Ecosystems and Materials Cycles Flashcards
SB9a Ecosystems
Describe the different levels of organisation in an ecosystem.
- All organisms that live and interact in an ecosystem form a community. The community is made up of populations of different species.
- These species depend on eachother for resources, so they are interdependant.
- Each organism lives in a particular habitat
SB9a Ecosystems
Describe what abundance is & provide the formula for it.
- Abundance is a measure of how common something is in an area, such as population size.
- Population size can be estimated using Quadrats, these are placed randomly
- Formula: Population size = num of organisms in all quadrats x total area/total area of quadrats
SB9b Energy transfer
Describe the role of biomass & trophic levels in an ecosystem
- Photosynthesis captures energy transferred by light from the Sun. Much of this energy is transferred to substances in new plant biomass ( the mass of tissue )
- The rest is transferred to the enviroment by heating, however other organisms cannot make use of energy transferred to the enviroment by heating.
- The energy stored in plants are transferred to herbivores, which are then transferred to a carnivore that eats that animal, and so on through the tropic levels ( feeding levels ).
- Some energy is transferred to the surroundings by heating during metabolic processes. Some remains stored in plant biomass in faeces & in urine. This is not available to the rabbit’s predator.
SB9c Abiotic factors and communities
A) Define what an abiotic factor is
B) Explain how communities may be affected by some abiotic factors
A) Non-living factors are called abiotic factors
B) Some ways are;
- Temperature: All organisms have adaptations that make them suited towards certain temperatures. So a long-term change in temp can result in a change of distrubtion of some organisms.
- Light: Light is essential for plants and algae to grow. So organisms are more likely to grow where there is sunlight.
- Pollutants: These can poison organisms or cause harm to organisms in other ways ( such as plastic being eaten by fish & other organisms ).
- Water: Most land plants cannot survive if their roots are underwater for too long.
SB9c Core practical - Quadrats & transects
Describe the core practical to investigate abiotic factors on living organisms using belt transects
Aim - Investigate the effects of abiotic factors on organisms.
- A: Peg out a long tape measure ( at least 20m ) on the ground, starting where there is no shade and ending in heavy shade. This is the transect line.
- B: Make measurements at regular intervals along the transect line. Decide on your measurement intervals which may depend on transect length and time.
- C: Place the top left-hand corner of the quadrat at a measurement point on the transect line.
- D: Measure the abiotic factor at that point & record them.
- E: Record the abundance of your selected plant in the quadrat.
- F: Repeat steps C to E at each measurement point along the transect.
SB9d Biotic factors & communities
A) Define what an biotic factor is
B) Explain how communities may be affected by some biotic factors
A) Biotic factors are the organisms in an ecosystem that affect other living organisms.
B) Some factors are;
- Competition: As a food source decreases, this will lead to an increase in competition between the predators of that food source.
- Predation: This is the act of predators preying on prey. By increasing the amount of predators the amount of prey will decrease, this will then decrease the amount of predators allowing for prey numbers to increase again - Predator prey cycle.
SB9e Assessing pollution
A) Define what an indicator species is
B) Provide some example of air pollution indicators.
A) An indicator species is an organism whose presence, absence reflects a specific environmental condition
B) Some examples include;
- Lecanora conizadoies - Lichen: This is a species of lichen that is the only one of its kind that is able to tolerate air polluted with sulfure-containing gases.
- Blackspot fungus: This is a pathogen of roses that cannot grow well where is alot of sulfure pollution.
SB9e Assessing pollution
A) Describe the different indicator species that can be used for water pollution.
B) Evaluate the use of living organisms for this.
A) Different invertebrates can be used to signal different water qualities.
- Clean water: Stonefly nymph, Dragonfly nymph, Freshwater shrimp
- Polluted water: Water louse, Bloodworm, Sludgeworm
B) Both water & air pollution can be measured using sensors, these give numerical data at the time of measurement.
- Indicator species do not give this level of detail, but they are usefull for the simple assessment of the long-term health of an ecosystem.
SB9e Assessing pollution
Describe the process of Eutrophication
- Fertilisers ( which contain nitrates ) pour into the water, this gives the algae on the surface of the water the nutrients it needs for rapid growth.
- This results in the algae blocking the sunlight from reaching the plants in the water, which result in their death ( As they can no longer respire and produce oxygen ).
- Decomposer bacteria then feed on the remains of the plants while also consuming the oxygen in the water, resulting in the death of other sea animals.
SB9f Parastisim and mutualism
Describe what;
A) Paratisim is
B) Mutualism is
A) Paratisim is a kind of feeding relationship in which one organism ( the parasite ) benefits by feeding off a host organism, causing harm to the host.
B) Mutualism is a kind of relationship where both organisms benefit from the relationship.
SB9f Parastisim and mutualism
Describe how;
A) Tapeworms are adapted to living in hosts intestines
B) Head lice are adapted to living in hair & skin
A) Adaptations are;
- Hooks and suckers that can attach the worm’s head firmly to the host’s intestine wall.
- Segments contain male and female sex organs so fertilisation can occur.
- A flattened body allows absorption of nutrients over whole surface without need for digestive or circulatory systems.
B) Adaptations include;
- Sharp mouthparts can pierce skin and suck blood
- Sharp claws grip on to hair and skin
- Eggs are glued to hairs to prevent them falling off.
SB9g Biodiversity and humans
Explain how;
A) Fish-farming
B) Introducing species
may affect biodiversity/ecosystems.
A) As the human population increases, we will need more fish. However, overfishing has damaged some aquatic ecosystems. Fish farming aims to produce more fish & so reduce overfishing of wild fish.
- This causes problems since so many fish are kept in a relatively small space. Uneaten food & faeces sinks to the bottom of the water.
- This can change conditions, also parasites & disease will also spread easier.
B) Some species are introduces in order to affect an ecosystem, such as to reduce the numbers of another species that has gotten out of control.
- For example, cane toad in SA were introduced to control cane beetles but now the number of cane toads have become an issue.
SB9h Preserving biodiversity
Explain the benefits of maintaining local and global biodiversity.
- Preserving biodiversity is not just important for conserving individual species or communities.
- Areas with greater biodiversity can recover faster from natural disasters such as flooding. We also use plants and animals for food & source of medicine and other products.
- As conditions change, we may need new varities of plants and animals to provide what we need.
- So it is important that we try to preserve as many species as we can.
SB9i Food security
A) Describe what is ment by food security
B) Describe the different biological factors affecting food security.
A) Food security means having access to enough safe and healthy food at all times.
B) Some factors include;
- Increasing human population - More humans means more food needed.
- People becoming wealthier - As people become wealthier, they tend to eat more fish and meat. This is worrying as alot more protien can be produced in the same space of land than meat.
- New pests and pathogens - These could kill off the different crops that we need to produce our food. Also farmers we produce the crops may also get sick & not be able to work.
- Environmental change - Droughts caused be climate change may kill off many different crops while excessive heat may also do the same.
- Sustainability issues - Most of the fertilisers used are made using a process that needs energy and burns CO2. This raises concerns about sustainability.
SB9j The water cycle
Describe the importance of the water cycle & the process of how potable water is made.
- Substances that organisms need ( water, carbon & nitrogen ) are limited so need to be recycled through organisms & the environment to support life.
Process:
- As water droplets get to large and heavy they fall as rain or snow
- Groundwater ( water that moves from soil and rock ) and normal water are lead by river’s to lakes that eventually lead to oceans.
- Water evaporates from oceans, lakes and rivers to form water vapour.
- As air rises it cools, so water vapour condenses to form clouds.
Being made potable:
- Obtaining fresh water from the sea or salty water is known as desalination. This can be done via distillation
- Dirty water is placed into the still at one area, water evaporates as it gets hotter inside the still.
- Water condenses under the cover and trickles to the bottom of the slope.
SB9k The Carbon cycle
Describe the importance of the carbon cycle and how it occurs.
- Decay is caused by microorganisms that we call decomposers. Decomposers include fungi & bacteria, which also breaks down the carbon compounds in animal waste.
Process:
- Plants absorb carbon dioxide in the atmoshpere for photosynthesis, plants will also undergo respiration which releases more co2 gas.
- Plants will also feed animals that as part of respiration with also release co2 gas, these animals waste will be decomposed by decomposers, which will include respiration that releases co2.
- The death of plants & animals contributes to the formation of fossil fuels, which when burnt release co2 gas into the atmosphere.
SB9l The nitrogen cycle
Describe the different roles of bacteria in the nitrogen cycle.
- Nitrogen fixing bacteria - These are bacteria protected inside nodules in the plant roots. They take nitrogen gas and turn it into nitrates.
- Nitrifying bacteria - Causes ammonia to turn into nitrates by oxidation ( in the soil )
- Denitrifying bacteria - breaks down nitrates to nitrogen ( puts nitrogen back into the air )
- Decomposers - bacteria which breaks down waste compounds/dead organisms containing nitrogen and return to ammonia.
SB9l The nitrogen cycle
Describe the nitrogen cycle
- Animals dying or excreeting will contain proteins and urea, this is then decomposed by decomposers including soil bacteria.
- This leads to nitrates in soils, that is converted into nitrogen by denitrifying bacteria. Nitrogen gas in the air is converted into nitrates in the soil by nitrogen-fixing bacteria, soil bacteria and lightning.
- Plants then absorb the nitrates in the soil or nitrogen fixing bacteria in the plants root nodules will convert nitrogen gas in the air into nitrates. These plants then feed the animals.
SB9m Rates of decomposition
Describe what most methods of food preservation rely on.
- Reducing temperature, for example in fridges and freezers
- Reducing water content, for example by salting and then drying meat to make ham or salami
- Irradation of packaged foods to kill decomposers
- Reducing oxygen, for example storing foods in oil. Foods that easily decay are often packages in an unreactive gas, like nitrogen or agon.
SB9m Rates of decomposition
A) Explain what compost is
B) Provide the formula to find the rate of decomposition
A) This is well-decayed garden waste that boosts soil fertility. The way a compost heap is constructed affects the conditions inside the heap, & so effect the rate of compost formation.
B) rate of decomposition = mass lost/number of days
