Presentation on theme: "B1 Topic 1 Influences on Life. B1.1 Classification Biologists classify living organisms according to how closely they are related to one another. Species."— Presentation transcript:
B1 Topic 1 Influences on Life
B1.1 Classification Biologists classify living organisms according to how closely they are related to one another. Species – groups of organisms that have many features in common Genus – contains several species with similar characteristics Family – comprising of several genera Order – comprising of several families Class – comprising of several orders Phylum – comprising of several classes
B1.1 The Five Kingdoms KingdomCharacteristics Animaliamulticellular, no cell walls, no chlorophyll, feed heterotrophically Plantaemulticellular, have cell walls, have chlorophyll, feed autotrophically Fungimulticellular, have cell walls, no chlorophyll, feed saprophytically Protoctistaunicellular, have a nucleus Prokaryotaunicellular, have no nucleus VIRUSES are classified as NON LIVING because… The virus does not show the characteristics of life such as growth and feeding,
B1.2 Phylum - Chordata Animals 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 skin b Reproduction – internal or external fertilisation, oviparous or viviparous c Thermoregulation – homeotherms and poikilotherms Key words: Chordata – Animals with backbones, homeotherm – can regulate temperature, poikilotherms – coldblooded, oviparous – animals which lay eggs, viviparous – internal embryo development
B1.3 Species Definition: 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 sapien First name – tells us the organisms are closely related Second name – species name
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.
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
B1.2 & 1.6 Difficult Classification Classification is difficult because of variation within a species. Variation – differences between individuals The 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.
B1.4 Can you use a key?
B1.4 Variation e.g. height e.g. eye colour, blood group Normal distribution curve Key words: 1.Continuous Variation 2.Discontinuous Variation
B1.6 Reasons for Variety Caused by GENES or ENVIRONMENT or BOTH Organisms adapt to their habitats Mutations increase genetic variation Key words: Mutation – a change in an organisms DNA
B1.6 The Polar Bear – 6 adaptations FeatureReason Small earsReduce heat loss Thick furInsulation Large feetSpread weight, help swimming, stop it sinking in the snow Rough solesGrip Thick blubberInsulation White furCamouflage
B1.6 Pompeii Worms – 4 adaptations Lives in deep sea vents 2km below sea level Has no eyes but sensitive tentacles Covered in bacteria to survive temperature changes Lives inside a tube to avoid predators Can survive pressures of 200atm
B1.7 Darwins theory of Evolution – 6 stages 1.variation – most populations of organisms contain individuals which vary slightly from one to another 2.over-production – most organisms produce more young than will survive to adulthood 3.struggle for existence – because populations do not generally increase rapidly in size there must therefore be considerable competition for survival between the organisms 4.survival – those with advantageous characteristics are more likely to survive this struggle 5.advantageous characteristics inherited – better adapted organisms are more likely to reproduce successfully passing on the advantageous characteristics to their offspring 6.gradual 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 lost New evidence from DNA research and the emergence of resistant organisms supports Darwin’s theory Summarise to 6 words: variation, overproduction, competition, survival, reproduction, change
B1.8 Genes – know the key words 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 characteristics Dominant – will always be expressed if present Recessive – will only be expressed in the absence of dominant allele Homozygous – two alleles the same e.g. hh, HH Heterozygous – two different alleles e.g. Hh Phenotype – the outward appearance e.g. brown eyes Genotype – the description of the genes e.g. BB, Bb, bb
B1.9 Punnett Squares You must be able to draw these and identify genotype and phenotype of offspring. You must work out % of offspring with each characteristic. T – tall t – short What % of the offspring will be short?
B1.10 Inherited Diseases – 4 symptoms for each Sickle Cell Become tired easily Shortness of breath Joint pain Blocked blood vessels Cystic Fibrosis Lungs clogged with mucus Difficulty breathing Repeated infections Weight loss due to blocked ducts in digestive system
B1.10 Pedigree Analysis Cystic 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?
B1 Topic 2 Responses to a changing environment
B1.11 Homeostasis Keywords Homeostasis – maintenance of a constant/stable internal environment Osmoregulation – Control of body water levels (involved the Thermoregulation – control of body temperature (human body temp - 37°C) Hypothalamus – part of the brain that monitors temperature and coordinates all the responses Vasodilation – 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) Factors controlled by homeostasis: A.Blood glucose B.Water C.Temperature Thermoregulation Responses to increased body temperature include: 1.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. 2.Sweat is produced. Heat from the body evaporates the water in sweat. 3.Body hair lies flat against the skin, preventing air becoming trapped next to it. Responses to decreased body temperature include: 1.Vasoconstriction - narrowing of blood vessels in the skin. Blood flow through the skin is reduced, therefore heat loss is decreased. Body temperature increases. 2.Shivering - tiny muscles under the skin contracting and relaxing very quickly. The muscle cells release heat. 3.Body hair rises away from the skin, trapping a layer of air next to it, insulating the body. Erector muscles contracting.
B1.12, 1.13 – Sensitivity, Skin sensitivity Keywords Neurone – a cell that transmits electrical impulses in the nervous system. Central Nervous system (CNS) – Brain and Spinal cord Peripheral Nervous system (PNS) - nerves connecting the sense organs and effectors to the CNS Sense organs – detect changes both in and outside your body. They contain receptor cells – Eye; Ear; Skin; Mouth; Nose Stimulus – Anything your body is sensitive to e.g. noise, heat, light Impulses – 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 neurones Types of Neurone : 1.Sensory neurones send impulses from receptors in the sense organs to the CNS. 2.Motor neurones send impulses from the CNS to muscles and glands. 3.Relay neurones found in the spinal cord/brain. The link sensory and motor neurones. They have no dendron, just dendrites on the cell body.
e e e 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 noise Reflex 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 2. Receptor 3. Sensory neurone 4. Relay neurone 5. Motor neurone 6. Effector
B1.14 Hormones and B1.15 Diabetes Keywords Hormone – 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 concentration Examples of hormones and their effects HormoneReleased fromEffect Anti-Diuretic Hormone Pituitary glandCauses the kidney to make more concentrated urine OestrogenOvariesDevelopment of the female reproductive system during puberty AdrenalineAdrenal GlandSpeeds up the heatbeat TestosteroneTestesDevelopment of the male reproductive system during puberty
B1.15 Diabetes Keywords - See previous page (B1.14) Type 1 Diabetes 1.Pancreas does NOT produce insulin 2.Inject insulin daily (into the fat layer beneath the skin) 3.Exercise and diet are used to help lower blood glucose levels too Type 2 Diabetes 1.Cells respond less well to insulin (they become resistant) 2.Control by changes in diet and exercise. 3.Risk factors of developing it are: 1.High-fat diets 2.Lack of exercise 3.Getting older 4.Obesity Body Mass Index (BMI) – used to determine obesity. The diagram shows normal blood sugar control (without diabetes)
B1.18 Plant Hormones Keywords: 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.
B1.18 Plant Hormones Auxin produced in the tip of the shoot Auxin moves to shaded side of the stem Auxin causes cell elongation
B1.18 Plant Hormones Auxin produced in the tip of the root Auxins have opposite effect in the root Auxins stop elongation and root grows down - geotropism
1.8 Plant Hormones Experiments with hormones. Why do the plants respond this way? Keywords: Auxin, tip, shoot, cell elongation, bend, light, stimulus
B1.19 Uses of plant Hormones 1.Selective Weedkillers – Auxin makes broad leaved plants grow out of control and die. 2.Rooting Powder – Auxin makes cuttings develop roots quickly. 3.Seedless Fruit – Flowers sprayed with hormones to make fruit develop but not seeds. 4.Fruit Ripening – Farmers use hormones to control fruit ripening.
B1 Topic 3 Problems of and solutions to a changing environment
B1.20 and 1.21 – Effects of drugs and reaction time Keywords Narcotic – Drug that makes you feel sleepy Addictive –people can become dependent on the drug and feel they NEED it to function Recreational drug – a drug used to change to way people feel e.g. alcohol Medicine – a drug that helps to limit the damage caused by disease or injury Drug Types 1.Halluginogen – changes the way the brain works (distorts senses) LSD/ cannabis 2.Stimulants – INCREASE the speed of neurotransmission which speeds up (decreases) your reaction time. Caffeine/ cocaine/ nicotine 3.Depressants – slows down the activity of neurones which causes relaxation. INCREASES reaction time Alcohol/ solvents 4.Painkillers – blocks some of the impulses to reduce the pain felt. Morphine/heroin/ asprin 5.Performance enhancer – improves muscle development Anabolic steroids
B1.22 – The damage caused by smoking Keywords Tar – sticky chemical in smoke that contains carcinogens Nicotine – addictive stimulant in tobacco smoke Carcinogen – something that causes cancer Carbon Monoxide – toxic gas found in cigarette smoke Health issues 1.Tar a)Increased risk of developing cancers b)Reduced surface area in the lung as it coats them in sticky tar 2.Carbon Monoxide a)Less oxygen in blood causing pain in active muscles b)Blood vessel narrow reducing blood flow c)Emphysema and chronic bronchitis 3.Nicotine a)Highly addictive to hard to give up Long term studies – evidence links smoking to many diseases including all cancers, respiratory diseases and circulatory diseases.
B1.23 – The effects of alcohol Short term effects 1.Affects all organs as absorbed quickly 2.Slows down brain activity resulting in longer reaction times 3.Reduced negative feelings so feel happier 4.Lower inhibitions so take risks 5.Vomiting 6.Large quantities can cause unconsciousness and death (stops breathing) Long term effects 1.Cirrhosis of liver – cells die and liver function fails 2.Brain damage – Memory loss – Blood clots 3.Addictive Cost to society 1.Violence when drunk 2.Accidents increase 3.Treatment of drink related illness
B1.24 – Ethics and transplants Ethical criteria 1.Similar tissue (closer match give greater chance of survival) 2.Similar age (increased success) 3.Geographically close (quicker transplant = increased success rate) 4.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: 1.Xenotranplantation (animal donors) 2.Genetic engineering (modified animal organs) 3.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. Keywords Transplant – Healthy organ taken from a donor and given to a recipient Ethical decision - uses ethical criteria to make a decision that is right or fair.
B1.25 – Pathogens and infection Keywords Pathogen – microorganism that causes disease Bacteria – microscopic organism (some are pathogens) Salmonella/ Cholera/ E.coli Fungi – organisms that feeds of dead or decaying material Athlete’s foot/ ring worm Viruses – a particle that can infect cells and cause them to make new copies of the virus Influenza/ chicken pox/ HIV/ HPV Protozoan – a single celled protoctist Malaria How are pathogens spread? (6 ways) 1.Water - Cholera 2.Vectors (animals that spread disease) – Malaria (mosquitoes) 3.Food - Salmonella 4.Contact – Athlete’s foot 5.Airborne – Influenza, colds or TB 6.Body fluid - HIV
B1.26 – Antiseptics and Antibiotics Keywords Antiseptics – kill microbes outside the body to reduce the spread of infection Antibiotics – chemicals that kill or prevent growth of bacteria and some fungi Antifungals – antibiotics that only affect fungi Defence against invasion 1.Physical barriers – prevent pathogens getting in 2.Chemical defences – kill pathogens before they harm us Resistance Some bacteria develop natural resistance to antibiotics During antibiotic treatment 1.Less resistant bacteria killed first 2.More resistant ones remain and will re-infect if full course not taken 3.Overuse of antibiotics can cause more resistance to develop MRSA – multi resistant to many antibiotics therefore very difficult to treat
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 environment transferred into BIOMASS as the organism grows moved to the next organism when it is eaten Carnivores, top predators Plants that photosynthesize Herbivores Carnivores, both predator and prey Keywords Trophic level – organisms that feed at the same level Interdependence – organisms in an area that depend on each other Dynamic relationship – constantly changing populations
B1.29 – Parasites and Mutualists Parasites One organism feeds off another while it is alive. Examples 1.Tape worm (inside the body) – They take food from the intestine causing weight loss. 2.Headlice (outside the body) 3.Fleas 4.Mistletoe – Roots grow into other plants to take their water and minerals Mutualists Both organisms benefit from either food, shelter or protection. Examples 1.Oxpecker and wild cows – Oxpecker eats insects that are parasites to the cow 2.Cleaner fish and sharks – Cleaner eats the dead skin to clean sharks 3.Legumes and nitrogen fixing bacteria – The bacteria help the plant to get nitrates while they get food from the plant and protection. 4.Chemosynthetic bacteria in tube worms 5.Intestinal bacteria in humans – Bacteria provide protection against pathogen and get food and place to live in return
B1.30 – Pollution Why did the human population grow so quickly? 1.Better food 2.Improved sanitation and living conditions 3.More medicines available Increased populations mean bigger demand on resources. More people means more… 1.food needed (increased pressure to grow crops) 2.housing and transport that uses fossil fuels (more gases pollute the air) Eutrophication Phosphate and nitrates increase plant and algae growth Can destroy the ecosystem as it kills plants and animals. Keywords Pollutants - a substance that harms living organisms when released into the environment. Eutrophication – The addition of chemicals, like fertilizers, to water which encourages plant growth Fertiliser – chemical compounds added to soil to increase the growth rate of crops Eutrophication stages
B pollution indicators Keywords Indicator 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 Indicators 1.Blackspot fungus (disease of roses) is killed by sulfur dioxide 2.Lichen – different species tolerate different pollutant levels. Feathery ones need clean air, crusty flatter ones can tolerate higher levels of supfur dioxide Water Pollution Indicators Different animals need varying amounts of oxygen. 1.Stonefly larvae and freshwater shrimps needs lots of oxygen (clean rivers) 2.Bloodworms and Sludgeworms can live with low oxygen (polluted rivers) Recycling Taking 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. 1.Metal cans Car parts, new cans 2.PaperNew paper, cardboard 3.Plastic bottlesFleece clothing
Keywords Detritivores – worms and maggots that feed on dead material Decomposer – organisms (bacteria and fungi) that feeds on dead material starting the process of decay Carbon is recycled as carbon dioxide (CO 2 ) through respiration and photosynthesis. 1.Plants absorb CO 2 to produce sugars - photosynthesis. 2.Animals and plants release CO 2 when they respire 3.Burning of fossil fuels releases CO 2 4.Chalk and other sedimentary rocks is formed from the fossilised remains of sea creatures. 5.When these rocks are exposed to rain (which is slightly acid), the rock dissolves and more CO 2 is released. B1.33 – The Carbon Cycle
B1.34 – The Nitrogen Cycle Nitrogen is needed to make biological molecules like proteins and DNA. Plants absorb nitrates from the soil Animals get nitrogen from their food. Bacteria in the Nitrogen Cycle 1.Nitrogen fixing bacteria- bacteria living in root nodules of legumes and soil. They convert: Nitrogen gasAmmonia 2.Nitrifying bacteria– converts AmmoniaNitrates 3.Denitrifying bacteria– converts Nitrates Nitrites NitritesNitrogen gas