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Variety of Life and Relation of Organisms with their Environment

Suggested Teaching Sequence F

Section 4 Variety of Life and Relation of Organisms with their Environment

Section 4 advocates the study of organisms in relation to their natural habitats, alongside with ecological field studies, in a local context. The purpose is to give students an appreciation both of biodiversity and of the way in which organisms are adapted to survive in their habitats. It extends the knowledge acquired in S4-5 and aims to further students’ understanding of the interrelationships between organisms and between organisms and their environment. This section also introduces the binomial system of naming organisms and the concept of taxonomic hierarchy. Students are expected to have the ability to construct and use dichotomous keys to identify animals and plants based on their distinguishing external features.

Prior study of Energetics (Section 2) offers a foundation to the comprehension of energy flow and nutrient cycling. An integrated study of ecology with Human Activities and the Environment (Section 5) is conducive to the deepening of students’ respect for living organisms, their respective habitats and the environment. The concepts of Variation and Mechanism of evolution (especially natural selection) learnt in Section 3 may also be applied to explain the diversity and distribution of organisms within a habitat and in different habitats.

Learning objectives Possible learning and teaching activities Expected learning outcomes

Students should learn Students should be able to

4.1 Variety of life

 the relationship between the diversity of

organisms and the variety of their ways of life.

 to use a range of organisms found in two different local habitats (preferably, one terrestrial habitat and one aquatic habitat) to illustrate how the organisms are adapted to their habitats and ways of life.

 Use specimens or audiovisual materials to illustrate the diversity of organisms, and their ways of life.

 Study organisms (e.g. algae, ferns, gymnosperms, angiosperms including monocotyledonous plants and dicotyledonous plants, molluscs, annelids, echinoderms, cnidarians, arthropods, vertebrates) in relation to their natural habitats during field studies.

 appreciate the wonders of the living world and the ways in which organisms are adapted to their habitats during field studies.

4.2 Classification

 that modern classification is based on the phylogenetic relationships of organisms.

 state that the classification system is subject to change as new evidences appears.

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Learning objectives Possible learning and teaching activities Expected learning outcomes

Students should learn Students should be able to

 the grouping of organisms into five kingdoms:

Prokaryotae, Protoctista, Fungi, Plantae and Animalia; the characteristics of each kingdom.

 Challenge the basis of the five kingdoms system, and consider alternative classification systems.

 distinguish among the five kingdoms.

 classify unknown specimens into the five kingdoms.

 the binomial system of naming organisms and the concept of taxonomic hierarchy: kingdoms, phyla/divisions, classes, orders, families, genera and species.

 explain the system of binomial nomenclature and the taxonomic hierarchy.

 to use external features to construct keys and use them to identify organisms to any level.

 Construct dichotomous keys using distinguishing external features of organisms e.g. Arthropoda (Classes Crustacea, Insecta, Arachnida and Myriapoda).

 Use dichotomous keys to identify plants and animals based on external features.

 construct and use dichotomous keys.

4.3 Ecology

4.3.1 Ecosystem

 the meaning of the terms: biosphere, biome, ecosystem, community and population.

 Show audiovisual materials of various biomes and ecosystems.

 Ask students to draw a concept map to illustrate the interrelationship among biosphere, biome, ecosystem, community and population.

 define biosphere, biome, ecosystem, community and population and describe their interrelationship.

 the concept of habitat and niche of an organism.  distinguish between habitat and niche.

 an outline of population growth and the factors affecting it.

 Guide students to investigate population growth, e.g. yeast.

 Design and perform investigations to study factors affecting population growth.

 state the factors that affect population growth.

 analyse and interpret data on population growth.

 an outline of biotic and abiotic factors in ONE local ecosystem and their effects on the distribution and abundance of organisms in that ecosystem.

 Propose hypotheses to explain the effects of abiotic and biotic factors on the distribution and abundance of organisms in a habitat. Design and perform experiments to test the hypotheses.

 explain the possible effects of biotic and abiotic factors on the distribution and abundance of organisms.

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Learning objectives Possible learning and teaching activities Expected learning outcomes

Students should learn Students should be able to

 Ask students to describe the physical features of one habitat, identify environmental factors that have a major impact on the distribution of organisms, and discuss how organisms adapt to such conditions.

 the use of an appropriate sampling method, such as the quadrat, line transect and belt transect, to study the distribution and abundance of organisms.

 Study the distribution of lichens on a tree trunk or boulder.

 Conduct an ecological study of a local habitat to measure the physical factors of the environment, and to find out the distribution of plants and animals, using appropriate sampling methods in the field.

 work in small groups in ecological studies.

 use appropriate sampling methods and develop an awareness of their limitations.

 communicate their ideas through ecological reports.

4.3.2 Energy flow and nutrient cycling

 the transfer of energy between different trophic levels and its relative efficiency; the importance of producers, consumers (including detritivores) and decomposers in the cycling of nutrients.

 the concepts of food chain, food web and trophic level; the pyramid of numbers, pyramid of biomass, and pyramid of energy.

 Provide students with a selected list of animals and plants for a chosen habitat, and ask students to suggest their feeding relationships or trophic level.

 Challenge students to find out as many food chains as possible within one ecosystem. Hence construct a food web using these food chains.

 explain the flow of energy within an ecosystem.

 assess the efficiency of energy transfer between trophic levels.

 relate the concept of energy flow between different trophic levels to photosynthesis, respiration and chemosynthesis.

 explain the roles of producers, consumers (including detritivores) and decomposers in the cycling of nutrients.

 appreciate the importance of photosynthetic organisms in an ecosystem.

 the nitrogen and carbon cycles.  Use audiovisual materials to illustrate nitrogen and carbon cycles.

 Construct concept maps to show the nitrogen or carbon cycles.

 state the major stages of the nitrogen and carbon cycles.

 evaluate the importance of the nitrogen and carbon cycles.

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Learning objectives Possible learning and teaching activities Expected learning outcomes

Students should learn Students should be able to

4.3.3 Interdependence of organisms

 the interactions between organisms: predation, competition, commensalism, mutualism and parasitism.

 Ask students to search for posters, photographs, pictures, video clips, preserved or live specimens, and ask them to identify features of the

interactions.

 Provide data for students to analyse the interactions of organisms.

 Use computer programmes to simulate the effects of the interactions between organisms over time.

 identify different interactions between organisms.

 explain how these interactions maintain the balance of nature.

 evaluate how human interference may disrupt such balance.

4.3.4 Succession

 a simple account of ecological succession, including primary and secondary succession, and climax community.

 Observe different types of vegetation communities in the uplands of Hong Kong to illustrate the transitional stages in succession.

 Observe the colonisation of wastelands (e.g. by grasses and herbs).

 outline the process of ecological succession.

 develop an awareness of the effects of human interference on succession.

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