Ecology and Environment Flashcards
Define population
All the organisms of one species that live in the same place at the same time
Define community
All the populations of all the species that live in the same ecosystem at the same time
Define habitat
The place where an organism lives
Define ecosystem
A distinct, self-supporting system of organisms interacting with each other and the physical environment
Define biotic component
All the living things in an ecosystem
Define abiotic component
All the non-living things in an ecosystem
Explain quadrats practical
- use two measuring tapes to create a grid of the area to be sampled
- use a random number table to choose a co-ordinate = prevents bias
- place bottom-left corner of a 0.5x0.5m quadrat on the Co-ordinate each time for consistency
- then count the number of organisms of desired species
- repeat 10 times for more reliability + accuracy and to create a mean of organisms/quadrat
How do you calculate the number of organisms/m2 of area?
- using the results from the 10 repeats, calculate a mean of organisms/quadrat
- area of quadrat = 0.25m2 so to get 1m2 times by 4
- times average number of organisms/quadrat by 4 = organisms/m2
Formula for estimated population size
Total area of one field/ area of quadrat x mean number of organisms per quadrat
Define biodiversity
The amount of variation shown by organisms of an ecosystem - it is a measure of species richness and evenness
Define species richness
The number of different species in an ecosystem
Define species evenness
The relative abundance of each species ; the number of individuals in each species
Simpson’s diversity index formula
D = N(N-1)/ the sum of n(n-1)
- D = diversity index
- N = total number of organisms of all species found
- n = total number of individuals found of the species we are interested in
Why is high biodiversity good for an ecosystem?
- it provides more habitats for animals to live in
- more food sources are available - if one source dies out, animals always have others
Define biotic factor
A biological factor affecting an ecosystem
Define abiotic factor
A physical or chemical factor affecting an ecosystem
Examples of biotic factors
- availability of food
- predation
- parasitism
- disease
- nesting site availability
- presence of pollinating insects
Examples of abiotic factors
- temperature
- light intensity
- water availability
- soil pH
- pollution
- O2 concentration
What are the 4 tropic levels?
Producer, primary consumer, secondary consumer, tertiary consumer/apex predator
Define producer
Organisms that make their own food (e.g phytoplankton, green plants)
Define consumer
Organisms that eat other organisms
What is the difference between primary and secondary consumers?
Primary consumers tend to be herbivores whilst secondary consumers tend to be carnivores
What are decomposers?
Bacteria and fungi that break down dead remains of other organisms, helping to recycle minerals
Define food chain
A flow diagram that shows the feeding relationships of an ecosystem and how energy is transferred between trophic levels
What do arrows show in food chains + webs?
The direction of energy transfer between trophic levels
Define food web
A diagram that describes how several food chains are interlinked
Why are food webs more realistic than food chains?
Plants and animals are often eaten by more than one species and tend to have more than one food source. Food chains oversimplify feeding relationships as they imply that one organism is only eaten by one other organisms
Describe the energy transfers in food chains
- producers photosynthesise and produce glucose and O2
- some glucose is used for respiration to keep producer’s cells alive
- this energy is essentially lost as heat so is not available to primary consumer
- some glucose is used to make new biomass which can be eaten + used by primary consumer
- molecules of cell contain chemical energy in C-C bonds, which can be used throughout the food chain
How much energy is transferred and wasted between trophic levels?
90% of energy is wasted between trophic levels and only 10% is transferred
How is energy lost between trophic levels of a food chain?
- plants and animals die and decompose so energy doesn’t enter food chain
- excretion so energy exits food chain as waste products of metabolism e.g urea and released
- egestion so energy exits food chain as faeces so not all food eaten is absorbed so is egested as faeces
- not all of previous organism consumed (e.g bones, fur and roots)
- biomass is used for respiration to release energy + some is used to convert o2 and glucose to co2 and H2O and this produces heat
- movement
What is a pyramid of biomass?
A diagram in which each block represents the total mass of all the organisms in the tropics level, regardless of their numbers
What happens to biomass before it’s measured ?
Biomass is dried before it’s is measured as water content can vary across organisms and therefore produce inaccurate results
Why are pyramids of biomass always a pyramid shape?
- biomass decreases as you go up the trophic levels
- biomass contains energy so if 90% of energy is lost between trophic levels, so is that much biomass
What is a pyramid of number?
A diagram in which each bar represents the number of organisms in each trophic level, regardless of their biomass
What is a pyramid of energy transfer?
A diagram in which each bar represents the amount of energy available at that trophic level
Why are pyramids of energy transfer always pyramid shaped?
90% of energy is wasted between trophic levels so only 10% is transferred so each bar is 10X smaller than the previous
Order of events in carbon cycle
- photosynthesis fixes CO2 from air into organic compounds
- respiration from producers + consumers + decomposers produces CO2 from organic compounds
- feeling relationships cause carbon atoms to pass between food chains and trophic levels by assimilation
- decomposers decompose dead plant and animal material
- fossil fuels are burnt by factories + vehicles and releases CO2 into air by combustion
Why can’t nitrogen gas be directly used by plants?
It is too unreactive
Order of events in the nitrogen cycle
- nitrogen fixing bacteria living in root nodules of legumes converts nitrogen gas into ammonium by ammonification
- nitrogen fixing bacteria freely living in the soil converts nitrogen gas into ammonium by ammonification
- decomposers (bacteria + fungi) break down proteins in dead and decaying matter into ammonium by ammonification
- nitrifying bacteria convert the ammonium in the nitrites and then nitrates
- the nitrates can either be directly assimilated by plants to make amino acids = proteins for growth
- denitrifying bacteria convert nitrates back into nitrogen gas
Why do plants need nitrates?
Plants can convert these into amino acids and proteins that can be used for growth
What are the 3 main gasses produced from pollution?
- Carbon dioxide (CO2)
- sulfur dioxide (SO2)
- nitrous oxides (NOx)
How do sulphur dioxide and nitrous oxides cause acid rain?
- sulfur is an impurity in fossil fuels so when this is burned in oxygen in car engines, it becomes hot enough to react with oxygen to form SO2
- nitrogen in air is unreactive so only reacts under high temp of car engine to produce NOx
- these gasses rise into the atmosphere and dissolve in water vapour to produce sulfuric and nitric acid which come down as acid rain
Why is CO bad?
- fatal product of incomplete combustion
- haemoglobin will bind to CO in preference to O2
- irreversibly binds to haemoglobin and produces carboxyhaemoglobin
- oxygen can no longer bind to haemoglobin so cannot be transported around the body
Biological consequences of acid rain
- acidification of lakes + kills aquatic plant and animal life
- kills trees + acidifies soil so important mineral ions leach out of soil and can accumulate to toxic levels in water bodies
- slow growth of plants as it damages root have cells so mineral ions can’t be absorbed as quickly
Name 5 greenhouse gasses
- water vapour
- carbon dioxide
- nitrous oxide
- methane
- CFCs = chlorofluorocarbons
Name 5 human activities that contribute to greenhouse gas production
- deforestation
- cattle farming
- manufacturing
- travel
- food waste
How does deforestation contribute to greenhouse gas production?
- slash and burn method
- cutting down + burning trees produces CO2 not only bc of combustion but also bc trees are carbon sinks
- fewer trees = less photosynthesis so less CO2 is removed from the atmosphere
How does cattle farming contribute to greenhouse gas production?
- cows fart methane + eating them causes more demand of them, therefore they are bred more
- this results in more cows flatulating methane into atmosphere
- area is cleared for cow pastures by deforestation so less CO2 is absorbed from atmosphere
How does manufacturing produce greenhouse gasses?
- fast fashion industry means that goods must be transported
- fossil fuels are burnt by vehicles, producing CO2
How does travel produce greenhouse gasses?
Vehicles burn fossil fuels = CO2 is produced
How does food waste produce greenhouse gasses?
CH4 produced as food decays in landfill
What does increase in greenhouse gas production mean?
An increase in greenhouse gas emission from human activity causes the enhanced greenhouse effect. This means that more thermal radiation is trapped in the earths atmosphere warming it further,causing global warming.
Name three biological consequences of global warming
- habitat destruction
- loss of biodiversity
- species migration
What is sewage?
Wet waste from houses factories farms, including : faeces, excretion, soap residue and food waste
Explain the biological consequences of pollution of water by sewage
- bacteria population increases due to rapid reproduction as there is lots of sewage to decompose
- more bacteria = more respiration so oxygen levels decrease
- freshwater plant and animal population decreases due to low oxygen levels as this means they cannot respire
- eventually, bacteria die out as there isn’t any plants to photosynthesise and produce oxygen anymore therefore they can no longer respire
- no life is left in the habitat
Define eutrophication
A process in which an aquatic habitat receives a large amount of minerals, either naturally or by pollution from fertilisers or treated/untreated sewage
Define leaching
When mineral ions such as nitrates are washed out the soil by rain
Explain eutrophication
- excess nitrates from fertilisers enter the habitat, resulting in the growth of an algal bloom on the surface of the water
- algae grow + block out the sunlight = aquatic plants can’t photosynthesise so die
- O2 levels drop as there isn’t photosynthesis
- aquatic animals die as there’s no oxygen for respiration
- bacteria pop. increase as they decompose the dead plant + animals
- O2 levels drop again as there isn’t photosynthesis too much bacteria respiration and no photosynthesis
- bacteria die out = no life left
How does deforestation cause leaching and soil erosion?
A larger surface area of soil is exposed to rainfall due to a lack of cover from canopy so the soil gets washed away, as well as mineral ions and neither of these are replaced
How does deforestation cause the disturbance of weather patterns and evapotranspiration?
- Trees are involved in the water cycle as they return water vapour from the soil to the air by transpiration through their leaves
- this water condenses to form clouds and causes rain, therefore deforestation disturbs whether patterns
How does deforestation cause global warming and the imbalance of atmospheric gases?
Less trees means less photosynthesis = less CO2 is removed from the atmosphere more is present in the atmosphere. This results in the enhanced greenhouse effect, causing global temperatures to rise.
Define sexual reproduction
Process involving the fusion of the nuclei of two gametes to form a zygote and the production of offspring that are genetically varied
Define asexual reproduction
Process that does not involve the fusion of gametes, genetically identical offspring are produced from one parent organism
Differences between sexual and asexual reproduction
- sexual has gametes but asexual hasn’t got gametes
- sexual has 2 parents but asexual has 1 parent
- sexual has genetically different offspring but in asexual offspring are clones of parents
Define fertilisation
Fusion of a male and female gamete to produce a zygote that undergoes mitosis and develops into an embryo
Define pollination
The transfer of pollen grains from the anther to the stigma
Describe the structures of an insect pollinated flower and explain how each is adapted for pollination
- stamen and stigma are enclosed within the flower so that the insect must make contact with it
- Stigma is sticky so that pollen grains can attach from insect
- Petals are colourful and large = attracts insects
- produce a sweet nectar + attracts insects to pollinate flowers
- pollen grains are large and sticky or have hooks to stick to insect’s bodies
Describe the structures of a wind pollinated flower and explain how each is adapted for pollination
- stamens are exposed so that pollen grains are easily blown away
- stigma is feathery + exposed to catch pollen blowing in the wind
- petals are small and green/dull
- no nectar
- pollen grains are small + smooth + inflated + inflated to help them carry in the wind
How does the nucleus of the pollen grain reach the nucleus of the ovum?
- pollen grain lands on stigma + pollen tube grows down through the style
- end of pollen tube enters the ovary and fuses w/ wall of ovule
- nucleus of pollen grain travels down pollen tube + fuses with the ovum nucleus
What are the parts of a seed?
- radicle = embryonic root
- plumule = embryonic shoot
- cotyledon = food store
- micropyle = tiny hole that lets water in to start germination
- testa = seed coat
What happens to the plant zygote after fertilisation?
Develops into embryonic plant w radicle + plumule
What happens to the contents of the ovule after fertilisation?
Develops into cotyledon/ food store
What happens to the ovule wall after fertilisation?
Develops into testa or seed coat
What happens to the ovary wall after fertilisation?
Becomes the fruit wall/ fruit
What are the components of a flower?
- stalk
- sepal
- petal
- stamen = filament + anther
- carpel = stigma + ovary + style
What are the structures of the carpel?
- stigma
- style
- ovary
- ovules containing ova
What are the structures of the stamen?
- anther
- filament
- pollen grains inside anther
Define germination
Sequence of events that take place when an embryo in a seed develops into a young seedling
When does germination start + end?
- starts = water enters seed via micropyle, starting chemical reactions such as respiration and the breakdown of the food store, resulting in embryonic growth
- ends = when the plumule breaks through the surface of the soil and can photosynthesise
What are the conditions needed for germination?
- warmth = allows enzymes to work as close to optimum temperature as possible bc this results in more enzyme substrate complexes bc of more frequent collisions + more kinetic energy
- water = starts chemical reactions in the seed
- oxygen = for respiration
How does water allow germination to start?
- softens the testa, allowing it to split as the plumule grows over time
- allows chemical reactions to take place such as respiration and the break down of the food store
What is the role of enzymes in germination?
- Enzymes break down the food store from starch into maltose by amylase and then from maltose into glucose by maltase
- glucose can then be used for respiration
Why is the food store important for the growing embryo? When is it used from and until?
- food source provides the growing embryo with protein to grow
- used until the seedling can photosynthesise
Describe the method of the germination experiment + explain the results
- 4 boiling tubes = A, B, C, D filled with cotton wool and 10 seeds, all were wet except A
- A+B were on the lab bench at room temperature
- C was in a dark cupboard at room temperature
- D was in a dark, cold fridge
- all germinated except A as there was no water, so water is essential for germination
- the most germinated in B as there was water, light and warmth. These are all needed for successful germination and growth
List the ways that plant can reproduce asexually, both naturally and artificially
- runners
- bulbs
- cuttings
Explain the burning food practical
- measure the mass of the food item
- add 20cm3 cold tap water to a boiling tube + place at an angle in a clamp and stand
- measure water temperature w/ thermometer
- set up a Bunsen burner away from the boiling tube
- hold the food item in extended tongs and set it on fire
- hold it under the boiling tube until the food item’s completely burnt
- measure water temperature w/thermometer
Formula for energy in food
Mass of water (g) x change in temperature x 4.2
Formula for energy/g of food
Energy in food / mass of food
What is biomass?
The amount of living material in a plant or animal, including carbohydrates, proteins and lipids
