Biology By2 Revision

leechlike Nutrition 21 May 2011 1043 = organisms that ope prise on or in another organism obtaining sustainment at the expense of the force and causing harm.Gut parasite (Taenia solium) = tapeworm Primary host = human (eat uncooked infected pork) Secondary host = pig (drainage carry contaminated by human faeces) Adaptations Suckers & hookers (attachment) Body covering (immune responses) Thick epidermis (inhibitory substances = enzymes) Simple body systems (reproduction) Very thin & crowing fold firmament ( feed absorbed over whole body surface = scattering) potent & pistillate person sex organs ( wild sweet pea roll in the hay only accommodate 1 tapeworm) repress of eggs produced ( affix prognosis of survival) Eggs have resistant shells ( outlast until eaten) Dormant embryos shag form cysts in organs damage surrounding tissue BY2 revise rascal 1 Adaptions to different diets 21 May 2011 1053 Reptiles & Amphibians = s wallow food whole Mammals = cut up and c hew (palate separates nasal b unrivaled fossa & mouth kept in mouth longer) Carnivore = short gut (easily run protein) Herbivore = long gut (plant digestion difficult)Dentition Mechanical digestion = easier to swallow & increases surface part for enzyme action Herbivore Incisors Canines Lower jaw, cuts against horny pad (upper jaw) Indistinguishable from incisors Carnivore precipitant (tear flesh from bone) Large, curved, pointed = seizing prey, killing & tearing flesh Carnassial (slide erstwhile(prenominal) each other = garden shears) molars = cutting/crushing) Vertical (open wide to take hold of & kill prey) Not horizontal (dislocation) Jaw muscles = well developed/ right (grip firmly on prey/crush bones) Cheek teeth Interlock. (W into M) pinched set ashore = sharp enamel ridges (efficiency). Open roots (grinding) Jaw search man Other Circular grinding.Horizontal plane Diastema = gap between front & side teeth. Tongue moves cut grass to grinding surfaces (cheek teeth) R uminants Produce about protein eaten by humans eg. Cows/sheep Mutualism/Symbiosis = close junction between members of 2 species, both derive some benefit from the relationship. Cant digest cellulose (no cellulose enzymes) Cellulose-digesting bacterium live in gut of cow Separated = food left long enough for digestion, bacteria isolated ( optimal pH & conditions) Cellulose digestion unwrap chopped (teeth), saliva, cud form, swallowed 1st potbelly = cellulose digesting bacteria (glucose = fermented thorough acids into farm animal. molder = co2 & methane Cud into next region, regurgitated & chewed again 3rd stomach = water system absorption 4th stomach (normal stomach) = protein digestion Small catgut = absorption first stomach = greater variety of mutualistic organisms than in caecum More efficient = more than complete breakdown of cellulose Bacteria = source of protein when dead BY2 adjustment pageboy 2 Digestion 21 May 2011 1135 = the break down of giving inso luble molecules into miserableer soluble molecules. Physical & chemical. Food passes through alimentary canal where it is digested & absorbed into the body. Digestive enzymes = hydrolases (catalyse hydrolysis of substrate addition of water) Carbohydrates (polysaccharides) disaccharides monosaccharides (Amylase = malt sugar glucose) Proteins polypeptides dipeptides amino-acids ( proteinase = endo/exo) Fats fatty acids & glycerol (lipase) Mouth (buccal cavity) Mechanical digestion (teeth) Saliva = salivary lands (mucus, salivary amylase & mineral ions = optimum pH slightly alkaline) = lubrication & some protein digestion (amylase = starch maltose) Swallowed as bolus Oesophagus Peristaltic contractions (longitudinal & circular muscles = not under conscious control) Occurs all trend through alimentary canal Stomach = muscular sac (2 anatomical sphincter muscles = cardiac & pyloric keep food in stomach) Muscles in stomach wall contract rhythmically (mix food with gastr ic juice = secreted by stomach wall) Gastric juice = optimum pH of enzymes (pH2. 0), kills most bacteria, peptidase enzymes = protein polypeptides Pepsinogen ( unoccupied) = activated by HCl to active peptidase enzyme Mucus = form line drive (protect wall from enzymes & acid/assist try) Food leaves as chyme Purpose of HCl = optimum pH for enzymes, kill microbes, activate pepsinogen (pepsin) Gastric glands = peptic/chief cells (pepsinogen = inactive until HCl), oxyntic (secretes HCl) & goblet cells (mucus) Small Intestine = duodenum (first 20cm) & ileum Bile = produced in liver, stored in novelty bladder, into duodenum via bile duct. = no enzymes.Bile salts = emulsifying lipids (lowers surface tension = globules droplets surface area) = neutralise sullenness = exocrine glands in Pancreas via Pancreatic duct. = Contains enzymes. Trypsinogen Trypsin (Enterokinase) = Endopeptidases (protein peptides) Pancreatic Amylase (starch maltose) Pancreatic Lipase (lipids fatty acids & glycerol) Pancreatic juice Walls of duodenum = Brunners Glands (secrete alkaline juice & mucus) correct pH & lubrication/protection Enzymes secreted by cells at tips of villi (Crypts of Lieberkuhn) Maltase = Maltose 2 Glucose Sucrase = sucrose glucose & galactose Endopeptidases/Exopeptidases = polypeptides amino acids Endo = fourth/tertiary smaller polypeptides. Exo = peptides amino acids compactness Ileum adapted Long BY2 revision Page 3 Long Lining folded = large surface area Villi = finger like projections Epithelial cells = surface of villi (microscopic projections microvilli) Large number of mitochondria = loads of energy required Glucose & Amino-acids = epithelium of villi (diffusion & active transport) into capillary network hepatic portal vein to liver Fatty acids & Glycerol = lacteal (blindly destruction lymph capillary) lymphatic system into blood stream (thoracic duct) Fatty acids, Glycerol & most vitamins = diffusion through epithelial cell membrane Gl ucose, Amino acids & dipeptides = need adenosine triphosphate (energy) co-transport (Na+ ion) Dipeptides digested intracellularly-pump ions out and then draws more in carries molecules in with it.Large intestine Caecum, Appendix, Colon & Rectum Water & mineral salts absorbed in colon vitamins secreted by micro-organisms (vitamin K & folic acid (Vitamin B9) Faeces = semi-solid condition (undigested cellulose, bacteria, sloughed cells) defaecation Uses Soluble food products bloodstream tissues (assimilation/provide energy) Glucose = energy release (respiration)/excess stored (fat cells) Amino Acids = protein-synthesis. Cannot be stored (deaminated carbamide disposed & carbs stored) Lipids = membranes/hormones/excess stored as fat BY2 revision Page 4 Structure of the gut 24 May 2011 0852 Peristalsis = support movement of food through alimentary canal 1) 2) 3) 4) Ingestion Digestion (mechanical = increase surface area/chemical = enzymes, glands in wall/ outdoor(a) wall) Ab sorption EgestionStructure of Mammalian Gut Outer serosa = mold of connective tissue (protection/reduces friction from other organs as it moves) Muscle layer = inner circular/outer longitudinal muscles = peristalsis Sub-mucosa = connective tissue, contains blood/lymph vessels absorption & nerves (co-ordinate muscular contractions peristalsis) Mucosa = innermost layer (lines wall of gut), secretes mucus (lubrication & protection), secretes digestive juices in some regions (stomach)/absorbs food (ileum) Lumen = cavity of gut BY2 revision Page 5 Glands 1) Large glands outside gut secretions pass through tubes/ducts into lumen Eg. Salivary gland, liver, pancreas 2) Glands in form of cells in sub-mucosa Eg.Secrete mucus in duodenum (Brunners glands alkaline juices also) 3) Glands in form of cells in mucosa Eg. Gastric glands(stomach) = gastric juice Crypts of lieberkuhn(in base of villus of small intestine) = enzymes (complete digestion) maltase = maltose Sucrase = sucrose E ndopeptidase/exopeptidase = peptides/dipeptides BY2 revision Page 6 Adaptions for nutrition 24 May 2011 0937 Nutrition = obtain energy to maintain purport functions and matter to create/maintain structure (from nutrients) Autotrophic plants Use open organic materials CO2 & H2O to manufacture energy & take up interlocking compounds (make own food) provide food for others = producers Green plants build up difficult organic molecules eg sugars from CO2 & H2O.Source of energy = sunlight (absorbed in chlorophyll & related pigments) 6CO2 +6H2O C6H12O6 + 6O2 Use energy from special methods of respiration to synthesize organic food Consume complex organic food material (cannot make own food) = consumers. Take food into bodies and break down by digestion. unremarkably natural in digestive system. Digested material absorbed (body tissues used by cells) Herbivores/Carnivores/Detritivores Dead/decaying matter no specialize digestive system. Secrete enzymes outside body & absorb. (e xtracellular digestion). Microscopic = decomposers (important cycle valuable nutrients nitrogen) PhotosynthesisPlants/algae/ certain bacteria Autotrophic bacteria Animals, fungi, some protoctists & bacteria Most animals Chemosynthesis Heterotrophic holozoic feeders Saprophytes (saprobionts) Parasites Mutualism (symbiosis) Fungi & some bacteria Tapeworm Organism that live in/on another organism and receive nutrition from it. array suffers harm. Highly specialized. Cellulose Involves close association between members of2 different species. digesting bacteria both derive some benefit from the relationship BY2 revision Page 7 Reproductive Strategies 24 May 2011 1008 Life cycle = chronological sequence of changes through which it passes during its life from origin in reproduction until death. Reproduction = readiness to produce other individuals of the same species agamous Rapidly produces large numbers racket (identical genetic composition = clone) Binary fission (eg. Unice llular organisms bacteria/amoeba) develop (eg. Hydra/yeast) Bulbs (eg. Onion/daffodil) Runners (eg. Strawberry) Tubers (eg. Potato) informal Involves 2 parents Less rapid than fissiparous Offspring are genetically different Fusion of haploid gametes Advantages/Disadvantages Asexual = lack of variety (adapting to environmental change) = if well suited to environment conditions, large numbers of triumphful type built up quickly Sexual = genetic variety (adapt to environmental change) = development of resistant stage in life cycle (can contain adverse conditions) = formation of spores, seeds, larvae = dispersal of offspring.Reduces intraspecies competition enables genetic variety to develop as required. = more see of mutation (complexity of process) Production of Gametes Diploid = body cells (mitosis) haploid = sex cells/gametes (meiosis) Haploid Sperm + Haploid Egg = Diploid Fertilized Egg Zygote formed mitosis to grow Male gamete = small& extremely motile Female game te = large/sedentary (presence of stored food) Mammalian eggs have only enough to survive until formation of placenta External Fertilization Discharge gametes directly into sea/fresh water Considerable wastage = eggs may not encounter sperm Brobdingnagian numbers of gametes produced Frogs joining of sperm/egg assisted by coupling.Male rubs hind legs on egg-producing(prenominal) for her to lay eggs, he immediately releases seminal fluid over them. Amphibians usually sublunary, must return to water to caudex = external fertilization Internal Fertilization Occurs inside body of female Requires intermittent organ to introduce sperm to females body Less hap of gametes being wasted BY2 revision Page 8 Less chance of gametes being wasted Allows male gamete to be independent of water for movement Fertilized egg can be enclosed with protective covering onward leaving female. (Animals lay eggs) Embryos develop within parent and derive nourishment from her (placenta) = greates t adaption (mammals)Development of Zygote Usually outside body swooning prey for predators Many eggs produced to ensure some survive Insects, internal fertilization (ensure sperm deposited in females reproductive tract), external development (laid on food source) Evolution of amniote egg (reptiles/birds) = fluid filled cavity, surrounded by membrane & protective shell, encloses embryo within yolk sac Birds shroud eggs = embryo development (external) Mammals = young retained in mothers uterus/uterus (no shell). Embryo nourished from mothers blood supply (placenta). Born in relatively advanced state of development. Parental Care Very pocketable usually Stickleback looks after eggs, defends territory, fans eggs to provide o2 until they hatch Birds & mammals = formulation of shelter, feeding, protection from predators, training for adult life. More parental care provided = less offspring produced Unisexual/Hermaphrodite Plants = male and female gametes produced in one in dividual Every individual capable of forming fertilized eggs Possibility of self-fertilization = inbreeding (reduced genetic variability) No intromittent organs special techniques evolved for transferring gametes Success of Insects Mainly terrestrial Depend on these to pollinate crops Competition for food also give disease eg. Malaria Incomplete Metamorphosis (eg. Grasshopper) Egg Intermediate form = nymph (resembles adult smaller) Hard exoskeleton doesnt grow, must shed skin/molt Does this a series of times until it make ites full size Complete metamorphosis (eg. comminute/housefly) Egg Lava (specialized for feeding/growing) Pupa/chrysalis complete change Emerges as adult specialized for dispersal and reproduction Plants Simple plants = algae (seaweeds = confined to sea) & mosses & ferns (confined to damp areas -male gamete can swim to egg) Successful plants = conifers & head for the hillsering plants (independent of water for reproduction able to colonize land) Flowering plants = morphology (Efficient water carrying xylem vessels & reproduction) Male pollen grains with hard cake = withstand desiccation (transfer to stigma of female affect by environmental conditions) Plants & grasses = small inconspicuous melt downers pollen carried by wind Brightly coloured flowers & cause to be perceived = attachment by insects (carry pollen to stigma) BY2 revision Page 9 Brightly coloured flowers & scent = attraction by insects (carry pollen to stigma) Male gametes travel through pollen tube to female part and egg (no longer needs film of water to reach egg) Fertilised egg develops into seed containing food store (with resistant coat) Key to success = relationship with animals (attract insects which pollinate/seed dispersal) & enclosure of eggs in ovary and ontogeny of seed Can survive adverse conditions Flowering plants are so successful because of Short interval between flower production and cathode-ray oscilloscope of seed (few wee ks) Seed with food store = embryo develops until leaves are produced preceding(prenominal) ground (photosynthesis) Seed protects embryo from desiccation & other hazards = resistant coat Leaves deciduous & succulent = decay when fall to ground humus produced. (rapid recycling of ions for reuse) BY2 revision Page 10 Translocation 24 May 2011 1441 = transport of soluble organic materials, sucrose and amino acids (bi-directional movement) Products of photosynthesis = bast.From source (area that makes the photosynthate sucrose = leaves) to sink (where needed for growth/storage) bast structure Sieve tubes (adapted for longitudinal flow of material = no nucleus ,have pores =sieve plates allows rapid flow of manufactured food substances) Companion cells (linked to sieve tubes by plasmodesmata with fibres & parenchyma, dense cytoplasm = lots of mitochondria lots of metabolic activity, large nucleus controls activity) Phloem fibres Phloem parenchyma Mass flow hypothesis There is a passive flow of sucrose from source to sink Does not account for observations such as movement in opposite directions at same time & rate Other hypotheses = diffusion, cytoplasmic streaming Evidence for translocation 1) Aphid (greenfly) Feed (proboscis), leave insert proboscis, liquid = sucrose & amino acids. Sectioning stem shows proboscis is in phloem sieve tube 2) Ringing Experiments Cut off ring of mouth (including phloem, leave xylem), immerse in water. Swelling above cut = collection of organic solutes, cannot continue. Will eventually die 3) Radioactive isotopes Carbon-14 supplied to plant set in glucose upon photosynthesis (14C6H12O6) Stem cut, x-ray = phloem contains radioactivity BY2 revision Page 11