biology

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microscopy

  • metre - m - 1, decimetre - dm - 0.1, centimetre - cm - 0.01, millimetre - mm - 0.001, micrometre - um - 0.000001, nanometre - nm - 0.00000001
  • magnification how much bigger image is than actual object = image / actual
  • resolution is how well you can distinguish between two close points
  • light microscope: resolution 0.2 um, max. magnification - x1500
  • TEM: resolution 0.0005 um, max magnification x500,000
  • SEM: resolution 0.0005 um, max maginifaction x100,000
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cell organisation

  • prokaryotic: small, no nucleus, cell wall - polysaccharide, few organelles, 70S ribosomes
  • eukaryotes: larger, nucleus, cell wall - cellulose in plants, chitin fungi, many organelles
  • cells adapted for particular functions
  • similar cells organised into groups = tissues
  • tissues organised into organs = groups of tissues working together to perform a particular function
  • animal cell: membrane, nucleus, nucleolus, nuclear envelope, nuclear pores, cytoplasm, DNA, mitochondria, rough ER, smooth ER, 80S ribosomes, golgi body, lysosomes, centrioles, cilia, flagella, microtubules, microfilaments
  • plant cell: cellulose wall, membrane, nucleus, nucleolus, nuclear envelope, nuclear pores, cytoplasm, plasmodesmata, DNA, mitochondria, chloroplast, starch grain, rough ER, smooth ER, 80S ribosomes, golgi body, lysosomes, tononplast, permanent vacuole, microtubules, microfillaments
  • prokaryotic: peptigoglycogen wall, membrane, cytoplasm, DNA 70S ribosomes, flagella
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organelles

  • nucleus - genetic information, cell activites
  • nucleolus - assembles ribosomes
  • envelope - keeps cytoplasm and DNA seperate
  • rough ER - synthesises proteins
  • smooth ER - synthesises lipids
  • golgi - modifies proteins and lipids for ER, sends them to ribosomes
  • ribosomes - assemble amino acids to proteins
  • mitochondria - site of respiration
  • lysosomes - break down waste and cell debris
  • chloroplast - photosynthesis, chlorophyll captures sunlight, stores energy
  • plasma membrane - phospholipids, controls substances in and out
  • centrioles - organise cell
  • flagella - propulsion and movement
  • cilia - epithelial cells, trap particles
  • microtubules - structure and transport
  • microfilaments - cell cytoskeleton
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cell surface membrane

  • fluid mosaic model, phopholipid bilayer
  • phospholipid has glycerol head = hydrophillic, fatty acid tail = hydrophobic
  • cholesterol = steriod - stability
  • carrier protein = active transport, facilitated diffusion - water soluble and charged particles
  • glycoprotein and glycolipid = cell signalling and recognition
  • channel protein = facilitated diffusion, special shape - ions and water solubles molecules
  • facilitated diffusion = large, water soluble charged carried down concentration gradient
  • diffusion = lipid soluble substances - pass through bilayer down concentration gradient
  • active transport = against concentration gradient using ATP - water soluble substances
  • osmosis = high water potential to low - straight through bilayer
  • hydrogen bonds between proteins and heads strengthen
  • high temp. boost kinetic energy of component molecules - more pemeable, high temps denature proteins, membrane destroyed
  • factors: diffusion distance, surface area, concentration gradient, temperature
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water potential

  • molecules move from high to low
  • highest is 0 lowest negative number
  • water potential inside cell = outside cell - isotonic
  • turgid = water into plant cells
  • plasmolysed = water out of plant cells
  • haemolysed = water into animal cells
  • crenated = water out of animal cells
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membrane function

  • divide up cell so each component can perform job efficiently
  • large surface areas for organelles to work
  • form vesicles to transport substances
  • allow cell recognition
  • receptors for horomones
  • barrier to unwanted substances
  • pemeable to small molecules - water and oxygen
  • selectively permeable to large molecules and ions
  • endocytosis = substances taken in, phago = large, phino = small
  • exocytosis = substances sent out, proteins ribosomes to ER to golgi to vesicles 
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mitosis

  • asexual reproduction
  • daughter cells identical to parent - growth and repair
  • G1 - cell growth, new organelles and proteins
  • S - DNA replication
  • G2 - cell grows, proteins for division made
  • prophase - chromosomes condense, centrioles to opposite ends, spindle fibres across
  • metaphase - chromosomesline up along equator - spindle fibres attach to centromere
  • anaphase - centromeres divide, sister chromatids to oppsite ends
  • telophase - chromatids uncoil, new nuclear membrane
  • cytokinesis - new cell wall and membrane, animals membrane pinches = cleavage furrows, plants cell wall growth plates
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meiosis

  • haploid number = 23 - gametes
  • diploid number = 46 - all other cells
  • gamete = sex cell, sperm males, ova female
  • diploid to haploid
  • DNA replicates
  • sister chromosomes pair
  • swapping of DNA
  • nucleus divides into two new cells
  • two cells divide to form four cells each with haploid number
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stem cells

  • unspecialised cells - can divide by mitosis and differentiate
  • embryonic = pleuripotent - specialise into any cell, from blastocysts 5 days old
  • adult = most tissues, growth and repair, limited differentiation
  • differentiation = changes in cells so they become specialised for particular function
  • changes can be size, shape, type and number of organelles
  • plants: meristems - apical and lateral
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specialised cells

  • ethyrocytes = no nucleus or golgi or mitochondria or rough ER, gain haemoglobin, biconcave disc shape
  • neutrophils = more lysosomes, nucleus elongates and changes shape
  • sperm cell = many mitochondria, acrosome (lysosome) on head, streamlined tail
  • root hair = large protrusion so more surface area
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surface area

  • smaller animals = bigger SA:V - not as much need for transport systems
  • larger animals - some cells deep within body
  • low SA:V ratio
  • high metabollic rate, constantly need oxygen and CO2 to be removed
  • tough impenetrable outer skin
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blood vessels

  • artery: small lumen, thick wall, 3 layers - endothelium: elastic fibres, collagen, smooth muscle - tunica media - tunica externa, no valves, oxygenanted blood, high pressure
  • veins: large lumen, thin wal, same as artery but thinner endothelium, valves present, deoxygenated blood, lvery low pressure
  • capillary:very small lumen, thin wall - single layer endothelial cells, no valves, oxygenated to deoxygenated blood, low pressure
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blood

  • transports: oxygen, carbon dioxide, urea, anitbodies, hormones
  • red blood cell: elastic membrane to squeeze through gap, carries oxygen and CO2
  • white blood cells - phagocytes: engulf pathogens and microoganisms, contain lysosomes, long nucleus - lymphocytes: produce antibodies, large nucleus
  • 45% blood cells and platelets
  • 55% plasma = liquid: 90% water, 10% other - proteins held in suspension, buffer blood, regulate water movement
  • carries erythrocytes, leucocytes and platelets
  • hormones and plasma proteins
  • fats = lipoproteins
  • glucose level = 80 -100mg per 100cm
  • more amino acids and oxygen than tissue fluid and lymph
  • less CO2 than tissue fluid and lymph
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tissue fluid

  • removes CO2 and other waste from cells
  • move out due to pressure diffusion or osmosis
  • blood leaving capilaries more concentrated due to lack of water so water goes back into capilaries
  • leucocytes and phagocytes
  • hormones and proteins
  • no fats, less glucose amino acids and oxygen than blood
  • more CO2 than blood
  • arteries to arterial capileries, very thin walls and high hydrostatic pressure
  • fluid forced through endothelium forms tissue fluid
  • tissue fluid moves back out of blood
  • oedma = tissue fluid not reabsorbed
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lymph

  • reabsorbtion of tissue fluid, re enters capilaries at venule end, lymph = plasma
  • 10% enters lymphatic system which returns to circulatory system
  • valves so lymph flows in one direction very slowly
  • lymph capilaries join to form vessels
  • lymphocyte cells, some proteins
  • more fats and CO2 than blood
  • les glucose, amino acids and oxygen than blood
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haemoglobin

  • oxygen carried in haemoglobin = oxyhaemoglobin - four oxygens each
  • four polypeptide chains, each has haem group, contains iron giving red colour
  • high affinity for oxygen
  • partial pressure = concentration of gases - greater concentration = higher partial pressure
  • oxygen loads where partial pressure high (in lungs), unloads where its low/ decreased (respiring cells)
  • curves: pp high - oxygen easily combines, pp low, harder, s shaped - changes shape of haem easier for other to join, then becomes more saturated = harder
  • carbon dioxide: gives up O2 more readily in higher pp of CO2, respiring cells nedd O2 and produce CO2 so more brought to cells, CO2 diffuses into red blood cells, converted to carbonic acid, dissociates to give hydrogen ions and hydrogencarbonate ions, acidity increases so oxyhaemoglobin dissociates and haemoglobin takes up hydrogen ions, hyrogencarbonate diffuses out of blood cells, transported in plasma, blood reaches lungs where pp CO2 low so hydrogencarbonate and hydrogen ions recombine, diffuses out of alveoli and breathed out
  • bohr shift = high pp CO2 right, lower pp CO2 left= curve to the left
  • fetal: womb - fetus must take O2 from mother blood - higher affinity = left
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heart systems

  • open: inveterbrates, insects - no separation between blood and intersitual fluid
  • closed: vertebrates, blood confined to vessels, one or more heart chambers, large vessels to smaller chambers, material diffuses from blood to tissue fluid
  • double circulation = blood passes through heart twice for one full circulation of the body
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heart structure

  • superior vena cava = right atrium from body
  • pumonary veins = left atrium from lungs
  • inferior vena cava = left atrium from body
  • pulmonary artery = right ventricle to lungs
  • aorta = left ventricle to body
  • coronary artery = heart supply
  • body to right atrium to right ventricle to lungs to left atrium to left ventricle to body
  • atrio ventricular valve = atrium to ventricle
  • semi lunar valve = right ventricle to pulmonary artery
  • tendonous chords = hold valves in place
  • septum = centre muscle of heart
  • apex = base of heart
  • purkyne tissue = conducting tissue in septum
  • collagen = insulting layer atria to ventricles
  • sino artial node = begins contractions
  • atrio ventricular node = generates waves top of purkyne tissue
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heart pressures

  • ventricles relax
  • atria contract - decrease volume, increase pressure - valve opens
  • blood into ventricles, atria relax
  • ventricles contract, less volume higher pressure av valve closes, semi lunar opens
  • blood into pulmonary artery and aorta
  • ventricles and atria relax - more volume, lower pressure, semi lunar valve shuts
  • diastole = relax
  • systole = contract
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heart beat

  • SAN initiates wave of excitation at reugular intervals
  • wave travels over walls of atria - they contract
  • disk of collagen prevents wave passing - pauses
  • AVN allows wave to pass after delay to atria have emptied
  • wave down purkyne tissue to apex, spreads out up and across ventricles
  • contract from bottom up
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PQRST complex

  • P wave = depolarisation of atria
  • PR interval = ventricles filling
  • QRS complex = depolarisation of ventricles - main pumping contraction
  • ST segment = ventricle repolarisation - flat line
  • T wave = ventricle finish repolarisation
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gas exchange

  • inhalation: diaphragm contracts - flat, increases volume of thorax, lower pressure, air moves in, external intercostal muscles contract, ribs raise, increase volume decrease pressure, air in
  • exhalation: diaphragm realxes - domed, decreases voume of thorax, higher pressure, interna intercostal muscles contract, ribs in and down, decrease volume, increase pressure, air forced out
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lungs

  • cartilage = rings of strong fibres - keep trachea open
  • goblet cells = produce muscus to trap dust
  • cilia = waft in syc to move mucus up to throat to be swalled
  • smooth muscle = narrow airways bronchi and bronchioles
  • elastic fibres = stretch lungs during inhalation recoil to expel air
  • pleural membrane = protective lining
  • diaphragm = muscle at bottom
  • alveoli: large number = large surface area, single layer of alveolar epithelium cells, surfactant - stops them sticking together, thin exchange sufrace, short pathway, steep diffusion gradient
  • tidal volume = volume fo air breathed in and out during normal breath
  • vital capacity = volume of air forcefully expelled after one ful inspiration
  • spirometer: movements of air chamber recorded by trace, nose clip worn, maintain constant temperature, medical grade oxygen used, ensure participants are healthy, soda lime used to absorb CO2
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trachea, bronchi, bronchioles

  • trachea and bronchi similar - bronchi narrower
  • thick walls, several layers
  • cartilage = majority of wall, c shaped rings
  • elastic fibres = maintain shape
  • smooth muscle = narrow airways
  • blood vessels = rich blood supply
  • cilia = trap particles
  • goblet cells = produce mucus
  • bronchioles: much narrower - no cartilage, have smooth muscle, elastic fibres, cila and goblet cells
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transpiration

  • loss of water from plants - stomata open for gaseous exchange - evaporates out
  • plants need gases for photosynthesis and respiration
  • factors: temperature, humidity, wind, light
  • potometer: measures water uptake, ruler used, plant healthy, no air bubbles, cut stem at angle and assemble underwater
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xerophytes

  • stomata sunk in pits
  • curled leaved stomata inside
  • epidermis with layer of fine hairs to trap moisture
  • fewer stomata
  • thick waxy cuticle on epidermis
  • leaves as spines to reduce surface area
  • stomata only open at night
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transport in plants

  • xylem = water mineral salts support
  • phloem = dissolved substances
  • root - xylem x phloem in gaps
  • stem - xylem outside, phloem inside
  • leaf - xylem ontop, phloem below
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water transport - xylem

  • adapted to carry water and mineral ions up
  • long tube like structures formed from vessel element cells end to ened
  • no end wlls - uninterupted tube, vessels contain no cytoplasm, free movement
  • walls thickened with lignin - support plants and waterproofs vessel - voume up with age
  • substances can enter and leave via pits in lignin
  • water enters through root hair cells, moves from area of high potential to low
  • high hydrostatic pressure at bottom of xylem, low at top due to water loss
  • creates pressure gradient, water moves down gradient up xylem, under tension
  • cohesion = hydrogen bonding sticks molecules together
  • adhesion = water molecules stick to xylem walls
  • three routes: symplast = cytoplasm, apoplast = cell wall, vacuolar = vacuoles
  • apoplast has least resistance - most used
  • endodermis has casperian ***** so water must enter cytoplasm or vacuole
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translocation - phloem

  • transports solutes - sucrose, transport only not support
  • sieve tube elements: living cells, transport solutes, joined end to end to form sieve tubes, sieve = end with many holes, no nucleus, thin cytoplasm with few organelles, sieve plates connect adjacent cytoplasm
  • companion cells: provides means of survival for sieve tube, very dense and active cytoplasm, carries out functions for both cells
  • both cells formed from single cell during phloem development
  • translocation = movement of organic solutes through plant via phloem
  • sugars - sucrose transported from leaves (source) to growing regions or storage (sink)
  • amino acids - made in root tips from nitrogen, taken to growing regions to make proteins
  • hydrogen ions actively transported out of companion cells into leaf cell
  • electrochemical gradient - H+ iions move back across via cotransporter protein with a sucrose, sucrose concentrations build up in companion cell
  • sucrose diffues into sieve tube element via plasmodesmata
  • lowers water potential in phloem - more water moves in creating high hydrostatic pressure
  • flow downwards to sink sucrose diffuses out, water back into xylem, sucrose to starch
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evidence

  • use of phloem: plant supplied with radioactively labelled CO2, appears in phloem, trees ringed cutting phloem, sugars collect in bulge above, aphid feeding on plant stem used to show the mouth parts are feeding on phloem
  • use of ATP: many mitochondria in companion cells, process stopped by using metabollic poison which inhibits formation of ATP, rate of flow too fast for diffusion alone
  • use of mechanism: pH of companion cells higher than those around them, indicates H+ ions actively pumped out, sucrose concentration higher in source than in sink
  • against: not all solutes move at the same speed, sucrose moved to different areas at same rate, no difference due to concentration, role of sieve plates unclear
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