Chapter 4 & 5: Ecology

Ecology

study of interactions between organisms and their relationship with their environment

Ecosystem

Consists of a community of organisms and their environment

Biosphere

Parth of the earth in which life can exist

Community

Populations of different species of organisms in an environment

Habitat

Where an organism lives and to which it is adapted

Abiotic

non-living features of an ecosystem that affect the community

Examples of Abiotic Environmental Factors

temperature, pH, light intensity, altitude,humidity

Biotic

living features of an ecosystem that affect the community

Examples of Biotic Environmental Factors

predators, prey, parasites, pathogens, competitors

Climatic

elements of climate that influence life and distribution of the organisms that live in a particular environment

Examples of Climatic Environmental Factors

temperature, rainfall, humidity, wind, day length

Edaphic

characteristics of soil that influence the community

Examples of Edaphic Environmental Factors

soil type, soil pH, available water, humus

Examples of Aquatic Factors

light penetration, currents, wave action

Energy Flow

pathway of energy transfer from one organism to the next in an ecosystem due to feeding

Food Chain

flow diagram that begins with a plant and shows how energy is passed through a series of organisms in a community

Grazing Food Chain

food chain where the initial plant is living

Detritus Food Chain

food chain that begins with dead organic matter and animal waste

Food Web

two or more interlinked food chains which show the feeding connections in a habitat/ecosystem

Producers

organisms capable of making their own food by photosynthesis

Consumer

organisms that feed on other organisms

Trophic Level

position of an organism in a food chain

Limited Size of Food Chains

due to 90% of energy lost as heat between organisms

Pyramid of Numbers

represents number of organisms at each trophic level in a food chain

Niche

functional role of an organism in an ecosystem

Nutrient Recycling

nutrients that make up bodies of living things are recycled and used time and time again

Carbon Cycle

CO2 in atmoshpere → photosynthesised by plants → eaten by animals → excreted and respired by animals → decay of animals releases CO2

Nitrogen Cycle

nitrogen in atmosphere → nitrogen fixation into nitrates → absorbed by plants → consumed, urea excreted by animals, death of plants and animals → ammonification into ammonia → nitrification into nitrites and then nitrates → denitrification by denitrifying bacteria back into nitrogen in atmosphere

Pollution

any harmful addition to the environment

Types of Pollution

air, water/river, domestic, agricultural

Agricultural Pollutant

slurry and fertiliser

Agricultural Pollutant Source

washed from land

Agricultural Pollutant Effects

algal blooms and eutrophication

Industrial Pollutant

sulphur dioxide

Industrial Pollutant Source

burning fossil fuels

Industrial Pollutant Effects

acid rain

Domestic Pollutant

plastic bags

Domestic Pollutant Source

shopping

Domestic Pollutant Effects

suffocate small animals, litter

Eutrophication

where lakes become over-enriched with nutrients and cause a rapid increase of algae as they use up the nutrients

Control of Agricultural Pollutants

avoid spreading on wet, water logged, frozen, or steeply sloping land, or within 1.5m of any watercourse

Control of Industrial Pollutants

use catalytic scrubbers in factory chimneys

Control of Domestic Pollutants

bag levy and reusable bags

Conservation

protection and management of organisms and their environment

Agricultural Conservation Practices

mixed farming, crop rotation, biological controls, gene banks

Fishing Conservation Practices

fishing net size, quotas, re-stocking

Forestry Conservation Practices

re-planting, broadleaf/conifer mix

Fishing Net Size

size of openings enclosed by threads of net

Fishing Quotas

fixed proportion of the total allowable catch allocated to each fishing nation

Restocking

translocation of species where they have naturally occurred which achieves permanent increase in a sustainable population of a species

Waste Management

collection, transport, processing, recycling or disposal of waste materials produced by human activity in an effort to reduce their effect on human health or local aesthetics or amenity

Role of Micro-Organisms in Waste Management

micro-organisms decompose organic matter into a stable substance called compost which recycles all the nutrients required for plant growth

Problems Associated with Waste Disposal

availability of suitable landfill sites, the toxic or pollution content of fumes from incineration, decaying waste produces methane gas which contributes to the greenhouse gases, harmful substances may leak into groundwater supplies, plants and animals in rivers and lakes are killed through direct poisoning or eutrophication

Waste Minimisation

reduce, reuse, recycle

Factors That Control a Population

competition, predation, parasitism, symbiosis

Competition

when organisms struggle for a limited resource

Types of Competition

intra-specific, inter-specific, contest, scramble

Intra-specific Competition

occurs between members of the same species

Inter-specific Competition

occurs between members of different species

Contest Competition

only one organism gets the resource

Scramble Competition

all competing individuals get some of the resource

Predation

catching, killing and eating of another organism

Predator

organism carries out predation

Prey

organism eaten by predator

Adaptations of Predators

hawks have excellent eyesight, ladybirds have strong mouth parts, cheetahs can run at 60km/h

Adaptations of Prey

plants may have thorns, spines or stings, nasty taste when eaten, faster than their predator, staying in herds or flock, camouflage

Parasitism

occurs when one organism feeds off of a living host and causes harm to the host

Ecto-Parasites

live on outside of the host

Endo-Parasites

live on inside of the host

Symbiosis

occurs when two organisms of different species live in harmony and at least one benefits

Examples of Symbiosis

nitrogen fixing bacteria in the nodules of legumes, bacteria in colon

Predator-Prey Dynamics

prey population increases, predators have more food and their population increases, number of prey being killed increases so predators have less food and their population decreases, prey population increases as a result

Predator-Prey Graph

• prey numbers are larger then predators

• waves are out of sync

Factors that Affect Predator-Prey Relationships

food supply, concealment

Food Supply

greater food supply, greater population increase, movement of predators

Concealment

prey can conceal themselves which allows their numbers to increase again

Movement of Predators

too few prey will lead to the predators moving out of the area

Factors Affecting Human Population Growth

famine, war, disease, contraception

Famine

famine leads to malnutrition which leads to death and low birth rates

War

war reduces population numbers through deaths and partners separating

Disease

advances in modern medicine has lead to population increase

Contraception

increased contraception has lead to a decrease in population growth