BIOLOGY AQA AS UNIT 2

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  • Created on: 21-05-14 11:06

CAUSES OF VARIATION

VARIATION - DIFFERENCES THAT EXIST BETWEEN INDIVIDUALS

INTERSPECIFIC - VARIATION BETWEEN DIFFERENT SPECIES

INTRASPECIFIC - VARIATION WITHIN A SPECIES

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INTRASPECIFIC

NO 2 MEMBERS OF A SPECIES ARE EXACTLY A LIKE

CAUSES OF VARIATION in INTRASPECIFIC....

GENETIC FACTOR - all species have same gene, however different versions of gene called ALLELES, alleles make up genotype, genotype determines phenotype, genetic variation inherited

PHYSICAL FACTOR  - affected by enviroment, e.g. plants in more salts and minerals grow more, or identical twins same alleles, grew up in different areas of womb

variation is often a combination of both e.g. someone could grow 6ft by their genes but need enviro factors e.g. diet

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STUDYING VARIATION

YOU HAVE TO TAKE A SAMPLE POPULATION - time cosuming to take whole thing, models for whole population

SAMPLE HAS TO BE RANDOM - to make sure it isnt biased, not due to chance

WHEN ANALYSING AND INTERPRETING DATA RELATING TO VARIATION...

  • DESCRIBE DATA - give figures
  • DRAW CONCLUSIONS
  • SUGGEST A REASON - give reasons why??
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STANDARD DEVIATION

MEAN - AVAERAGE OF VALUES IN SAMPLE - can be used to tell variation between samples

MOST SAMPLES GIVE YOU A NORMAL DISTRIBUTION CURVE (bell like shape)

STANDARD DEVIATION - how much the values vary around the mean

A large standard deviation means the value in sample vary alot

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DNA STRUCTURE

POLYNUCLEOTIDE - made up of lots of nucleotides joined together

NUCLEOTIDE - MADE UP OF A SUGAR (DEOXYRIBOSE), PHOSPHATE AND AN ORGANIC BASE

FOUR BASES - A T G C

SUGAR AND PHOSPHATE STAYS THE SAME ORGANIC BASE CHANGES

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DOUBLE HELIX

NUCLEOTIDES JOIN TO FORM POLYNUCLEOTIDE STRANDS

SUGAR AND PHOSPHATE GROUP JOIN THROUGH COVALENT BOND TO FORM A SUGAR PHOSPHATE BACKBONE

TWO POLYNUCLEOTIDES JOIN TOGETHER BY HYDROGEN BONDS BETWEEN THE BASES

ONE OF STRANDS IS CALLED CODING STRAND - THE OTHER NON CODING STRAND 

EACH BASE CAN ONLY JOIN TO THERE COMPLEMENTARY BASE

WIND UPTO FORM DOUBLE HELIX

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DNA FUNCTION

CONTAINS GENETIC INFO NEEDED TO GROW AND DEVELOP

LONG AND COILED, PACKED UP IN SMALL SPACE IN NUCLEUS - HOLDS ALOT OF GENETIC INFO

DNA HAVE PAIRED STRUCTURE - EASIER TO COPY ITSELF - CALLED SELF REPLICATION - GOOD FOR PASSING GENETIC INFO FROM GENERATION TO GENERATION

DOUBLE HELIX STRUCTURE MEANS IT IS STABLE  

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EUKARYOTIC CELL DNA

EUKARYOTIC CELLS - contain DNA molecules that exist as chromosomes

DNA MOLECULE is really long so it has to be wound up so it can be fit into the NUCLEUS.

IT GETS WOUND UP IN TO PROTEINS CALLED HISTONES - THEY SUPPORT IT 

LINEAR DNA MOLECULES

COILED AND PACKED TIGHTLY INTO CHROMOSOME 

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PROKARYOTIC CELL DNA

CARRY DNA AS CHROMSOMES - DNA MOLECULES ARE SHORTER AND CIRCULAR

DNA ISNT WOUND IN PROTEINS - IT CONDENSES TO FIT IN THE CELL BY SUPERCOILING

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GENES

GENES - section of dna found on chromosomes, they code for proteins- contain instructions to make them

PROTEINS - made from amino acids, proteins have differed number/order of amino acids, order of bases determines order of amino acids - 3 bases - triplet code e.g. GTC codes for a specific amino acid which will make up a protein

 

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NON CODING DNA

GENES IN DNA THAT DONT ACTUALLY CODE FOR AMINO ACIDS 

CALLED INTRONS - EXONS DO CODE FOR AMINOS 

INTRONS DURING PROTEIN SYNTHESIS ARE REMOVED

MULTIPLE REPEATS OF DNA ALSO DONT CODE FOR AMINO ACIDS E.G. CCTCCTCCTCCT

THESE ARE CALLED MINISATELIITES 

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DNA GENES AND DEVELOPMENT

 order of bases in GENE  DETERMINES AMINO ACID SEQUENCE to make proteins  

ENZYMES ARE PROTEINS  - enzymes speed up our metabolic pathways - these determine how we grow and develop - phenotype

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ALLELES

DIFFERENT VERSIONS OF THE SAME GENE 

ORDER OF BASES IN EACH GENE IS SLIGHTLY DIFFERENT -  code for slightly different versions of the same group 

e.g. EYE COLOUR IS THE GENE THE ALLELES WILL BE WHETHER ITS GREEN OR BLUE

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GAMETES

SPERM AND EGG CELLS (gametes) - fertilise to form a zygote - divides and develops into new organism 

GAMETES ARE HAPLOID - HALF THE NUMBER OF CHROMOSOMES 

WHEN IT FUSES TO FORM ZYGOTE IT BECOMES DIPLOID AGAIN

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MEOSIS

TYPE OF CELL DIVISION - DIPLOID TO START - CELLS FORMED HAPLOID, happens in sexual reproduction 

DNA REPLICATES - each chromosome becomes doubled, forms 2 identical strands of DNA

2 DIVISIONS;

MEOSIS 1 - HALVES THE NUMBER OF CHROMSOMES after being arranged in homologus pairs, CHROMATIDS CROSS OVER AND BITS OF CHROMATIDS SWAP - DIFFERENT COMBINATION OF ALLELES 

MEOSIS 2 - THE PAIRS OF SISTER CHROMATIDS THAT MAKE UP EACH CHROMOSOME ARE SEPERATED

FOUR HAPLOID GAMETES WHICH ARE GENETICALLY DIFFERENT FORM  

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HOW MEIOSIS PRODUCES GENETICALLY DIFFERENT CELLS

1) CROSSING OVER - crossing over in meoisis 1 - 4 daughter cells have different alleles

2) INDEPENDENT SEGREGATION OF CHROMOSOMES - different combinations of maternal and paternal chromosomes go into each cell - 4 daughter cells have different combinations of chromosomes 

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GENETIC DIVERSITY

WITHIN A SPECIES - DNA VARIES A LITTLE (99.5% SAME) SAME GENES DIFFERENT ALLELES 

DIFFERENT SPECIES - DNA VARIES ALOT - DIFFERENT GENES 

THE MORE ALLELES IN A POPULATION, THE MORE DIVERSE IT IS

GENETIC DIVERSITY INCREASED BY;

  • MUTATIONS - FORMS NEW ALLELES 
  • DIFFFERENT ALLELES BEING INTRODUCED - individuals from another porulation migrate in and reproduce - called GENE FLOW  
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GENETIC BOTTLENECKS

AN EVENT THAT CAUSES A BIG REDUCTION IN A POPULATION E.G. HUNTING OF SEALS

REDUCED ALLELES IN POPULATION

WHEN THE SURVIVORS START TO REPRODUCE AGAIN THERE WILL BE A LARGER POPULATION CREATED FROM A FEW INDIVIDUALS 

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FOUNDER EFFECT

WHAT HAPPENS WHEN A FEW INDIVIUDALS FROM A POPULATION START A NEW COLONY 

ONLY A SMALL NUMBER OF ORGANISMAS HAVE CONTRIBUTED ALLELES TO NEW GENE POOL - MORE INBREEDING 

E.G. AMISH PEOPLE SEPERATED THEMSELVES BECAUSE OF RELIGION 

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SELECTIVE BREEDING

HUMANS SELECTING WHICH DOMESTICATED ANIMALS OR PLANTS REPRODUCE TOGETHER TO PRODUCE HIGH-YIELDING BREEDS

LEADS TO REDUCTION IN GENETIC DIVERSITY - ONCE THE ORGANISM WITH DESIRED CHARACTERISTICS PRODUCED - IT WILL CONTINU TO BE BRED

REDUCES ALLELES IN GENE POOL 

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ARGUMENTS OF SELECTIVE BREEDING

FOR ;

IT CAN PRODUCE HIGH YEILDING ANIMALS AND PLANTS 

IT HELPS PRODUCE ANIMALS AND PLANTS THAT HAVE INCREASED RESISTANCE TO DISEASE - buy less drugs and pesticides 

BRED TO INCREASE TOLERANCE TO BAD CONDITIONS E.G. DROUGHT

AGAINST ;

HEALTH PROBLEMS - dairy cows, short life expectancy - strain whilst carrying vast amounts of milk

REDUCES GENETIC DIVERISTY - LESS ALLELES - MORE SUCEPTIBLE TO NEW DISEASES 

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HAEMOGLOBIN

PROTEIN WITH QUATERNARY STRUCTURE - RED BLOOD CELLS CONTAIN HAEMOGLOBIN 

BINDS TO OXGEN TO FORM OXYHAEMOGLOBIN IN THE LUNGS - OXYGEN THEN LEAVES THE HAEMOGLOBIN NEAR THE BODY CELLS - DISSACCOCIATES 

 EACH POLYPEPTIDE CHAIN HAS A HAEM GROUP WHICH GIVES IT ITS RED COLOUR 

HIGH AFFINITY FOR OXYGEN - IT CAN CARRY 4 OXYGEN MOLECULES

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HAEMOGLOBIN SATURATION AND PARTIAL PRESSURE

PARTIAL PRESSURE OF OXYGEN - measure of oxygen concentration, the more o2 the higher the partial pressure 

OXYGEN LOADS ON TO HAEMOGLOBIN WHERE THERES HIGH PARTAL PRESSURE OF O2

OXYGEN UNLOADS ITS OXYGEN WHERE THERES A LOWER PARTIAL PRESSURE OF O2 

ALVEOLI HAVE A HIGH PARTIAL PRESSURE IN THE LUNGS, SO OXYGEN BINDS HERE TO HAEMOGLOBIN 

WHERE CELLS RESPIRE - THEY USE UP OXYGEN - LOWERING PARTIAL PRESSURE - RED BLOOD CELLS DELIVER OXYHAEMOGLOBIN TO RESPIRING TISSUE WHERE THE OXGEN DISSOCIAES 

HAEMOGLOBIN RETURNS TO LUNGS 

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DISSOCIATION CURVES

                                (http://click4biology.info/c4b/h/images/H6/foetal.gif) 

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DISSOCIATION CURVES

SHOWS HOW SATURATED HAEMOGLOBIN IS WITH OXYGEN AT A GIVEN PARTIAL PRESSURE 

WHEN PO2 IS HIGH - haemoglobin has a high affinity for oxygen, so it has a high stauration of oxygen 

WHEN PO2 IS LOW - haemoglobin has a low affinity for oxygen, low saturation of oxygen 

SATURATION OF OXYGEN MEANS THE AMOUNT OF O2 MOLECULES IT HAS ON IT - E.G. 100% SATURATION WOULD MEAN IT WOULD HAVE THE MAXIUM OF 4 MOLECULES BINDED 

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DISSOCIATION CURVES AND CO2

HAEMOGLOBIN GIVE UP MORE OXYGEN AT HIGHER PARTIAL PRESSURES OF CO2 

WHEN CELLS RESPIRE THEY PRODUCE C02 WHICH RAISES PP

INCREAES RATE OF UNLOADING 

THIS IS CALLED BOHR AFFECT 

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DISSOCIATION CURVES IN DIFFERENT ORGANISMS

ORGANISMS THAT LIVE IN ENVIROMENTS WITH LOW CONCENTRATION OF OXYGEN HAVE HAEMOGLOBIN WITH A HIGHER AFFINITY THAN HUMAN (TO THE LEFT)

ORGANISMS THAT ARE VERY ACTIVE AND HAVE A HIGH OXYGEN DEMAND HAVE HAEMOGLOBIN WITH LOWER AFFINTY FOR OXYGEN THAN  HUMAN (TO THE RIGHT)

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POLYSACHARIDES

3 TYPES 

STARCH 

GLYCOGEN 

CELLULOSE 

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STARCH

MAIN ENERGY STORAGE IN PLANTS 

CELLS GET ENERGY FROM GLUCOSE - PLANTS STORE GLUCOSE AS STARCH (when it needs more energy it breaks down starch to get glucose)

STARCH IS A MIXTURE OF 2 POLYSACHARIDES -

  • AMYLOSE - a long unbranched chain of a glucose, cylinder shape, compact good for storage and can fit into small spaces 
  • AMYLOPECTIN - a long branched chain of a glucose, side branches allow enzymes to get to glycosidic bonds easier - glucose can get relasesd quicker  

STARCH INSOLUBLE - GOOD FOR STORAGE 

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GLYCOGEN

MAIN ENERGY STORAGE IN ANIMALS 

ANIMAL CELLS GET ENERGY FROM GLUCOSE - STORE IT IN GLYCOGEN 

LOTS OF BRANCHES COMING OFF OF IT - STORED GLUCOSE CAN GET RELEASED QUICKER 

COMPACT SO GOOD FOR STORAGE 

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CELLULOSE

MAJOR COMPONENT OF CELL WALLS IN PLANTS

LONG UNBRANCHED CHAINS OF BETA GLUCOSE - STRAIGHT

LINKED TOGETHER BY HYDROGEN BONDS TO FROM STRONG FIBRES CALLED MICROFIBRILS.

THE STRONG FIBRES MEANS IT PROVIDES STRUCTURAL SUPPORT FOR CELL 

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DIFFERENCE BETWEEN ANIMAL AND PLANT CELLS

ANIMALS - PLASMA MEMBRANE, CYTOPLASM, NUCLEUS, MITOCHONDRIA, RIBOSOMES 

PLANTS - ALL THE SAME AND EXTRA 

  • RIDGID CELL WALL - MADE OF CELLULOSE - SUPPORTS AND SRENGTHENS 
  • VACOULE - CELL SAP A WEAK SOLUTION OF SUGAR AND SALTS 
  • CHLOROPLASTS - WHERE PHOTOSYNTHESIS OCCURS - MAKES FOOD FOR PLANT - CONTAIN CHLORPHYLL 
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CELL CYCLE

PROCESS OF CELL GROWTH AND DIVISION - IN MULTICELLULAR ORGANISMS 

G1 PHASE - CELL GROWS, NEW PROTEINS AND ORGANELLES ARE FORMED

SYNTHESIS - CELL REPLICATES DNA 

G2 - CELL KEEPS GROWING AND SPINDLE PROTEINS ARE MADE FOR CELL DIVISON 

THESE 3 PHASES ARE PART OF INTERPHASE.

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DNA REPLICATION

ENZYME DNA HELICASE BREAKS HYDROGEN BONDS BETWEEN HYDROGEN BONDS 

HELIX UNZIPS TO FORM 2 SINGLE STRANDS 

ORIGINAL STRANDS ACT AS A TEMPLATE, FOR A NEW STRAND, FREE FLOATING DNA NUCLEOTIDES JOIN TO EXPOSED COMPLEMENTARY BASES 

ENZYME DNA POLYMERASE JOINS THE TEO TOGETHER 

HYDROGEN BONDS FORM BETWEEN THEM 

SEMI - CONSERVATIVE BECAUSE HALF THE NEW STRANDS OF DNA ARE FROM THE ORIGINAL PIECE OF DNA 

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MITOSIS

CELL DIVISION, PRODUCES GENETICALLY IDENTICAL 

PARENT CELL DIVIDES TO PRODUCE 2 IDENTICAL DAUGHTER CELLS 

NEEDED FOR GROWTH OF MULTICELLULAR ORGANISMS AND FOR REPAIRING DAMAGED TISSUE

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STAGES OF MITOSIS

INTERPHASE - prepares to divide, dna unravelled and replicated (to double genetic content) organelles are replicated and ATP content increases (energy needed for cell division)

PROPHASE - chromosomes condense and becomes visible as 2 chromatids held together by a centromere, nuclear envelope starts to break down

METAPHASE - spindle forms, centromeres attatch chromatids to spindle and line up in the middle of the cell

ANAPHASE - centomeres divide, spindle fibres pull sister chromatids to opposite poles of the cell

TELOPHASE - spindle fibres break down, nuclear envelope forms around each chromsome at eaither end, chromsomes uncoil 

CYTOKENISIS - where the two identical cells form.

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CANCER

CELL GROWTH AND DIVISION CONTROLLED BY GENES 

THEY STOP WHEN THEYVE DIVIDED ENOUGH TIMES - HOWEVER IF THERES A MUTATION IN A GENE THAT CONTROLS CELL DIVISION, THE CELLS CAN GROW OUT OF CONTROL

IF CELLS CARRY ON DIVIDING THEY CAN FORM A TUMOUR 

CANCER IS A TUMOUR THAT INVADES SURROUNDING TISSUE 

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CANCER TREATMENT

DESIGNED TO DISRUPT CELL CYCLE - dont distinguish normal cells to tumour cells and kill them both - doesnt matter because tumour cells divide much quikcer so our more likely to kill tumour cells

TREATMENTS INCLUDE; CHEMOTHERAPY - prevents synthesis of enzymes needed for dna replication - cant enter synthesis so kills itslef 

RADIATION AND DRUGS - damage dna so when cell in synthesis it detcts damaged dna so it kills itself 

TO REDUCE IMPACT ON NORMAL CELLS - tumour removed using surgery, this removes a lot of tumour cells and increases the access of any left to nutrients and ocygen which trigger them to enter the cell cycle making them more suceptible to treatment. 

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CELL DIFFERENTIATION

ALL CELLS ARE SPECIALISED TO SPECIFIC FUNCTIONS 

STRUCTURE ADAPTED TO ITS PARTICULAR JOB THE PROCESS OF BECOMING SPECIALISED IS DIFFERENTIATION 

2 EXAMPLES - SQUAMOUS EPITHELIUM CELLS - thin,in the lungs and allow gases to pass through them easily - lining alveoli 

PALISADE MESPHYLL CELLS - in leaves where photosynthesis occurs - contain lots of chloroplasts , so they can absorb a lot of sunlight

TISSUE IS A GROUP OF SIMILAR CELS THAT PERFORM THE SAME FUNCTION 

ORGANS STRUCTURES WITHIN AN ORGANISM THAT ARE MADE UP OF SEVERAL TISSUES ALL WITH A DIFFERENT FUNCTION WHICH CONTRIBUTE TO THE OVERALL FUNCTION OF THE ORGAN 

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EXCHANGING SUBSTANCES

CELLS NEED TO TAKE IN OXYGEN AND NUTRIENTS BY EXCHANGING WITH THE ENVIROMENT 

THEY ALSO NEED TO EXCRETE WASTE PRODUCTS LIKE CO2 AND UREA 

MOST ORGANIMS NEEED TO STAY AT THE SAME TEMP SO HEAT NEEDS TO BE EXCHANGED 

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SURFACE AREA TO VOLUME RATIO

DETERMINES HOW EASY THE EXCAHGE OF SUBSTANCES IS 

SMALLER ANIMALS HAVE A LARGER SURFACE AREA TO VOLUME RATIO THEN BIGGER ANIMALS 

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DIFFERENT EXCHANGE SYSTEMS

SINGLE CELLED ORGANISMS - substances diffuse diretcly in/out of cell acroos membrane - diffusion rate is quick becaue small distance to travel 

MULTICELLUAR ORGANISMS - diffusion across membrane is too slow because some cells to deep in body, and large and animals have a small surface area to volume ratio

SO MULTICELLULAR ORGANIMS NEED SPECIALISED EXCHANGE ORGANS 

IT ALSO NEEDS A EFFICENT SUBSTANCE TO CARRY SUBSTANCES TO AND FROM CELLS - MASS TRANSPORT - CIRCULATORY SYSTEM 

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BODY SHAPE AND SIZE ; HEAT

THE RATE OF HEAT LOSS DEPENDS ON ITS SURFACE AREA - A BIGGER ANIMAL WITH A SMALL SURFACE AREA WILL LOSE LESS HEAT 

IF ORGANISM SMALL AND HAS A LARGE SA TO VLUME RATIO THEN IT LOSES HEAT QUICKER 

SHAPE - IF ITS MORE COMPACT AND ROUND THEN IT WILL MAINTAIN BODY HEAT BECAUSE THERES LESS SURFACE AREA IF ITS LESS COMPACT AND HAS STICKY OUT BITS LARGER SURFACE AREA MEANS MORE HEAT ESCAPES 

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ADAPTIONS TO AID EXCHANGE

ANIMALS WITH HGIH SA TO V RATIO - LOSE MORE WATER AS IT EVAPORATES FROM SURFACE - some small desert mamals have kidney structure adaptions so they produce less urine 

SMALL ANIMALS IN COLDER AREAS - higher metabolic rate to compensate for high sa to v - this helps them keep warm by creating heat - eat lots of high energy food e.g. nuts 

SMALLER MAMMALS - thick hair or hibernate when it gets cold 

LARGER ORGANISMS IN HOT REGIONS - find it hard to keep cool - elephants developed large flat ears which increase surface area alowing them to lose more heat - hippos spend alot of time in water 

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FISH GAS EXCHANGE

WATER CONTAING O2 ENTERS FISHES MOUTH AND PASSES THROUGH THE GILLS

GILLS ARE MADE UP OF GILL FILAMENTS WHICH GIVE A BIG BIG SURFACE AREA FOR EXCHANGE OF GASES - filaments covered in llamale which increase surface area further 

LLAMALE HAVE LOTS OF CAPPILARIES AND THIN SURFACE AREA TO INCREASE DIFFUSION 

COUNTERCUREENT (blood flows in one direction and water in the opposite) MAINTAINS A LARGE CONCENTRATION GRADIENT - as much oxygen can be passed on 

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INSECTS GAS EXCHANGE

THEY USE TRACHAE - AIR ENTERS THESE THROUGH PORES ON SURFACE CALLED SPIRICALES

OXYGEN TRAVELS DOWN CONCENTRATION GRADIENT TOWARDS CELLS, CO2 MOVES DOWNS ITS OWN CONCENTRATION GRADIENT TO SPIRICALES 

TRACHAE BRANCH OFF INTO TRACHEOLES WHICH HAVE THIN PERMEABLE WALLS AND GO TO INDIVIDUAL CELLS 

INSECTS USE ABDOMINAL MUSCLES TO MOVE AIR IN AND OUT OF SPIRICLALES 

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PLANT EXCHANGE

NEED CO2 FOR PHOTOSYNTHESIS - O2 WASTE GAS 

NEED 02 FOR REPSIRING CO2 WASTE GAS 

GAS EXCHANGE SURGFACE IS A SPONG MESOPHYLL CELLS IN LEAF - LARGE SURFACE AREA 

THE MESPHOPHYLL CELLS ARE IN THE LEAF - GAS MOVES IN THROUGH PORES CALLED STOMATA 

STOMA CAN OPEN AND CLOSE TO ALLOW GASES IN OR OUT DEPENDING IF PLANTS LOSING TO MUCH WATER - GUARD CELLS CONTROL THIS 

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INSECTS AND PLANTS AND WATER LOSS

IF INSECTS ARE LSOING WATER THEY CLOSE THEIR SPIRACLES USING MUSCLES, THEY HAVE WATERPROOF WAXY CUTICLE ALL OVER THEM  AND TINY HAIRS AROUND SPIRACLES TO REDUCE EVAPORATION 

PLANTS - STOMATA KEPT OPEN DURING DAY TO ALLOW GAS EXCHANGE -  water will flow in and make guard cells trugid -if dehydrated it will become flacid and stoma will close

CURLED LEAVES WITH STOMATA INSIDE PROTECTING FROM DRY WIND

REDUCED AMOUNT OF STOMATA SO LESS WATER CAN ESCAPE 

WAXY WATERPROOF CUTICLES SO LESS WATER CAN ESCAPE 

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CIRCULATORY SYSTEM

MASS TRANSPORT SYSTEM - large mamals have a small surface area to volume ratio so need specialised gas exchange system 

MADE UP OF HEART AND VESSELS - heart pumps blood through veins atreries and cappilaries to diffeent parts of the body 

BLOOD TRANSPORTS - RESPIRATORY GASES, PRODUCTS OF DIGESTION AND HORMONES IN IT 

2 CIRCUITS - ONE TAKES BLOOD FORM HEART TO LUNGS WHILST THE OTHER - TO THE REST OF THE BODY 

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BLOOD VESSELS AND ORGANS

HEART - AORTA AND VENA CARVA 

LUNGS PULMONARY ARTERY/VEIN 

GUT - HEPATIC PORTA VEIN 

LIVER - HEPATIC VEIN AND ARTERY

KIDNEY - RENAL ARTERY AND VEIN 

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ARTERIES

CARRY BLOOD FROM THE HEART TO THE REST OF THE BODY, THICK MUSCULAR WALLS - ELASTIC TISSUE TO COPE WITH HUGH BLOOD PRESSURE 

ALL CARRY OXYGENATED BLOOD - APPART FROM PULMONARY 

THEY DIVID INTO SMALLER ARTERIOLES - FORM A NETWORK THROUGOUT THE BODY

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VEINS

VEINS TAKE DEOXGENTAED BLOOD BACK TO THE HEARTUNDER LOW PRESSURE 

WIDER LUMEN AND LITTLE ELASTIC IN TISSUE 

VEINS CONTAIN VALVES TO STOP BACKFLOW 

PULMONARY VEIN CARRIES OXGENATED BLOOD FROM HEART TO THE LUNGS 

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CAPILLARIES

ARTERIOLES BRANCH INTO CAPILLARIES - SUBSTANCES ARE EXCHNAGED BETWEEN CAPPILARIES AND CELLS E.G. OXYGEN AND GLUCOSE 

ADAPTED FOR DIFFUSION 

NEAR CELL - SHORT DIFFUSION PATHWAY

WALLS ONLY ONE CELL THICK 

LARGE NUMBER OF THEM - INCREASES SURFACE AREA 

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TISSUE FLUID

FLUID THAT SURROUNDS CELLS IN TISSUES - made from substances that leave the blood e.g. oxygen water and nutrients - cells take these in from the tissue fluid - and release metabolic waste into it 

SUBSTANCES MOVE OUT OF CAPILLARIES INTO TISSUE FLUID BY PRESSURE FILTRATION 

AT THE START OF THE CAPPILARY WHIC HAS COME FROM THE ARTERY - pressure is higher in cappilary than tissue fluid so some of it comes out into tissue fluid 

this means less pressure in cappilaries - nearer the end going to the vein 

due to fluid loss - water potential is high out side of cappilary so it moves in through osomosis 

TISSUE FLUID DOESNT CONTAIN REDBLOOD CELLS AND PROTEINS BECAUS THEY ARE TO BIG TO BE PUSHED OUT 

ANY EXCESS TISSUE FLUID  IS DRAINED INTO LYMPHATIC SYSTEM 

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WATER TRANSPORT IN PLANTS

WATER ENTERS A PLANT THROUGH ITS ROOT CELLS - HIGH TO LOW WATER POTENTIAL - covered in root hairs - increases surface area so more water is take in

ONCE WATER IS ABSORBED IT GOES THROUGH THE CORTEX BEFORE IT GETS INTO THE XYLEM

LEAVES EVAPORATE WATER - CREATES A CONSTENT WATER POTENITIAL GRADIENT THAT KEEPS WATER MOVING FROM ROOTS TO LEAVES 

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ROUTES THROUGH THE ROOT

SYMPLASTIC PATHWAY -  goes through living parts of the cell - the cytoplasm - cytoplasm of neighbouring are linked by plasomodesmata (small channels in cell walls)

APOPLASTIC PATHWAY - goes through non living  - cell walls - water diffuses through them 

APOPLASTIC PATHWAY GETS BLOCKED BY CASPARIAN STRIP - FORCES IT TO USE SYMPLASTIC PATHWAY - MADE OF SUBERIN WHICH IS IMPERMEABLE TO WATER 

IT THEN MOVES TI XYLEM 

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HOW WATER MOVES UP A PLANT

COHESION AND TENSION -

  • water evaporates from leaves at top of xylem
  • creates a tension/suction which pulls more water into the leaf
  • water molecules are cohesive (bond together) forcing them upwards

ROOT PRESSURE -

  • when water is transported into the xylem it creates a pressure and forces water already in the xylem further upwards 

TRANSPIRATION - water evaporates from moist cell walls and out of the stomata when it opens 

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FACTORS THAT AFFECT TRANSPIRATION

LIGHT - lighter it is the faster - stomata open in daytime

TEMPERATURE - higher the temp fatser - warmer water molecules have more energy - evaporate faster - makes water diffuse out faster 

HuMIDITY - lower the humidity the fasster the transpiration - if air around the plant is dry - concentration gradient between leaf and air is increased- increasing transpiration 

WIND - windier it is the faster - air movement blws water molecules from around the stoma - increasing concentration gradient

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CLASSIFICATION

TAXONOMY - naming and organising organisms into groups based on similarities and differences 

SIMILAR ORGANISMS ARE SORTED IN TO LARGE GROUP DUE TO SIMILARITIESAND PLACED IN A KINGDOM AND THEN GOES DOWN IN ORDER OF ;

KINGOM, PHLUM, CLASS, ORDER, FAMILY, GENUS, SPECIES 

SPECIES ARE A GROUP OF SIMILAR ORGANISMS THAT ARE ABLE TO REPRODUCE TO GIVE FERTILE OFFSPRING 

PHYLOGENETICS TELL US ABOUT AN ORGANIMS EVOLUTIONARY HISTORY - ALL ORGANISMS HAVE EVOLVED FROM RELATIVES AND COMMON ANCESTORS.

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WHY DEFINING AN ORGANIM AS A DISTINCT SPECIES COUL

YOU CANT ALWAYS SEE THERE REPRODUCTVE BEHAVIOUR :

  • MAY BE EXTINCT
  • REPRODUCT ASEXUALLY
  • PRACTICAL AND ETHICAL ISSUES - E.G. CHIMPS AND HUMANS ARE CLASSED AS A SEPERATE SPECIES - BUT HAS ANYONE TRIED MATING THEM 

SO SCIENTISTS COMPARE DNA INSTEAD TO SEE HOW RELATED 

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CLASSYFING SPECIES

SPECIES CAN BE CLASSIFIED BY PROTEINS OR DNA/SIMILARTIES IN GENES ]

COMPARE DNA BASE SEQUENCE OR LOOKING AT THEIR PROTEINS 

ORGANISMS THAT ARE MORE CLOSELY RELATED WILL HAVE MORE SIMILAR DNA THAN DISTANTLY RELEATED ORGANIMS 

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COMPARING DNA

DNA SEQUENCING - directly compared by looking at the order of the bases, closely related species will have a high percentage of similarity in their DNA base order 

DNA HYBRIDISATION - DNA from 2 different species is collected, seperated and into single strands and mixed together - where base sequence of DNA are complementary a hydrogen bond will form - the more bonds the more alike - dna is then heated to seperate strands - similar dna will have more bonds connecting so a higher temp would mean more energy would be required to break all the bonds 

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COURTSHIP BEHAVIOUR

CARRIED OUT TO ATTRACT A MATE OF THE RIGHT SPECIES 

SPECIES SPECIFIC  - PREVENTS INTERBREEDING 

IT CAN BE USED TO CLASSIFY ORGANISMS 

THE MORE CLOSELY RELATED THE MORE SIMILAR COURTSHIP BEHAVIOUR 

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ANTIBIOTICS

CHEMICALS THAT KILL/ INHIBIT GROWTH OF BACTERIA 

DIFFERENT TYPES OF ANTIBIOTICS - an example some prevent growth of a cell wall (which provides structural support) this can lead to osmotic lysis (water moves into cell and bursts it!)

IF A MUTATION OCCURS IN THE BASE SEQUENCE OF AN ORGANISMS DNA IT CAN CAUSE A DIFFERENT CHARACTERISTIC

SO MUTATION IN A BACTERIAL CELL - COULD MEAN ITS NOT AFFECTED BY ANTIBIOTICS ANYMORE

E.G. METHECILLIN IS AN EXAMPLE - bacteria have developed resistance to it because of mutation - methecillin inhibits a enzyme for cell wall formation - a mutated gene will produce a mutated enzyme which methecillin no longer ecognises  

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PASSING ON ANTIBIOTIC RESISTANCE

VERTICAL GENE TRANSMISSION - bacteria reproduce asexually (exact copy) - this meand each daughter cell has the same genesincluding antibiotic resistance - found in plasmids 

HOROZONTAL GENE TRANSMISSION - two bacteria join together (conjugation) and a copy of plasmid is passed on 

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ANTIBIOTIC RESISTANCE AND NATURAL SELECTION

INDIVIDUALS IN A POPULATION SHOW VARIATION IN CHARACTERISTICS

PREDATION, DISEASE AND COMPETITION CREATE STRUGGLE FOR SURVIVAL

INDIVIDUALS WITH BETTER ADAPTIONS ARE MORE LIKELY TO SURVIVE E.G BACTERIA WITH ANTIBIOTIC RESISTANCE ARE MORE LIKELY TO SURVIVE WHEN EXPOSED TO ANTIBIOTIC RESISTANCE 

OVER TIME NUMBER OF ORGANISMS WITH ADVANTAGEOUS VHARACTERISTICS INCREASE 

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ANTIBOTIC RESISTANCE AND DISEASES

ANTIBACTERIAL RESISTANCE MAKES IT MORE DIFFICULT TO TREAT SOME BACTERIAL INFECTION;

TUBERCULOSIS - lung disease, natural selection has caused resistance to bacteria mycrobacterium tuberculosis, multidrug resistance, 

MRSA - methecillin resistance, resistance to nearly all antibiotics on offer, take along time for doctors to decide which one will kill the bacteria 

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SPECIES DIVERISTY

SPECIES DIVERISTYIS THE NUMBER OF DIFFERENT SPECIES AND ABUNDANCE OF EACH SPECIES IN A COMMUNITY 

THE HIGHER THE AMOUNT OF TREES AND PLANTS THE MORE THE ANIMALS - PROVIDES HABITATS

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DEFORESTATION AND AGRICULTRUE

DEFORESTATION - decreases species diveristy, reduces species of trees, destroys habitats, this means other animals wont have a home and migrate, 

AGRICULTURE -

  • woodland clearence for room
  • monculture - growing one plant 
  • pesticides - chemicals that kill pests that feed on crops 
  • herbecides - chemicals that kill unwanted plants 
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