Introduction  Habitat: the place where an organism occurs  Population: a group of organisms of the same species in an area  Community: all population & plants in the same area

Introduction  Ecosystem: a stable, self-supporting system which consists of communities interacting with each other  Ecology: the study of the interactions between living organisms & their environment

Different Habitats Freshwater Pond Freshwater Stream Grassland

Different Habitats Mangrove Rocky Shore Coral Reef

What is Environment ? Composed of 2 components, Physical Factors & Biotic Factors, which influence the lives of organisms

 Temperature  Light  Rainfall & Humidity  Wind Speed  Soil (esp. for plants)  pH Physical Factors

Biotic Factors Consists of all the other organisms living together in the same habitat

Energy Flow within an Ecosystem SUN Producers Primary Consumers Secondary Consumers Tertiary Consumers DECOMPOSITION HEAT Respiration Dead remains, excreta, etc

Food Chain / Food Web shows the feeding relationship between organisms green plants rabbitsnake hawk grasshopperlizard toad

Decomposers  not shown in food chain  consist of Bacteria & Fungi  break down organic wastes & dead bodies of other organisms to simpler compounds which are then absorbed by green plants  significance: enable the recycling of materials within an ecosystem

Trophic Level Green plantProducerFirst RabbitPrimary ConsumerSecond Snake Secondary ConsumerThird Hawk Tertiary ConsumerFourth OrganismType

Pyramids of Numbers (Examples) Producers Primary Consumers Secondary Consumers Tertiary Consumers

Pyramids of Biomass 500 Producers Primary Consumers Secondary Consumers 50 1

Why is there energy loss ? –Uneaten food –Respiration –Egestion & Excretion ∴ solving the food problem by… –consuming organisms in lower trophic levels –down a level, increase at least 10 times of food available Energy Lost up a Food Chain

Pyramids of Biomass Biomass is the total dry mass of organisms at a trophic level 500 Producers Primary Consumers Secondary Consumers 50 1

Effects of DDT  DDT is an effective pesticide  DDT has been used for about 20 years  It had been banned for over 20 years  But, nowadays, the body of every people still has DDT

Effects of DDT  Reasons : –it has excessively long degeneration period (it requires tens of years) –it is not easy be destroyed by metabolism of living organisms, so it is easily accumulated along the food chain  It killed many predatory birds due to its accumulation to high concentration through the food chain

DDT Accumulation

Carbon Cycle Carbon dioxide in air organic substances in plants organic substances in animals absorption & photosynthesis respiration fossil feeding respiration burning incomplete decomposition

Nitrogen Cycle nitrate in soil protein in plantsprotein in animals ammonia nitrogen in air absorption & photosynthesis feeding putrefying bacteria (decomposition) faeces, urine, dead body nitrifying bacteria (nitrification) denitrifying bacteria (denitrification) nitrogen- fixing bacteria

Investigation of a Balanced Aquarium

Why is it necessary to use tap water which has been standing for a few day ? Ans: Because fresh tap water contains chlorine which is harmful to organisms in the aquarium. lid water water snail freshwater plant

Why is it unsuitable to introduce large carnivores into the glass jar ? Ans: Because they require more food to survive and they will eat up all the organisms in the aquarium. lid water water snail freshwater plant

Describe the appearance of the water snails and the freshwater plants after a few days if the aquarium is balanced ? Ans: The water snails and the aquatic plants will remain healthy even after a few weeks. lid water water snail freshwater plant

What will happen to the aquarium if it is placed in darkness all the time ? Why ? Ans: Both the water snails and the freshwater plants will gradually die since there is no light for the aquatic plants to carry out photosynthesis to make food… lid water water snail freshwater plant

What will happen to the aquarium if it is placed in darkness all the time ? Why ? Ans: so the plants cannot survive without food supply. As all aquatic plants died, the water snails also die due to starvation. lid water water snail freshwater plant

Ecological Independence of Organisms Predation (Predator-prey relation) Time Number prey predator HareLynx

Time Number Competition (competitors) the winner the loser Cuckoo displacing the host’s egg Ecological Independence of Organisms

Commensalism one gets (physical) benefit, one feels no effect organism benefited: Commensal organism with no effect: Host easy separate from each other eg. barnacle on crab (barnacle gets transport)

both obtain benefits not easy separate (even cannot be separated) e.g.1. lichen (mutualism of specific algae & fungi) –fungi absorb moisture from air and moist the algae –algae provide carbohydrates for the fungi Mutualism

e.g.2. Nitrogen-Fixing Bacteria & Leguminous Plants –bacteria fix atmospheric nitrogen to nitrogenous compounds for the plant –the plant provides carbohydrates to bacteria Mutualism

Parasitism parasite obtains benefits (food & protection) host gets harmful effects eg. tapeworm in man (endoparasites)

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