Presentation on theme: "Topic 1 Influences on Life"— Presentation transcript:
1 Topic 1 Influences on Life B1Topic 1 Influences on Life
2 B1.1 ClassificationBiologists classify living organisms according to how closely they are related to one another.Species – groups of organisms that have many features in commonGenus – contains several species with similar characteristicsFamily – comprising of several generaOrder – comprising of several familiesClass – comprising of several ordersPhylum – comprising of several classes
3 B1.1 The Five Kingdoms Kingdom Characteristics Animalia multicellular, no cell walls, no chlorophyll, feed heterotrophicallyPlantaemulticellular, have cell walls, have chlorophyll, feed autotrophicallyFungimulticellular, have cell walls, no chlorophyll, feed saprophyticallyProtoctistaunicellular, have a nucleusProkaryotaunicellular, have no nucleusVIRUSES are classified as NON LIVING because…The virus does not show the characteristics of life such as growth and feeding,
4 B1.2 Phylum - ChordataAnimals with a supporting rod running the length of their body.Example – a backbone in vertebrates.How are vertebrates classified?a Oxygen absorption methods – lungs, gills and skinb Reproduction – internal or external fertilisation, oviparous or viviparousc Thermoregulation – homeotherms and poikilothermsKey words: Chordata – Animals with backbones , homeotherm – can regulate temperature, poikilotherms – coldblooded, oviparous – animals which lay eggs, viviparous – internal embryo development
5 B1.3 SpeciesDefinition: A group of similar individuals that can interbreed to produce fertile offspring.Limitations to this definition…Some organisms reproduce asexually.Some hybrids are fertile.The Binomial System – uses two names e.g. Homo sapienFirst name – tells us the organisms are closely relatedSecond name – species name
6 B1.2 & 1.6 Difficult Classification Some amphibians have gills as adults.Sharks use internal fertilisation unlike most other fish.Duck billed platypus…and it lays eggs!So…scientists use many characteristics to classify organisms.
7 B1.2 & 1.6 Difficult Classification Hybridisation in Ducks – Mallard ducks can hybridise with other closely related species. This produces a range of hybrids that are all fertile.Ring Species – Neighbouring populations can still interbreed. The two populations at either end of the chain cannot
8 B1.2 & 1.6 Difficult Classification Classification is difficult because of variation within a species.Variation – differences between individualsThe binomial system is needed to identify, study and conserve species and can be used to target conservation efforts.Scientists must collaborate using journals, peer review to agree new classifications.
10 B1.4 Variation e.g. height e.g. eye colour, blood group Key words: Continuous VariationDiscontinuous VariationB1.4 VariationNormal distribution curvee.g. height e.g. eye colour, blood group
11 Key words: Mutation – a change in an organisms DNA B1.6 Reasons for VarietyCaused by GENES or ENVIRONMENT or BOTHOrganisms adapt to their habitatsMutations increase genetic variationKey words: Mutation – a change in an organisms DNA
12 B1.6 The Polar Bear – 6 adaptations FeatureReasonSmall earsReduce heat lossThick furInsulationLarge feetSpread weight, help swimming, stop it sinking in the snowRough solesGripThick blubberWhite furCamouflage
13 B1.6 Pompeii Worms – 4 adaptations Lives in deep sea vents 2km below sea levelHas no eyes but sensitive tentaclesCovered in bacteria to survive temperature changesLives inside a tube to avoid predatorsCan survive pressures of 200atm
14 B1.7 Darwins theory of Evolution – 6 stages Summarise to 6 words: variation, overproduction, competition, survival, reproduction, changeB1.7 Darwins theory of Evolution – 6 stagesvariation – most populations of organisms contain individuals which vary slightly from one to anotherover-production – most organisms produce more young than will survive to adulthoodstruggle for existence – because populations do not generally increase rapidly in size there must therefore be considerable competition for survival between the organismssurvival – those with advantageous characteristics are more likely to survive this struggleadvantageous characteristics inherited – better adapted organisms are more likely to reproduce successfully passing on the advantageous characteristics to their offspringgradual change – over a period of time the proportion of individuals with the advantageous characteristics in the population will increase compared with the proportion of individuals with poorly adapted characteristics, and the poorly adapted characteristics may eventually be lostNew evidence from DNA research and the emergence of resistant organisms supports Darwin’s theory
15 B1.8 Genes – know the key words The nucleus of the cell contains chromosomes, on which genes are located.Genes exist in alternative forms called alleles which give rise to differences in inherited characteristicsDominant – will always be expressed if presentRecessive – will only be expressed in the absence of dominant alleleHomozygous – two alleles the same e.g. hh, HHHeterozygous – two different alleles e.g. HhPhenotype – the outward appearance e.g. brown eyesGenotype – the description of the genes e.g. BB, Bb, bb
16 B1.9 Punnett SquaresYou must be able to draw these and identify genotype and phenotype of offspring.You must work out % of offspring with each characteristic.T – tallt – shortWhat % of the offspring will be short?
17 B1.10 Inherited Diseases – 4 symptoms for each Sickle CellBecome tired easilyShortness of breathJoint painBlocked blood vesselsCystic FibrosisLungs clogged with mucusDifficulty breathingRepeated infectionsWeight loss due to blocked ducts in digestive system
18 B1.10 Pedigree AnalysisCystic Fibrosis is caused by a recessive allele. What is the genotype of person Z? The first generation parents? What are the chances of person X and Z having a baby with CF if they mated?
19 Topic 2 Responses to a changing environment B1Topic 2 Responses to a changing environment
20 B1.11 Homeostasis Thermoregulation Factors controlled by homeostasis: Blood glucoseWaterTemperatureB1.11 HomeostasisKeywordsHomeostasis – maintenance of a constant/stable internal environmentOsmoregulation – Control of body water levels (involved theThermoregulation – control of body temperature (human body temp - 37°C)Hypothalamus – part of the brain that monitors temperature and coordinates all the responsesVasodilation – Blood vessels widen (to increase heat loss by radiation)Vasoconstriction – blood vessels narrow (to reduce heat loss by radiation)Negative feedback – a control mechanism that occurs when a change in one direction (e.g. getting hot) causes a response to bring the level back to normal (i.e. cooling down)ThermoregulationResponses to increased body temperature include:Vasodilation - widening of blood vessels. Blood flow is increased and more heat is lost through the skin. Nerve impulses pass along the nerves from the thermoregulatory centre to the muscles in the walls of blood cells, stimulating contraction and causing them to narrow. When the muscles relax the blood vessels widen.Sweat is produced. Heat from the body evaporates the water in sweat.Body hair lies flat against the skin, preventing air becoming trapped next to it.Responses to decreased body temperature include:Vasoconstriction - narrowing of blood vessels in the skin. Blood flow through the skin is reduced, therefore heat loss is decreased. Body temperature increases.Shivering - tiny muscles under the skin contracting and relaxing very quickly. The muscle cells release heat.Body hair rises away from the skin, trapping a layer of air next to it, insulating the body. Erector muscles contracting.
21 B1.12, 1.13 – Sensitivity, Skin sensitivity KeywordsNeurone – a cell that transmits electrical impulses in the nervous system.Central Nervous system (CNS) – Brain and Spinal cordPeripheral Nervous system (PNS) - nerves connecting the sense organs and effectors to the CNSSense organs – detect changes both in and outside your body. They contain receptor cellsEye; Ear; Skin; Mouth; NoseStimulus – Anything your body is sensitive to e.g. noise, heat, lightImpulses – Electrical signals in the nervous system that travel through neurones. This is called neurotransmission.Dendron – extension of a neurone that carries the impulse to the cell body. It ends in many dendrites and is usually shorter than the axon.Dendrite – many fine extension of a dendron that collect impulses from other neurones or receptors.Axon – the long extension of a neurone that carries an impulse away from the cell body towards other neuronesTypes of Neurone :Sensory neurones send impulses from receptors in the sense organs to the CNS.Motor neurones send impulses from the CNS to muscles and glands.Relay neurones found in the spinal cord/brain. The link sensory and motor neurones. They have no dendron, just dendrites on the cell body.
22 B1.14 –Responding to stimuli Keywords – (all from previous slide B1.12 and 1.13 also needed)Reflex – a response to a stimulus that does NOT require processing by the brain. The response is automatic.Examples: Blinking/ removing hand from hot surface/ knee jerk reflex/ covering ear to loud noiseReflex Arc – Connection of a sensory neurone to a motor neurone (usually via a relay neurone) that allows reflex actions to occur.Neurotransmitter – Substance that diffuse across the synapse between two neurones and triggers an impulse to be generated in the neurone on the other side of the synapse.Synapse - Point at which 2 neurones meet. There is a tiny gap which cannot transmit an impulse without a neurotransmitter.Myelin Sheath – fatty covering around the axons of many neurones. It speeds up transmission of impulses and help to insulate them from one another.1. Stimulus Receptor Sensory neurone Relay neurone Motor neurone Effector654321e
23 B1.14 Hormones and B1.15 Diabetes KeywordsHormone – Chemical messengers that cause certain parts of the body to respond to their presence. E.g. Human Growth Hormone causes bones and muscles to grow at a faster rate during puberty.Endocrine glands – Glands that produce and release hormones.Target organ – an organ on which a hormone has an effect. (e.g. Insulin has an effect on the Liver)Pancreas- organ that produces digestive enzymes and the hormones insulin and glucagon.Insulin – hormone that decreases blood glucose concentration by causing liver cells to convert glucose into glycogen for storage.Glucagon – hormone that causes liver cells to convert glucagon back into glucose to increase blood glucose concentrationExamples of hormones and their effectsHormoneReleased fromEffectAnti-Diuretic HormonePituitary glandCauses the kidney to make more concentrated urineOestrogenOvariesDevelopment of the female reproductive system during pubertyAdrenalineAdrenal GlandSpeeds up the heatbeatTestosteroneTestesDevelopment of the male reproductive system during puberty
24 B1.15 Diabetes Keywords - See previous page (B1.14) Type 1 DiabetesPancreas does NOT produce insulinInject insulin daily (into the fat layer beneath the skin)Exercise and diet are used to help lower blood glucose levels tooType 2 DiabetesCells respond less well to insulin (they become resistant)Control by changes in diet and exercise .Risk factors of developing it are:High-fat dietsLack of exerciseGetting olderObesityBody Mass Index (BMI) – used to determine obesity.The diagram shows normal blood sugar control (without diabetes)
25 B1.18 Plant HormonesKeywords: Tropism – plant growth response to a stimulus. Phototropism – A plant growth response to light. Geotropism –A plant growth response to gravity. Positive Tropism – towards the stimulus. Negative Tropism – away from the stimulus. Auxin – Plant growth hormone.
26 B1.18 Plant Hormones Auxin produced in the tip of the shoot Auxin moves to shaded side of the stemAuxin causes cell elongation
27 B1.18 Plant Hormones Auxin produced in the tip of the root Auxins have opposite effect in the rootAuxins stop elongation and root grows down - geotropism
28 Keywords: Auxin, tip, shoot, cell elongation, bend, light, stimulus 1.8 Plant HormonesKeywords: Auxin, tip, shoot, cell elongation, bend, light, stimulusExperiments with hormones.Why do the plants respond this way?
29 B1.19 Uses of plant Hormones Selective Weedkillers – Auxin makes broad leaved plants grow out of control and die.Rooting Powder – Auxin makes cuttings develop roots quickly.Seedless Fruit – Flowers sprayed with hormones to make fruit develop but not seeds.Fruit Ripening – Farmers use hormones to control fruit ripening.
30 Topic 3 Problems of and solutions to a changing environment
31 B1.20 and 1.21 – Effects of drugs and reaction time KeywordsNarcotic – Drug that makes you feel sleepyAddictive –people can become dependent on the drug and feel they NEED it to functionRecreational drug – a drug used to change to way people feel e.g. alcoholMedicine – a drug that helps to limit the damage caused by disease or injuryDrug TypesHalluginogen – changes the way the brain works (distorts senses)LSD/ cannabisStimulants – INCREASE the speed of neurotransmission which speeds up (decreases) your reaction time.Caffeine/ cocaine/ nicotineDepressants – slows down the activity of neurones which causes relaxation. INCREASES reaction timeAlcohol/ solventsPainkillers – blocks some of the impulses to reduce the pain felt.Morphine/heroin/ asprinPerformance enhancer – improves muscle developmentAnabolic steroids
32 B1.22 – The damage caused by smoking KeywordsTar – sticky chemical in smoke that contains carcinogensNicotine – addictive stimulant in tobacco smokeCarcinogen – something that causes cancerCarbon Monoxide – toxic gas found in cigarette smokeHealth issuesTarIncreased risk of developing cancersReduced surface area in the lung as it coats them in sticky tarCarbon MonoxideLess oxygen in blood causing pain in active musclesBlood vessel narrow reducing blood flowEmphysema and chronic bronchitisNicotineHighly addictive to hard to give upLong term studies – evidence links smoking to many diseases including all cancers, respiratory diseases and circulatory diseases.
33 B1.23 – The effects of alcohol Short term effectsAffects all organs as absorbed quicklySlows down brain activity resulting in longer reaction timesReduced negative feelings so feel happierLower inhibitions so take risksVomitingLarge quantities can cause unconsciousness and death (stops breathing)Long term effectsCirrhosis of liver – cells die and liver function failsBrain damageMemory lossBlood clotsAddictiveCost to societyViolence when drunkAccidents increaseTreatment of drink related illness
34 B1.24 – Ethics and transplants KeywordsTransplant – Healthy organ taken from a donor and given to a recipientEthical decision - uses ethical criteria to make a decision that is right or fair.Ethical criteriaSimilar tissue (closer match give greater chance of survival)Similar age (increased success)Geographically close (quicker transplant = increased success rate)Degree of illness (the more ill a patient the less likely they will survive)Organ donors can be:Living: live donors can donate tissues such as bone marrow or an organ such as a kidney, where there are two doing the same job.Dead: people can give permission for their organs to used if they are killed in an accident. Most organ donors are victims of accidents.Rejection of the organ is less likely to happen if the donor is related to the recipient.Need is far greater that supply so alternatives looked at:Xenotranplantation (animal donors)Genetic engineering (modified animal organs)Transplant tourism (looking abroad)Morals are what people think is right or wrong.Ethics are the actions people take as a result of their moral judgement.
35 B1.25 – Pathogens and infection KeywordsPathogen – microorganism that causes diseaseBacteria – microscopic organism (some are pathogens)Salmonella/ Cholera/ E.coliFungi – organisms that feeds of dead or decaying materialAthlete’s foot/ ring wormViruses – a particle that can infect cells and cause them to make new copies of the virusInfluenza/ chicken pox/ HIV/ HPVProtozoan – a single celled protoctistMalariaHow are pathogens spread? (6 ways)Water - CholeraVectors (animals that spread disease) – Malaria (mosquitoes)Food - SalmonellaContact – Athlete’s footAirborne – Influenza, colds or TBBody fluid - HIV
36 B1.26 – Antiseptics and Antibiotics KeywordsAntiseptics – kill microbes outside the body to reduce the spread of infectionAntibiotics – chemicals that kill or prevent growth of bacteria and some fungiAntifungals – antibiotics that only affect fungiDefence against invasionPhysical barriers – prevent pathogens getting inChemical defences – kill pathogens before they harm usResistanceSome bacteria develop natural resistance to antibioticsDuring antibiotic treatmentLess resistant bacteria killed firstMore resistant ones remain and will re-infect if full course not takenOveruse of antibiotics can cause more resistance to developMRSA – multi resistant to many antibiotics therefore very difficult to treat
37 B1.28 – Interdependence and food webs Energy is -used in metabolic processes (respiration)transferred into ‘waste’ energy forms e.g. heat which is lost to the environmenttransferred into BIOMASS as the organism growsmoved to the next organism when it is eatenKeywordsTrophic level – organisms that feed at the same levelInterdependence – organisms in an area that depend on each otherDynamic relationship – constantly changing populationsCarnivores, top predatorsPlants that photosynthesizeHerbivoresCarnivores, both predator and prey
38 B1.29 – Parasites and Mutualists One organism feeds off another while it is alive.ExamplesTape worm (inside the body)They take food from the intestine causing weight loss.Headlice (outside the body)FleasMistletoeRoots grow into other plants to take their water and mineralsMutualistsBoth organisms benefit from either food, shelter or protection.ExamplesOxpecker and wild cowsOxpecker eats insects that are parasites to the cowCleaner fish and sharksCleaner eats the dead skin to clean sharksLegumes and nitrogen fixing bacteriaThe bacteria help the plant to get nitrates while they get food from the plant and protection.Chemosynthetic bacteria in tube wormsIntestinal bacteria in humansBacteria provide protection against pathogen and get food and place to live in return
39 B1.30 – Pollution food needed (increased pressure to grow crops) KeywordsPollutants - a substance that harms living organisms when released into the environment.Eutrophication – The addition of chemicals, like fertilizers, to water which encourages plant growthFertiliser – chemical compounds added to soil to increase the growth rate of cropsWhy did the human population grow so quickly?Better foodImproved sanitation and living conditionsMore medicines availableIncreased populations mean bigger demand on resources. More people means more…food needed (increased pressure to grow crops)housing and transport that uses fossil fuels (more gases pollute the air)EutrophicationPhosphate and nitrates increase plant and algae growthCan destroy the ecosystem as it kills plants and animals.Eutrophication stages1543267
40 B 1.31 - pollution indicators KeywordsIndicator species- an organism that is particularly sensitive to or tolerant of pollution so it can be used to measure pollution levels.Lichen – Mutualistic relationship between a fungus and an algae.Air Pollution IndicatorsBlackspot fungus (disease of roses) is killed by sulfur dioxideLichen – different species tolerate different pollutant levels. Feathery ones need clean air, crusty flatter ones can tolerate higher levels of supfur dioxideWater Pollution IndicatorsDifferent animals need varying amounts of oxygen.Stonefly larvae and freshwater shrimps needs lots of oxygen (clean rivers)Bloodworms and Sludgeworms can live with low oxygen (polluted rivers)RecyclingTaking materials out of waste so they can be converted in new products. This means we need less of the raw materials that could be difficult to find or expensive.Metal cans Car parts, new cansPaper New paper, cardboardPlastic bottles Fleece clothing
41 B1.33 – The Carbon CycleKeywords Detritivores – worms and maggots that feed on dead material Decomposer – organisms (bacteria and fungi) that feeds on dead material starting the process of decayCarbon is recycled as carbon dioxide (CO2) through respiration and photosynthesis.Plants absorb CO2 to produce sugars - photosynthesis.Animals and plants release CO2 when they respireBurning of fossil fuels releases CO2Chalk and other sedimentary rocks is formed from the fossilised remains of sea creatures.When these rocks are exposed to rain (which is slightly acid), the rock dissolves and more CO2 is released.
42 B1.34 – The Nitrogen CycleNitrogen is needed to make biological molecules like proteins and DNA.Plants absorb nitrates from the soilAnimals get nitrogen from their food.Bacteria in the Nitrogen CycleNitrogen fixing bacteria- bacteria living in root nodules of legumes and soil. They convert:Nitrogen gas AmmoniaNitrifying bacteria– convertsAmmonia NitratesDenitrifying bacteria– convertsNitrates NitritesNitrites Nitrogen gas