Module 4 Revision

Classification and evolution Taxonomic groups = hierarchial groups in classification Kingdom, Phylum, Class. Order, Family, Genus, Species Recently, scientists have added another kingdom and 3 domains Why use it? identify species predict characteristics find evolutionary links Binomical nomenclature --> Genus species (Canis familiaris) Five kingdoms Prokaryotae --> bacteria unicellular  no nucleus or membrane-bound organelles circular DNA no visible feeding mechanism Protoctista --> amoeba mostly unicellular nucleus and membrane-bound organelles are present some have chloroplasts some have cilia or flagella Fungi --> mushrooms, moulds or yeast unicellular or multicellular nucleus and membrane-bound organelles are present cell wall = chitin no chloroplasts nutrients acquired from dead or decaying material Plantae  multicellular nucleus, membrane-bound organelles and chloroplasts present gametes move with cilia or flagella autotrophic feeders cell wall = cellulose food stored as starch Animalia  multicellular nucleus and membrane-bound organelles present no chloroplasts or cell walls hetereotrophic feeders food stored as glycogen Evolutionary relationships as they become different their DNA changes so their proteins and sequence of amino acids also change The 3 domains Based on differences in the sequence of nucleotides in rRNA and the cell membrane lipid structures  and sensitivity to antibiotics Eukarya 80S ribosomes RNA polymerase has 12 proteins Archaea 70S ribosomes RNA polymerase has 8-10 proteins Bacteria 70S ribosomes RNA polymerase has 5 proteins Under this system, the Prokaryotae kindgom is split into Archaebacteria and Eubacteria Archaebacteria "ancient" bacteria live in extremes like thermal vents Eubacteria "true" bacteria found in all environments Phylogeny = evolutionary relationships between organisms Phylogenetic trees show the relationships with branches from the common ancestor relies on physical characteristics and genetic makeup can be done without reference to classification continuous tree --> no groups means there's no species that there's debate over where they belong  Evidence for evolution Palaentology --> study of fossils bacteria in the oldest rocks and invertebrates and vertebrates in the more recent ones which supports evolution because there's time between the lesser and more complex organisms sequence in which organisms are found matches with ecological links (plants older than animals) similarities in anatomy of fossils shows how closely related organisms  evolved from common ancestor BUT fossil record isn't complete Comparative anatomy --> similarities and differences in the anatomy of organisms used because the fossil record isn't complete homologous structure = structure that appears superficially different in different organisms or has a different function provides evidence for divergent evolution (species have evolved from a common ancestor into different forms) Comparative biochemistry --> similarities and differences in the proteins and other essential molecules some molecules are highly conserved so changes can show evolutionary links mostly study cytochrome c (protein in respiration) or rRNA neutral evolution = most of the variability of the molecule occurs outside of its functional region so accumulation isn't affected by natural selection therefore changes to these regions can show how close two species are the number of differences between a molecule is plotted against the rate at which the molecule undergoes neutral base pair substitutions so a point can be estimated where they last shared a common ancestor rRNA is used because it has a slow rate of substitution  Variation interspecific variation = variation between members of different species intraspecific variation = variation between members of the same species causes = genetic or environmental Genetic variation alleles  mutations meiosis -->...

Biodiversity Importance = essential for maintaining a balanced ecosystem for all organisms --> they provide food, oxygen and other materials for us to survive Measuring a baseline for the biodiversity of an area means you can work out how much of an effect a change has had/ will have on the area Habitat biodiversity = number of different habitats found within an area each habitat will have different numbers of different species so the higher the habitat diversity the higher the biodiversity Species biodiversity has two compononents: ​​​​​​​species richness --> number of different species living in a particular area species evenness --> comparison of the number of individuals of each species in a community overall species diversity can be different even if it has the same number of species, it also depends on the evenness Genetic biodiversity = variety of genes that make up a species many of the genes are the same for all individuals in the species but alleles do exist and they cause the genetic variation within and between species genetic biodiversity can result in different characteristics being exhibited (dogs can be big or small, round or pointy eared)  greater genetic biodiversity within a species allows for better adaptation to a changing environment Sampling = taking measurements of a limited number of individual organisms within a particular area Used to estimate the number of organisms in an area aka the abundance of the organisms Also used to measure a particular characteristic of an organism (average height of crop) Random sampling = selecting individuals by chance each population has equal chance of being recorded mark out a grid on the grass using tape measures use random numbers to determine coordinates take a sample from each randomly generated coordinte pair Non-random sampling = sample is not chosen at random opportunistic --> weakest form of sampling as it is not representative of the whole population (uses organisms that are conveniently available) stratified --> some population can be divided into sub-groups based on a particular characteristic, a random sample is then taken from each of the groups proportional to its size systematic --> areas are identified within a habitat that are then sampled separately --> usually with line (line along the ground and take samples from specified points) or belt transect (two parallel lines marked and samples taken in the area between them) Reliability Sample is never entirely representative because: sampling bias --> may be by accident or deliberate (you choose an area because you know it'll give you good numbers for certain species) chance --> the organisms selected may not be representative of the whole population --> can never be removed but its effects can be minimised with large sample sizes  Sampling animals pooter to catch insects sweep nets to catch insects in long grass pitfall traps for small invertebrates tree beating for invertebrates that live in trees or bushes (shake it over a white cloth to catch them) kick sampling for organisms in a river (the riverbed is "kicked" for a while before to disturb the substrate then a net catches anything that's disturbed downstream) Estimating animal population size capture-mark-release-recapture technique capture as many as you can mark them all and then release them time is allowed for the organisms to redistribute themselves repeat the capture process and compare the numbers that are new or recaptured the greater the marked individuals recaptured the smaller the population size Sampling plants point quadrat --> frame with a horizontal bar, at set intervals a pin is pushed through to the soil and each plant that touches the pin is recorded frame quadrat --> sqaure frame divided into a grid, the type and number of species and individuals within each section is recorded used to measure: density --> if plants can be seen clearly, counting how many...

Communicable diseases Types of pathogen bacteria prokaryotes classified by shape: rod = bacilli spherical = cocci comma shaped = vibrios spiralled = spirilla corkscrew = spirochaetes classified by cell walls and how they appear after gram staining: gram positive bacteria = purple-blue under light microscope --> MRSA gram negative bacteria = red under light microscope --> E.coli useful because it effects how they react to antibiotics viruses non-living infectious agents some genetic material surrounded by protein they invade living cells, hijack the biochemistry and make more virsuses reproduce rapidly and evolve by developing adaptations to their host there are even ones that attack bacteria called bacteriophages considered ultimate parasites proctoctista (protista) eukaryotic microorganisms with various feeding methods percentage act as pathogens for both plants and animals --> parasitic many need a vector to transfer them or they may enter the body through contaminated water fungi cause more devastation in plants eukaroyitc organisms but the ones that effect humans tend to be single-celled some are parasitic and feed on living plants and animals normally stop plants from photosynthesising Modes of action damaging the host tissues directly viruses take over cell metabolism --> make host cell create loads of copies of them then they burst out which destroys the cell some protoctista take over cells but don't take over genetic material they just digest the cell's contents when they reproduce fungi digest living cells and destroy them  producing toxins most bacteria produce toxins that poison or damage host cells --> breakdown the membranes, inactivate enzymes or interfere with genetic material some fungi produce toxins Plant diseases ring rot effects tomatoes, potatoes and aubergines caused by gram positive bacteria damages leaves, tubers and fruit tobacco mosaic virus effects tobacco plants, tomatoes, peppers and cucumbers caused by virus damages leaves, flowers and fruit  potato blight effects potatoes and tomatoes caused by protoctist  destroys leaves, tubers and fruit no cure black sigatoka effects bananas caused by fungus penetrates and digests cells can cause 50% reduction in yield no cure Animal diseases tuberculosis bacterial disease damages lung tissue and suppresses immune system both curable and preventable in humans bacterial meningitis  bacterial infection of meninges of the brain which can spread to the rest of the body mainly effects young children and teenagers antibiotics cure it if given early enough vaccines prevent it HIV/AIDS acquired immunodeficiency syndrome caused by human immunodeficiency virus HIV targets T cells in immune system gradually destroys immune system so people infected are open to other diseases (TB or pneumonia)  HIV = retrovirus so infects the host cell, uses reverse transcriptase to make DNA from its own RNA which interacts with the host's DNA passed through bodily fluids  no vaccine and no cure anti-retroviral drugs slow the process Influenza viral infection of ciliated epithelial cells in the gas exchange system (kills them which opens the airways to secondary infection) three main strains - A, B & C strain A are the most virulent and classified further by proteins on their surfaces mutate regularly  vaccines available every year with the predicted variations no cure Malaria protoctista spread by bites of mosquitoes female mosquitoes bite for blood to get protein before she lays her eggs the protoctista invades the red blood cells, liver and brain the disease recurs making them weak and vulnerable no vaccine and limited cures need to control the vector / mosquitoes Ring worm fungus affecting mammals not damaging, just looks unsightly and is itchy antifungal creams clear it Athlete's foot human fungal disease form of ring worm that digests the skin between the toes antifungal creams cure it Transmission of pathogens between...