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Revision (Physical Chemistry (Redox (Oxidation number for elements is…

- - - - The slowest step in the reaction.
      - The rate equation, rate = k[species], only includes reactants in the rate-determining step.
      - The orders in the rate equation match the number of species in the rate-determining step.
    - - First order: straight line through origin. Rate is directly proportional to concentration. Find gradient of the line to find k. rate = k[A]
      - Second order: Graph is a curve. Plot a second graph of rate against concentration squared. This gradient is k. rate = k[A]^2
      - Zero order: straight line with no gradient. Change in concentration does not change rate of reaction. Intercept on y axis gives k. rate = k
  - - - Ionisation of new shells will cause a large increase in ionisation energy.
      - Predictions can be made from a table or graph showing energy by looking at where the large increase is.
      - Ionisation of electrons in the same shell will increase slightly due to an increased attraction from the nucleus.
      - Periodic trends provide evidence for sub shells and shells. eg. first ionisation energies decrease down a group because less nuclear attraction, more shielding, increased atomic radius.
      - Across a period: atomic radius decreases, shielding is similar, nuclear attraction increases, nuclear charge increases, so first ionisation energy increases.
    - - Nuclear charge: more protons = more attraction to the nucleus = higher ionisaton energy
      - Electron shielding: more electrons in inner shells will shield the force of attraction from the nucleus = lower ionisation energy.
      - Atomic radius: more shells = valence electrons are further from the nucleus = lower ionisation energy
- - - - Amines
      - Amides
      - Amino Acids
    - - Condensation
      - Addition
- - - - Romanian Orphanages
        
        Privation: no maternal attachment formed
        
        Deprivation: maternal attachment formed and then removed.
        
        Rutter et al (2007) study of children in orphanages adopted by UK or Romanian families. Poor conditions in the orphanage, babies did not form attachment. Disinhibited behaviour was most common in older Romanian babies adopted by a UK family. Many children showing disinhibited attachment behaviour were also receiving help from special education or mental health services.
      - Ethical implications of studying children: must be overt observation and since many carers deny observation being done, results are not always consistent. When children turn 16 the retain the right to deny being studied so any longitudinal study would have to face denial if the child did not want to be studied at this age
      - Institutionalisation
        
        Almost all adopted children (at age 4) formed good attachments with their adoptive families, more so than the restored children. This was the case at age 8 and at age 16. Adoptees, restorees and institutionalised children all struggled with peer relationships although adoptees got on better with siblings.
        
        Quality of care: close attachments with carers in institutions generally negates the effects of institutionalisation (Dontas et al, 1985).
        
        Disinhibited attachment: indiscriminate demand for attention, even with strangers, and separation anxiety despite no attachment (Tizard and Hodges, 1984 - 1989). Rutter (2006) explains this as an adaptive response to the lack of a consistent caregiver.
  - - - Anxiety
        
        The Weapon Effect (Loftus, 1979) particular attention on a weapon during a crime, so other info is lost eg. perpetrator's face.
        
        Loftus and Burns (1982) impaired recall when watching footage of a violent crime.
      - Leading Questions
        
        Loftus and Zanni (1975) car crash with broken headlight - fewer I don't know responses from leading question condition, as well as 10% more yes responses.
        
        Loftus and Palmer (1974) car crash with verbs - correlation between intensity of verb and speed estimate. More people in the smashed condition reported broken glass.
        
        Loftus (1979) more striking information is less susceptible to misleading information.
        
        Tomes and Katz (1997) more susceptible individuals are more misled by incorrect information and recall is poorer.
    - - Kohnken et al (1999) recall of more incorrect information while doing a cognitive interview.
      - Fisher et al (1990) Miami police found the interview effective.
      - Gieselman et al (1985) cognitive interview increases number of correct answers in comparison to standard interview and hypnosis.
      - Gieselman et al (1985) context reinstatement, report, changed perspective, reverse order.
      - Kebbell et al (1999) UK police found the technique useful but lots of incorrect info recalled. Police mostly used RE and CR but not so much the other two techniques.
      - Milne and Bull (2002) CR and RE are the most effective.
      - Gieselman (1999) not effective on children under 6 because they don't completely understand instructions.
- - - - Hydrogen bonding creates a surface tension (cohesion)
      - High latent heat of vaporisation (sweating uses body heat to evaporate water to make it a good way to cool down)
      - A dipolar molecule
      - Due to hydrogen bonding, water acts as a buffer against temperature changes (aquatic environment is very stable) and has a higher boiling point than expected.
      - Metabolism
        
        Very important material in photosynthesis.
        
        Lots of chemical reactions take place in aqueous conditions.
        
        Used in hydrolysis and produced in condensation reactions.
      - Solvent
        
        Urea and ammonia
        
        Inorganic ions and small hydrophilic molecules
        
        Dissolves oxygen and carbon dioxide
        
        Enzymes which have many uses in the body
      - Important Features
        
        Not easily compressed (turgor pressure and hydrostatic forces)
        
        Light rays can penetrate through - important for light to pass through the retina and for photosynthesis in plants.
        
        Important in homeostasis (evaporation)
    - - Lipids
        
        Triglycerides: 3 fatty acids and glycerol joined by ester bonds with condensation reaction. Low mass to energy ratio, insoluble (have no effect on water potential), high energy C-H bonds, release water when oxidised so good source of water for organisms in dry conditions.
        
        Phospholipids: hydrophilic phosphate and hydrophobic tail: glycerol, 2 fatty acids and phosphate. Forms the membrane of cells (phospholipid bilayer), form glycolipids by bonding with carbohydrates (good for cell recognition)
        
        Protection, insulation, energy store, waterproofing
        
        Test: add 5cm of ethanol to 2cm of sample in a clean dry test tube. Add 5cm of water and shake gently. Cloudy precipitate indicates presence of a lipid.
      - Proteins
        
        Secondary structure: the way the polypeptide chain is folded due to interactions of hydrogen bonds, forming an alpha helix or beta pleated sheet.
        
        Tertiary structure: hydrogen, disulfide, and ionic bonds contribute to form the protein into a compact structure.
        
        Primary structure: the order of amino acids in a polypeptide chain.
        
        Quarternary structure: the combination of multiple polypeptide chains and the addition of prosthetic groups into a large complex molecule.
        
        Formed from polypeptide chains made from amino acids joined by peptide bonds (OH bonded to NH2 group) to form water and a dipeptide.
        
        Biuret test - place sample in a test tube with equal volume of sodium hydroxide. Add a few drops of 0.05% copper (II) sulfate solution and gently mix. Purple colouration indicates presence of peptide bonds. If not, the solution remains blue
    - - Starch: alpha glucose joined by condensation reactions to form glycosidic bonds. Energy storage, compact, can be an unbranched coil or branched, insoluble.
      - Glycogen: energy store for animal cells. Similar to starch but shorter and more branching. Insoluble, no effect on water potential, compact, rapid breakdown due to high branching.
      - Cellulose: beta glucose unbranched chains with alternating orientations, cross links hydrogen bonds for stability, grouped to make microfibrils, prevents influx of water by adding structural integrity to plant cell wall.
  - - - They cause agglutination of the bacterial cells, making them less spread out within the body.
      - They serve as markers to stimulate the phagocyte to engulf the agglutinated cells.
      - Antibodies have a variable region which is complementary to a specific antigen.
      - Monoclonal Antibodies
    - - Phagocytosis
        
        Lysosomes containing lysozymes fuse with the phagosome to create a phagolysosome complex. The enzymes inside the lysosome break down the pathogen or abnormal cell.
        
        The broken down material is expelled from the cell through exocytosis. Useful substances such as proteins are released into the bloodstream. Waste materials are removed from the cell.
        
        The phagocyte reaches the target and engulfs it inside a vesicle made from the phospholipid bilayer. The vesicle moves into the cell.
        
        The phagocyte is attracted to the pathogen or abnormality by chemoattractants which are toxins or other chemicals released by dying cells or pathogens,
      - Cell-mediated
        
        Each type of T cell respond to a different antigen. They only respond to body cells with foreign antigens, not antigens that are free in body fluids.
        
        The process
        
        The receptors on a specific T helper cell fit the foreign antigen.
        
        This activates the T cell to divide into several more genetically identical T cells.
        
        Pathogens invade body cells or are taken in by phagocytes. The phagocyte places the antigens on its cell surface membrane.
        
        The T cells then:
        
        Stimulate phagocytes to engulf pathogens by phagocytosis.
        
        Stimulate B cells to divide and secrete antibodies.
        
        Activate cytotoxic T cells. These kill abnormal cells and pathogens by producing perforin, a chemical that makes holes in the cell-surface membrane. The cell then becomes permeable to all substances and dies.
        
        Develop into memory cells that enable a rapid response to the same antigens in the future.
        
        T cells distinguish self cells with non-self antigens on their surface. This can include phagocytes that display the antigens of a pathogen that has been engulfed, cancer cells, transplanted cells, and virally infected body cells that show viral antigens on the surface.
        
        Involves T lymphocytes
      - Humoral
        
        T helper cells bind to the processed antigens and stimulate the B cell to divide by mitosis and form many clones, all of which produce the complementary antibody to the foreign antigen. This is called clonal selection.
        
        Lots of pathogens also produce toxins that act as antigens.
        
        The antigen is processed by the B cell and appears on the cell surface membrane.
        
        Each clone of the B cell only produces one specific antibody - these are known as monoclonal antibodies.
        
        Each type of B cell has receptors on its surface that fit a specific antigen exactly.
        
        Plasma cells survive a few days but make around 2000 antibodies per second. They are responsible for the primary immune response.
        
        In the secondary response more antibodies are produced at a faster rate. This prevents any damage being done before the pathogen is destroyed.
        
        Memory cells can live for decades. They are responsible for the secondary immune response. When the antigen is detected at a later date they divide rapidly into more plasma cells and memory cells. The plasma cells then produce the antibodies necessary to destroy the pathogens.
      - The immune system can recognise pathogens, non-self material, abnormal cells such as cancer, and toxins produced by certain pathogens.
      - Non-specific defense mechanisms: skin barrier and phagocytosis
      - In a developing fetus, some lymphocytes have receptors that fit body cells, which die or are suppressed. In adults, when anti-self lymphocytes are produced, they undergo apoptosis before they are able to create an immune response to self-material.