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Introduction

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

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Introduction

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  1. 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

  2. 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

  3. Different Habitats Freshwater Pond Freshwater Stream Grassland

  4. Different Habitats Rocky Shore Mangrove Coral Reef

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

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

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

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

  9. Food Chain / Food Web • shows the feeding relationship between organisms rabbit snake green plants hawk grasshopper lizard toad

  10. 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

  11. First Green plant Producer Second Rabbit Primary Consumer Snake Third Secondary Consumer Hawk Fourth Tertiary Consumer Trophic Level Organism Type

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

  13. Pyramids of Biomass 1 Secondary Consumers 50 Primary Consumers 500 Producers

  14. 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

  15. 1 Secondary Consumers 50 Primary Consumers 500 Producers Pyramids of Biomass Biomass is the total dry mass of organisms at a trophic level

  16. 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

  17. 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

  18. DDT Accumulation

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

  20. 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

  21. Investigation 23.1 Investigation of a Balanced Aquarium

  22. 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.

  23. 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.

  24. 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.

  25. 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…

  26. 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.

  27. Ecological Independence of Organisms Predation (Predator-prey relation) Number prey Hare Lynx predator Time

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

  29. 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)

  30. 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

  31. 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

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

  33. ~END~

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