ecology

ECOLOGY

study of the interaction between living things and between living things and their enviroment

BIOSPHERE

part of the earth that contains living organism

ECOSYSTEM

group of clearly distinguished organisms that interact with each other and with their evniroment

HABITAT

where a plant or animal lives

POPULATION

members of the same species living in an area

COMMUNITY

all the different populations in an area

ABIOTIC FACTORS

non living factors
e.g aspect - direction a surface is facing
exposure - wind, sunlight, water currents
steepness - steep slopes lose water quickly
currents - plants and animals can be washed away

BIOTIC FACTORS

living factors

Food - the more food available the greater the number of organisms
Competition - plant ans animals fight for scarce reosues like food water shelter space
Predation - catching and eating of prey
Parasitism - feeding off of a live host, weakens the host and reduces their numbers
Humans - positive or negative effect on other organisms

CLIMATIC FACTORS ( also abiotic )

concern weather over a long period of time
Temperature - affects the rate of reactions in living things
Rainfall - all organisms need water to grow
Light Intensity - affects the rate of photosynthesis
Wind - causes physical damage

EDAPHIC FCATORS

factors relating to soil

soil ph
soil type
humus - decaying organic matter, increases the growth of plants
Water air and mineral content of soil - increase growth of plants

AQUATIC FACTORS

relate to organisms living in or near water based environments

light, currents, wave action, oxygen concentration

ECTOPARASITE

lives on a host, usually cases harm e.g feas, ticks, leech, mites

ENDOPARASITE

lives in a host, usually causes harm e.g tapeworm, stomach worms, lung worms

FOOD CHAIN

sequence of organisms where each organism is eaten by the next one in the chain

Dandelion → Snail → Thrush → Hawk

TROPHIC LEVEL

feeding stage in a food chain

DETRIUS FOOD CHAIN

begins with dead decomposing material

Dead Leaves → Earthworm → Thrush → Hawk

FOOD WEB

interlinked food chains, realistic way of representing the relationships in an ecosystem

PYRAMID OF NUMBERS

shows the number of organisms at each trophic level

why do the numbers at each trophic level decrease

-less energy at each trophic level
- size of the organisms increases at each trophic level

limitations of pyramid of numbers

- does not take into account the size of organisms
- difficult to draw pyramids of numbers to scale

NICHE

functional role of an organism in an ecosystem or habitat

- each habitat is adopted to occupy a different niche in the ecosystem e.g swallows and bats both eat insects but swallows feed by day and bats feed by night

NUTRIENT CYCLE

the way in which elements or minerals are absorbed by organisms, released into the atmosphere when organism decompose and absorbed by other organisms

NUTRIENTS INVOLVED IN THE CARBON CYCLE INCLUDE

-plants and algae - removes co2 from the enviroment in photosynthesis and return it in respiration
- animals - release carbon dioxide in respiration
- Fungi and bacteria - decompose dead organisms

TWO REASONS CONCENTRATION OF CO2 IN THE ATMOSPHERE IS INCREASING

- significant increase in the burning of fossil feuls
- Deforestation

what do plants need in order to make protein

nitrogen

where are nitrogen fixing bacteria found

in swellings called nodules on the roots of a group of plants called legumes ( peas, beans, clover)

what do nitrogen-fixing bacteria convert nitrogen gas from the atmosphere into

nitrates

what do plants use nitrates for

to make protein

SYMBIOSIS

two organisms from different species live and have to live in close association where at least one benefits

MUTUALISTIC

both the organisms benefit from each other

e.g the bacteria and legumes benefit from the relationship in a plant
e.g bacteria live in the large intestine of humans

how is the nitrogen in plants transferred to animals

when the eat and absorb the plant proteins

NITRIFICATION

- nitrifying bacteria in the soil convert ammonia into nitrites and then into nitrates
- these nitrates are absorbed by the roots of plants and recycled to make plant proteins

what do denitrifying bacteria do in the soil

convert nitrates into nitrogen gas

Bacteria involved in nitrogen cycle

- nitrogen fixing
- decomposing bacteria
- nitrifying bacteria
- dentrifying

POPULATION

consist of all the members in a species in an area

what does population ensure

numbers of different species in a habitat remain relatively constant over time

factors that control population

competition
predation
parasitism
symbiosis

Community

group of different species living in a habitat

When does competition occur

it occurs when two or more organisms actively struggle for a resource that is in short supply

animals compete for....

animals - food, water, shelter, territory, mates

plants compete for ....

plants - light, space, water, minerals

inter-specific competitions vs intra-specific competitions

inter-specific competitions - competition between members of different species
intra-specific competitions - competition between the members of the same species

competition tends to....

reduce the number of organisms

What are the two types of competition

Contest
scarmble

what is contest competition

when there is a active physical struggle between different organisms producing one winner and one loser

what is scramble competition

all competing organsims get some of the resource

Adaptations to survive competition

in order to survive competition, organisms are adapted to their environment

PREDATION

catching, killing an eating of another organism for food

adaptations of predators

- foxs coat colour can camoflauge
- ladybirds have strong mouthparts to chew aphids
- spiders catch prey using webs
- hawks have excellent eyesight

adaptations of prey

-rabbits have large hind legs to run fast
- frogs are camouflaged, difficult to see
- hedgehogs have tough spines to protect against predators

behavioural adaptations of fox and rabbits

fox - hunts at night (nocturnal)
rabbit - hide in burrows to avoid predators

PARASITE

living thing that takes its food from another living thing (called a host) and usually causes harm
e.g mosquitoes, tapeworms

PARASITISM

form of symbiosis where one species gains and the second species loses

draw nitrogen and carbon cycle

-

POPULATION DYNAMICS

factors that cause population numbers to change (rise or fall)

predator prey relations are what?

they are inter-related

fox and rabbit relationship. draw graph and explain

predator always feeds on prey. the peak value for prey will always be higher than peak value for predator
when predators first feed on prey, predator number rises and number of prey falls. because number of prey falls, number of predator falls aswell cause less food is available. when number of prdator falls, number of prey can rise again

why is the prey never completely wiped out

some of them can hide or conceal themselves

what happens to the predators if the number of prey fall low

they move to a new area, which allows prey numbers to rise again

Factor affecting human population numbers

war
famine
contraception
disease

reasons for increasing population

vaccination
improved sanitation
antibiotics
improved surgical methods

pollution

any undesirable change in, or harmful addition to, the environment

what does pollution result from

from unwanted materials called pollutants

human activity also play a part in pollution. give expamples

litter, sewage, disposal, noise, radioactivity. these can be released into air waterways or land

what is a natural source of pollution

volcanoes

give an accounts of a named pollutant (agriculture) and describe how it can be controlled

excessive fertilizer

- if too much fertilizer is spread it can be washed into streams and rivers and lakes. the minerals in the fertiliser cause algae to grow in the water. When algae die they are decomposed by bacteria. This uses up oxygen. all the oxygen in the water gets used up so all the living things die. this is known as eutrophication

this can be controlled by limiting the use of fertilizer.
animal slurry can also be spread

What is eutrophication?

artificial enrichement of water by nutrients

what is conservation

wise mangagement of our existing natural resources in order to allow us many species as possible to survive

why is conservation important

prevents extinction of organisms

how do humans alter the enviroment

we destroy fields, hedges and woods in order to build houses, roads, factories
we use weed killer and insecticides
we destroy woods and bogs to make oil and feul

Conservation in Agriculture

hedges should not be cut when birds are rearing their young

Waste management in agricluture

animal waste is stored in concrete pits
spread on land in dry weather to allow minerals to be absorbed by plants

problems with waste disposal

-waste can contain many microorganisms that could cause disease. it can be spread by wind or enter drinking water supplies
-toxic chemicals can be released from wastes and enter water supplies. can also have serious effects on plants and animals
- nutrients released from waste can cause enrichment of water supplies. this can lead to the death of aquatic plants and animals
-dumping at sea can lead to pollution of the sea
- incinerators burn waste at high temperatures. poisonous gases may be released in the process

role of microorganism in landfill sites and sewage sites

landfill- waste is covered with soil. bacteria and fungi break down the organic materials
sewage - small amounts enter the river and can be broken down by bacteria and fungi. large amounts should be safely treated so it can be released into rivers and sea

primary physical sewage treatment

screening - metal grills remove large objects e.g branches
sedimentation - water stored in tanks and particles like stones and sand settle in the bottom. the solid waste the settle out is sludge

Secondary biological treatment

treatment with bacteria and fungi to break down organic matter

Tertiart treatment

removes mineral nutrients from the water e.g nitrates

qualitative survey

records that a species is present or absent. identifys the species directly in the habitat, or by collecting and later identifying the species

quantitative survey

gives the number of each species that are in a habitat. provides a great deal of information than a qualitative survey

when are transects used

used where changes occur along a gradient

capture recapture method

calculates the number of moving animals in a habitat

sources of error in an ecosystem

human error - mistakes in measuring or recording
information
sample size - single habitat may not be a fair representation of the entire ecosystem. the larger the number of habitats the more accurate the results
changing conditions
- nature is never static or constant