Bio seminar 2012 (with answers)


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Am too shy to put this on public :/ so this is a private video. Just let me know who are those that i have missed out alright. Hee, have fun studying!

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  • One cell thick/ moist/surface area
  • Bio seminar 2012 (with answers)

    1. 1. TTC BiologySeminar 2012 JaySze Yong WELCOME!
    2. 2. Let’s start!It’s not about how many times have you studied, but how muchdid you understandSyllabus of the day: Transport Dynamic Ecosystem Endangered Ecosystem
    3. 3. ☺ TransportThe system and its components: Blood Circulatory system Pump Blood vessels
    4. 4. Question!But why do we need a circulatory system?Because… Multicellular organisms have small TSA/V ratio(long distances between body cells and environment. Impermeable skinThese lead to inefficiency in substances exchange.
    5. 5. Circulatory Systems Open Circulatory System Closed Circulatory System ☺ Movie time!
    6. 6. ☀ Open Circulatory SystemFound in INSECTS, prawns, snails and etc. Aorta HaemocoelHaemolymph flows out of circulatory Dorsal Ostiasystem into body cavities. Vessel Dorsal DiaphragmHaemolymph reaches the body cells DIRECTLY.
    7. 7. Start pumping! heart haemolymph heart haemolymph flow into flows backcontracts haemocoel relaxes into the heart
    8. 8. ☀ Closed Circulatory SystemFound in ALL vertebrates (e.g. humans/fishes) and someinvertebrates(earthworms)Blood flows within the blood circulatory system WITHOUTmoving into body cavities
    9. 9. Has a two- Has a three- Has a four-chambered heart, chambered heart, chambered heart,single and closed double, closed double, closedcirculatory circulatory system circulatory systemsystem
    10. 10. 2 types of closed circulation Pulmonary Circulation ( heartlungheart) Blood flows from the right ventricle to the lungs via pulmonary artery and return to the left atrium via pulmonary vein. Systemic Circulation ( heartrest of bodyheart) Blood flows from the left ventricle to the body tissues via aorta and return to the right atrium via vena cava.
    11. 11. HeartThe PUMP! Four chambers : two atria and two ventricles Made up of MYOGENIC cardiac muscles Located in the thoracic cavity Connected to the lungs
    12. 12. Sequence of Heart Pumping 1) The contractions of the heart are initiated by the sinoatrial(SA) node. SA node 2) SA node generates electrical impulses which make atria contract to pump blood into ventricles. Purkinje AV node Fiber Electrical signals reach the atrioventricular Electrical impulses node(AV) node, Bundle Bundle of spread to the ventricles of His, Purkinje fibres. His and causes ventricles to contract and pump blood out of heart.
    13. 13. Question!What is meant by the term MYOGENIC?It means the ability to contract and relax without stimulation of nervoussystem.Describe the sequence of heart pumping!Everything in previous slide! What is the function of valves?Ensure one way flow of blood/ prevent back flow.Why left ventricle is thicker than right ventricle?Left ventricle needs to pump blood at higher pressure through the body.
    14. 14. Overall flow of blood Deoxygenated blood!Vena cava  Right atrium  Right ventricle Pulmonary Arteries  Lungs Oxygenated blood!Lungs  Pulmonary veins  Left Atrium  Left Ventricle Aorta  Body Cells ☺ Movie time!
    15. 15. We the • Arteriescontainers! Blood vessels • Capillaries • Veins
    16. 16. Let’s compare!
    17. 17. Question!Explain two characteristics of capillaries which allowefficient substances exchange.State THREE differences between arteries, capillariesand veins.
    18. 18. BloodHmm…what is in a drop of blood? Let’s see..
    19. 19. ! A yellowishfluid containingsolublesubstances ! Formed elements containing RBC, WBC, Platelets
    20. 20. Red blood cells *Erythrocytes• Red in colour• Biconcave disc shape• Elastic• Contain haemoglobin for respiratory gases transportation• Manufactured in bone marrow, destroyed in spleen and liver• Lose nucleus upon maturity
    21. 21. Question! Why RBC need all those characteristics? WHY.. BECAUSE.. Biconcave disc shape? Increase surface area for rapid substances exchange. Lose nucleus upon maturity? Accommodate more haemoglobin to transport oxygen. Elastic membrane? Easily squeeze through small capillary membrane. Blood is red? Red pigments are present in haemoglobin. RBC can act as binding site of Oxygen can bind with Iron oxygen? atom in the haem group.
    22. 22. White blood cells *Leucocytes• Nucleus present• Irregular in shape• Important in body defense mechanisms against disease• Manufactured at bone marrow and spleen• TWO BASIC TYPES : GRANULOCYTES AGRANULOCYTES
    23. 23. Types of WBCGranulocytes• Multi lobed nucleus• Rich in granules• Short live span (often few days)Members:
    24. 24. Agranulocytes• No granules• Compact nucleusMembers:
    25. 25. Platelets• Cell tiny fragments of large cell in bone marrow• Involved in blood clotting mechanism• Short life-span (few days)• Irregular shape
    26. 26. Let’s compare!
    27. 27. Blood clotting mechanismPlatelets adhere to damaged wall of Platelets release Platelet plug blood vessels clotting factors. formed Thrombokinase (activator) released Blood clot dries off to form scab. Fibrinogen - Fibrin by Thrombin Fibrin forms threads network over the wound Prothrombin - trapping RBC and form Thrombin blood clot. in the presence of calcium ion + Thrombokinase + Vit K
    28. 28. Why blood clotting is so important?• Prevent excessive loss of blood• Maintain blood pressure• Main circulation of blood in a closed system• Prevent entry of microorganisms and foreign particles into the body• Form scab and helps in healing wounds
    29. 29. Cardiovascular disorders
    30. 30. Blood pressure regulation• Increase in blood pressure  Baroreceptor stimulated  Increase stimulation of cardiovascular centre  Increase discharge of parasympathetic nerve  reduce heart rate  reduce contractility of heart  vasodilation of blood vessels → Blood pressure drops back to normal
    31. 31. • Decrease in blood pressure  Baroreceptor less stimulated  Decrease stimulation of cardiovascular centre  Increase discharge of sympathetic nerve  increase heart rate  increase contractility of heart  vasoconstriction of blood vessels  Blood pressure rise back to normal
    32. 32. Lymphatic systemWhat is a lymphatic system?✐ Lymphatic system is a network of lymph vessels running alongside the veins✐ Lymph is found inside lymph vessels✐ Lymph composition = interstitial fluid composition but maybe lymph has more fats
    33. 33. Why need a lymphatic system?☃ Interstitial fluid formed in the interstitial space must be returned into the circulation☃ 90% returns to the venule ends☃ 10% can only return into the circulation by lymphatic system
    34. 34. How is interstitial fluid formed?• Changes in the diameter of lumen between arterioles and capillaries• High hydrostatic pressure at the arteriole ends• Forces blood contents into interstitial space forming interstitial fluid* Interstitial fluid composition is almost the same as blood contentsEXCEPT WITHOUT • Erythrocytes • Platelets • Plasma proteins
    35. 35. Sequence of lymphatic pathway interstitial spaces back into the heart lymphatic capillaries (circulatory system thoracic duct flow to left subclavin vein right lymphatic vessel lymphatic duct flow to right subclaviab duct In between, lymph thoracic duct right lymphatic duct nodes are present for filtration of lymph contents
    36. 36. Lymphatic vessels return the lymph to the heart via twoducts:Right lymphatic duct drains lymph from the right arm, theright side of the head and the thorax and opens into theright subclavian vein near the heart.Thoracic duct receives lymph from left side head, neck,chest, upper limb and the rest of the body into the leftsubclavian vein near the heart.
    37. 37. Lymphatic flow Hmm…How do lymph flow back to the heart? What aids its movement? Present of valves in lymphatic system which prevent the back flow of lymph. Contraction of skeletal muscles around the lymphatic channels which milk the lymph towards the heart. Peristaltic contraction of intestinal organs Changes in body cavities pressure during respiration # What happens if tissue fluid is not returned completely? • Oedema
    38. 38. Defense mechanism First line Second line Third line defense defense defense First line defense • Physical and chemical barriers • Non-specific defense (do not distinguish, destroy all kind of pathogen bacteria) • Inborn (natural built in) • Do not involve circulatory system lymphatic system• Examples : Skin, Mucus membrane, Saliva, Tears, Gastric acid • Prevent entrance of pathogens into circulatory system and body tissues.
    39. 39. Second line defense• Non specific defense• Eliminate bacteria or ANY TYPE of pathogens by phagocytosis (meal time! *eat up everything)• Involve circulatory system• Phagocytosis carried out by phagocytes#iNFO! The makan members are all M-E-N of white blood cellsM: Macrophages E: Eosinophils N: Neutrophils
    40. 40. Phagocytosis is a process where an organism or aspecific type of cell surrounds, engulfs and ingestsa pathogen.
    41. 41. Third line defense• VERY SPECIFIC DEFENSE (Recognises pathogens - produces specific antibodies to destroy them)• Involve immune, circulatory, lymphatic system *produces lymphocytes• Involves the interaction between antigen and antibody• What’s an antigen? “Name tag” of all cells – Membrane surface protein found in every cell but differ in type in each individual• Antigen STIMULATES the production of antibody in the body• What’s an antibody? The “killer” – Protein produced on the surface of LYMPHOCYTES• Antibody have specific binding site(antigen receptors) that bind with specific antigen#To fight against PERSISTENT infections
    42. 42. After pathogens killed by antibodies, phagocytosis carried out by MACROPHAGES. • Mechanisms of action: Agglutination NeutralisationAntibodies cause Antibodiespathogens to clump neutralise toxinstogether, making produced bythem easy for bacteria by bindingphagocytes to to toxin molecule.destroy. Opsonisation LysisAntibodies bind to Antibodies bind toantigens to act as antigens and causemarkers so that the antigens toantigens can be rupture.recognised anddestroyed byphagocytes. #All by which the specific antibodies bind to specific antigens of pathogens
    43. 43. Types of immunity Immunity – The ability of human body to resist infection. Active immunity Passive immunityBody produces own antibodies to Body obtains antibodies directly fight against infection when from outside source infected Short term immunity – Antibodies die Requires the present of antigens off, or removed from body as foreign (infection) protein Long term immunity
    44. 44. Active immunity• Natural active : Lymphocytes activated by antigens to produce antibodies naturally when infection attacks. (You fall sick - recover)  Example? If you have throat infection, lymphocytes in your body actively produce antibodies to combat it• Artificial active : Antigens are injected on purpose to artificially stimulate lymphocytes to produce antibodies(Vaccination) (Without falling sick) Vaccine is a preparation of  Example? All vaccine injections – weakened, dead or non-virulent Hepatitis B, Cervical cancer forms of pathogen that is harmless vaccination to the person who receives it.
    45. 45. Passive immunity• Natural passive : • Baby in the uterus • Breastfed babies• Obtained antibodies naturally from mother across placenta/when babies breastfeed.• Artificial passive :  Antibodies extracted from other infividual/animal are injected as a serum into body of person who has no immunity  Immediate, temporary  Example? Antivenom injection given to treat snake bites
    46. 46. Let’s compare!Graph A Graph B Which type of immunity are they?
    47. 47. AIDSWhat’s AIDS? Acquired Immune Deficiency Sydromecaused by HIV (Human Immunodeficency Virus)How does it occur? Attacks a specific type of lymphocyte Leading to failure of defense activation(Other infections/cancers take advantage to come in!) Vulnerability to minor infections which can cause dead
    48. 48. Mode of transmission  Direct transmission  Body fluids (blood, semen, vaginal AIDS is NOT secretion, joint fluids , TRANSMITTED spinal cord fluid) #by insect bites  Indirect transmission #through the air – sneezing  Contaminated blood#by hugging, touching, products, needles handshaking  Vertical transmission#by living in the same house  From mother to baby #by sharing food and through placenta water #by sharing cups, glasses, plates
    49. 49. Prevention of AIDS☀ Screen blood products for HIV☀ Sex education program☀ Safe sex (wear condom)☀ Avoid needle sharing (tattoos, drugs, body piercing practices)☀ Avoid multiple sex partners☀ Avoid free sex☀ Avoid exposure to blood products and bodily fluids
    50. 50. ☺Chapter 8 revision time!! What are the interactions between living things (biotic components)?  Symbiosis  Saprophytism  Prey-predator  Competition Memorise TWO EXAMPLES at least for each! 
    51. 51. Symbiosis Commensalism – Benefits one species(commensal) but neither benefits nor harms the other species(host) Examples : Epiphytes(Plants) , Epizoic(Animals) Parasitism – Parasite benefits, but the host is harmed Examples : Endoparasites , Ectoparasites Mutualism – Both species gain benefit Examples : Lichen, Sea anemone and hermit crab
    52. 52. Saprophytism Living organism obtain food from dead and decaying organic matter.☂ Examples of saprophytes(plants) : Bread mould, Mushrooms, Fungus☂ Examples of saprozoites(animals) : Protozoa in frog intestine
    53. 53. Prey-predator weaker animal (prey) is hunted eaten by another stronger animal (predator) Examples : Snake(predator) hunts and eats a rat(prey)
    54. 54. Colonisation and successionColonisation : occurs in newly formed area where no life has existed previouslySuccession : gradual continuous process in which one community changes theenvironment so that it is replaced by another community
    55. 55. Adaptations of Mangrove Swamps Problems faced Adaptations Soft muddy soil strong · Long, extensive cable roots coastal winds pose support · Ex. Avicennia sp. Sonneratia sp. problems · Prop roots @ aerial roots · Ex. Rhizophora sp. · Buttress roots · Ex. Bruguiera sp. · These roots anchor the plants onto the muddy soil Waterlogged conditions of · Breathing roots (pneumatophores) which grow the soil reduce the amount vertically upwards have numerous pore for of O2 leading to anaerobic gaseous exchange during low tides environment · Ex. Avicennia sp. Sonneratia sp. · Lenticels are present on the bark of the plants for gaseous exchange to occur Direct exposure to the sun · Leaves are covered by a thick layer of cuticle to leads to a high rate of reduce transpiration during hot days transpiration · Leaves are thick succulent to store H2O High salinity of sea H2O · Cell sap of root cells of mangrove plants has a causes the surrounding higher osmotic pressure than surrounding soil H2O H2O in the soil hypertonic · This enables diffusion of salty H2O into root cells compare to cell sap of root · Excessive mineral salts will be then excreted cells through hydathodes in the form of crystalline salt Seeds which fall onto the · Mangrove plants show viviparity where the seeds ground die because they germinate while still attached on mother plant are submerged in the soft · This increase the chance of survival as the waterlogged soil seedlings can float horizontally on the H2O subsequently get washed up on the sand or mudflats where they start to grow · During low tide, the seedlings fall vertically bind to the mud that prevent them from carry away by H2O current
    56. 56. ☼ Zonation of Mangrove SwampsSeaward zone(exposed to high tides twice daily) Avicennia sp. Sonneratia sp.Middle zone Rhizophora sp.Inland zone(less frequent covered by sea H2O receives freshwater fromground) Bruguiera sp.
    57. 57. Colonisation and succession in Mangrove SwampsPioneer species!Avicennia sp. andSonneratia sp. Extensive root systems trap collect sediments Soil becomes more compact firm The condition favours the growth of Rhizophora sp.Successor species: Rhizophora sp Successore species: Bruguiera sp. Replaces pioneer species  Replaces Rhizophora sp. Prop root system traps silt mud, creating  Buttress root system form loops to trap more silt firmer soil structure mud Ground becomes higher less submerged by  As more sediments are deposited, shore extend sea H2) further to the sea is like terrestrial ground The condition now favours the growth of  Terrestrial plants (nipah palm Pandarus sp.) begin Bruguiera sp. to replace Bruguiera sp. Gradual transition succession from a mangrove swamp to a terrestrial forest eventually to a tropical rainforest which is climax community takes a long time
    58. 58. Colonisation and succession in a pondPioneer species: submerged plants (Hydrilla sp., Cabomba sp.,Elodea sp., phytoplankton algae. ) Fibrous roots penetrate deep into the soil to absorb nutrients bind sand particles together Able to photosynthesise When pioneer species die decompose, organic nutrients are released into the pond being converted into humus at the pond base Humus soil eroded from the sides of the pond are deposited on the base of the pond, making the pond shallower The conditions become unfavourable for submerged plants but more suitable for floating plants.
    59. 59. Succession by the aquatic floating plants (Lemna sp., Eichornia sp., Nelumbium sp.) Float freely on the surface of H2O Reproduce by vegetative propagation spread to cover a large area of H2O surface, preventing sunlight from reaching the submerged plants Submerged plants die due to unable to photosynthesise the decomposed remains of the submerged plants add more organic matter on the base of the pond At the same time, erosion at the pond edge results in more sediments being deposited on the base of the pond Pond becomes more more shallow which makes it unsuitable for floating plants Submerged plants are subsequently replaced by emergent plants which can live in H2O lands.Successor species: Emergent plants (sedges, cattails) Rhizomes grow horizontally Extensive roots bind soil particles together penetrate deeply to absorb more mineral salts Grow from the edge of the pond towards the middle of the pond as the pond becomes more shallow When these plants die, decomposed remains add to the sediments on the base of pond further reduce the depth of the pond The condition of the pond becomes more favourable for land plants.
    60. 60. At the end….Successor species : Land plants (Ageratum conyzoides, Euphoria hirta,Oldentandia dichotoma, shrubs, bushes, woody plants) As time passes, the land becomes drier land plants become more numerous Primary forest emerges turns into tropical rainforest which is known as climax community
    61. 61. ☺ Population ecologyFew formulas! Percentage frequency = X100% Density = X 100% Percentage coverage = X 100% Population size = For capture, X 100% mark, release and recapture technique!
    62. 62. Maintains theThe Nitrogen Cycle nitrogen balance in water, soil and atmosphere!
    63. 63. ☺Chapter 9 revision time!! What is meant by eutrophication?Eutrophication is the process whereby a body ofwater (e.g. pond or lake) becomes rich in dissolvednutrients (nitrates or phosphates) either naturally ordue to human activities.
    64. 64. Eutrophication Algae boom is the increase of rate of growth of algae and blue green bacteria. Causes of eutrophication: ☃ Overuse of fertiliser ☃ Run-off of manure from farms ☃ Discharge of untreated and treated sewage ☃ Erosion from cultivated land
    65. 65. Describe Eutrophication1. Eutrophication is the artificial enrichment of an aquatic system with nutrients, causing the excessive growth of aquatic plant life.2. Excess nutrients from agricultural run-off cause the rapid growth of algae, which is algae boom.3. Algae use a lot of oxygen and block sunlight penetration.4. Photosynthesis decreases and further depletes oxygen in the lake.5. Algae and some aquatic plants die.6. Dead matter is decomposed by bacteria.7. Aerobic bacteria use up oxygen, deplete oxygen content in the water.8. B.O.D high, dissolved oxygen low.9. Aquatic animals die.
    66. 66. Describe how CFCs destroy the ozone layer1. UV radiation strikes a CFC molecule  causes a chlorine atom to break away.2. The chlorine atom collides with an ozone molecule  steals an oxygen atom to form chlorine monoxide and leaves a molecule of oxygen.3. When a free atom of oxygen collides with the chlorine monoxide  the two oxygen atoms form a molecule of oxygen. The chlorine atom is thus released and free to destroy more ozone molecules.
    67. 67. What is greenhouse effect?1. Solar energy from the sun enters the atmosphere.2. Some energy is reflected back to space.3. Earth’s surface is heated by the sun.4. Earth radiates the heat back towards space.5. However, greenhouse gases in the atmosphere trap some of the heat and cause global warming.6. Greenhouse gases are produced by burning fossil fuels.
    68. 68. Formation of acid rainCaused by oxidation process :• SO2 (Sulphur Dioxide) + ½02 + H20  H2S04 (Sulphuric Acid)• 2NO2 (Nitrogen Dioxide) + ½O2 + H20  2HNO3 (Nitric Acid)1. Acidic gases(Sulphur Dioxide and Oxides of Nitrogen) released by factories2. Gases carried by the wind.3. Gases dissolved in rainwater to form acid rain.4. Acid rain kills plant life, pollutes rivers and streams, and corrodes stonework.