biology paper 1

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  • Created by: 13froyle
  • Created on: 07-12-17 16:04
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  • biology paper 1
    • cells
      • magnification
        • electron microscope-special conditions-expensive-x2000000
        • light microscope-cheap-easy to use-x2000
        • magnification=size of image/size of real object
      • prokaryotic
        • Prokareotes consist of cytoplasm, cell membrane, cell wall, slime capsual and flagella
        • the genetic information isa DNA loop and may be accompanied py plasmids, small DNA rings
        • about 1um
      • eukariotic
        • plant
          • -cell wall to add support
          • chloroplasts that contain chlorophll fo photosyntheis
          • large vacuole keeps the cell rigid
          • about 10-100um
        • animal
          • cell membrane to control what enters and leaves the cell
          • ribosomes for protein synthesis
          • mitochondria for energy release through aerobic respiraation
          • nucleus contains instructions for making new cells
          • cytoplasm- sap where chemical reactions take place
      • specialisation
        • as an organism develops, cells differentiate to carry out specific functions
        • sperm cells
          • -lots of mitochondria-long tail-digstive enzymes-large nucleus
        • muscle cells
          • lots of mitochondria-can store glycogen-contain special proteins that make muscles contract
        • nerve cells
          • -dendrites to form connections with other cells-long axon to caarry impulses-mitochondria to produce energy for transmitter chemicals at synapses
        • root hair cells
          • mitochondria for active transport
          • large vacuole and surface area
        • xylem
          • lignin/dead cells form a hollow tube
        • phloem
          • seive cells and companion cells
    • diffusion
      • particles moving from a high to low concentration along a concentration graadient
      • effected by surface area, difference in concentration and temperature
      • dissolved substances such as urea and glucose, gases such as oxygen and carbon dioxide move in and out of cells by diffusion
    • osmosis
      • osmosis is the movement of water through a partially permeable membrane from a high to low concentration/dilute to concentrated solution.
      • animal cells rely on osmosis
        • isotonic
          • equal water
        • hypertonic
          • outside is higher
        • hypotonic
          • higher in cells
      • plants become flaccid or plasmosysed (when the cell membrane pulls away from the cell wall)
      • turger is the pressure in the vacuole that keeps cells rigid
    • active transport goes against a concentration gradient and requires energy
      • it allows sugar molecules to be absorbed from the gut into blood
      • it allows root hair cells to absorb mineral ions for growth
    • surface area to volume ratio
      • the larger the organism, the lower the surface area to volume ratio
        • simple diffusion is no longer good enough
        • waste cannot be moved quick enough
      • adaptations for exchange
        • ventilationblood supplysurface areathin membrane
    • cell division
      • chromosomes carry genesgenes carryinformation that controls charactoristics/ section of DNA
      • important for growth and repair
      • mitosis
        • -chromosomes copy and subcellular structures-the chromosomes condense-they are pulled to opposite poles-nuclear membrane breaks down-2 new cells are produced
        • produces genetically identical cells
        • can cause cell mutations
        • in animals differentiation happens in early stages of development
        • plant cells differentiate throughout life in meristems found in roots and tips
      • stem cells
        • embrionic and adult (from bone marrow) stem cells can be cloned
        • can cure paralysis, blindness and diabetes
        • it is easy to clone plants from tissue economically
        • could cause cancerexpensive could be rejectedethics
    • organisation and the digestive system
      • tissues are a group of cells that carry out a special function
      • organs are collections of tissues
      • organs are organised into organ systems that mke up organisms
      • the digestive system is a large muscular tube starting at the mouth and finishing at the anus.
      • the stomach and small intestine is where food is digestedthe small intestine also allows molecules to be absrbed into blood
        • large surface area from villigood blood supplyshort diffusion distance
      • large intestine absorbs water and produces feaces which is stored in the rectum
      • Mouth Where food enters the alimentary canal and digestion begins Salivary glands Produce saliva containing amylase Oesophagus Muscular tube which moves ingested food to the stomach Stomach Muscular organ where digestion continues Pancreas Produces digestive enzymes Liver Produces bile Gall bladder Stores bile before releasing it into the duodenum Small intestine - duodenum Where food is mixed with digestive enzymes and bile Small intestine - ileum Where digested food is absorbed into the blood and lymph Large intestine - colon Where water is reabsorbed Large intestine - rectum Where faeces are stored Large intestine - anus Where faeces leave the alimentary canal
      • food moves down the esophogus by paristalsis
      • teeth are an exmple of mechanical digestion
      • Proteases catalyse the breakdown of proteins into amino acids in the stomach and small intestine
      • Lipases catalyse the breakdown of fats and oils into fatty acids and ycerol in the small intestine
      • Amylase catalyses the breakdown of starch into maltose in the mouth and small intestine
      • Enzymes can break down nutrients into small, soluble molecules that can be absorbed.
      • The enzymes in the stomach work best in acidic conditions – at a low pH.
      • ile is secreted into the small intestine where it has two effects: it neutralises the acid - providing the alkaline conditions needed in the small intestine it emulsifies fats - providing a larger surface area over which the lipase enzymes can work
      • enzymes include a substrate and an active site
    • the circularitry system
      • blood, blood vessels and the heart
        • blood
          • plasma is a yellow liquid that transports bllod cells and molecu;es such as urea around the body
          • white blood cells protect the body against microorganisms
          • platlets are small fragments of cells with no nucleus that contain fibrines and cause bllod to clot
          • red blood cells have no nucleus, are concvave and contain heamoglobin
            • heamoglobin binds to ocygen to form oxyheamoglobin
        • ArteriesBlood in the arteries is under high pressure generated by the heart. The arteries have: thick outer walls thick layers of muscle and elastic fibres.
        • The blood in veins is under lower pressure than the blood in arteries. The veins have: thin walls thin layers of muscle and elastic fibres. Unlike arteries, veins have one-way valves in them to keep the blood moving in the correct direction.
        • The function of capillaries is to allow food and oxygen to diffuse to cells while waste is diffused from cells. Capillaries have thin walls - only one cell thick - that allow them to effectively perform their function.
        • blood pressureThe higher number (140) show the pressure when the heart is contracting. The lower number shows the pressure when the heart is relaxing.
        • Heart attacksA heart attack can happen because: Fatty deposits build up in the coronary arteries A blood clot can form on a fatty deposit The blood clot can block a coronary artery Some heart muscle cells do not get the oxygen and nutrients they need These cells start to die.
        • humans have a double circularitry sytem
        • Atria (left and right)Ventricles (left and right)
        • The left ventricle has a thicker muscle wall than the right ventricle. This is because the left ventricle has to pump blood all the way around the body, but the right ventricle only has to pump it to the lungs.
        • The four main blood vessels of the heart: Vena cavaPulmonary arteryPulmonary veinAorta
      • statins can reduce colestrol levels and stents open up blocked valves
      • artificial hearts can cause blood clottingheart transplants can cause rejection
      • pacemakers send strong electical impulses to the heart
    • breathing and gas exchange
      • the lungs are in the chest cavity protected by the ribs and separated from the abdomen by the diaphragm
      • When you inhale: The intercostal muscles contract, expanding the ribcage outwards and upwards. The diaphragm contracts, pulling downwards to increase the volume of the chest. Pressure inside the chest is lowered and air is sucked into the lungs.
      • When you exhale: The intercostal muscles relax, the ribcage drops inwards and downwards. The diaphragm relaxes, moving back upwards, decreasing the volume of the chest. Pressure inside the chest increases and air is forced out.
      •  exchange of gases takes place between the gases inside the alveoli and the blood. Blood arriving in the alveoli has a higher carbon dioxide concentration However, the air in the alveoli has a much lower concentration of carbon dioxide, meaning there is a concentration gradient which allows diffusion. blood arriving in the alveoli has a lower oxygen concentration and  air in the alveoli has a higher oxygen concentration. Therefore, oxygen moves into the blood by diffusion and combines with the haemoglobin in red blood cells to form oxyhaemoglobin.
    • plant tissues and organs
      • epidermal tissues prroduce wax to protect the plant
      • palisade mesophll contain chlorophll
      • spongy mesophll have large air spce for gas exchange
      • xylem transports water and minerals to leaves and stem
      • phloem transports dissolved sugars to storge organs
    • transpiration
      • Transpiration explains how water moves up the plant against gravity
      • More water is drawn out of the xylem cells inside the leaf to replace what's lost. through transpiration
      • transpiration is slower in humidity, faster in wind, light and high temperature
      • stomata and guard cells control transpiration
    • infection and response
      • health is a state of pysical and mental well being
      • facters that lead to ill health can be dietstressdisease
      • communicable means infectious
      • diseases interacteg ill health can lead to depression
      • pathogens
        • bacteria
          • Bacteria are living cells and, in favourable conditions, can multiply rapidly. Once inside the body they release poisons or toxins that make us feel ill.
            • salmonella  causes vomiting and daiorrhea and comes from uncooked meat
            • gonnorea is an STI and causes yellow discharge and pain urinating
        • fungi
          • produce hyphe that penetrate human skin
            • spores carried by wind. rose black spot
        • virus
          • consist of a fragment of genetic material inside a protective protein coat.Viruses can only reproduce inside host cells, and they damage the cell when they do this. A virus can get inside a cell and, once there, take over and make hundreds of thousands of copies of itself. fill the whole host cell and burst it open.
            • measles
              • fever and skin rash spread by dropets
            • tobaco mosaic virus
              • destroys cells so they cant photosynthesise
            • HIV/AIDS
        • protists
          • travel by vectors such as malaria
            • the spread of malaria can be controlled by avoiding contact with the vector.  using mosquito netting at windows, doors and around beds. The mosquitoes may be killed using insecticides. The parasite itself can be killed by giving infected people drugs such as Lariam.
      • The first line of defence is the body's natural barriers. These include:skinnasal hairs, mucus and ciliatearsstomach acid - it destroys the protein structure of the bacteria’s enzymes. This results in the bacteria being unable to carry out its bodily processes.
      • Plants produce antibacterial chemicals to help so that they can defend themselves against microorganisms. Some of these chemicals are now used by humans. eg mint
      • Antibiotics are substances that kill bacteria or stop their growth. They do not work against viruses: it is difficult to develop drugs that kill viruses without also damaging the body’s tissues.Antifungal agents kill fungi.
      • penicillin breaks down cell walls
      • white blood cells ingest, produce antibodies and produce ant-toxins
      • immunity
        • passive
          • Sometimes you may be treated for infection by an injection of certain antibodies from someone else. This is passive immunity because you receive antibodies, rather than make them yourself.
        • active
          • Once you have been infected with a particular pathogen and produced antibodies against it, some of the white blood cells remain. If you become infected again with the same pathogen, these white blood cells reproduce very rapidly and the pathogen is destroyed.
      • antibiotic resistance
        • Over time, bacteria can become resistant to certain antibiotics. MRSA is very dangerous because it is resistant to most antibiotics. To slow down or stop the development of other strains of resistant bacteria, we should:avoid the unnecessary use of antibioticsalways complete the full course.
      • Vaccination involves putting a small amount of an inactive form of a pathogen, or dead pathogen, into the body. Vaccines can contain:live pathogens treated to make them harmlessharmless fragments of the pathogentoxins produced by pathogensdead pathogens.
      • plant deficiencies and desiese
        • stunted growth=nitrate defficiancy
        • malformed leaves=aphid
        • yellow leaves=magnesium deficiancy
        • identifyable by labatory testing, garden manuals, MCA
        • growths = bacterial
      • plant protection
        • tough waxy cuticle
        • cellulose walls
        • bark
        • spikes
      • aphids feed on phloem sap
      • drugs from plants
        • digitalis from foxgloves slows the heart
        • aspirin comes from willow trees
      • tumors
        • benign=contained and don't spread but can cause pressure on organs
        • malignant= spread and are cancerouscan cause secondry tumors
    • producing new drugs
      • tested for efficacy, toxicity and dosage
      • preclinical=in labs on tissues and animals
      • clinical=healthy volunteers to find optimum doses
      • in double blind trials, a placebo may be given
    • monoclonal antibodies
      •  pregnancy test kits to identify the small levels of a hormone called HCG, which is present in the urine of pregnant women. used to locate blood clots as they bind to clots. used to diagnose and then treat some cancers. They can bind to the cancerous cells and help the person’s immune system attack them.
      • monoclonal antibodies create more side effects than expected.
      • Vaccinate mouse to stimulate the production of antibodies > Collect  cells that ofrm antibodies from mouse = Tumor cells (myeloma) > Spleen and myeloma cells fuse to form hybridoma cells > Grow hybridoma cells in tissue culture and select antibody-forming cells > Collect monoclonal antibodies
    • photosynthesis
      • limiting factors=lighttemperatireCO2chlorophll
      • Test leaf for starch Remove leaf from a plantBoil in water to killTurn off bunsen burnerRemove leaf put into a boiling tube of Ethanol . Place boiling tube into hot water for a few minutesDip in warm water ( this is to de-brittle it)Spread leaf on white tile and add iodine
      • Carbon Dioxide + Water = Glucose + Oxygen
      • 6CO2 + 6H2O = C6H12O6 = 6O2
      • Photosynthesis uses sunlight energy to transform it into chemical energy in the bonds of glucose.
      • Glucose -  stored as starchused in respiration for the  release of  energy turned into sucrose = transported in the phloem to the rest of the plantturned into cellulose = cell wallswith nitrates, produces protein for growth
      • light intensity = inverse square law
      • greenhouse
        • parafin heaters
        • hydroponics
        • artificial light and heating
        • automatic watering
      • Epidermis is thin and transparent To allow more light to reach the palisade cellsThin cuticle made of waxTo protect the leaf without blocking out lightPalisade cell layer at top of leafTo absorb more lightSpongy layerAir spaces allow carbon dioxide to diffuse through the leaf, and increase the surface areaPalisade cells contain many chloroplastsTo absorb all the available light
    • respiration
      • a series of reactions in which energy is released from glucose. uses oxygen. :glucose + oxygen ? carbon dioxide + water (+ energy)Aerobic respiration happens all the time in the cells of animals and plants. Most of the reactions involved happen inside mitochondria, inside the cytoplasm of the cell. The reactions are controlled by enzymes.
      • During exercise, the muscle cells respire more than they do at rest. This means that:Oxygen and glucose must be delivered to them more quicklyWaste carbon dioxide must be removed more quicklyThis is achieved by increasing the heart rate, rate of breathing and the depth of breathing.
      • The muscles store glucose as glycogen. This can then be converted back to glucose for use during exercise.
      • Anaerobic respirationNot enough oxygen may reach the muscles during exercise. When this happens, they use anaerobic respiration to obtain energy.
      • glucose ? lactic acid (+ little energy)
      • Anaerobic respiration produces an oxygen debt. This is the amount of oxygen needed to oxidise lactic acid to carbon dioxide and water. The existence of an oxygen debt explains why we continue to breathe deeply and quickly for a while after exercise.
      • Muscles become fatigued (tired) during long periods of vigorous activity. This means that they stop contracting efficiently. One cause of this is the build-up of lactic acid in the muscles from anaerobic respiration. The lactic acid is removed from the muscles by blood flowing through them.

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