human impact on the environment Flashcards
how does deforestation effect the carbon cycle?
increases the co2 content in the atmosphere
how does climate change effect the carbon cycle?
global and regional climate patterns have been changing noticeably due to the huge rise in atmospheric CO2 and the rise in greenhouse gases.
the two main reasons are combustion, the burning of fossil fuels releases CO2 that was previously locked up and deforestation
how does global warming effect the carbon cycle?
- carbon dioxide is an important greenhouse gas, as it absorbs radiation from the Earth. if it accumulates in excess, it can lead to global warming
- this has resulte in increased frequency of extreme weather conditions, polar ice caps melting and an increased frequency of forest fires
- as a consequence, species distribution may change; plants and animals may be driven to extinction if they cannot find a suitable new habitat fast enough, which reduces biodiversity.
- in some regions, there may be increased crop yields, but pest populations may also increase
how does ocean warming effect the carbon cycle?
oceans can store a lot of heat so there is a time lag between warming of the atmosphere and the warming of the ocean
list some consequences of global warming and climate change on aquatic habitats
- decreases pH of oceans (acidification) - corals die
- eutraphication
- less oxygen dissolved in water at higher temperatures
- fish migrate to cooler waters
state some possible changes in farming practices
- rotating crops to reduce pests and mineral depletion
- salt-tolerant crops to overcome rising sea levels
- feeding cows high-sugar grasses with less cellulose to reduce the release of the greenhouse gas methane
- keeping the soil healthy by using minimal preparation of land for growing crops and cover crops like clover to protect and improve soil
- drought-resistant crops to tackle low and fluctuating water supply
- improving drainage to aerate water-logged and anaerobic soils
what is carbon footprint?
the total amount of carbon attributable to the actions of an individual, a product or service over a period of one year
how can we reduce our carbon footprint?
- recycling packaging material
- driving less
- use less AC and heating
- choosing a diet low in animal protein
- avoiding food waste
- planting trees
why is nitrogen important to all living organisms?
- component of organic molecules
- used for amino acids + DNA
- chlorophyll
by which processes do these ions get taken up by plant roots?
- facilitated diffusion
- active transport
what are the 5 main processes in the nitrogen cycle?
- ammonification
- nitrification
- nitrogen fixation
- assimilation
- denitrification
describe ammonification
decomposers (saprotrophs and detritivores) result in the decay of dead plants and animals, faeces and urine into ammonium ions
describe nitrification
the ammonium ions produced by decomposes are converted into nitrites then nitrates by nitrifying bacteria.
- aerobic conditions are required
- plants can absorb these nitrate ions and incorporate them into amino acids, nucleotides and chlorophyll
what are the key nitrifying bacteria?
NITROSOMONAS - convert ammonium ions into nitrites
NITROBACTER - convert nitrites into nitrates
describe nitrogen fixation
nitrogen fixing bacteria can directly fix nitrogen gas into ammonium ions
what are the key nitrogen-fixing bacteria?
AZOTOBACTER - free living in the soil
RHIZOBIUM - found in root nodules of leguminous plants
describe the relationship between rhizobium and root nodules of legumes
when nitrogen gas diffuses into the root nodule, rhizobium produces nitrogenase enzyme which catalyses the fixation of nitrogen gas into ammonium ions
- these ammonium ions can then be converted into amino acids for use by the plant.
- however, nitrogenase is inhibited by oxygen. therefore, haemoglobin is present in root nodules to bind with the oxygen, giving it a pink colour
why can the relationship between the bacteria in the root nodule and the legume be classed as a symbiotic relationship?
- bacteria gains sugars from photosynthesis
- plants gain nitrogenous compounds
both benefit
describe assimiliation
the formation of organic compounds (e.g amino acids) from inorganic nitrogen compounds present in the environment
describe denitrification
denitrifying bacteria convert nitrate from the soil into nitrogen gas. this is a problem as it removes useful nitrogenous compounds from the soil.
anaerobic conditions are required for this and it occurs in waterlogged soil
what human activities aid the nitrogen cycle?
- ploughing and drainage of soil to improve aeration. this enables nitrifying bacteria to convert ammonium ions into nitrate and prevents denitrifying bacteria from completing denitrification
- cultivation of legumes in soils lacking nitrogen so that rhizobium will carry out nitrogen fixation within the plants and then when the plants die these nitrogenous compounds will enter the soil to be broken down by decomposers in ammonification
- application of artificial fertilisers and manure to soil that will enable a greater yield of crop plants
what do fertilisers contain?
nitrates, phosphate, potassium
why do crops need fertilisers?
nitrates - nitrogen for amino acids, nucleic acids
potassium - stomatal opening
phosphates - nucleic acids + ATP + phospholipids
describe the process of eutrophication`
- fertilisers leach into watercourses, increasing levels of nutrients
- there is a bloom of algae, blocking out the light to plants below. these plants die as they cant photosynthesise
- decomposers such as bacteria and fungi decompose the dead organic matter
- as these bacteria respire aerobically they use most of the available oxygen, this creates a biological oxygen demand
- aquatic animals die due to lack of oxygen
- anaerobic bacteria then flourish