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IB Biology Y11, *THIS FORMULA CAN ALSO BE INVERTED TO CALCULATE THE ACTUAL…

- - - - Hybrids: offsprings produced by cross-breeding of 2 diff species --> are reproductively sterile
      - Population: a group of organisms of the same species living in the same area at the same time
        
        Community: group of populations living together & interacting with each other within a given area
        
        Ecosystem: A community and its abiotic environment (i.e. habitat)
        
        MESOCOSMS: enclosed env that allow a small part of a natural environment to be observed under controlled conditions
        
        3 main components for sustainability in an ecosystem:
        
        Energy availability: light from the sun provides the initial energy source for almost all communities
        
        Nutrient availability: saprotrophic decomposers ensure constant recycling of inorganic nutrients within env
        
        Recycling of wastes: bacteria detoxify harmful waste byproducts
      - Habitat:The environment in which a species normally lives/the location of a living organism
    - - Autotrophy - Self-feeding: Organisms which synthesize organic mol from inorganic sources
        
        Photoautotroph - photosynthesis: Makes organic comp using energy derived from the sun (solar energy)
        
        Chemoautotroph - chemosynthesis: Makes organic comp using energy derived form the oxidation of chemicals
        
        Autotrophs obtain inorganic nutrients from the abiotic environment - -> from the air/water/soil
        
        Simple inorganic substance/nutrients needed: carbon, nitrogen, hydrogen, oxygen and phosphorus
        
        Heterotrophs obtain some simple inorganic substances from env., but principally obtain their C and N from the organic mol produced by autotrophs
      - Heterotrophy - other source feeding: Organisms which obtain organic mol from other organisms (living, recently killed & detritus)
        
        Types - Classified by feeding pattern
        
        Detritivores - earthworms, woodlice: Ingests non-living OM like detritus and humus
        
        Detritus: dead, particulate OM – such as decaying organic material / fecal matter
        
        Humus: decaying leaf litter intermixed within the topsoil
        
        Saprotrophs - Decomposers like bacteria & fungi: Feeds on non-living OM by secreting digestive enzymes and absorbing the products
        
        Do not ingest food --> use enzymatic secretion to facilitate external digestion
        
        Bc saprotrophs facilitate breakdown of dead OM --> commonly referred to as decomposers
        
        Consumers - herbivores, carnivores, scavengers Ingests OM which is living or recently killed
        
        Herbivores: consumers that feed principally on plant matter
        
        Carnivores: consumers that feed principally on animal matter
        
        Omnivores: consumers that have a principle diet composed of both plant and animal matter
        
        Scavengers: consumer that principally feed on dead and decaying carcasses rather than hunting live prey
    - - Nutrient = material required by an organism. Include: carbon/nitrogen/phosphorus.
      - Autotrophs get inorganic nutrients from the air/water/soil --> convert into organic comp.
        
        Heterotrophs ingest these organic comp. --> use for growth and respiration, releasing inorganic byproducts
        
        Saprotrophs decompose the remains of dead organisms --> free inorganic materials into soil
        
        Return of inorganic nutrients to soil ensures the continual supply of raw materials for the autotrophs
  - - - Types
        
        Other gases including methane and nitrogen oxides have less impact
        
        Methane = emitted from waterlogged habitats (like marshes) and landfills – it is also a gaseous waste produced by ruminants
        
        Nitrogen oxides = released naturally by certain bacteria and also is emitted in the exhaust by certain vehicles
        
        Co2 and water vapour are the most significant greenhouse gases
        
        Co2 made by cell respiration & burning fossil fuels –> removed via photosynthesis & absorption by oceans
      - Impact of gas depends on:
        
        ability to absorb long wave radiation --> + capacity = greater impact per mol
        
        Gas conc. in atmosphere --> + conc = more impact. Conc depends on rate of release/persistance in atmosphere
      - Greenhouse effect: natural process whereby the atmos. behaves like a greenhouse to trap & retain heat --> ensures Earth maintains moderate temp needed by organisms to maintain life processes (homeostasis)
        
        Recent increases in atmospheric CO2: largely due to increases in the combustion of fossilised organic matter.
        Main activities that emit green house gasses: deforestation/increased farming & agriculture
    - - When oceans absorb atmospheric CO2, some of it will remain dissolved in a gaseous state but most will be chemically modified:
        
        Ocean -Atmosphere carbon dioxide exchange
        
        CO2 + H20 --> carbonic acid
        dissociates into hydrogen ions and hydrogen carbonate
        
        Acidification: H+ ions lower ocean pH
        H+ ions + free carbonate ions --> form more hydrogen carbonate
        
        There is - free carbonate ions in water = marine organisms - able to produce calcium carbonate (via calcification)
        
        Calcium carbonate used to form the hard exoskeleton of coral and is also present in the shells of certain molluscs
        
        Thus, + concc of dissolved CO2 threatens viability of coral reefs and certain molluscs
  - - - Sunlight: used by photoautotrophic animals (all green plants and some bacteria)
        
        Initial source of energy for almost all communities
        
        Light energy absorbed by photoautotrophs and is converted into chemical energy via photosynthesis
        
        Light energy used to make: organic comp from inorganic sources
        
        Heterotrophs ingest organic comp and break them down vua respiration --> derive ATP (chemical energy) for metabolic process
    - - Chemical energy stored in carbon comp flows through food chains by feeding:
        
        Trophic levels (TL): position an organism occupies within feeding sequence
        
        1 TL: Producers - E enters ecosystem as sun --> converted into chemical E by producers through photosynthesis.
        
        2 TL: Primary Consumers - feed on producers
        
        Further Consumers occupy subsequent trophic levels:
        TL 3: Secondary Consumer
        TL 4: Tertiary Consumer
        
        Food Chain: shows linear feeding relationships between species in a community
        
        Arrows = transfer of energy & matter through feeding (point in direction of E flow)
        
        1 organism is always a producer, followed by consumers
    - - Not all E is transferred through feeding --> chemical E lost by:
        
        excretion through faeces
        
        unconsumed/uneaten portions of food
        
        Heat (byproduct of exothermic reactions in organisms) --> heat lost in ecosystem not recycled --> thus ecosystems require continues entry of E from external sources like sun
      - E stored in organic mol --> released by cell respiration to produce ATP (used for metabolic reactions for growth & homeostasis) & byproduct heat (thermal E --> organisms ccannot turn heat to other forms of usable E)
    - - E losses between trophic levels restrict length of food chains & biomass of higher trophic levels
        
        E transformations are ~10% efficient, ~90% of available E lost between trophic levels
        
        Biomass: total mass of a group of organisms – consisting of the carbon compounds contained in the cells and tissues
        
        It diminishes along food chains with loss of CO2, H20 and waste products to the environment
    - - units of energy per area per time: kJ m–2 year–1)
      - Characteristic:
        
        never appear inverted as E stored in one source is always lost upon transfer
        
        Each level is roughly 1/10 the size of the preceding level (E transformations = ~10% efficient)
        
        Bottom level = producers
        
        Subsequent levels = consumers
  - - - Autotrophs convert inorganic CO2 into organic comp. (carbs, lipids, proteins) via photosynthesis
        
        Autotrophs use Co2 for photosynthesis --> levels of co2 within organism should always be low --> co2 should always be at a higher conc in atmosph. (or water)
        
        Concentration gradient ensures co2 will passively diffuse into the autotrophic organism as required
        
        In aquatic producers, CO2 can usually diffuse directly into the autotroph; whereas in terrestrial plants, diffusion occurs at stomata
        
        Compensation point: at which the net co2 assimilation is zero (intake = output) --> this is when uptake of CO2 by photosynthesis is balanced by the production of CO2 by respiration
        
        Similarly, the amount of carbon dioxide in the environment will be determined by the level of these two processes:
        
        more net photosynthesis than cell respiration occuring in biosphere = atmospheric carbon dioxide levels drop
        
        more net respiration than overall photosynthesis occuring = atmospheric carbon dioxide levels should increase
      - Heterotrophs cannot synthesise their own organic mol. --> instead obtain carbon comp via feeding
        
        All organisms produce the chemical E (ATP) required to power metabolic processes via the cell respiration
        
        Respiration = breakdown of organic mol (e.g. sugars) & produces co2 as by-product
        
        Build up of CO2 in respiring tissues creates concentration gradient --> removed by passive diffusion
    - - Methanogens: archaean microorganisms that produce CH4 as a metabolic by-product in anaerobic conditions
        
        Anaerobic conditions:
        
        Wetlands
        
        Marine sediments
        
        Digestive tract of ruminant animals
- - - - Oxygen
      - link reaction, citric acid cycle (or Krebs cycle) and the electron transport chain
      - LARGER ATP FIELD
    - - NO Oxygen
      - ANIMALS: pyruvate is converted into lactic acid
      - PLANTS & YEASTS: pyruvate converted into ethanol & Carbon Dioxide
      - SMALLER ATP FIELD
  - - - CHLOROPHYLL
        
        Green light reflected, Blue & red are the optimum
        
        green pigment found in photosynthetic organisms that is responsible for light absorption
    - - Indicates the wavelengths of light absorbed by each pigment (e.g. chlorophyll)
    - - Indicates the overall rate of photosynthesis at each wavelength of light
    - - The different components of the mixture travel at different speeds, causing them to separate
      - A retardation factor can then be calculated (Rf value = distance component travels ÷ distance solvent travels
      - An experimental technique by which mixtures can be separated. A mixture is dissolved in a fluid & passed through a static material.
    - - Temperature
        
        Light Intensity
        
        Carbon Dioxide Concentration
  - - - Enzymes
        
        a globular protein which acts as a biological catalyst by speeding up the rate of a chemical reaction
        
        The active site is the region on the surface of the enzyme which binds to the substrate molecule. It complements the substrate in terms of shape and chemical properties, so a particular substrate has to bind to the enzyme.
        
        MODELS OF ACTION
        
        Lock & Key model
        
        Induced Fit Model
        
        Biofuels
        
        Medicine
        
        Biotechnology
        
        Food production
        
        Textiles
        
        Paper
      - Amino Acids structure
        
        Amino acids all share a common basic structure, with a central carbon atom bound to:
        
        An amine group (NH2)
        
        A carboxylic acid group (COOH)
        
        A hydrogen atom (H)
        
        A variable side chain (R)
      - Proteins are comprised of long chains of recurring amino acids
        
        Amino acids are joined together on the ribosome by peptide bonds to form polypeptides.
        
        This condensation reactions can form the primary, secondary, tertiary or quartenary structure of proteins
      - DENATURATION
        
        A structural change in a protein that results in the loss (usually permanent) of its biological properties,
        because the way a protein folds determines its function, any change or abrogation of the tertiary structure will alter its activity.
        
        Can happen due to too extreme pH or temperature values
      - PROTEOME
        
        The totality of proteins expressed within a cell, tissue or organism at a certain time. The proteome of any given individual will be unique, as protein expression patterns are determined by an individual’s genes
      - FUNCTIONS
        
        Structure – e.g. collagen, spider silk
        
        Hormones – e.g. insulin, glucagon
        
        Immunity – e.g. immunoglobulins
        
        Transport – e.g. haemoglobin
        
        Sensation – e.g. rhodopsin
        
        Movement – e.g. actin, myosin
        
        Enzymes – e.g. Rubisco, catalase
    - - FATTY ACIDS
        
        Long hydrocarbon chains that are found in certain types of lipids (triglycerides & phospholipids)
        
        Polyunsaturated (+1 double bond)
        
        Unsaturated (1 Double bond)
        
        Saturated (No double bonds)
      - TRYGLICERIDES
        
        largest class of lipids and function primarily as long-term energy storage molecules
        Animals tend to store triglycerides as fats (solid), while plants tend to store triglycerides as oils (liquid)
      - HEALTH RISKS
        
        High cholesterol levels
        
        Discfunctioning cells
        
        Clogging of arteries
        
        Coronary Heart Disease
      - BODY MASS INDEX
        
        Mass in kg/(height in m^2)
    - - Disaccharides
        
        Carbons 1 & 4 participate in reaction using E to form oxygen bridge/glycosidic bond.
        
        formed by the bonding of 2 monosaccharides via a condensation reaction, to form a glycosidic bond and water as a by-product.
      - Monosacharides
        
        Glucose
        
        Alpha Glucose has the hydrocyl goup of C1 below
        
        Starch
        
        Energy storage found in plants
        
        Amylose
        
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        Amylopectin
        
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        Glycogen
        
        extra 1-6 Hydrogen bonds for branch
        
        Branched (~per 10 subunits)
        
        Main Energy storage of glucose in animals & humans.
        
        Beta-Glucose has the hydrohyl group of C1 above
        
        Cellulose
        
        Linear and Straight Structure
        
        Indigestible (bc of β-glucose) for most animals → lack enzyme
      - POLYSACCHARIDES
        
        cellulose, glycogen, starch
      - Quick source of energy
    - - DNA
        
        DNA replication
        
        is a semi-conservative process, because when a new double-stranded DNA molecule is formed; One strand will be newly synthesised & one strand will be from the original template molecule
        
        ENZYMES
        
        HELICASE
        
        unwinds the double helix and separates the two polynucleotide strands by breaking the hydrogen bonds that exist between complementary base pairs
        
        DNA POLYMERASE
        
        synthesises new strands from the two parental template strands. Free deoxynucleoside triphosphates (nucleotides with 3 phosphate groups) align opposite their complementary base partner. DNA polymerase cleaves the two excess phosphates and uses the energy released to link the nucleotide to the new strand
        
        The polymerase chain reaction (PCR)
        
        an artificial method of replicating DNA under laboratory conditions
        
        TRANSCRIPTION
        
        process by which an RNA sequence is produced from a DNA template
        
        RNA polymerase separates DNA strands and synthesises a complementary RNA copy from one of the DNA strands. When the DNA strands are separated, ribonucleoside triphosphates align opposite their exposed complementary base partner. RNA polymerase removes the additional phosphate groups and uses the energy from this cleavage to covalently join the nucleotide to the growing sequence. Once the RNA sequence has been synthesised, RNA polymerase detaches from the DNA molecule and the double helix reforms.
        
        TRANSLATION
        
        process of protein synthesis in which the genetic information encoded in mRNA is translated into a sequence of amino acids on a polypeptide chain
        
        Ribosomes bind to mRNA in the cytoplasm and move along the molecule in a 5’ – 3’ direction until it reaches a start codon (AUG). Anticodons on tRNA molecules align opposite appropriate codons according to complementary base pairing (e.g. AUG = UAC). Each tRNA molecule carries a specific amino acid (according to the genetic code). Ribosomes catalyse the formation of peptide bonds between adjacent amino acids (via condensation reactions). The ribosome moves along the mRNA molecule synthesising a polypeptide chain until it reaches a stop codon. At this point translation ceases and the polypeptide chain is released
        
        more stable double stranded form that stores the genetic blueprint for cells
        
        Deoxyribose
        
        Has Thymine
        
        Double Stranded
        
        Two polynucleotide chains of DNA are held together via hydrogen bonding between complementary nitrogenous bases
      - RNA
        
        more versatile single stranded form that transfers the genetic information for decoding
        
        Ribose
        
        Has Uracil
        
        Single Stranded
      - Chains of nucleotides
      - CODONS
        
        a sequence of three nucleotides which together form a unit of genetic code in a DNA or RNA molecule. Each codon codes for one amino acid with a polypeptide chain
        
        64 codon possibilities (43)
      - GENETIC CODE
        
        the set of rules by which information encoded within mRNA sequences is converted into amino acid sequences (polypeptides) by living cells. The genetic code identifies the corresponding amino acid for each codon combination
    - - Structure
        
        Covalent bond, as there is a shari of electrons, but not shared equally between atoms.
        
        Resulting in Water as a polar molecule because of its slight charge difference across the different poles of the molecule.
        
        Oxygen → higher electronegativity → attracts electrons + strongly → oxygen atom slightly negative (δ–) → negative pole
        
        Hydrogen → lower electronegativity → attracts electrons - strongly → hydrogen atoms slightly positive (δ+) → positive pole
      - Properties
        
        Cohesion
        
        Binding of water molecules through hydrogen bonds.
        
        enables surface tension as in liquid resists low external forces
        
        Water’s Dipolarity allows hydrogen bonding between the molecules. As the
        
        Adhesion
        
        Binding of water molecules with other polar substances by hydrogen bonds.
        
        → enables Capillary action as it allows water to flow against gravity
        
        Dipolarity: Allows it to to attract other polar substances (+ or -) by hydrogen bonding.
        
        Thermal
        
        Has Higher specific heat capacity (Energy needed to raise 1°C 1g)
        
        → High boiling point. Water can absorb much heat before changing state (good temperature regulator)
        
        Hydrogen Bonds: For water to evaporate, its particles should start dispersing and moving quicker. For this to happen, + Energy is required to break the H-bonds. → harder
        
        Solvent
        
        Can dissolve any substance hydrophilic substance (either contains ions or electronegative (polar) atoms) → considered the universal solvent.
        
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        Density
        
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- - - - Fluid Mosaic Model
        
        FLUID
        
        Phospholipid bilayer is viscous & phospholipids can move position
        
        MOSAIC
        
        Phospholipid bilayer is embedded with proteins, = mosaic of components
    - - Phospholipids held by weak hydrophobic interactions
      - Integral proteins (for transport, enzymatic activity & intercellular joining)
      - Peripheral Proteins (cell to cell recognition, attachment)
      - Cholesterol (reduces membrane fluidity)
    - - SIMPLE DIFFUSION
        
        OSMOSIS
        
        FACILITATED DIFFUSION
        
        ACTIVE TRANSPORT
        
        Active transport of particles through a p.p membrane carried out by globular or pump proteins in the membrane, against the concentration gradient, using ATP.
        
        Passive movement of particles through a p.p. membrane down a concentration gradient, through channels with proteins embedded in the phospholipid bilayer
        
        Passive movement of water molecules across a semi permeable membrane from a region of ↓ solution concentration to a region of ↑ solution conc., due to differences in conc. of substances dissolved in water (solutes), until equilibrium is reached
        
        Passive mov. of small hydrophobic particles ↓ a concentration gradient through a partially permeable membrane, w/out help from other substance (proteins). Driven by random movement, until reaches an equilibrium, even distribution (no net mov. of molec. from either side).
  - - - Reproduction
        
        Sensitivity
        
        Homeostasis
        
        Excretion
        
        Nutrition
        
        Growth
        
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        Living things exchange materials and gases with the environment
        
        Living things exhibit the removal of waste products
        
        Living things maintain a stable internal environment
        
        Living things are responsive to internal and external stimuli
        
        Living things produce offspring, either sexually or asexually
      - Living things undertake essential chemical reactions
  - - - If the rate of exchange decreases --> Cell can't get waste products out fast enough --> Cell devides in order not to die
  - - - Organ systems collectively carry out the life functions of the complete organism
        
        Organs that interact may form organ systems capable of carrying out specific body functions
        
        Organs are then formed from the functional grouping of multiple tissues
        
        Cells may be grouped together to form tissues
  - - - All cells of an organism share an identical genome – each cell contains the entire set of genetic instructions for that organism
        
        The activation of different instructions (genes) within a given cell by chemical signals will cause it to differentiate
        
        Gene Packing
        
        Within the nucleus of a eukaryotic cell, DNA is packaged with proteins to form chromatin
        
        Active genes are packaged in an expanded form called euchromatin that is accessible to transcriptional machinery
        
        Inactive genes are typically packaged in a more condensed form called heterochromatin (saves space, not transcribed)
  - - - Interphase
        
        Prophase
        
        Metaphase
        
        Anaphase
        
        Telophase
        
        Once the 2 chromosome sets arrive at poles, spindle fibres dissolve. Chromosomes decondense (no longer visible under light microscope). Nuclear membranes reform around each chromosome set. Cytokinesis occurs concurrently, splitting the cell into 2.
        
        Contraction of spindle fibres. Sister chromatids separate, & are now considered an individual chromosome. The chromosomes move to the opposite poles of the cell
        
        Microtubule spindle fibres from both centrosomes connect to centromere of chromosomes. Chromosomes align in the metaphase plate
        
        DNA supercoils & chromosomes condense & comprise into chromatids, centrosomes move to opposite poles & form spindle fibers, nucleus dissolves.
        
        DNA as uncondensed chromatin, in nucleus, organelles duplicated, cell enlarged.
      - MITOTIC INDEX
        
        ratio between the number of cells in mitosis and the total number of cells
    - - ANIMAL
        
        Contractile ring of microfilaments cause constriction at all centre
      - PLANT
        
        Vesicles fuse to form a cell plate
    - - A family of regulatory proteins that control the progression of the cell cycle
  - - - Self Renewal – They can continuously divide and replicate
      - Potency – They have the capacity to differentiate into specialised cell types
        
        They can have different types of potencies:
        
        Totipotent – Can form any cell type, as well as extra-embryonic (placental) tissue (e.g. zygote)
        
        Pluripotent – Can form any cell type (e.g. embryonic stem cells)
        
        Multipotent – Can differentiate into a number of closely related cell types (e.g. haematopoeitic adult stem cells)
        
        Unipotent – Can not differentiate, but are capable of self renewal (e.g. progenitor cells, muscle stem cells)