Biology - Chapter 4: Ecology

ecology

the study of the interactions between living things and between organisms &their environment

biosphere

part of the planet that containing living organisms

ecosystem

a group of clearly distinguished organisms that interact with their environment as a unit

habitat

a place where a plant or animal lives

abiotic factors

non-living factors

e.g. shade, currents, altitude

biotic factors

living factors

e.g. presence of predators, parasitism

climatic factors

the average weather conditions over a long period of time

e.g. rainfall, salinity (salt conc.), wind

edaphic factors

the soil

e.g. minerals in the soil/soil type

energy flow from the sun

• sun is primary source of energy

• feeding allows energy to flow from one organism to another in an ecosystem

producers

organisms capable of making their own food by photosynthesis and other means, e.g. green plants

primary producers

the first members of a food chain, usually green plants

consumers

organisms that take in food from another organism/feed on other organisms. they cannot make their own food

primary consumers

feed on producers

e.g. herbivores, decomposers, detritus feeders

secondary producers

feed on primary consumers

e.g. carnivores

tertiary consumers

feed on secondary consumers

e.g. humans

food chain

the feeding relationship between organisms in which energy is transferred

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a sequence of organisms in which each one is eaten by the next member in the chain

food web

consists of two or more intersecting food chains

trophic level

feeding level in a food chain

pyramid of numbers

shows number of individuals at each trophic level of a food chain

niche

the functional role an organism plays in the community

decomposers

play an important role in breaking down dead matter and returning nutrients to the soil

detritus food chain

one where the chain begins with dead organic matter & animal waste

matter

this is recycled over and over again, primarily in the CO2 cycle

nutrient recycling

the ways in which the elements (e.g. N and C) are exchanged between the living and non-living components of an ecosystem

pollution

the addition of any unwanted or harmful substance to the environment by humans

human impact on an ecosystem

pollutant: single-use plastic

effects: build up of plastic in the oceans, hence destroying wildlife. microplastics enter the food chain → accumulation in the body may lead to certain cancers

control: RRR; avoid single-use plastic

conservation

the wise management of resources for future generations

conservation in fisheries

Problem → small mesh size of fishing nets catch immature fish before they can spawn, hence fish population declines

Conservation practice → use fishing nets with larger mesh size

Waste management in fisheries:

• problem: disposing fish heads, skin and bones produced during fish processing…very alkaline

• waste management: dry and pulp waste used as pig feed → treated with formic acid to neutralise it

use of microorganisms in waste management and pollution control

biologically treats sewage to break down most organic matter

nitrogen fixation

the conversion of nitrogen gas into ammonia, ammonium or nitrate

nitrification

the conversion of ammonium and ammonia compounds to nitrite and then to nitrate

denitrification

the conversion of nitrates to nitrogen gas