Biodiversity
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Biodiversity

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Biodiversity Biodiversity Document Transcript

  • HKDSE Biology – BiodiversityBiodiversity ● Refers to the existence of a great variety of life forms in the planet Earth7 Characteristics of Living Organisms ● Living organisms should have all the 7 characteristics in certain stages oflife 1. Nutrition Organisms take in food for energy and to maintain life 2. Irritability Organisms react to changes in their environment 3. Respiration Organisms break down food in their cells to supply energy for body activities 4. Growth Organisms increase in size and complexity 5. Movement Animals move from place to place using legs, wings or fins. Plants generally move by growing 6. Reproduction Organisms produce offspring 7. Excretion Organisms remove waste products produced from chemical reactions inside bodiesBy Michael Ho~* 1
  • HKDSE Biology – BiodiversityCell Type ● Cells can be divided into 2 types (prokaryotic and eukaryotic cell)  Prokaryotes: Organisms having prokaryotic cells, e.g. bacteria  Eukaryotes: Organisms having eukaryotic cells, e.g. fungi, plants, animalsFeatures Prokaryotic cell Eukaryotic cellNucleus - No true nucleus - True nucleus  - No nuclear envelope - Nuclear envelope Genetic material - A single circular DNA - DNA associated with lying free in cytoplasm proteins forming chromosomes in nucleusMembrane boundedorganelles  Cell membrane  Size Smaller LargerBy Michael Ho~* 2
  • HKDSE Biology – BiodiversityClassification of Organisms ● Separate organisms into different groups based on their features ● All organisms on Earth are classified into 3 domains and 6 kingdoms(A) Classifying Organisms Classification levels Amounts of organisms Similarities among organisms The most The least Domain 域 Kingdom 界 ︽ Phylum 門 ︾ Class 綱 ︽ Order 目 ︾ Family 科 Genus 屬 ︾ ︽ The least The most Species 種Species - A group of organisms that can interbreed to produce fertile offspring(B) Naming of Organisms ● Each species has a scientific name consisting of 2 words ● The 1st word is the name of genus, the 2nd word is the name of species; separated by space ● The 1st letter of the first word being capital, the rest all being small ● Underlined if written Students should know the scientific name of modern human  Homo sapiens (Dont underline the space!)By Michael Ho~* 3
  • HKDSE Biology – Biodiversity3 Domains (Bacteria, Archaea, Eukarya) Prokaryotes EukaryotesDomain Bacteria Archaea EukaryaKingdom Eubacteria Archaebacteria Protista Fungi Plantae AnimaliaPhylum - - - - - -Class - - - - - -Order - - - - - -Family - - - - - -Genus - - - - - -Species - - - - - -Domain Bacteria and Archaea ● Bacteria domain has 1 kingdom, Eubacteria. ● Archaea domain has 1 kingdom, Archaebacteria.Similarity between Bacteria and Archaea ● They are prokaryotes Nucleus - No true nucleus - No nuclear envelope Genetic material - A single circular DNA lying free in cytoplasm Membrane bounded organelles  Cell membrane  Size Smaller ● Unicellular (Each organism contains only 1 cell) ● Different shapes (rod, spherical, spiral shape) ● Different methods to obtain nutrients  by photosynthesis (use sunlight to make food)By Michael Ho~* 4
  • HKDSE Biology – Biodiversity  by chemosynthesis (use minerals to make food)  parasitic 寄生 (live in/on other organisms bodies)  saprophytic 腐生 (depend on dead organic compounds)Differences between Bacteria and Archaea Domain: Bacteria Domain: Archaea (Kingdom: Eubacteria) (Kingdom: Archaebacteria)Larger SmallerCell membrane is made of lipids Cell membrane is made of lipids (different structure than those in all other organisms)(similar to those of eukaryotes)Cell wall made of peptidoglycan Cell wall contains no peptidoglycanRibosomes more different from Ribosomes resemble more closely toeukaryotes eukaryotesLive in a wide variety of habitats Live in extreme environments Example:  Hot springs (very hot)  Salt lakes (very salty)  Acid mine drainage (very acidic)  Deep ocean floor (anaerobic condition)By Michael Ho~* 5
  • HKDSE Biology – BiodiversityDomain Eukarya ● This domain has 4 kingdoms (1.Protista, 2.Fungi, 3.Plantae, 4.Animalia). ● They are eukaryotes with nucleus and membrane bounded organelles. 1. Kingdom Protista  Most are unicellular; if multicellular, lack differentiation  2 types of Protista: Algae (autotrophic) and Protozoans (heterotrophic)(A) Algae (B) Protozoans Varies from single cells, colonies,  Unicellular filaments to sheet-like forms Autotrophic nutrition All 3 types of heterotrophic nutrition Contain chlorophylls and carry out 1. Holozoic photosynthesis in chloroplasts -Mobile (∵pseudopodia, flagella, cilia) -Feed on bacteria, yeast or protozoans 2. Parasitic 3. Saprophytic Presence of cell wall made of  No cell wall cellulose Most are aquatic  Live in freshwater or marine, in damp soil or in plants and animals Some unicellular algae may live in soil or associate fungi to form lichens E.g. seaweeds  E.g. amoeba 2. Kingdom Fungi  Unicellular/Multicellular  Heterotrophs: saprophytic, parasitic  Presence of rigid cell wall made of chitin  Body is made up of a network of hyphae  No roots, stems, leaves or chlorophyll  Use spores for asexual reproduction  Live in damp places  E.g. yeast (unicellular), mould and mushroom (multicellular)By Michael Ho~* 6
  • HKDSE Biology – Biodiversity 3. Kingdom Plantae  Plants are divided into non-vascular plants and vascular plants  Autotrophic nutrition: Contain chlorophylls and carry out photosynthesis in chloroplasts  Presence of cell wall made of cellulose Non-vascular plants Major group Characteristics Mosses  There is no vascular tissues  Possess simple leaves and stems  No true roots but possess rhizoids for anchoring, absorption of water and minerals  Asexual reproduction by spores  Lack cuticle so restricted to damp, shady areas Vascular plants  With vascular tissue  Have true roots, stems and leaves  Have vascular tissues for transport of water, mineral salts and soluble food substances  Cuticle on leaf surface to reduce water loss Major group Characteristics Ferns  Asexual reproduction by spores which are stored in sporangia  Sporangia are located on the undersurface of the leafBy Michael Ho~* 7
  • HKDSE Biology – Biodiversity Major group Characteristics Gymnosperms  They are trees with needle-shaped leaves  Seeds are not enclosed in ovary and hence not enclosed in fruits  Naked seeds are protected by seed coat They are found in cones Angiosperms  Seeds are enclosed, protected and dispersed in ovary and hence enclosed in fruits  Possess flowers  2 types of angiosperms: Monocotyledons and DicotyledonsSummary of Kingdom Plantae Non-flowering plants Flowering plants Mosses Ferns Gymnosperms Monocotyledons Dicotyledons Possess simple Possess leaves, stems and true rootsleaves and stems Large leaves Usually needle- Leaves with Leaves with and rhizoids subdivided into shaped leaves veins in parallel veins in leaflets network No vascular Possess vascular tissues tissues Reproduce by spores Reproduce by seeds No cone Possess cone No cone No flower/fruit Possess flowers/fruits No cuticle Possess cuticle Terrestrial Terrestrial (can live in dry places) (wet area only) 4. Kingdom Animalia • Multicellular organismsBy Michael Ho~* 8
  • HKDSE Biology – Biodiversity • Compose of eukaryotic cells without cell wall and chloroplasts • Animals are divided into invertebrates and vertebrates 1) Invertebrates ⇒ Usually restricted body size as they lack supporting vertebral columns ⇒ E.g. Jellyfish 水母 , Tapeworms 絛蟲 , Earthworms 蚯蚓 , Snails 蝸牛 , Sea urchin 海膽, Insects 昆蟲 2) Vertebrates ⇒ Divided into 5 groups: (A) fish, (B) amphibians, (C) reptiles,(D) birds, (E) mammals (A) Fish  Skin is covered with slimy scales  Gills present for gas exchange in both larvae stage and adult stage  Present of fins for balance and movement - External fertilization - Lay eggs in water - Poikilotherms Students should realize that sea horses 海馬 (have gills) are fish. (B) Amphibians  Skin is covered with moist naked skin  Present of gills in larvae stage; lungs and skin surface in adult stage for gas exchange - External fertilization - Lay eggs in water - Poikilotherms Students should realize that salamanders 蠑螈 (have moist naked skin) are amphibians.By Michael Ho~* 9
  • HKDSE Biology – Biodiversity (C) Reptiles  Dry skin is covered with hard scales - Present of lungs for gas exchange - Internal fertilization - Lay eggs with hard shells on land - Poikilotherms Students should realize that crocodiles 鱷魚 (have dry hard scales) are reptiles. (D) Birds  Body is covered with feathers  Present of beak - Present of wing for flying - Present of dry scales on their legs - Present of lungs for gas exchange - Internal fertilization - Lay eggs with hard shells on land - Homoiotherms - Parental care is highly developed Students should realize that penguins 企 鵝 (have beak and no mammary gland) are birds. (E) Mammals  Skin is covered with hairs  Present of mammary glands to feed young  Young develops in uterus (EXCEPT platypus 鴨嘴獸, spiny ant eater 食蟻獸- lay eggs)  Present of diaphragm - Present of lungs for gas exchange - Internal fertilization - Homoiotherms - Parental care is highly developed Students should realize that bats 蝙蝠 (have hair), whales 鯨魚 (have mammary gland), dolphins 海豚 (have mammary gland) are mammals.By Michael Ho~* 10
  • HKDSE Biology – BiodiversitySummary of Kingdom AnimaliaInvertebrates VertebratesNo backbone Possess backbone Fish Amphibians Reptiles Birds Mammals Unique Unique Unique Unique Unique features: features: features: features: features: -Slimy scales -Moist naked -Dry scales -Feathers -Hair -Gills skin -Beak -Mammary -Fins -GillsLungs glands -Uterus -Pinnae -Diaphragm Live in water Live in water Most live on land and on land (aqueous) External fertilization Internal fertilization Egg-laying Born alive Eggs without shell Eggs with shells No eggs Poikilotherm HomoiothermDichotomous Key 二叉式檢索表• Key is a tool for identifying organisms• Done by sorting organisms into smaller groups according to their characteristics• Dichotomous key is the one commonly used, providing 2 alternative features at each step• The key can be presented in 2 forms (sentence form and chart form)By Michael Ho~* 11