ALL Ecology

Pollution

any addition of harmful substances to the environment

Pollutant

substance which contaminates the environment

Name + describe the effect of an industrial pollutant?

How can it be managed?

• CO₂, formed by the combustion of fossil fuels

• contribute to the enhanced greenhouse effect

• plant more trees, change to more sustainable sources of energy

Name + describe the effect of an agricultural pollutant?

How can it be managed?

• slurry

• slurry washed into waterways causing eutrophication

What is eutrophication?

• artificial fertilisers or slurry are washed into rivers and lakes

• causes rapid increase in microscopic algae called an algae bloom

• when the algae die they are broken down by bacteria which use up all the O₂ in the water causing fish to die

Conservation

the wise management of the environment to ensure survival of organisms and their habitats

What are the reasons for conservation?

• maintain population for breeding

• prevent extinction of endangered species

• balance of nature for food chains

Give examples of conservational practices:

• habitat protection

• maintaining habitat + population of prey

nb - always look at text provided to help

Give and example of a fishing conservation practice:

• fishing quota to prevent overfishing of an area, and maintain numbers for breeding

What problems are associated with waste disposal?

• wastes can be toxic

• can cause disease

• plastics are non-biodegradable

• can pollute water causing eutrophication

• incinerators release dioxins into the air which can cause cancer

• rotting organic matter produces methane gas

Agricultural waste management

• animal slurry is stored in waterproof concrete pits

• diluted and spread on dry land as fertiliser

Fishing waste management

• fish processing produces waste, eg fish heads, fins, intestines

• treated with chemicals, dried, pulped and then used as fertiliser

Forestry waste management

• timer wastes are recycled to make chipboard or MDF

• some trees allowed to rot in ground after cutting, allowing minerals to return to the soil

What role to micro-organisms play in waste management?

bacteria and fungi break down organic wastes such as compost, sewage, oil spills

How to control domestic pollution?

• reduce packaging buy loose veg

• reuse jars, tupperware, reusable straws and cups

• recycle, use compost bins or bottle banks

• use biodegradable single use bags

Why do populations live together?

• food and shelter

• safer for individuals

• for breeding

What are the factors that control population size?

• competition

• predators

• parasites

• symbiosis

Competition

struggle between organisms for resources, which are in short supply

What is the different between intra-specific competition + inter-specific competition

intra-specific competition - takes place between members of the same species

inter-specific competition - takes pace between members of different species

Describe + example for contest competition:

one organism wins the resource and the organism loses the resource

1. stags lock antlers to fight for antlers

2. birdsong as males warn off other birds

Describe + example of scramble competition:

each organism tries to get as much of the resource as possible

1. young chicks in a nest want food

2. overcrowding of seeds in a flower bed, trying to get nutrients and water from the soil

Give an example of how organisms can adapt to survive competition:

• weeds produce a huge number of seeds

• bees swarm and move on when a colony gets too crowded

• animals occupy different food niches

Predation

the catching, killing and eating of another organism

Predator

organism that kills and eats another organism called prey

Prey

organism killed and eaten by a predator

Describe a predator/prey relationship

• predators are bigger in size and fewer in number than prey

• get as much energy as they need without destroying the prey population

• if the prey population drops too low the predator population will starve

Predator/prey relationship graph

• as one goes up the other also goes up

• the more prey eaten the more they would reduce in number

• as one goes down the other also goes down

• the predator will either stay in the habitat and die from lack of food or move to a new habitat

• that gives the prey a chance to increase in number again

What factors affect predator/prey numbers?

• availability of food, starvation

• ability to conceal themselves

• migration, moving to an area where there is more food

Example of predator adaptations

hawks have excellent eyesight to locate prey

cheetah built for speed to catch prey

chameleon camouflage to avoid being seen by prey

fox eyes in the front of head to judge size and distance well

Example of prey adaptations

crabs use their flat body to hide under rocks and camoflage

ladybirds produce formic acid which tastes bad

caterpillars have a nasty taste

rabbits long, mobile ears to detect predators and eyes at side of head for good peripheral vision

Parasite

an organism that lives in or on another living organism of a different species causing it harm

What is the difference between an endoparasite and ectoparasite?

endoparasite - inside the organism

ectoparasite - on the surface of the organism

Symbiosis

relationship between 2 organisms of different species in which at least one of them benefits

What are the 3 types of symbiosis?

mutualism - both benefit, eg nitrogen fixing bacteria in the nodules of legumes

commensalism - 1 organism benefits but does not cause harm, staphylococcus aureus bacteria on the skin

parasitism - 1 organism benefits but causes the other organism harm, streptococcus throat

Population dynamics

study of the changes that occur in a population and the factors that cause these changes

What factors cause population growth to slow down

• food runs out, starvation

• not enough room for breeding

• overcrowding spreads diseases

• individuals are more easily killed off by predators

Reasons for changes in human population:

• famine

  • caused by poor farming technique

  • crop failure

  • badly managed food supplies

• disease

  • vaccines, sanitation + insecticides

  • antibiotics developed prevent death

• wars

  • reduces the human population

  • increased birth rates after

• contraception

  • reduced birth rates,

  • more family planning, average family size 2.1

Nutrient recycling

the conversion of mineral elements such as carbon and nitrogen back and forth between abiotic and biotic for use in the ecosystem

Carbon cycle

the way in which carbon is taken from and added to the environment by organisms

Describe the main steps in the carbon cycle:

• plants take in CO₂ through stomata for photosynthesis to make food (carbohydrates)

• plants die and either:

  • incomplete decay leads to the formation of fossil fuels

  • they are consumed by animals; plant proteins are assimilated to form animal proteins

• animals consume plants and respire which releases Co₂

• the animals die and either:

  • incomplete decay leads to the formation of fossil fuels

  • they are decomposed by micro-organisms, which release CO₂ as they respire

• bones, teeth and shells decay by slow weathering to produce CO₂

Carbon cycle diagram:

Why do we need the carbon cycle?

• supports photosynthesis + respiration

• maintain a balance, so it does not run out

Describe the main steps in the nitrogen cycle:

• nitrogen fixation: nitrogen gas is ‘fixed’/ converted into nitrates by nitrogen fixing bacteria

  • can also be converted into nitrates by lightning which splits nitrogen molecules allowing them to join with oxygen

• nitrates are absorbed and assimilated into plant proteins

• plants die and are either

  • eaten by animals and assimilated to form animal proteins

  • decomposed by decomposing bacteria, which release ammonia into the soil

• animals either

  • excrete ammonia in urea

  • decompose by decomposers, which release ammonia into the soil

• nitrification: nitrifying bacteria convert ammonia into nitrite then nitrate

  • some of this nitrate is absorbed and assimilated by plants

• denitrification: denitrifying bacteria convert nitrates back into nitrogen gas

Name a pollutant produced by the nitrogen cycle + its impact on the environment?

• ammonia

• can cause eutrophication

Nitrogen cycle diagram:

Why do we need the nitrogen cycle?

• to change nitrogen into a usable form for organisms

• to maintain a balance

Why do organisms need nitrogen?

• to make proteins and enzymes

Ecology

study of the interaction between groups of organisms and their environment

Population

group of organisms of the same species living in part of an ecosystem

Community

group of organisms of different species, group of populations

Ecosystem

community of organisms interacting with their environment

Biosphere

part of the earth and its atmosphere where organisms can live

Habitat

place where an organism lives

Environmental factors affecting organisms

biotic - living factors

abiotic - non-living factors

climatic - effect of weather over long periods of time

edaphic - soil factors

Biotic factors

food - the more food available, the more organisms will survive,

eg - number of berries affects the number of blackbirds

competition - plants and animals fight for food, water, minerals, light, space, mates and shelter

eg - number of foxes in an area compete for rabbits

predators - organisms which kill and eat other organisms', called prey

eg - ladybirds eat greenfly

parasites - organism that lives in or on another living organism (called a host) for nourishment causing it harm

pollination + seed dispersal - plants need animals to carry pollen and seeds

eg - birds eat fruits and egests seeds, dandelion is dependent on wind pollination

Terrestrial abiotic factors

altitude - higher altitudes are cooler, wetter and windier, rocky soil is not suitable for trees and other producers, not habitable

aspect - north-facing slopes are cooler and darker, south-facing slopes get more sunlight, and therefore have more vegetation

Aquatic abiotic factors

currents - seaweed clings to rocks to prevent being washed away

exposure - mucilage/slime on algae prevents them from drying out in the sun

Terrestrial climatic factors

temperature - effects the rate of reactions, high temperatures can cause rapid plant growth, low temperatures enzymes work slowly and can bring on hibernation in animals, such as hedgehogs

light - intensity affects the rate of photosynthesis, can cause drought which results in no crops

rainfall - plants that live in deserts are adapted to survive dry, harsh conditions, plants in rainforest are adapted for prolonged periods of heavy rainfall

Aquatic climatic factors

salinity - salt content

light intensity - plankton grows best in upper layers of water due to greater light intensity

Edaphic factors

pH - plant enzymes are adapted to specific soil pHs, acidic soils are found in bogs, neutral soils support most flora, alkaline soils support lime (CaCO₃) loving plants (eg tomatoes)

soil particle size - sandy soils have large particles, resulting in good drainage and air content, clay soils have smaller particles, but are compact and poorly aerated

humus content - refers to the amount of dead decaying organic matter in soil which supports mineral content

water content - water is needed for photosynthesis, but too much water interferes with aeration

Primary producers

green plants which make their own food by photosynthesis

Consumers/heterotrophs

organisms that eat other organisms

Top consumer

the last consumer in a food chain

Food chain

feeding relationship between organisms in which energy is transferred from the sun to plants, and then to animals

Why do food chains have a limited number of trophic levels?

due to the large loss of energy (approximately 90%) during the transfer between trophic levels, due to use of energy for metabolism

Grazing food chain

starts with a green plant

rose leaves → greenfly → ladybird → spider

Grazing Food Web

Detritus food chain

starts with dead organisms/detritus

dead leaves → woodlouse → blackbird

Decomposers

break down the dead remains of plants and animals to recycle nutrients

Food web

2 or more intersecting food chains

Trophic level

feeding level in a food chain

Pyramid of numbers

a diagram which shows the number of each organism at each trophic level

What gives a regular pyramid of numbers its shape?

• lots of energy lost between trophic levels

• organisms increase in size

What are the limitations of use of pyramid of numbers?

• does not take into account the size of the organism

• parasites cannot be represented to scale

What causes an inverted pyramid of numbers?

when the number of primary producers is low

What causes a distorted pyramid of numbers?

large number of top consumers, eg parasites

Niche

functional role of an organism in its habitat

Why don’t organisms occupy the same food niche?

too much competition for food, space, shelter

eg. swallow eats flying insects, thrush eats ground insects, blackbird eats fruit and worms

How many questions are needed in a key?

3