B18 Flashcards
Biodiversity and ecosystems
What is biodiversity ?
variety existing between all different organisms on Earth, or within a certain ecosystem
Why is having high levels of biodiversity important ?
- high levels of biodiversity reduce the dependency of organisms on each other for food/shelter/maintenance of the local environment
[] changes to a population can occur without making others drop in number or go extinct - MAKES ECOSYSTEMS MORE STABLE
Why has the human population grown so much so quickly ?
- no natural predators
- developed agriculture
[] can produce more food than we can physically gather; no competition for food with other species - developed medicine
[] natural balance cannot be restored via mass disease, as figured out how to prolong live past disease
What is the effect of human population rising on resources, land and biodiversity ?
- more and more land used for civilisation, farming/agriculture, roads etc.
[] destroys natural habitats of many other animals/insects/organisms
[] agricultural areas plant only one type of crop, reducing biodiversity and making local ecosystems less stable
[] those that depended on those habitats extinct or on the verge of extinction; reduction in biodiversity
[] reduces space for other species’ populations to grow and live - waste produced by humans pollutes air, land and water, sometimes making inhospitable for other organisms; also takes up land to process it causing a reduction in biodiversity
Describe the main ways in which humans pollute land, and their effects
- improper treatment/disposal of sewage
[] toxic chemicals and gut parasites pollute soil and other lands
[] make areas inhospitable - improper disposal of industrial waste
[] landfill sites take up lands and destroy habitats and thus biodiversity
[] toxic chemicals can spread from the waste to soil
[] nuclear waste and radiation can contaminate soil across thousands of miles, making crops unsafe to eat as well as greatly reducing biodiversity - side effect of pesticides/herbicides in agricultural processes
[] the poisons may get into soil and even wash into nearby water sources/bodies
[] when plants grow on contaminated soil and are eaten by animals, who are then eaten by others etc., bioaccumulation of poisons can occur in predatory animals and cause massive adverse health effects, even death
Describe the main ways in which humans pollute water, their effects and how we can work to reduce these effects
- by-product of agricultural processes and poor treatment/disposal of waste
[] bioaccumulation of toxins in aquatic food webs - fertilisers
[] minerals (especially nitrates) from fertilisers used on agricultural land wash into local streams, ponds and rivers from the soil
[] nitrates + mineral ions stimulate algal and aquatic plant growth, which occurs rapidly
[] the algae outcompete other aquatic plants for light, food and minerals, leading the aquatic plants to die
[] huge rise in decomposers breaking down the aquatic plants
[] these microorganisms use up a lot of oxygen in the water for respiration, leading to a decrease of dissolved oxygen in the water
[] other animals die out due to the lack of oxygen
[] death means MORE decomposers and even less oxygen
[] this repeats until all aerobic aquatic life in the water dies and the pond/lake/stream becomes “dead” - can use bioindicator species to monitor pollution levels in water
[] salmon only are present in streams if the water is very clean
[] bloodworms are only present in very polluted water
[] other organisms may have a tendency to quickly react to very slight changes in pollution levels - can use instrumental methods to monitor pH and oxygen levels
- strict regulations can be put on processing of waste and the use of chemicals on farmland
What is a bioindicator ?
a species/organism which is sensitive to its surrounding conditions, reacting even to the smallest changes
[] used to manage conditions in an ecosystem, such as pollution
[] bioindicators like salmon and bloodworms are often found only in very clean or very polluted water respectively; when they appear, can monitor changes in the environment and pollution levels
What is sewage ?
bodily waste and waste water produced by humans
How is acid rain formed ?
- fossil fuels are burned, releasing carbon dioxide gas and nitrate/sulfur gases
- sulfur and nitrates react with the oxygen in the air to form sulfur dioxide and nitrogen oxide
[] ACIDIC GASES - these gases react with water vapours in clouds to form dilute acids which become acid rain when precipitation occurs
What are the effects of acid rain ?
- if falls on plants, can damage leaves, stems, buds etc
[] if on leaves, can damage photosynthetic abilities - soaks into soil and raises pH, making certain plants that need lower pH soil die out
[] lowers biodiversity - raises pH of rivers/lakes/ponds; can make them “dead”
- if falls as snow, the acid snow melts all at once causing an “acid flush”
[] makes the acid have a more devastating effect on the environment, soaking into soil all at once in higher concentrations and flowing into waters nearby - as acid rain is produced in countries with high levels of industry, the clouds get carried over to other countries (often more agricultural or less industrialised) before the rain falls
How has the UK worked to prevent formation and fall of acid rain ?
- low-sulfur petrol and diesel used in vehicles
- systems to clean flue gases from factories/power stations that use fossil fuels
- catalytic converters fitted to vehicles to remove polluting gases from exhaust fumes
- strict emission levels are set for these gases and the use of fossil fuels in conjunction
What is smoke pollution and what are its effects ?
- smoke from burning fossil fuels has many soot and other particulates
- particulates in smoke reflect light upwards and have a dimming/cooling effect on the earth in large quantities
- cause breathing problems, as particulates may be irritants to lungs and cardiovascular system
- damages the health of local wildlife, and dimming may impair photosynthesis if in significant amounts
What is smog ?
thick haze of smoke and other chemicals/gases like nitrogen oxides and sulfur dioxides
What are the three main reasons for deforestation ?
- to grow large monocultures of crops to feed humans/for the agricultural industry, as well as biofuel farming
- space to rear cattle
- space for industrialisation/civilisation
What are the main effects of deforestation ?
- increases release of carbon dioxide gas into the atmosphere
[] plants and trees act as huge “carbon sinks” due to using carbon dioxide for photosynthesis
[] when these plants are burnt or left to decompose, all of the carbon dioxide they used for photosynthesis is released back into the environment - loss in biodiversity, as certain tree species host a multitude of insect species and provide food for other organisms too
[] increases dependency of any remaining organisms after the trees are destroyed
Why are peat bogs being destroyed ?
- useful as a fuel
- useful as fertiliser as is made up of lots of dead but partially decayed plant material
What is a peat bog ?
- made up of lots of partially decayed plant material
[] cannot fully decay as conditions are too acidic - builds up over millions of years (non-renewable resource)
[] being destroyed quicker than it is made - have specially adapted and rare ecosystem that thrives off of the acidic conditions, like carnivorous plants
- HUGE CARBON SINK
How is the government trying to stop the destruction and thus the extinction of peat bogs ?
promoting composts or artificial fertilisers to farmers that are “peat-free”
Why are the levels of greenhouse gases like carbon dioxide and methane rising ?
- deforestation
- industrialisation/human activity on such a large scale due to big population that cannot be reabsorbed into the environment
- destruction of carbon sinks
- burning fossil fuels
- farming of rice (methane)
- cattle farming (methane)
Describe how the greenhouse effect works
- light energy from the sun reaches the earth and warms it
- most of the energy is reflected back out into space
- some energy is reflected towards space then back at the earth by greenhouse gases in the atmosphere, keeping it warm
- the more greenhouse gases there are, the more warmth is retained/reflected back at earth, warming it significantly more than normal
What are the main (general) effects of global warming on organisms and Earth ?
- loss of habitats
[] flooded by rising seas - changes in organism migration patterns
- changes in distribution of organisms
- reduced biodiversity
- water becomes less useful to aquatic life and the atmosphere as an oxygen and carbon dioxide sink
What are the key changes by which the distribution of organisms is changed ?
- seasonal changes
[] in temperate areas of the world, natural changes in environment and climate occur throughout the year and different seasons cause different organisms to migrate into or out of certain areas - geographical changes
[] differences in soil pH, saltiness of water, altitude etc. - as a result of human interaction with the environment
[] global warming
[] acid rain
[] pollution
[] maintenance of forests
[] conservation measures
[] new diseases/pathogens/pests brought to an area by human travel
[] introduction of new predators/plants that outcompete native species for resources
Describe 5 ways in which humans can work to protect and increase biodiversity
- reintroduction of hedgerows and field margins
[] farmers leave some forest/woods between fields and surrounding fields
[] increases habitat for wildlife, thus increasing biodiversity as more organisms move into the area - breeding programmes for endangered species
- legal protection and conservation of rare habitats, like heathland and peat bogs
[] protection allows these to build up naturally again without being destroyed by humans; criminalises destruction of these areas for ANY reason
[] maintains biodiversity - reduction of deforestation + CO2 emissions
[] protects ozone layer + minimises greenhouse gases in the atmosphere, thus decreasing the greenhouse effect and global warming
[] planting trees takes CO2 out of the atmosphere again as they are carbon sinks, and are good to reduce the impact of CO2 emissions - recycling materials more instead of going through emission-producing industrial processes to make new goods
[] also allows less waste, meaning less landfill sites, less pollution of the land and water via improper handling of waste and creates more space for organisms to live, increasing biodiversity
What are the four trophic levels ?
- trophic level 1: plants/algae
- trophic level 2: herbivores/primary consumers
- trophic level 3: secondary consumers
- trophic level 4: tertiary consumers
What is a decomposer ?
organisms that break down organic material by secreting enzymes into the environment
small soluble molecules then diffuse into the microorganism
include:
[] fungi
[] bacteria
[] detritivores (maggots, larvae, worms etc.)
What is biomass ?
the total organic mass of material in an organism
What are the advantages and disadvantages of measuring biomass in grams as wet biomass vs dry biomass ?
- dry biomass
[] more accurate and repeatable measurements, as amount of dry matter will not change as often as water levels in an organism
[] have to kill the organism to measure its biomass - wet biomass
[] less repeatable measurements, as water levels vary throughout the day in most organisms
[] can measure biomass whilst the organism is still alive
Why is measuring biomass important in ecology ?
- unlike relying on the number of individuals in a population in a food chain, can draw pyramids of biomass which accurately display what is actually happening in terms of the transfer of biomass from organism to organism in a food chain
- good for observing feeding relationships in a food chain
How do you draw a pyramid of biomass ?
- WILL ALWAYS BE PYRAMID SHAPED
- always start with trophic level one at the bottom and trophic level 4 at the top
How do you draw a pyramid of biomass ?
- not always pyramid shaped
- always start with trophic level one at the bottom and trophic level 4 at the top
- draw sizes of each level according to the population size of each level
Why does the amount of biomass reduce at each trophic level ?
- organism might not consume all of previous organism
[] eg. not eating bones/cartilage - organism loses some biomass through excretion of waste, water vapours expelled during breathing etc.
[] most herbivores don’t possess the enzymes to digest cellulose, so egest it as faeces
[] excess consumed proteins get broken down into amino acids, then deaminised to form urea, then passed out through the urine
[] biomass used in respiration to regulate body temperature and contract muscles so can move - large amount of biomass is used for respiration rather than building more biomass of the organism’s own
How much biomass is transferred between trophic levels ?
up to 10%
What is food security ?
Having enough food to feed a population without risk of running out
Describe the key factors affecting food security around the world
- changing diets of developed countries
[] in the search for new and exotic foods, scarce foods relied on by local populations are exported to developed countries, reducing food security for locals - increasing birth rates
- new pests/pathogens affecting farming
[] eg. the gros michel dying out because of a new banana disease - changing environmental conditions that affect farming/agriculture (less of a problem where there are industrial greenhouses)
- war/conflict affecting food supply and agriculture
- rising costs of agricultural inputs, especially for local farmers unaffiliated with big corporations
What are some things to consider when coming up with a sustainable solution to food insecurity in the world ?
- maintaining soil quality so that crops grow well for many years
- maintaining fish stocks in the ocean (not overfishing)
- looking at more energy efficient ways to produce food
[] eating less meat, as is very energy inefficient
How can farmers increase the efficiency of food production in terms of maximising biomass transfer to humans (and what are the ethical problems with these methods) ?
- food land animals:
[] kept in small spaces or cages so that can’t move around too much, thus reducing energy expenditure/respiration and loss of biomass
[] always given plenty of food
[] kept in carefully temperature-controlled enclosures, so that the animal can use more biomass for growth of its own biomass rather than respiration to regulate temperature
[] high protein feeds, like ground up dried fish, are added to the animals’ diets - fish farming:
[] same techniques as land animals but in water - benefits:
[] maximum growth achieved with maximum efficiency
[] produce meats quickly to sell for a profit
[] limited space needed - disadvantages/ethical concerns:
[] animals kept in close quarters are more susceptible to spreading disease quickly
[] animals in close quarters are often stressed, and this hurts their growth in biomass
[] temperature-controlled areas are expensive to maintain
[] addition of other animal products to the diet actually reduces overall efficiency
[] indoor-grown animals have much more restriction and thus less quality of life than free-range/outdoor animals (though these animals grow biomass more slowly and often have to deal with adverse weather conditions, also hurting the rate at which they grow in their biomass
What would be the most efficient way for humans to get food ?
grow plants and directly eat them
[] in this way, food security for everyone on earth, and maximum biomass transfer achieved as steps in the chain are as small as possible
NOTE: in some situations, like on land where crops can’t be grown but grass can, rearing food animals who can process the grass’ biomass into meat and protein that are valuable nutritionally to humans is an advantage over this efficient method
Why must overfishing be stopped ?
- can cause certain species of fish and aquatic life to become extinct
- when catching in commercial fishing nets, organisms that were not part of the intended catch are caught as well
[] these are thrown back into the oceans, dead - bottom-trawling destroys ocean/seafloor ecosystems like coral reefs and aquatic plants
- overfishing can result in a lack of breeding adults in a population, thus catching smaller, younger individuals that are both less useful as food, but that are not replaced by other members of the species, leading to extinction
Describe ways in which overfishing can be stopped
- government-set quotas on the amount of fish that people are allowed to catch
[] reduces fishing trips made, preserving fish stocks
[] however, of limited use, as if fishermen are over quota, they will simply throw the surplus catch back, dead, which doesn’t preserve populations - strict limits set on the sizes of holes in nets
[] let only biggest fish through and allow smaller, younger fish that are still waiting to breed to slip through, allowing the species to continue without extinction - bans on fishing during breeding seasons
How do GM crops increase sustainability of food production ?
can modify crops to have bigger yields, thus needing less space and cost to grow bigger amounts of food
What is mycoprotein ?
- protein made through the fermentation of Fusarium fungi cultured in industrially controlled vats
[] microorganisms can be produced in the same conditions to produce insulin on a large scale for medical use - pale yellow solid
[] can be shaped and flavoured in many ways - sustainable, as is cheap and quick to produce in large quantities, and production doesn’t require much space
[] also use cheap food that save on waste products from other processes
Describe how mycoprotein is made
- Fusarium fungus grows + reproduces rapidly in fermenting vats
[] feeds on relatively cheap glucose syrup made from waste starches - needs aerobic conditions to grow successfully
- inside the fermenters:
[] large motorised paddles to stir the culture and aerate it for proper growth
[] probe to monitor pH, temperature, oxygen levels etc.
[] water-cooled external jacket to maintain ideal temperature - after fermentation, the culture is harvested
- harvested culture is purified, then dried
[] processed to make mycoprotein
