* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Biology revision
Survey
Document related concepts
Hybrid (biology) wikipedia , lookup
Genetic engineering wikipedia , lookup
Natural environment wikipedia , lookup
Organisms at high altitude wikipedia , lookup
Photosynthesis wikipedia , lookup
Living things in culture wikipedia , lookup
Introduction to evolution wikipedia , lookup
Soil food web wikipedia , lookup
Developmental biology wikipedia , lookup
Hologenome theory of evolution wikipedia , lookup
Koinophilia wikipedia , lookup
Sexual reproduction wikipedia , lookup
History of genetic engineering wikipedia , lookup
Evolutionary history of life wikipedia , lookup
Transcript
B1 – Influences on life. 23 May 2017 A Massawe How science works • Independent variable – this is the quantity that you change • Dependent variable - this is what you measure • Control variable – this is what must be kept the same to ensure a fair test • Hypothesis – an idea based on observations without experimental evidence • Secondary evidence - data collected by someone else, you may find it in a book or on the internet 23 May 2017 A Massawe 2 How do scientist validate results? 1. they repeat experiment results 2. they publish their findings in scientific journals 3. conference presentation 4. peer review/other scientists investigate the same findings. 23 May 2017 A Massawe 3 Kingdom characteristics They are unicellular, with a nucleus. e.g. amoeba and euglena - protoctists They are unicellular, with no nucleus e.g. bacteria – prokaryotes they are multicellular, saprophytic feeders, e.g. moulds, mushrooms, yeast - fungi 23 May 2017 They are multicellular and autotrophic feeders plants They are multicellular, heterotrophic feeders, e.g. fish, amphibia, reptiles, birds and mammals - animals A Massawe Kingdom to species • • • • • • • Kingdom Phylum Class Order Family Genus Species HUMANS Animalia Chordata Mammalia Primates Hominidae Homo Sapiens LIONS Animalia Chordata Mammalia Carnivora Felidae Panthera Leo Kings Prawn Curry Or Fat Greasy Sausages 23 May 2017 A Massawe What is binomial classification? • Binomial classification is a system for naming plants and animals by two Latin names: the first indicating the genus and the second the species to which the organism belongs e.g. Homo Sapiens genus 23 May 2017 species Panthera Leo genus A Massawe species How do scientists classify vertebrates? • The vertebrates are animals with a backbone. Scientist classify them according to: 1. how the animal takes in oxygen – lungs, gills or through the skin 2. thermoregulation – maintains own temperature (homeotherms) or temperature varies with surroundings (poikilotherms) 3. reproduction – internal or external fertilisation, lay eggs (oviparous) or give birth to live young (viviparous). 23 May 2017 A Massawe Vertebrates have gills, external fertilisation, oviparous, poikilotherm - fish some have lungs or gills, external fertilisation, oviparous, poikilotherm – amphibian have lungs, internal fertilisation, oviparous, poikilotherm - reptiles have lungs, internal fertilisation, oviparous, homeotherm - birds 23 May 2017 have lungs, internal fertilisation, vivaparous, homeotherm - mammals A Massawe Why is it difficult to classify sharks? • Sharks are fish but give birth to live young and use internal fertilisation like mammals. 23 May 2017 A Massawe Why are whales classified as mammals? • Whales breathe surface air (no gills, they just hold their breath for a really long time), • They give birth to their young , • They are homeotherms (maintain their own body temperature). 23 May 2017 A Massawe What is a species? • Species is a group of organisms that can reproduce/interbreed with each other to produce a fertile offspring. • Hybrid is an organism that is the result of breeding together two different species, e.g. zedonk (zebra & donkey), liger (lion & tiger) 23 May 2017 A Massawe Why classification is complicated ? 1. variation within a species 2. hybridisation (closely related species breed to produce offspring that have characteristics of both – the hybrids are often infertile) 3. ring species – neighbouring populations of species may have slightly different characteristics but can still interbreed as part of a chain but the two ends of the chain can’t interbreed. 23 May 2017 A Massawe Why is it difficult to classify virus? 1. It does not show all seven processes for life i.e. reproduction and movement 2. It can only reproduce inside the host cell 23 May 2017 A Massawe Why is it difficult to classify euglena? • Because euglena has – 1. chloroplasts, like a plant 2. no cell wall, like an animal 3. a flagellum to swim with, like some bacteria. • A fifth kingdom, called the protoctista, was made for organisms like euglena 23 May 2017 A Massawe Variation • Continuous variation - characteristic that changes gradually over a range of values shows continuous variation, e.g. height, weight 23 May 2017 Disontinuous variation - characteristic with only a limited number of possible values, e.g. gender (male or female) blood group (A, B, AB or O) and eye colour. A Massawe Charles Darwin theory of evolution • How do species adapt and change? 1. variation – in any population of organisms there will be some differences 2. over-production – many organisms produce more offspring than necessary 3. struggle for existence – there is competition for survival and resources between the organisms 4. survival - those with helpful characteristics are more likely to survive to breed 5. useful characteristics inherited by the offspring 6. gradual change of the species over a period of time as useful characteristics are passed to offspring. 23 May 2017 A Massawe Charles Darwin theory of evolution • The theory is supported by evidence from 1. fossils 2. rapid changes that can be seen to occur in microorganisms such as antibiotic-resistant bacteria – MRSA 3. DNA - scientists can now examine the DNA from different species of organism and use the data produced to see how closely related the two species are to each other. 23 May 2017 A Massawe Genes and inheritance • The cell’s nucleus • Alleles are different contains chromosomes forms of a gene. made from long DNA • Alleles can be molecules. dominant or recessive. • A gene is a short section of DNA. 23 May 2017 A Massawe Genetic diagrams • The alleles in the organism are the genotype. What the organism looks like, e.g. red flower is the phenotype. • Offspring with two alleles the same are homozygous e.g FF or ff. • If the alleles are different e.g Ff then it is heterozygous. 23 May 2017 A Massawe Genetic diagrams • F = red flower (dominant), f = white flower(recessive) 23 May 2017 A Massawe Punnett Squares Ff parental genotype: possible gametes: possible combination of allele in offspring x F or f Ff F or f F f F FF Ff f Ff ff probability of getting white flower 1 in 4 percentage of getting white flower 25% chance 23 May 2017 A Massawe Cystic fibrosis • Cystic fibrosis (CF) is caused by two copies of recessive allele. • People with CF produce abnormally thick and sticky mucus in their lungs and airways. • As a result, they are more likely to get respiratory infections. • Daily physiotherapy helps to relieve congestion, while antibiotics can fight infection. 23 May 2017 A Massawe Sickle cell disease • Sickle cell disease is a caused by two copies recessive genes. • The red blood cells of sufferers are misshapen and can stick together which can block blood vessels. • Sickle cell disease sufferers can become very tired and quickly get out of breath. 23 May 2017 A Massawe Blood glucose control • Homeostasis is maintaining constant internal environment i.e. blood glucose, core body temperature and water Glucose rises (eat food) Normal blood glucose level. Glucose falls 23 May 2017 (exercise) Insulin produced by the pancreas causes ______to glucose _______ change to glycogen ______ and stored in the liver. Negative feedback Normal blood glucose level. glucagon _______ released by pancreas. Glucagon convert glycogen from the liver ______ back to glucose A Massawe Thermoregulation – negative feedback • The hypothalamus controls core body temperature HOT hairs lowered sweating vasodilatation COLD hairs raised no sweating 23 May 2017 vasoconstriction A Massawe Hormones • Hormones are chemicals secreted by glands in the body. • Blood transports hormones from the glands to the target organs. Gland ovary ovary pancreas Hormone oestrogen progesterone insulin testes testosterone 23 May 2017 A Massawe Target organs ovaries, uterus uterus liver male reproductive organs Plant hormones • Auxin is a plant hormone produced in the stem tips and roots, which controls the direction of growth • Plant hormones are used in 1. selective weedkillers - kill some plants but not others. 2. rooting powder - makes stem cuttings quickly develop roots. 3. control fruit ripening - some hormones slow the ripening of fruits and others speed it up. 4. seedless fruits – some seedless fruits are produced using plant hormones 23 May 2017 A Massawe Tropisms • A 'tropism' is a growth in response to a stimulus. Response Part of plant Direction of growth to get maximum light for photosynthesis less chance of drying out stem tip negative root tip phototropism positive geotropism negative stem tip geotropism 23 May 2017 Advantage towards gravity away from gravity A Massawe more chance of finding light Tropism Phototropism Geotropism - causes elongation of the tip of the plant on the side of the shoot furthest from the light - tip is bent towards the light/the plant grows in the direction of the light gives maximum light for photosynthesis - carbohydrate/starch produced during photosynthesis with provides energy for growth and metabolism. - causes roots to grow towards gravity into the soil - the plant get anchored to the ground hence maximises 1. water uptake 2. mineral uptake minerals and water are important for photosynthesis. 23 May 2017 A Massawe The nervous system • The nervous system allows the body to respond, through effectors (e.g. muscle contracting to move the arm) to changes in the environment detected by receptors (e.g. ear, eye and skin) touch, pressure, pain 23 May 2017 chemical in food chemical in the air sound and position of the head A Massawe Neurones • Neurones carry information as tiny electrical signals, there are three types of neurones 1. sensory neurones carry signals from receptors to the spinal cord and brain. 2. relay neurones carry messages from one part of the CNS to another. 3. motor neurones carry signals from the CNS to effectors. 23 May 2017 A Massawe Typical Neurones • The axon is surrounded by a fatty layer known as the myelin sheath • This helps to insulate and speeds up signals in the axon. 23 May 2017 A Massawe Synapses • Where two neurones meet 1. An electrical impulse travels along an axon. 2. neuron releases chemical messengers called neurotransmitters. 3. These chemicals diffuse across the synapse (the gap) 4. The receptor molecules on the second neuron bind only to the specific chemicals released from the first neuron. This stimulates the second neuron to transmit the electrical impulse 23 May 2017 A Massawe Reflex actions 1. receptor detects a stimulus - change in the environment 2. sensory neurone sends signal to relay neurone 3. motor neurone sends signal to effector 4. effector produces a response 2 23 May 2017 3 A Massawe 1 4 Groups of drugs • Drugs can affect nerves impulses, reaction times and behaviour. 1. Stimulants e.g. tea and coffee. They increase the transmission of signals from one nerve cell to the next, which then increases alertness, heart rate and breathing rate. 2. Sedatives e.g. alcohol slow down the nervous system and reactions. 3. Hallucinogens e.g. LSD changes our response to what we see, feel and hear. 4. Painkillers e.g. paracetamol and morphine. They block nerve impulses from the painful part of the body, or block nerve impulses travelling to the part of the brain responsible for perceiving pain. 23 May 2017 A Massawe Groups of drugs • Why is it difficult to give up cigarettes? • Cigarettes contains nicotine which is addictive • It is difficult to give up because the body needs a constant 'top-up' to maintain the effect as the receptor sites in the brain become more used to the nicotine • smoking more means an increased exposure to tar, which is a carcinogen (chemicals cause cancer). 23 May 2017 A Massawe Transmission of pathogens 1. Direct contact i.e. kissing(cold sore), touching(chicken pox) and sexual intercourse(HIV, gonorrhoea) I. Vertical transmission - when pathogens pass from a mother to her unborn baby through the placenta, e.g. measles, HIV. II. Horizontal transmission - when pathogens pass from one person to another by touching, kissing or sexual intercourse. 2. Indirect contact i.e. droplets in air(TB, flu, cold), water (cholera), food(salmonella, food poisoning) 23 May 2017 A Massawe Body defences Physical barriers 1. skin - protecting against microbe infection and dehydration. 2. nasal hairs, mucus and cilia - Nasal hairs keep out dust and larger microbes. - Sticky mucus traps dust and microbes, which are then carried away by cilia 23 May 2017 Chemical barriers 1. hydrochloric acid in stomach kills microbes. 2. tears, saliva and mucus - contain an enzyme called lysozyme which destroys microbes. A Massawe How do plant defend themselves? • Plants produce antibacterial chemicals that kill microbes by breaking their cell wall. Mint - has chemicals that kill bacteria. It is used in toothpaste because of its fresh taste. Witch hazel can be used to prevent an infection getting in through the skin. 23 May 2017 A Massawe Antibiotic resistance 1. Mutations occur in the genes of individual bacterial cells 2. Some mutations protect the bacterial cell from the effects of the antibiotic. 3. Bacteria without the mutation die or cannot reproduce with the antibiotic present 4. The resistant bacteria are able to reproduce with less competition from normal bacterial strains. 23 May 2017 A Massawe Interdependence • Food chains show the feeding relationships in a habitat. Food chains always start with producers. oak tree → caterpillar → blue tit → sparrowhawk • Pyramids of biomass are charts that show the mass of living organisms at each step in a food chain. 23 May 2017 A Massawe Pyramid Of Numbers And Biomass 23 May 2017 A Massawe Interdependence • Consumers eat plants or animals, or both. • A food chain can be used to rank different types of consumers seaweed limpet producer primary consumer crayfish secondary consumer human tertiary consumer • producers – make their own food; • primary consumers – eat producers; • secondary consumers – eat primary consumers; • tertiary consumers – eat secondary consumers. 23 May 2017 A Massawe Parasitism • Parasitism - relationship between two species of plants or animals in which one benefits at the expense of the other, e.g. tapeworms live in gut to absorb food mistletoe - their roots absorb nutrients and minerals from host tree. 23 May 2017 A Massawe How are tapeworms adapted? 1. Hooks and suckes – to attach it to the intestine 2. Flat body – large surface area for food absorption 3. Each segment has male and female reproductive organs – so it can fertilise its eggs if others are not nearby 4. Surface contain substance – protect it from digestive enzymes. 23 May 2017 A Massawe Mutualism • Mutualism relationship between organisms of two different species in which each is benefited, e.g. Bees eat nectar from flower and spread pollen. The rhinoceros' relief of its ticks and the birds feed 23 May 2017 The bird gets a meal and the crocodile gets a valuable tooth cleaning: they both benefit A Massawe Air pollution • The most common source of air pollution is the combustion of fossil fuels. Pollutant Typical effect deposits soot on buildings and trees, causing them damage. smoke Permeates the air, making it difficult for living creatures to breathe. carbon monoxide poisonous gas greenhouse gas that contributes to carbon dioxide global warming sulfur dioxide contributes to acid rain 23 May 2017 A Massawe Indicators of air pollution • Lichens are natural indicators of air pollution. • Air pollutants (sulfur dioxide) dissolved in rainwater damage lichens and prevent them from growing. • In places where no lichens are growing, it's often a sign that the air is heavily polluted with sulfur dioxide. 23 May 2017 A Massawe Indicators of water pollution • Nitrate fertilisers, pesticides(used by farmers to kill weeds) may be washed or blown into rivers. Sulfur dioxide in the air can dissolve in water to form an acidic solution fresh water shrimp indicator clean water Bloodworm indicate polluted water 23 May 2017 A Massawe Eutrophication 23 May 2017 A Massawe The Carbon Cycle 1 combustion Decomposers 2 respiration e.g. bacteria waste material Carbon dioxide in air 3 respiration 7 death Fossil fuel 6 feeding 23 May 2017 Plants 4 photosynthesis 5 respiration A Massawe The Nitrogen Cycle death & excretion feeding proteins & nitrogen fixing urea by root nodule bacteria nitrogen gas decomposers in the air , bacteria in lightning & soil breakdown by nitrogen fixing denitrifying by soil bacteria ammonia bacteria absorption by the roots 23 May 2017 nitrates in the soil A Massawe oxidation by nitrifying bacteria Revision tips • Make your own revision cards • Learn ALL keywords, make use you understand them • Ask if in doubts • Use your revision guide & BBC Bitesize. 23 May 2017 A Massawe