B9 - ECOSYSTEMS AND MATERIAL CYCLES

What is an organism?

a single living individual

What is a population?

all the organisms of the same species in an area

What is a community?

all the populations in an area

What is an ecosystem?

all the living organisms (the community) and the non-living components in an area

What does interdependence mean?

the survival of one species is closely linked with another species

What is a parasite?

An organism that feeds on another organism (the host) while they are living together

Give examples of parasites

fleas, head lice, tapeworms, mistletoe

What is mutualism?

when two organisms live closely together in a way that benefits them both

What type of sampling is done with quadrats?

random sampling

What type of sampling is done with belt transects?

systematic sampling

Why are belt transects used?

to see how a change in a factor affects a population

How can you calculate the number of organisms in an area using data from quadrats?

divide the total area by the area of one quadrat and then multiply your answer by the mean number of organisms in one quadrat

Why would repeating the transect multiple times and comparing the results be a good idea?

it would help to average out any random variables

growing one kind of fish in an area, the fish are fed and the waste they produce is removed from the tanks

What is fish farming?

Give two disadvantages of fish farming

the waste can pollute the local area, changing conditions so that some local species die out;

diseases from the farmed fish (such as lice) can spread to wild fish and kill them

Give an advantage of fish farming

it reduces fishing of wild fish

Give two disadvantages of the introduction of non-indigenous species to an ecosystem

they may reproduce rapidly as the have no natural predators in the new area; they may out-compete native species for food or other resources

Give an advantage of the introduction of non-indigenous species to an ecosystem

they may provide food for native species

What is eutrophication?

an excess of nutrients such as phosphates and nitrates in water from fertilisers dissolving in rain water

How can eutrophication lead to a loss of biodiversity?

Plants and algae grow more quickly and block light to deeper water

deeper plants die

bacteria decompose the dying plants and take oxygen from the water;

fsh die due to lack of oxygen

Why should humans maintain local and global biodiversity?

humans should respect other organisms;

people enjoy seeing variety of organisms in different habitats;

some organisms have an important role in ecosystems;

some species are particularly useful to humans.

What is reforestation?

replanting forests where they have been destroyed

Give advantages for reforestation

restores habitat for endangered species;

reduces concentration of CO2 in the air due to photosynthesis;

tree roots bind the soil and minimise soil erosion;

reduces the range of temperature variation in the local climate

What is the role of microorganims in the carbon cycle?

decomposers

How does respiration fit into the carbon cycle?

it releases carbon dioxide into the air

How does photosynthesis fit into the carbon cycle?

it absorbs carbon dioxide from the air

How does combustion fit into the carbon cycle?

it releases carbon from fuels into the air as carbon dioxide

What is desalination?

producing drinking water from salty (sea) water

Name a process used to produce potable water in a area that is close to the sea

distillation

Draw and label the water cycle

labels: precipitation, condensation, evaporation, transpiration

What is added to fertilisers to help plants to grow better?

nitrates

What is crop rotation?

growing different crops each year on a rotation basis

How does crop rotation improve soil fertility?

different crops remove different nutrients from the soil; some plants have nitrogen fixing bacteria in their roots which can be ploughed back into the soil.

Draw and label the nitrogen cycle

labels: death and excretion, proteins and urea, nitrates, nitrogen-fixing bacteria, lightening, ammonium compounds, air, soil, plant roots