4 Ecology and the environment Flashcards
What is a population?
the total number of individuals of one species in a particular habitat at a particular time
What is a habitat?
places where specific organisms live
What is an ecosystem?
area where organisms interact with their physicals environment
What is a community?
formed of the populations of all the species present in an ecosystem at a particular time
Investigating population using quadrats
calculate area of habitat
measure number of individuals in one quadrat and repeat many times to check result is reliable (10 quadrats)
calculate average number of individuals in a quadrat
calculate how many quadrats fit into area
multiply average number by number of quadrats
use random sampling
two tape measure at right angles to make 10m by 10m set of axes
What are abiotic factors?
non-living
e.g. temperature, carbon dioxide and oxygen concentrations, minerals in the soil
what are biotic factors?
living
e.g. competition between two species, predators, disease
How do abiotic/biotic factors affect population size and distribution of organisms?
light: less photosynthesis
temperature: warm conditions needed for growth
moisture levels: water needed for growth
competition
What are producers?
organisms which make their own food (e.g. photosynthesising plants)
What are consumers?
organisms which eat other living things (e.g. animals)
What are decomposers?
organisms which secrete digestive enzymes to decay dead organic matter to obtain their food; help recycle nutrients
What do the arrows show in food chains/webs?
direction energy and biomass moves
What do food chains/ food webs show?
feeding relationships in an ecosystem
food webs show links
e.g. one animal removed, look at web to predict what might happen, other populations increase/decrease
What are pyramids of number?
show number of each organism counted in ecosystem
What are pyramids of biomass?
show total mass of organisms in each trophic level (mass of one individual x number of individuals)
What are pyramids of energy?
show total energy available in each trophic level per square metre per year
Where can energy be lost?
evaporation, movement, heat loss, egestion of waste
How much energy is transferred from one trophic level to next?
around 10%
What are the stages of the carbon cycle?
plants:
CO₂ used by plants in photosynthesis/ release CO₂ to atmosphere in respiration
Release CO₂ to dead remains/ excretory products by death
animals:
release CO₂ to atmosphere by respiration
release CO₂ to dead remains/ excretory products by death and excretion
decomposers:
release CO₂ to atmosphere by respiration
take in CO₂ from remains/ excretory products by decay and absorption
fossil fuels:
release CO₂ to atmosphere by combustion
PAPER 2 Describe the nitrogen cycle
bacteria to nitrate ions = nitrification using nitrifying bacteria
bacteria in soil to ammonium ions/ nitrogen in air to bacteria = nitrogen fixation using nitrogen-fixing bacteria found in soil and root nodules
nitrate ions to nitrogen in atmosphere = denitrification using denitrifying bacteria
decomposers to ammonium ions = decomposition
What are the greenhouse gases?
water vapour, carbon dioxide, methane, nitrous oxide and CFCs
How do greenhouse gasses result in a greenhouse gas effect?
sun emits solar radiation, some reflected by earth’s atmosphere, some pass through and absorbed by earths surface. Warms earth surface which emits infrared
some infrared passes through atmosphere, but some gases absorb the infrared, preventing it from escaping back into space, and re-emit to earths surface, surface gains more heat and infrared emitted again
What is an enhanced greenhouse gas effect?
extra greenhouse effect cause by human activity
What human activities contribute to greenhouse gases?
CO₂: burning fossil fuels, slash and burn forest clearance
Methane: cattle produce large volumes from anaerobic activity of bacteria in their gut, bacteria in waterlogged paddy fields for rice cultivation give off methane
Nitrous oxides: burning fossil fuels
CFCs: until 1990s used as solvent for aerosols such as deodorants. Used in fridges and freezers
What are the potential effects of global warming?
melting of polar ice caps leading to sea levels rise, causing flooding in coastal regions worldwide
drought and desertification leading to crop failure and food shortage and famines
increased extreme weather events such as hurricanes as more energy present in weather systems
increase in heat related illness
What is biodiversity?
The measure of how many different species live in an ecosystem
How do you measure biodiversity using quadrats?
Use quadrats and random sampling (random coordinates to place multiple quadrats in same area)
for each quadrat, use an identification key and record the number of each different species
To find effect of abiotic/biotic factors:
select at least two different areas where variable is different,
estimate biodiversity is each area
PAPER 2 What does deforestation destroy/cause?
destroys habitats
causing extinction and reducing biodiversity
PAPER 2 How does deforestation effect the carbon cycle?
During photosynthesis CO₂ taken into plants. Plant becomes a ‘carbon sink’
Less plants to store carbon and CO₂ levels in atmosphere increase, O₂ levels decrease as less photosynthesis
Burning trees for energy also releases CO₂ back into atmosphere, further increase in atmospheric CO₂
PAPER 2 What are the effects of deforestation?
leaching
soil erosion
disturbance of evapotranspiration and carbon cycle
PAPER 2 What is leaching?
Loss of nutrients from soil due to run off/washing out of soil
PAPER 2 Describe leaching
Normally, water absorbed by soil and taken up by roots of plants. Deforestation means water begins to ‘run off’ from soil into rivers and lakes
Mineral ions (Nitrates, phosphates, potassium) in soil are dissolved in soils water. Deforestation causes dissolved mineral ions (meant to be used for plant growth)to be removed from soil which runs off to rivers/lakes
Can lead to eutrophication
PAPER 2 What is soil erosion?
Water run off in deforested areas may carry away some topsoil causing erosion
No roots to hold soil in place
Top soil contains most fertile, mineral ion rich materials: when lost to erosion, minerals are also lost, making land very difficult to use for crop growth and reducing chance of plants re-growing
PAPER 2 What is evapotranspiration?
Water transferred from land to atmosphere by evaporation from soil and other surfaces and by transpiration from plants
PAPER 2 How does deforestation cause disturbance of evapotranspiration?
evaporated water moves in atmosphere and eventually makes rain in rain clouds
Rain onto plants and cycle continue
Cycle broken due to deforestation: Transpiration stops, so water not put into atmosphere, and rain does not occur. Can lead to droughts
How can sulphur dioxide be released into atmosphere?
Sulphur dioxide, nitrogen monoxide, nitrogen dioxide released into atmosphere from cars and factories
Consequences of air pollution by sulphur dioxide
Gases react with atmospheric water vapour to form dilute acids (sulphuric and nitric acids)
Dilute acid can dissolve limestone buildings and statues
When rain falls, can decrease pH of rivers and lakes. Effects enzymes of organisms in rivers and lakes, resulting in death of fish and other animals
Acid rain can also kill trees and other plants.
How had increased human population led to increase pollution?
more fossil fuels burnt for heat and power
more movement and use of transport
higher levels of industry for houses and goods
How is carbon monoxide formed?
when substances containing carbon are burned in a limited supply of oxygen
e.g. vehicle exhaust gases contain significant amounts of carbon monoxide
What is carbon monoxide a dangerous pollutant?
binds more strongly with haemoglobin than oxygen
person can lose consciousness, and die due to reduced aerobic respiration
How do fertilisers cause leaching?
farmers add fertilisers to soil to increase yield of crops. Usually contain nitrates and phosphates. Very soluble in water
When lots present on farmland surrounding river it is washed out of soil when rains into river
What are the effects of leached nitrates?
EUTROPHICATION:
nitrates absorbed by green algae in water
Multiply rapidly, growth called algae bloom
Blocks out sunlight for other plants
Unable to photosynthesise and die
algae on top eventually die
dead remains provide food for bacteria
bacteria multiply rapidly
large pop of bacteria respire, increasing BOD, using up oxygen in water
Decreases level of oxygen and results in death of other organisms in water e.g. fish, cannot respire
How can sewage enter water supplies? What does it contain?
due to leaking pipes, or run off from farm land
Undigested food material - lots of biological molecules, including carbs, proteins, nucleic acids, fats
What are the consequences of pollution of water by sewage?
sewage provide food source for bacteria
bacteria multiply rapidly
large pop of bacteria respire, increasing BOD, using up oxygen in water
decreases level of oxygen and results in death of other organism in water e.g. fish as cannot respire aerobically
NOT EUTROPHICATION AS NO ALGAE BLOOM
