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Biology (B5 - Coordination and Control (Plant Hormones (Plants produce…

- - - - Glucose levels in blood
      - Core body temperature
      - Water levels
    - - Chemical take longer to occur but are longer lasting
      - Nervous are quick acting - often a response to physical stimuli
    - - Receptor cells - Detect stimuli, can be either internal or external
      - Coordination centres - Such as brain or spinal chord
      - Effectors - Cells that carry out the action determined by the control centres
      - The exception to this is a reflex circuit, which relays the receptor signal straight to an effector. An example of this is flinching away from a hot object
  - - - Brain - signals go to the brain for a more deliberate reaction
      - Spinal Chord - used for more hard-wired reactions
    - - Motor neuron - convert the electrical impulse from the relay neuron to an action by the effector
      - Sensory neuron - convert stimuli into electrical impulses
      - Relay neuron - transfer signals from sensory neurons to motor neurons
    - - The brain is a collection of millions of neurons and controls complex behaviour
      - Components we need to know:
        
        Cerebral Cortex - memory and conscious thought
        
        Cerebellum - receives input from sensory systems and controls motor action based on that
        
        Medulla - connects the upper levels of the brain to the spinal chord
      - We can map the brain using MIR scanners and this allows us to more easily treat mental diseases and disorders
  - - - Pituitary Gland - Master gland. Found at the base of the brain.
      - Adrenal Gland - Produces adrenaline which increases reflexes etc. Found just above the kidneys.
      - Pancreas - Produces insulin to control blood glucose levels.
      - Ovaries - produce oestrogen and progesterone to control / guide the menstrual cycle.
      - Thyroid - Found in the neck. Produces hormones to monitor the body's metabolic rate.
      - Testes - Found in the scrotum. Produce testosterone which controls the rate of puberty and affects behaviour (anabolic steroid).
  - - - Type 1
        
        Pancreas is disfunctional - can't produce enough or any insulin.
        
        Leads to high blood glucose levels.
        
        Can be deadly in some cases.
        
        Have to take insulin injections.
      - Type 2
        
        Body has become desensitised to insulin / can't produce enough to keep up with glucose entering the blood.
        
        Leads to high blood glucose levels.
        
        Can be deadly.
        
        Have to take insulin injections / tablets.
      - Risk factors of diabetes include poor diet, low amounts of exercise and parents having had diabetes.
  - - - There is no control over water, ion or urea loss by the lungs or the skin.
      - Any excess water, urea or ions are removed from the blood by the kidneys and released as urine.
      - Water leaves the body either via the lungs during exhalation, or in sweat with ions and urea.
    - - The digestion of proteins produces amino acids.
      - Any excess of amino acids is removed by the liver. First they are deaminated to form ammonia. Ammonia is toxic so this is instantly converted to urea to be transferred to the urine.
    - - Any urea or unwanted ions are removed from the blood by the kidneys (mainly by the selective reabsorbtion of glucose, some ions and water) where they are then transferred into the urine in the bladder.
      - Any excess water is also removed this way.
    - - ADH is released form the pituitary gland if the blood is too concentrated.
      - The ADH makes more water be absorbed back into the blood from the kidney tubules.
      - This is done by a negative feedback loop.
  - - - FSH - Stimulates the follicles to mature an egg.
      - LH - Stimulates the release of an egg.
      - Oestrogen and progesterone control the lining of the uterus (it's thickness).
    - - Hormonal
        
        Oral contraceptives (the pill) the stop the production of FSH.
        
        Injections, implants or skin patches that release progesterone over long time frames to prevent the maturation of the egg.
        
        Intrauterine devices that release a hormone.
      - Non-hormonal
        
        Barrier methods (e.g. condoms).
        
        Intrauterine devices that prevent the implantation of an embryo.
        
        Spermicidal agents that kill the sperm before they can impregnate the egg,
        
        Abstaining from sex when she might be ovulating.
        
        Surgical methods for sterilisation.
- - - - The environment changes, selecting for different traits.
      - Members of a species that have these traits thrive, those without die off.
      - The new animals then get more chance to reproduce, becoming the dominant variation of their species.
      - The process repeats.
      - After millions of years, the phenotype of this evolutionary branch of this species will be so different from the original that they will no longer be able to breed with other members of the same species to produce fertile offspring. This means they have become a new species.
  - - - Imprint Fossils
        
        Imprints from feet or bones of animals left in the sediment layers as more was deposited over the top.
      - Replacement Fossils
        
        As organic tissue decayed, it was replaced by minerals.
      - Mineralisation Fossils
        
        Slowly, over millions of years, the solid parts of the remains of an animal are replaced by minerals as they dissolve. This leaves behind a mineral replica.
    - - Carried out experiments on plants.
      - Found that traits passed on depended on certain 'units' to be passed on.
      - Mendel's Laws
        
        1) The Law of Segregation: Each inherited trait is defined by a gene pair. Parental genes are randomly separated to the sex cells so that sex cells contain only one gene of the pair. Offspring therefore inherit one genetic allele from each parent when sex cells unite in fertilization.
        
        2) The Law of Independent Assortment: Genes for different traits are sorted separately from one another so that the inheritance of one trait is not dependent on the inheritance of another.
        
        3) The Law of Dominance: An organism with alternate forms of a gene will express the form that is dominant.
  - - - Selects for:
        
        Disease resistance
        
        Fruit size
        
        Fruit yield
        
        Seeded / seedlessness
    - - Selects for:
        
        More meat / milk yield
        
        Personality
        
        Ability to perform (competing horses)
        
        Appearance
  - - - Enzymes are used to isolate the gene to be implanted into the organism's genome.
      - This gene is inserted into a vector (usually a bacteria plasmid or a virus.
      - Genes are hence transferred into the cells of the organism. This occurs at early stages in their development so that they develop with the desired characteristics.
  - - - Cuttings - older, more simple method involves cutting the tips of branches or stems to grow new plants from.
      - Tissue Culture - a small group of cells is grown up in a petri dish to grow identical plants. Can be used to save rare and endangered plant species.
    - - Embryo Transplants - splitting the cells of an embryo up before any become specialised and then transplanting them into the host mothers.
      - Adult Cell Cloning - The nucleus is removed from an unfertilised egg cell and replaced with one from an adult cell. The cell is stimulated by an electric shock to start dividing to form an embryo. This is then implanted into the uterus of a host mother.
  - - - Some strains are resistant to antibiotics.
      - Those strains are able to survive when others die out.
      - These strains then thrive, creating a new colony in the host with a resistance to antibiotics.
      - These resistant strains spread faster as people aren't immune and there are no treatments for it. An example of this is MRSA.
    - - No prescriptions of antibiotics where they will be ineffective - such as viral infections.
      - Completing the course of antibiotics to ensure all bacteria have been killed.
      - Use of antibiotics in agriculture has now been restricted.
  - - - Protista
      - Fungi
      - Plantae
      - Animalia
      - Eubacteria
      - Acheobacteria
    - - Chordata
    - - Hominidae
    - - Homo Sapiens
    - - Mammalia
    - - Primates
    - - Homo
- - - - The organisms in an ecosystem are interdependent - a change to one affects many others.
      - An ecosystem is the interaction of the biotic components with the abiotic environment.
      - Comprised of many different levels.
    - - To survive and reproduce, organisms need to have a supply of materials from their surroundings.
      - Animals Compete For:
        
        Water
        
        Food
        
        Mates
        
        Territory
      - Plants Compete For:
        
        Light
        
        Water
        
        Space
        
        Ions from the soil
    - - Abiotic Factors
        
        Light intensity
        
        Temperature
        
        Moisture Levels
        
        Soil pH and minerals
        
        Wind intensity and direction
        
        CO2 levels for plants
        
        O2 levels for animals
      - Biotic Factors
        
        Availability of food
        
        New predators arrive
        
        New pathogens
        
        One species outcompeting another so the other cannot breed (insufficient numbers)
  - - - Physical
      - Behavioural
      - Functional
  - - - The Carbon Cycle
        
        Returns carbon from organisms into the atmosphere as CO2 to then be used in photosynthesis by plants.
      - The Water Cycle
        
        Provides fresh water to plants and animals on land before draining into the sea. Water is continuously evaporated and precipitated,
      - All materials in the living world are recycled to provide the building blocks of future organisms.
    - - Gardeners and farmers try to create optimal conditions for the decomposition of organic matter as this compost (waste produced through decomposition) can be used to allow plants to grow better.
      - Anaerobic decay produces methane gas so this can be used as fuel (produced in biogas generators).
      - Microorganisms break down waste matter into its constituent ions. This process requires energy so the microorganisms respire - producing CO2. The unneeded mineral ions are then expelled into the soil as waste products to be used by the ecosystem again.
    - - Temperature
      - Availability of H2O
      - Composition of atmospheric gases
  - - - A high biodiversity ensures the stability of an ecosystem by reducing the dependence of a species on any one other for food, shelter and maintenance of the environment.
      - Biodiversity is the variety of species in an ecosystem.
      - The future of the human race on Earth may well depend on us maintaining a high level of biodiversity on Earth.
    - - As the human population grows, the amount of waste (pollution) produced also grows.
      - Causes of Pollution
        
        Combustion
        
        Chemical Processes (Industry)
        
        Human wastefulness (landfill)
      - Types of Pollution
        
        Chemical - sewage, fertiliser or toxic chemicals in water.
        
        Atmospheric - smoke and acidic gases in the air.
        
        Physical - Landfill and toxic chemicals on land.
      - Effects of Pollution
        
        Kills plants and animals - reduces biodiversity.
        
        Cause health problems in humans.
        
        Costly to clean up.
      - The destruction of peat bogs for fertiliser and garden compost releases CO2 into the atmosphere.
    - - As levels of CO2 and CH4 in the atmosphere increase, the temperature increases. This is called the greenhouse effect.
      - This effect is causing global warming.
    - - Breeding programs for endangered species.
      - Protection and regeneration of rare habitats.
      - Reintroducing field margins and hedges to agricultural areas to provide a habitat forsmall local organisms.
      - Reduction of deforestation and CO2 emissions by some governments.
      - Recycling resources rather than dumping them on landfill.
  - - - Level 1 - Plants and algae that make their own food through photosynthesis.
      - Level 2 - Herbivores that eat the plants and algae (primary consumers).
      - Level 3 - Carnivores that eat herbivores (secondary consumers).
      - Level 4 - Carnivores that eat other carnivores (tertiary consumers.
      - Decomposers - Break down organic matter by secreting enzymes into the environment. Small soluble food molecules then diffuse into the organism.
    - - Used to represent the amount of the biomass (relatively) at each stage in the food chain.
      - Only approx. 10% of the biomass actually makes it to the next level in the food chain.
      - Loses of Biomass
        
        Faeces.
        
        CO2 and Water in respiration (lost as waste).
        
        Urea in urine.
        
        Part of the animal and plant that cannot be eaten such as bones.
        
        Biomass used to grow the organism.
  - - - The increasing birth rate means more demand in some countries.
      - Changing diets in developed countries mean scarce food resources are transported around the world.
      - New pests and pathogens affecting monocultural farming severely.
      - Environmental changes that affect yield from a year's harvest.
      - Cost of agricultural inputs.
      - Conflicts which have lead to the destruction of agricultural areas or the acquisition of produced food.
    - - This can be done by limiting their movement and controlling the temperature in their surroundings.
      - The efficiency of food production can be increased by restricting energy transfer from animals to the environment.
    - - GM crops will grow faster and have a higher yield as well as being more resistant to pathogens and droughts.
      - Fusarium is a fungus which can be grown on glucose syrup and will produce mycoprotein, which is a protein rich food suitable for vegetarians.
      - GM bacterial are used to produce insulin which can be used to treat people with diabetes.
- - - - Meiosis
        
        Produces non-identical cells (produces gametes).
        
        Produces sex cells in complex organisms (e.g. humans).
        
        Process
        
        Chromosomes double up.
        
        Half of the chromosomes go to one cell during the first stage of division, the other half go to the others.
        
        The cells then split again, so each of the four daughter cells has half the normal number of chromosomes.
        
        Ends with four gametes with 23 chromosomes each.
        
        Allows for genetic variation.
      - Binary Fission
        
        Produces identical cells.
        
        Occurs in bacteria and other prokaryotes.
        
        Process
        
        Everything doubles in cell.
        
        Half moves to one side, the rest moves to the other.
        
        The cell splits in half.
        
        Allows for far less genetic variation.
      - Mitosis
        
        Produces identical cells.
        
        Used by eukaryotes (multicellular ones).
        
        Process
        
        Doubles all subcellular structures.
        
        Chromosomes double and then split.
        
        Each half is pulled to either side of the parent cell.
        
        The cell membrane then splits the cell in half.
        
        The nuclei of the two daughter cells are reformed.
    - - Wider variation in offspring.
      - If environment changes then there is a greater chance the species will survive.
      - Natural selection can be sped up in other animals by humans.
    - - Only needs one parent
      - More energy efficient and time efficient.
      - Many identical offspring can be rapidly produced when conditions are favourable.
    - - DNA is a double helix shape made up of nucleotide pairs.
      - Nucleotides contain:
        
        A base
        
        A phosphate ion
        
        A sugar molecule
      - Genes
        
        Each gene codes for a specific protein.
        
        Every three base pairs in a gene codes for a specific amino acid.
        
        A gene is a small section of a strand of DNA.
      - The entire human genome has been mapped.
      - Terms
        
        Gamete - a sex cell
        
        Chromosome - a section of DNA (we have 46 in total)
        
        Gene - a code for a specific protein (also change our characteristics such as eye colour)
        
        Allele - varieties of genes
        
        Dominant - an allele that will override any recessive alleles
        
        Recessive - will be overridden by any dominant alleles
        
        Homozygous - only one allele of a gene
        
        Heterozygous - two alleles of a gene
        
        Genotype - the genetic makeup of an organism
        
        Phenotype - how the genetic and environmental factors affected an organism's development.
      - Protein Synthesis
        
        DNA splits in half.
        
        An enzyme cuts the section to be duplicated.
        
        The selected section is passed to a ribosome, which follows the rules of base pairing to create a complementary RNA strand.
        
        The RNA is then read and the correct amino acids fetched to add to the protein chain.
        
        Once complete, the protein folds up to form a unique shape specific to that protein.
      - C pairs with G and T pairs with A (and vice versa)
    - - Some characteristics are controlled by a single gene (fur colour in animals and red-green colour blindness in humans) and some are controlled by several.
      - Each gene has different forms called alleles.
      - Punnet Rules
        
        DD - Dominant expressed
        
        Dd - Dominant expressed
        
        dD - Dominant expressed
        
        dd - Recessive expressed
      - Ordinary human body cells contain 23 chromosome pairs.
      - Sex Chromosomes
        
        Female is XX
        
        Male is XY
    - - Some disorders are inherited through certain alleles.
      - Polydactyl disorder is caused by a dominant allele.
      - Cystic fibrosis is caused by a recessive allele.
      - Some social and moral stuff about embryo screening.