
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a group of living organisms with similar characteristics living in a specific habitat. They can breed to give rise to fertile offspring.
11
Q
non species eg:
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sheep, goat- geep
zorse- zebra and horse
12
Q
A food chain is
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a representation of the flow of chemical energy from one trophic level to another, producer to the top predator.
13
Q
The source of any food chain is the
A
sun (solar energy)
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Q
Pyramid of biomass
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As the chemical energy flows from one trophic level (producer) to another (primary consumer, secondary consumer, tertiary consumer) energy is ‘lost’ (transferred) into other forms of energy.
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Q
How is energy lost?
A
Heat (thermal) Growth (Biomass) Excretion (EgeStion) solid Respiration Movement
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Q
Q: If/ suppose trophic level 2 is removed, how will this affect the total food chain
A
- population of organisms in trophic level 1 will increase
- organisms in trophic level 3 will decrease and those in trophic level 4
- organisms in trophic level 3 may have to change their diet in order to survive.
17
Q
pollen is a
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carbon reserve
18
Q
What is variation?
A
The differences in the characteristics of individuals within a population.
19
Q
Key steps in natural selection
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mutation of gene –> advantage to survival –> breed –> pass on genes
20
Q
The theory of evolution by natural selection states that
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All species of living things have evolved from simple life forms that first developed over 3 billion years ago.
21
Q
allopatric speciation
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Is due to geographical isolation as they evolve differently.
22
Q
speciation
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when two organisms can no longer breed to produce offspring
23
Q
What can environmental change cause?
A
The distribution of living organisms to change
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Q
What does a change in distribution mean?
A
A change in where an organism lives
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What are some changing environmental factors that can affect the distribution of organisms?
-temperature
-availibility of water
-composition of atmospheric gases
The changes can be seasonal, geographic or caused by human interaction
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Effects on distribution-temperature
- organisms have adaptations that enable them to survive within a certain temperature range
- As climate change occurs and average temperatures rise, the distribution of species is changing
eg: the distribution of some plant, bird and insect species in Europe is spreading northwards into areas they were not previously able to inhabit, as these areas now have higher average temperatures as a result of global warming.
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Effects on distribution - water availability
- all organisms require water to survive, either directly (water is essential for the biological processes that sustain living organisms or indirectly (water may provide a habitat for species and is essential for the growth of plants that support the whole food chains and food webs)
- eg: every year in Africa, wildebeest migrate first northwards and then southwards again, following the rainfall as this provides them with fresh grazing and water.
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Effects on distribution-composition of atmospheric gases
- oxygen is required for aerobic respiration in plants and animals
- some aquatic animals (such as fish) can only survive in water with high oxygen concentrations
- As pollution increases in freshwater systems, growth of anaerobic microorganisms is encouraged which can lead to a drop in oxygen when they die as a result of decomposition, fish cannot survive in these conditions.
- carbon dioxide is required for photosynthesis in plants
- some species are very sensitive to air pollution
- eg: some species of lichen are not able to grow where sulphur dioxide is present (produced during certain industrial processes due to the combustion of fossil fuels).
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What is biodiversity?
The variety of different species of organisms on Earth, or within an ecosystem.
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What do different species depend on each other for?
- food
- shelter
- maintenance of the physical environment
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Maintenance of the physical environment example
Tree roots provide stability for soils, ensuring they do not get washed away. This in turn provides a stable habitat for other plant species.
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What does a high biodiversity ensure?
It ensures the stability of ecosystems by reducing the dependence of one species on another for these three things.
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What are many human activities doing?
They are reducing biodiversity in individual ecosystems and on a global leve.
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How do human activities reduce biodiversity?
- Producing waste
- Deforestation
- Global warming
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What does producing waste lead to?
The destruction of habitats to make space for landfill and toxic chemicals from landfill waste can leac into the soil.
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What does deforestation lead to?
Destruction of forest habitats that contain high biodiversity.
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What does global warming lead to?
The disruption of ecosystems and reduced biodiversity due to flooding of coastal habitats, coral bleaching, increased frequency of extreme weather events. and many other factors caused by increasing global temperatures.
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What does the future of the human species on Earth rely on?
It relies on us maintaining a good level of biodiversity.
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How do humans rely on other species to survive?
- we rely on many plant species for medicine
- we rely on pollinator species such as bees to pollinate our food crops
- we rely on photosynthetic organisms to produce oxygen, without which we cannot respire.
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how do you calculate the number of biodiversity in an area?
-Use of quadrat
-Quadrats of given area eg: 0.25 m2 or 1m x 1m
-Quadrats are placed randomly
method of obtaining randomness- eg: random coordinates from a calculator or throw over shoulder or throw with eyes closed
-suitable number of quadrats (10 or more or a large number)
-count number of plants in each quadrat
-calculation of mean per quadrat or per unit area
-determination of area of field (length x width)
-population = mean per m2 x area of field
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individual organism
a single member of a species
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population
a number of individuals of the same species living in the same area at the same time.
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Community
multiple populations (of different species) living and interacting in the same area.
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Ecosystem
The interaction between a community (the living, biotic part) and the non-living (abiotic) parts of the environment.
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competition
If a group of organisms all need the same resource in order to survive and reproduce but there is a limited amount of resource available.
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intraspecific competition
competition between members of the same species
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interspecific competition
competition between members of different species
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Adaptation
If an organism has certain features, behaviours, or other characteristics that help it to survive and reproduce in its habitat.
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What is an ecosystem?
It is the interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment.
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eg of a small ecosystem
a tree
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eg of a large ecosystem
Antarctica
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What do organisms need in order to survive and reproduce and what does this mean?
They need certain resources from their surroundings, meaning that members of a species will often interact with members of its own species or other species
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Examples of interactions within an ecosystem
- predators (carnivores) eating prey
- herbivores eating plants
- plant species being pollinated by bees
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What do plants in a community compete with each other for?
Light and space, and for water and mineral ions from the soil.
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What do animals in a community compete with each other for?
Food, mates and territory
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Why do plants compete for light?
Plants require light for photosynthesis in order to produce glucose, which provides them with energy for growth.
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Why do plants compete for space?
Plants require space above soil (so leaves can absorb maximum sunlight) and below soil (so roots can absorb water and mineral ions).
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Why do plants compete for water (from soil)
Water is essential for photosynthesis and therefore plant growth
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Why do plants compete for mineral ions (from soil)
Plants require various mineral ions such as nitrate ions (used to make proteins) and magnesium ions (used to make chlorophyll).
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Why do animals compete for food?
Food provides animals with the energy they require for growth and reproduction
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Why do animals compete for mates?
Animals require mates in order to reproduce and pass on their genes
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Why do animals compete for territory?
A territory is an area of habitat that provides an individual with resources such as water, food, shelter and mates
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What is interdependence
Within a community, each species depends on other speces for food, shelter, pollination, seed dispersal etc. If one species is removed it can affect the whole community.
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What is a stable community?
It is one where all the species and environmental factors are in balance so that population sizes remain fairly constant.
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What abiotic factors can affect a community?
light intensity, temperature, moisture levels, soil pH and mineral content, wind intensity and direction, carbon dioxide levels for plants, oxygen levels for aquatic animals
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How does light intensity affect the community?
Light is needed by plants for photosynthesis. More light leads to an increase in the rate of photosynthesis and an increase in plant growth rate.
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How does temperature affect a community?
It affects the rate of photosynthesis in plants
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How do moisture levels affect a community?
Plants and animals require water to survive
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How does soil pH and mineral content affect a community?
Different species of plant are adapted to different soil pH levels and nutrient concentration levels.
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How does wind intensity and direction affect a community?
Wind speed affects transpiration rate in plants. Transpiration affects the rate of photosynthesis as it ensures water and mineral ions are transported to the leaves.
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How does carbon dioxide levels for plants affect a community?
CO2 is required for photosynthesis in plants. CO2 concentration affects the rate of photosynthesis.
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How do oxygen levels for aquatic animals affect a community?
Some aquatic animals (such as fish) can only survive in water with high oxygen concentrations.
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What are biotic factors that affect a community?
- availability of food
- new predators arriving
- new pathogens
- one species outcompeting another so the numbers are no longer sufficient to breed
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How does availability of food affect a community?
More food means organisms will have a higher chance of surviving and reproducing. This means their populations can increase.
(eg: rainforest ecosystems have a rich food supply allowing many species to live there. Deserts have a poor food supply, allowing fewer species to live there)
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How do new predators affect a community?
In balanced ecosystems, predators catch enough prey to survive but not so many that they wipe out the prey population. If a new predator is introduced to the ecosystem, ot may become unbalanced.
(eg: red foxes were introduced for recreational hunting in Australia in the 1800s but have since caused the decline of many native species they feed on like small mammals and birds and this has also reduced the food supply for native predators)
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How do new pathogens affect an ecosystem?
If a new pathogens enters an ecosystem, the population will not have immunity to it so will decline or may be wiped out.
(eg: Coronavirus caused a global pandemic and a decline in many human populations around the world because it was a new pathogen.)
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How does competition affect a community?
If two species compete for the same resource and one is better adapted to taking advantage of that resource, then that species will outcompete the other. This may continue until there are too few members of the lesser adapted species to breed successfully.
(eg:North American grey squirrels caused decline in our native red squirrel. Have outcompeted red squirrels for resources such as food and nest sites. They also carry a new virus which red squirrels are not resistant to).
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What are the three types of adaptation to the environment?
- structural
- bahevioural
- functional
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Structural adaptation to the environment
- description: A physical part or feature of an organism
- eg: the white fur of a polar bear provides camouflage in the snow so it has less chance of being detected by prey
- eg: seals have a thick layer of fat (blubber) to insulate them against the cold conditions they live in.
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Behavioural adaptation to the environment
- description: the way an organism behaves
- cold-blooded reptiles bask in the sun to absorb heat and rabbits dig burrows so their offspring can live in them and rabbits can raise them.
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Functional adaptation to the environment
- description: biological processes that take place within the organism
- eg: snakes produce venom to kill prey and mosquitos produce chemicals that stop the animal's blood clotting when they bite so they can feed more easily.
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Adaptations to the cold regions
STRUCTURAL ADAPTATIONS
- animals often have a small SA:V ratio to minimise heat loss to their surroundings (rounded shape of penguins/seals and the smallears of the Arctic fox).
- A thick layer of fat (seal blubber) or fur (polar bears) insulates aganst the cold
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Adaptations to the desert regions
- some desert animals have specially adapted kidneys which produce very concentrated urine, helping the animal to retain water- concentrated urine
- some are only active in the early mornings, late evenings or at night when it is cooler - behavioural adaptation
- Some animals have structures to increase their SA:VR ratio to aid heat loss (large ears of African elephants)- structural adaptations
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Adaptations of a cactus
- thick,water-storing stem
- spines instead of leaves to reduce SA to reduce water lost from transpiration
- extensive root systems to maximise water uptake
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What are organisms that live in extreme enviroments called?
extremophiles
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What is an example of habitats where extremophiles are found?
Deep sea volcanic vents, where the conditions are extremely hot, under high pressure and there is no sunlight.
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What are chemoautotrophs?
They are bacteria which survive by using inorganic chemicals to obtain energy (rather than using sunlight in photosynthesis as photoautotrophs do). Other species can then use the bacteria as a source of nutrition - the bacteria are producers in this food chain.
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What are the producers of biomass for life on earth?
Photosynthetic organisms
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How do photosynthetic organisms produce their own food?
Using energy from the sun
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What are the characteristics of a producer?
- they are at the start of every food chain (the biggest first trophic level)
- They can photosynthesize (producers are normally green plants or algae)
- They can make glucose by photosynthesis
- They use this glucose to produce other biological molecules, which then make up the producer's biomass (some of the glucose produced is also used in respiration to release energy for the cell)
- In extreme environments (such as underwater volcanic vents), the producers are not photoautotrophs but chemoautotrophs who produce organic molecules without using energy from the sun.
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What does a food chain show?
It shows the feeding interactions between organisms in a community.
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What is a consumer?
An organism that obtains its energy by feeding on other organisms.
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Stages of a food chain
Producer- Food chains always begin with this
Primary consumer- They eat producers (herbivores/omnivores)
Secondary consumer- primary consumers are eaten by secondary consumers
(carnivores/omnivores)
Tertiary consumer- they ear secondary consumers
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What do the arrows in a food chain show?
The transfer of energy from one organism to the next.
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What is ecology?
- It is the branch of biology that studies the distribution and abundance of species, the interactions between species, and the interactions between species and their abiotic environment
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Quadrats
- they are square frames made from wood or wire
- they can be a variety of sizes eg: 0.25 m2 or 1 m2
- They are placed on the ground then the organisms within them are recorded
- should be placed in a random order
- They can be used to measure the abundance of plants or slow-moving animals
- repeating increases the sample size
- random generator avoided bias
- Take several readings and calculate mean- quantitative sampling
- calculate area
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How can quadrats be used to measure abundance?
- By recording the number of individual species: the total number of individuals of a single species (eg. buttercups) is recorded
- By recording the species richness: the total number of different species (but not number of individuals of each species) is recorded.
- Percentage cover: It is used when it is difficult to count individuals of the plant species being recorded eg: grass and moss and it is the approximate percentage of the quadrat area in which an individual species is found is recorded.
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What is a transect used to measure?
It is used to measure how the abundance of a species changes as you move along a changing habitat eg: changing altitude on a hillside/ rocky shore/ or from an open field to dense woodland, or along the shoreline at the coast.
- a line called a transect is set up through the changing habitat you want to investigate with a tape measure
- A quadrat is then placed at regular intervals (eg. every 5 metres) along the transect
- At each interval, the quadrat can be used to record the number of an individual species, species richness or percentage cover
- systematic sampling
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What are transects useful for?
They are useful for investigating how the abundance of a species is affected by an abiotic factor eg: light intensity, moisture levels, soil depth, altitude etc.
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What are predators?
consumers that kill and eat other animals
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What are prey?
Those who are eaten
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What happens in a stable community?
The number of predators and prey rise and fall in cycles.
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Describe a normal predator-prey cycle
1, The number of predators increases as there is more prey available
2, The number of prey then decreases as there are now more predators
3, The number of predators decreases as there is now less prey available
4, The number of prey increases as there are now fewer predators
5, The cycle now repeats
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Why are predator-prey cycles always out of phase?
It takes time for one population to respond to a change in the other population so the peaks for predators and prey may occur one after the other. It takes time for the prey to reproduce and their numbers to increase.
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How much of each element is there on the planet?
A finite amount
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Why do elements need to be recycled?
In order to allow new organisms to be made and grow.
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What are the main processes of the carbon cycle?
- carbon is taken out of the atmosphere in the form of carbon dioxide to be used by plants for photosynthesis. The carbon is used to make glucose , which can then be turned into carbohydrates, fats and proteins- biomass- within plants and algae
- The carbon is passed on to the animals (and microorganisms) when they feed on plants and algae
- It is returned to the atmosphere in the form of CO2 during respiration by plants, animals and microorganisms which release CO2 during decomposition
- If animals and plants die in conditions when decomposing microorganisms are not present, the carbon in their bodies can be converted over millions of years and significant pressure, into fossil fuels
- When wood or fossil fuels are burned through combustion, the carbon within them combines with oxygen and carbon dioxide is released into the atmosphere.
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What does the water cycle provide?
It provides fresh water for plants and animals on land before draining into the seas.
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Water is continually
evaporated and precipitated
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How does water enter the atmosphere?
- Energy from the Sun heats the Earth's surface and water evaporates from oceas, lakes and rivers
- transpiration from plants releases water vapour into the air
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Describe the stages of the water cycle
1, Water enters the atmosphere as water vapour in one of two processes-
-energy from the sun heats the earth's surface and water evaporates from rivers, lakes and oceans
-transpiration from plants releases water vapour into the air
2, The warmer air of the lower atmosphere rises, taking the water vapour with it.
- The moist air cools down as it rises
- Water vapour condenses back into liquid water, forming clouds.
3, Water returns to Earth in the form of precipitation
- As the water droplets in the cloud get bigger and heavier, they begin to fall as rain, snow and sleet
- This is called precipitation.
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What are the main processes of the water cycle?
evaporation, condensation, transpiration and precipitation
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Evaporation
Energy from the Sun turns water from a liquid to a gas
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Transpiration
Plants allow some water to evaporate from the surface of their leaves to ensure water is continuously pulled from the soil and travels through the plant to its leaves (the transpiration stream).
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condensation
When water vapour cools, water turns from a gas to a liquid
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Precipitation
The falling of rain, snow and sleet from the sky
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What affect the rate of decay of biological material?
Temperature, water and availability of oxygen
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What is decomposition (decay/rotting)
It is the breaking down and digestion of biological material (waste products and dead organisms) by organisms called decomposers.
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What do decomposers include?
Microorganisms (bacteria and fungi) and detritus feeders)
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Why is decomposition crucial?
It ensures that materials such as carbon and mineral ions are recycled and returned to the environment.
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What is the rate of decay?
It is the speed that decomposers break down biological material.
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What is the rate of decay affected by?
Temperature, water, availibility of oxygen
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How does temperature affect the rate of decay?
- at warmer temperatures, enzymes involved in decomposition can work at a faster rate, increasing the rate of decay
- If the temperature is too high, the enzymes will denature and the rate of decay will decrease
- At low temperatures, the enzymes involved in decomposition work slowly, decreasing the rate of decay- so we keep food in the fridge.
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How does water affect the rate of decay?
- decomposers require water to survive (water being essential for certain biological processes)
- Many decomposers also function by secreting enzymes onto decaying biological matter and absorbing the products of this chemical digestion - without water these reactions cannot occur
- As water availibility decreases, the rate of decay decreases.
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How does the availibility of oxygen affect the rate of decay?
- Oxygen is needed by many decomposers for aerobic respiration so they need it to survive
- For these decomposers, the rate of decay decreases as oxygen availibility decreases
- However, some microorganisms can respire anaerobically (they don't require oxygen to survive), resulting in anaerobic decay (such as in biogas generators).
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Uses of decomposition-compost
- Gardeners and farmers try to provide optimum conditions (warmth,moisture and an oxygen supply) for rapid decay of waste biological material (eg: waste plant matter)
- The compost produced is used as natural fertiliser for growing garden plants or crops
- Once the compost is spread onto the soil, it is broken down further by decomposing microorganisms (bacteria and fungi) and detritivores (eg: earthworms and woodlice).
- This ensures the recycling of minerals (such as magnesium and nitrates) that can then be absorbed by plants to be used for growth (magnesium is used to make chlorophyll, nitrates to make amino acids).
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Biogas generators
- some decomposing microorganisms can break down biological material without oxygen
- this is called anaerobic decay
- Anaerobic decay produces methane gas (as well as carbon dioxide)- together these products are given the term 'biogas'
- The methane produced can be used as a fuel
methane + oxygen --> carbon dioxide + water
- Biogas generators are large containers in which animal or plant waste is allowed to decay anaerobically.
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Biogas is
methane gas and carbon dioxide
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conditions in biogas generators
- make sure the decomposing microorganisms are kept in anaerobic conditions (no oxygen) in order to ensure anaerobic decay occurs
- water (moisture) is still required for the microorganisms to survive
- the biogas generator should be kept at a constant, optimum temperature to allow the decomposing microorganisms to continue respiring and decomposing the biological material.
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Why is human population exponentially growing?
- This is due to improved technology leading to an abundance of food --rapid increase in birth rate
- improved medicine,hygiene and health care --> decrease in death rate
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What is the disadvantage of the growing human population?
Increasingly more resources are being used to sustain the human population meaning more waste is produced and more pollution is created.
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Water pollutant - toxic chemicals (pesticides and herbicides)
source: Sprayed on crops to prevent damage by insects and growth of weeds. Runoff occurs from agricultural land if these toxic chemicals are applied in too high a concentration, causing them to enter watercourses.
How pollutant affects biodiversity: These chemicals cannot be broken down by organisms. They can be absorbed by aquatic plants or invertebrates and can build up in the tissues of these organisms over time. This is called bioaccumulation. At each stage of the food chain, increasing levels of the chemicals build up in organisms, which can eventually build up to dangerously toxic levels in top predators, leading to death or failure to breed. This is called biomagnification.
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Water pollutant-untreated sewage
- Lack of sewage treatment plants in inhabited areas (due to poor infrastructure or lack of money) means that the sewage runs or is pumped into watercourses.
- How pollutant affects biodiversity- Sewage provides a good source of food for bacteria which increase rapidly, depleting the oxygen dissolved in the water (as they respire aerobically). This lack of oxygen eventually results in the death of aquatic organisms such as fish and aquatic invertebrates. This is known as eutrophication.
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Water pollutant-fertilisers
- source:runoff occurs from agricultural land is fertilisers are applied in too high a concentration, causing fertilisers to enter watercourses.
- How pollutant affects biodiversity: Fertiliser causes increased growth of algae and water plants. The resulting 'algal bloom' blocks sunlight so water plants on the bottom start to die, as does the algae when competition for nutrients becomes too dense. Dead plants and algae are a good source of food for bacteria. This eventually leads to eutrophication and the deat of many aquatic organisms.
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eutrophication
The leaching of fertilisers into rivers and lakes which causes an increase in the levels of minerals such as nitrate and phosphate in the water.
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What is bioaccumulation?
It is the increase in concentration of a toxic chemical in a particular organism over time.
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What is biomagnification?
It is the increase in concentration of a toxic chemical the higher the organism is in the food chain.
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Land pollutant- Toxic chemicals (pesticides and herbicides)
Source: When sprayed onto crops, these toxic chemicals also get into the soil
How pollutant affects biodiversity: These chemicals cannot be broken down by organisms. They can be absorbed by plants ot taken in by other organisms living in the soil and can build up in the tissues of these organisms over time. This is called bioaccumulation. At each stage of the food chain, increasing levels of the chemicals build up in organisms, which can eventually build up to dangerously toxic levels in top predators, leading to death or failure to breed- biomagnification.
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Land pollutant-discarded rubbish
source:Household waste that cannot be recycled is buried in landfill sites.
How pollutant affects biodiversity: Landfill sites take up a lot of room and their creation often results in the destruction of natural habitats. Toxc chemicals can spread from the waste into the soil. Much rubbish, such as that made from plastic, is non-biodegradeable and remains in the environment for hundreds of years.
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Air pollutant- sulphur dioxide and nitrogen oxides.
source:Combustion of fossil fuels that contain sulphur impurities creates sulphur dioxide. Nitrogen oxides are also produced during fossil fuel combustion. These gases react with oxygen and dissolve in rainwater to produce dilute sulphuric acid and nitric acid, which leads to acid rain.
How pollutant affects biodiversity: Acid rain can damage the leaves, buds, flowers and roots of trees and other plants. It can make rivers and lakes too acidic, resulting in the death of certain aquatic organisms. It can also cause the leaching of minerals that are toxic to fish, such as aluminium, into lakes.
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What does the increasing human population mean for land?
It means an increasing amount of land is required for activities such as building, quarryong, farming and dumping waste.
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What is the problem of increasing land use?
It is causing the destruction of many habitats, such as rainforests and woodlands. This reduces the biodiversity of these areas and interrupts food chains and webs, meaning more species may die because their prey is gone.
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What are the main reasons for habitat destruction?
- clearing land for farming and housing
- extraction of natural resources
- landfill sites
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increasing human land use- clearing land for farming and housing
- As there is an increasing population and demand for food, the amount of land available for these requirements must be increased by clearing habitats such as forests (deforestation).
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Increasing human land use- extraction of natural resources
- natural resources such as wood, stone and metals are used to make many different products
- Many trees are cut down, destroying forest habitats
- Quarrying and mining take up a large amount of space and the land must be cleared first.
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Increasing human land use- Landfill sites
- Many materials cannot be recycled and are discarded when they have been used
- Landfill sites take up a lot of room and their creation often results in the destruction of natural habitats.
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Peat bogs
- Bogs are areas of land that are waterlogged and acidic – plants living in bogs do not decay fully when they die due to a lack of oxygen
- The partly decomposed plant matter accumulates over very long periods of time and forms peat
- The carbon that would have been released into the atmosphere as carbon dioxide (if the plants had been able to fully decompose) is instead stored in the peat
- Peat bogs are also important habitats for many species (eg. migrating birds)
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Why are peat bogs being destroyed?
- Peat bogs are drained so that the area can be used for farming
- Peat can be dried and used as a fuel
- Peat can be used to produce compost for gardens or farms to increase food production
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Negative impacts of peat bogs
- Carbon dioxide is released into the atmosphere when peat is burned as a fuel- this contributes to global warming
- Similarly to fossil fuels, peat bogs take so long to form that peat is effectively a non-renewable energy source
- The available peat bog habitat area for many species of animals, plants and microorganism is decreasing, reducing biodiversity
- Peat bogs are being destroyed faster than they can form – they are being used unsustainably
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What is biomass?
- It is the mass of living tissues (or recently dead tissues that have not yet been decomposed) that a plant or animal is made up of.
- It is the ‘dry mass’ of the organism (how much mass the plant or animal would have without including all the water that is in the organism)
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What happens to biomass as you move up the trophic levels in a food chain or food web?
Biomass decreases
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Biomass transfer
- energy flows from the sun to the first trophic level in the form of light
- Producers convert light energy into chemical energy: this occurs during photosynthesis , when producers convert carbon dioxide and water into glucose and oxygen
- Producers use this glucose (during respiration) to produce their own biomass (a store of chemical energy)
- When primary consumers consume (eat) producers, they break down the biomass of the producer (digestion) and use the chemical energy to increase or sustain their own biomass
- When secondary consumers consume (eat) primary consumers, they break down the biomass of the primary consumer (digestion) and use the chemical energy to increase or sustain their own biomass, and so on
- In this way, as chemical energy is transferred from one trophic level to the next, biomass is also transferred.
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How much biomass of each trophic level is passed on to the next?
Approximately 10%
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Why are food chains rarely made up of more than six trophic levels?
- The total amount of biomass available eventually becomes too small to support another trophic level.
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Why do losses of biomass occur?
-Some of the biological materials of plants and animals may be inedible
-not all the ingested material is digested and absorbed, some is egested as faeces
- Some absorbed material is lost as waste:
. Carbon dioxide and water are waste products of respiration (when glucose is used by an organism to provide energy for moving and keeping warm, rather than to produce more biomass)
.Water and urea are the waste products in urine, which is produced when proteins are broken down
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What is food security?
Having enough food to feed a population
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What are biological factors threatening food security?
changing population, changing diets, changing environment, pests and pathogens, costs and conflicts.
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How is a changing population threatening food security?
An increasing population due to increasing birth rate (especially in developed countries)- more demand on food.
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How are changing diets threatening food security?
Changing diets in developed countries means scarce food resources (often from developing countries) are transported around the world,meaning these food sources become even more scarce in the countries which need them the most.
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How is a changing environment threatening food security?
Environmental changes can affect food production, leading to widespread famine in some countries (eg: is the rain fails one year).
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How are pests and pathogens threatening food security?
Farming is threatened by new pests or pathogens that affect crops or livestock.
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How do costs affect food security?
Farming has high input costs. The costs of irrigation, machinery and livestock can make farming too expensive, leading to a lack of farming and food production in some areas.
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How do conflicts affect food security?
Conflicts in some parts of the world have already affected the availability of water or food and will continue to do so as these resources become increasingly scarce.
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What is needed to overcome food security?
sustainable methods of farming to overcome food shortages.
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What does sustainable food production involve?
It involves making enough food but making sure this is done without using resources (water,soils) faster than the resources can be renewed and used again,
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How can the efficiency of food production be improved?
By restricting enrgy transfer from food animals to the environment.
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How can farmers restrict the energy transfer of animals?
-By limiting their movement by keeping them in small pens or cage so they use less energy moving around and by controlling the temperature of their surroundings so that livestock use less energy regulating their body temperature themselves.
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What are two main processes that require the energy released in respiration?
movement and staying warm
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Why is it important to restrict movement and regulate temperature?
There is more energy available for growth.
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What are some animals fed to increase growth?
High-protein foods
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Why may some people have ethical objections to keeping livestock in confined spaces? (modern farming technique)
Keeping livestock in confined spaces is controversial because disease can spread easily and many people think it is unethical for livestock to live in unnatural and uncomfortable conditions.
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Modern farming technique- livestock fed antibiotics in their food
ADVANTAGES:
-Antibiotics prevent diseases and bacterial infections in livestock
DISADVANTAGES:
- Scientists think this may be leading to antibiotic resistance in bacteria.
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Modern farming technique- Monocultures
Advantages:
- Farmers only grow a single crop type across vast areas of land as this maximises the amount of food produced and their profits.
Disadvantages:
- Monocultures only support a low level of biodiversity.
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Modern farming technique- fertiliser use
Advantages:
- increases plant growth and therefore maximises food production
Disadvantage:
- Runoff occurs from agricultural land if fertilisers are applied in too high a concentration, causing fertilisers to enter watercourses. This can lead to eutrophication and eventually the death of aquatic organisms.
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Modern farming technique- Hedgerow removal
Advantages:
- This has made fields bigger and easier to maintain with big farm machinery.
Disadvantages:
- Reduces biodiversity as hedgerows provide a habitat for a large number of species.
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What is another word for decomposers?
detritivores
