bio topic 7

4 examples of what humans use land for

building

quarrying

farming

dumping waste

what r peat bogs

bogs are areas of land that r acidic and waterlogged

plants that live in bogs don’t fully decay when they die, bc theres not enough oxygen, the partly rotted plants gradually build up to form PEAT

carbon in the plants is stored in the peat instead of being released into the atmosphere

peat / peat bog uses

peat bogs r drained so the area can be used as farmland which reduces biodiversity

peat is cut and dried to be used a fuel

peat sold to gardeners as compost

peat is being used faster than it forms

what happens when peat is drained

it comes into contact w air and some microorganisms which start to decompose it

when these microorganisms respire, they use oxygen and release CO2, contributing to global warming

CO2 also released when peat is burnt as fuel

reasons for deforestation

to clear land for farming to provide more food

to grow crops from which biofuels base don ethanol can be produced

problems of deforestation and why

less co2 taken in

• amount of co2 removed from the atmosphere during photosynthesis is reduced

• trees r carbon sinks which actively remove carbon dioxide from the atmosphere

more co2 in the atmosphere

• when trees r burnt

• microorganisms feeding on bits of dead wood release co2 as a waste product of respiration

less biodiversity

• the variety of different species

• when habitats r destroyed, there is a danger of many species becoming extinct and reducing biodiversity

population vs community meanings

pop - all the organisms of 1 species living in a habitat

community - the population of dif species living in a habitat

def ecosystem

the interaction of a community of biotic and abiotic parts of their environment

example of stable communities

tropical rainforests and ancient oak woodlands

example of abiotic factors

1. moisture level

2. light intensity

3. temperature

4. co2 level

5. wind intensity and direction

6. oxygen lvel

7. soil pH and mineral content

different organisms are adpated to dif abiotic conditions

example of biotic factors that can vary in an ecosystem

1. new predators arriving

2. competition

3. new pathogens

4. availability of food

what do adaptations allow

an organism to survive

types of adaptations

1. structural - features of an organisms body structure - shape/colour

2. behavioural - way they behave

3. functional - things that go on inside an organisms body that can be related to processes like reproduction and metabolism

what is biomass

energy stored in a plant

energy is transferred through living organisms in an ecosystem when organisms eat other organisms

what do populations of prey and predators do

go in circles, constantly changing

prey increase, predator increase

predator increase, prey decrease etc

what is the distribution of an organism

where an organism is found which is affected by environmental factors

2 methods to study the distribution of an organism

measure how common an organism is in 2 sample areas w/ quadrats and compare them

study how the distribution changes across an area, quadrats along a transect

how to use quadrats to study the distribution of small organisms

1. place a 1m2 quadrat on the ground at a random point within the first sample area (use random number generator to get coordinates)

2. count all the organisms in the quadrat

3. repeat steps 1 and 2 as many times as u can

4. work out the mean number of organisms per organisms

5. repeat steps in the 2nd sample area

6. finally compare the 2 means

how to use transects to study the distribution of organisms

u can use lines called transects to find out how organisms are distributed across an area

1. mark out a line in the area u want to study using a tape measure

2. then collect the date along the line

3. u can do this by counting all the organisms ur interested in that touch the line

4. or u could use quadrats (place next to eachother or at specific intervals)

environmental changes affecting the distribution of organisms

1. temperature

2. availability of water (wet/dry seasons)

3. composition of atmospheric gases (air pollution perhaps)

can be caused by seasonal factors, geographic factors or human interaction

process of the water cycle

water is endlessly recycled:

1. energy from the sun makes water evaporate from land and sea, turning it into water vapour and by transpiration in plants

2. the warm vapour is carried upwards, when it gets higher up it cools and condenses to form clouds

3. water falls from the clouds as precipitation onto land, where it provides freshwater for plants and animals

4. it then drains into the sea, before the whole process starts again

how r elements cycled back to the start of the food chain by decay

1. living things r made of materials which take from the world around them, they make compounds etc and pass them up the food chain

2. these materials r returned to the env as waste products or when the organisms die and decay

3. materials decay bc they r broken down by microorganisms, this happens faster in warm, moist, aerobic conditions bc microorganisms r more active in these conditions

4. decays put the stuff plants need to grow back into the soil

5. in a stable condition, the materials taken out the soil are balanced by those put back in

process of the carbon cycle

1. co2 removed from atmosphere by green plants by photosynthesis, it is used to make glucose which can be turned into carbs, fats and proteins

2. when the plants respire, some carbon is returned to the atmosphere as co2

3. when the plants r eaten by animals some carbon becomes part of the fats and protein in their bodies, the carbon then moves through the food chain

4. when animals respire, some carbon is returned to the atmosphere as co2

5. when plants and animals die, microorganisms and other animals feed on their remains, when these organisms respire co2 is returned to atmosphere

6. animals also produce waste that is broken down by microorganisms

7. the combustion of wood and fossil fuels also releases co2 back into the air

8. so the carbon and constantly being cycled - from the air, through food chains and eventually back out into the air