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Introduction. Habitat: the place where an organism occurs Population: a group of organisms of the same species in an area

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slide2
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
slide3
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
Different Habitats

Freshwater Pond

Freshwater Stream

Grassland

different habitats5
Different Habitats

Rocky Shore

Mangrove

Coral Reef

what is environment
What is Environment ?

Composed of 2 components, Physical Factors & Biotic Factors, which influence the lives of organisms

physical factors
Physical Factors
  • Temperature
  • Light
  • Rainfall & Humidity
  • Wind Speed
  • Soil (esp. for plants)
  • pH
biotic factors
Biotic Factors

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

energy flow within an ecosystem
Energy Flow within an Ecosystem

Tertiary Consumers

Respiration

DECOMPOSITION

Dead remains, excreta, etc

HEAT

Secondary Consumers

Primary Consumers

Producers

SUN

food chain food web
Food Chain / Food Web
  • shows the feeding relationship between organisms

rabbit

snake

green

plants

hawk

grasshopper

lizard

toad

decomposers
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
slide12
First

Green plant

Producer

Second

Rabbit

Primary Consumer

Snake

Third

Secondary Consumer

Hawk

Fourth

Tertiary Consumer

Trophic Level

Organism

Type

pyramids of numbers examples
Pyramids of Numbers(Examples)

Tertiary Consumers

Secondary Consumers

Primary Consumers

Producers

pyramids of biomass
Pyramids of Biomass

1

Secondary Consumers

50

Primary Consumers

500

Producers

slide16
Energy Lost up a Food Chain
  • 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
pyramids of biomass17
1

Secondary Consumers

50

Primary Consumers

500

Producers

Pyramids of Biomass

Biomass is the total dry mass of organisms at a trophic level

effects of ddt
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 ddt19
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
carbon cycle
Carbon Cycle

Carbon dioxide in air

absorption &

photosynthesis

respiration

respiration

organic substances

in animals

feeding

organic substances

in plants

burning

incomplete

decomposition

fossil

nitrogen cycle
Nitrogen Cycle

nitrifying bacteria

(nitrification)

ammonia

nitrate in soil

denitrifying

bacteria

(denitrification)

putrefying

bacteria

(decomposition)

nitrogen

in air

nitrogen-

fixing

bacteria

faeces, urine, dead body

absorption &

photosynthesis

protein in animals

protein in plants

feeding

slide23
Investigation 23.1

Investigation of a Balanced Aquarium

slide24
lid

water

water snail

freshwater plant

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.

slide25
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.

slide26
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.

slide27
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…

slide28
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.

ecological independence of organisms
Ecological Independence of Organisms

Predation

(Predator-prey relation)

Number

prey

Hare

Lynx

predator

Time

ecological independence of organisms30
Ecological Independence of Organisms

Number

Competition

(competitors)

the winner

the loser

Time

Cuckoo displacing the host’s egg

commensalism
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)
mutualism
Mutualism
  • 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
mutualism33
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
parasitism
Parasitism
  • parasite obtains benefits (food & protection)
  • host gets harmful effects
  • eg. tapeworm in man (endoparasites)
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