Biology - Unit 1

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  • Biology - Unit 1
    • 4. Adaptation for Survival
      • 4.1: Adapt and Survive - All organisms need a supply of materials to survive and reproduce. They get these from their surroundings and other living organisms; organisms are adapted to survive in the conditions which they normally live.
        • NOTE: Microorganisms have a wide range of adaptations which enable some of them to live in extreme conditions.
      • 4.2: Adaption in Animals - Adaptations help organisms survive in their environment; animals in cold areas are usually large, with a small SA:Volume ratio; animals in hot dry areas may have a large SA:Volume ratio; fur, hair and skin may change colour, thickness and quantity during different seasons.
      • 4.3: Adaption in Plants - Plants lose water vapour from the leaf surface; to survive in dry conditions plants have adaptations to reduce the SA of leaves, to develop tissues which store water, and extensive root systems
      • 4.4: Competition in Animals - Animals often compete with each other for food, territory, dominance and mates; well adapted animals are good competitors.
        • NOTE: Some animals compete by simply evolving better defenses (usually smaller insects and reptiles further down the food chain)
      • 4.5: Competition in Plants - Plants compete with each other for light, water, mineral ions and space; well adapted plants are good competitors.
      • 4.6: Survival - Organisms that have the best adaptations have a higher rate of survival and greater chance of reproduction. This is called 'survival of the fittest.'
        • NOTE: Contrary to popular belief'survival of the fittest' was not coined by Charles Darwin, but by Herbert Spencer after reading Darwin's magnum opus 'On The Origin of Species.'
      • 4.7: Measuring Environmental Change - Animals and Plants may be adapted to cope with specific features of their environment: eg. thorns, poisons, warning colours; environmental changes may be caused by living or non-living things; environmental changes can be measured using non-living indicators; living organisms can be used as indicators of pollution.
      • 4.8: The Impact of Change - Both living and non-living factors can causing changes in the environment that affects the distribution of living organisms; reproducible data on the effect of environmental change are not always easy to collect or interpret.
    • 3. Medicine and Drugs
      • 3.1: Developing new medicines - New drugs have to be tested thoroughly before they can be sold as medicines; Drugs are tested to see if they work, to find out if they are toxic and to see if they cause (harmful) side effects.
        • NOTE: New drugs have to be tested in a specific order - first in a computer model or on culture skin cells, then on small animals (rats and mice), then on larger animals which bear resemblance biologically to humans (apes and pigs), then on healthy volunteers, then on a select group of patients. This is where double-blind trials begin, with 50% of the patients and doctors unknowingly being given a false drug which has no effect (this way the developers can measure the placebo effect of the drug). After tests on larger groups of patients, it is licensed for sale, with a 20 year period for the company to make back the average £3 million spent developing it before it can be reproduced by other companies.
        • NOTE: Thalidomide is an example of an untested drug causing widespread damage. Developed in the 1950s as a sleeping pill, doctors realised that it worked to cure morning sickness in pregnant women and so thousands of women were prescribed it. Soon after, in the late 50s and early 60s, people noticed the disturbing rise in babies born with limb deformities among women who had taken thalidomide. It was instantly banned and new drug testing measures were forced into effect worldwide.
      • 3.2: How Effective are Medicines - Statins are drugs which lower blood cholestrol levels - their use has lowered cardiovascular disease in the population by over 40%: Double-blind trials should be used to check if both non-prescribed and prescribed drugs actually work
      • 3.3: Drugs - 'chemicals which alter the body's chemistry, nervous state and internal conditions; animals can become addicted to a drug if they use it too often; both legal (eg. alcohol, tobacco) and illegal (eg. cocaine, heroin) drugs may have a harmful effect on the body; illegal drugs are separated by strength and danger into Class C (eg. Valium), Class B (eg. cannabis), and Class A (eg. cocaine)
        • NOTE: Cannabis is one of the most debated legal drugs in the UK and US. It has proven medicinal benefits but can also hinder mental development and cause depression if taken too young. Some US states have legalised the sale and purchase of cannabis for medicinal uses, hoping that it will ensure the purity and safety of goods, and also drive it off the highly profitable black market.
      • 3.4: Legal Drugs - Many recreational drugs cause changes in the brain and nervous system; the impact of legal drugs can be more damaging as it is easily available and there is less negative stigma attached in certain countries (*cough-Scotland-cough*).
        • NOTE: The definition of recreational drugs is any drug, legal or illegal, consumed for non-medical reasons.
      • 3.5: Cannabis and Gateway Drugs - There is evidence that cannabis causes mental illness in young people; as it is still illlegal in the UK it must be bought from dealers, putting the smoker in contact with 'hard' drugs.
      • £.6: Drugs in Sport - Some athletes use drugs such as steroids to make their performance better; it is considered unethical and banned by most sports.
        • NOTE: Many competitions and organisations hold spot drug tests before, during and after events to try and catch out cheaters. They can be disqualified instantly and banned for either a fixed term or life.
        • NOTE: Any athlete who is later discovered to have cheated can be retrospectively disqualified and stripped of any titles - eg. Lance Armstrong's seven consecutive Tour de France titles.
    • 5. Energy and Biomass
      • 5.1: Pyramids of Biomass - The Sun's light energy is captured by plants and algae in photosynthesis to make new biomass; biomass is the dry organic matter of living mattering in organisms; the biomass at each stage of the food chain is less than the previous stage. This forms a pyramid as the chain grows longer.
        • NOTE: Radiation from Sol is the primary source of energy for all living things on Earth and the rest of the Sol System. Other sources include geothermal (from inside a planet) and extrasolar, such as passing supernovae.
      • 5.2: Energy Transfers – The amount of biomass and energy gets less at each stage of a food chain; This is because some material and energy are always lost in waste or respiration. Much of the energy is transferred to the surroundings as heat.
      • 5.3: Decay Process - Living organisms remove materials from the environment as they grow. They return them when they die through the action of decomposition; materials decay because they are broken down by microorganisms - which work faster in warm, moist conditions. Many also need oxygen.
      • 5.4: The Carbon Cycle - The constant flow of carbon in nature is known as the carbon cycle; carbon dioxide is removed from the atmosphere by photosynthesis. It is returned by respiration (both animal and plant) and the combustion of plants or fossil fuels.
        • NOTE: The carbon dioxide stored away in fossil fuels such as coal and peat is from millions of years ago, and therefore is of a far higher percentage and purity.
      • 5.5: Recycling Organic Waste - Materials made from organic matter (eg. wood, cotton, food) is easily biodegradable and therefore can (AND SHOULD) be recycled; a common form of organic recycling is composting.
        • NOTE: Non-organic materials such as metals and plastics can be recycled but not organically.
    • 6. Variation, Reproduction and New Technology
      • 6.1: Inheritance - Parents pass on genetic information to their offspring in the sex cells (gametes); genetic information is found in the nucleus of every cell; different genes or combinations of genes control different characteristics.
        • NOTE: The nucleus contains 23 pairs of chromosones, which are double helix strands of D(eoxyribo) N(ucleic) A(cid). There are four types of gene - guanine, adenine, thymine, and cytosine
      • 6.2: Types of Reproduction -  In asexual reproduction there is no joining of gametes and only one parent. There is no genetic variation in the offspring; the genetically identical offspring of asexual reproduction are clones; in sexual reproduction  male and female gametes join. The mixture of two genetic strands leads to variation in the offspring, meaning no two strands are the same.
      • 6.4: Cloning - New plant clones can be produced quickly and repetitively by taking cuttings from mature plants which creates genetically identical plants; a modern technique involves tissue culture, where cells from the original plant are removed and grown as microplants - this allows hundreds of identical plants from a single; dividing embryos in the early stages is a way of creating animal clones which are effectively identical.
      • 6.5: Adult Cell Cloning - The nucleus is removed from a cell of the desired animal and fused by electricity into an empty ovum with its information removed; the embryo is implanted into a surrogate mother and the offspring will be an identical clone of the first animal.
        • NOTE: Extinct animals such as the woolly mammoth, Tasmanian tiger, Pyrenean ibex are all targets for reintroduction by cloning from preserved samples.
        • NOTE: The technology, knowledge and expertise is now available for human clones to become feasible but due to opposition from moral and ethical standpoints it is currently illegal.
        • NOTE: The first (and most famous) mammal to be cloned using adult cell cloning was Dolly the Sheep in 1997.
      • 6.7: Making Choices About Technology - There are many economic, social and ethical issues surrounding GE, cloning and general advancements in biological technology. With the increasing funds and technology now available to scientists and research companies, along with overpopulation, greater disease and less food, genetics is set to become a hugely divisive issue in the near future.
      • 6.3: Genetic and Environmental Changes - The different characteristics between individuals of a family or species may be due to genetic causes, environmental causes, or a mixture of both; the comparison of upbringing circumstances with genetic basecode is called 'nature vs. nurture.'
        • NOTE: The play 'Blood Brothers' by Russel is one example of the nature vs. nurture investigation.
    • 1. Keeping Healthy
      • 1.1: Diet and Exercise - Seven nutrition groups: Protein, Fat, Carbohydrate, Sugar, Vitamins, Minerals, Fibre.
        • NOTE: Metabolic rate is the rate at which respiration reactions take place in cells. It can be affected by inherited factors, mass, diet and age.
        • NOTE: If Energy taken in is less than the Energy used in exercise then the person will lose mass.
      • 1.2: Mass problems - If Energy taken in is greater than the Energy used then the person will gain mass.
        • NOTE: People with a BMI (Mass over Height sq,) of higher than 30 are considered obese; Obesity can lead to problems such as Type 2 diabetes.
      • 1.3: Inheritance, Exercise and Health - Inherited factors include metabolic rate and cholesterol levels.
        • NOTE: Exercise has a direct effect on health due to it using up excess energy.
      • 1.5: Defence Mechanisms - The body prevents most pathogens from even entering; pathogens which enter the body through inhalation, being consumed or by blood can be killed and destroyed by white-blood cells.
        • NOTE: White blood cells use three methods of defence: releasing anti-toxins to combat the toxin molecules created by bacteria, releasing anti-bodies which neutralise the antigens of bacteria, or by engulfing and digesting the bacteria.
      • 1.6: Using Drugs to Treat Disease - Not all medicines kill the pathogens, some only neutralise the symptoms of disease; antibiotics cure bacterial infections by killing the bacteria.
        • NOTE: ANTIBIOTICS DO NOT WORK ON VIRUSES (SUCH AS COLD AND FLU) BECAUSE THE VIRUS IS INSIDE THE CELL ITSELF MEANING IT IS PROTECTED.
      • 1.7: Growing and Investigating Bacteria - Bacteria can be grown under control conditions on agar jelly; all materials and equipment must be sterilised so that unwanted microorganisms do not infect the culture; uncontaminated cultures can be used to investigate the effect of anti-biotics and disinfectants on the bacteria.
      • 1.9: Immunity - A wide range of vaccines are given to immunise people against disease - both bacterial and viral; vaccines contain dead or inactive pathogens, allowing the white blood cells to recognise and develop anti-bodies for that pathogen.
        • NOTE: The first vaccines were developed by Jenner, who noticed that milkmaids who caught cowpox from the cattle they milked would never develop the deadlier smallpox. He used this knowledge to deliberately infect test subjects with cowpox - they then did not catch smallpox, proving he was correct.
        • NOTE: 'Herd immunity' is when an entire population save a few are immunised against a disease. As everyone around them is immunised, they have no chance of coming into contact with the disease. The few may not be immunised because of immuno-compromisation or because of personal choice.
        • NOTE: Some vaccines are now bundled together, such as the MMR vaccine. This saves time and money but also puts some people at risk from reaction with one of the three pathogens, meaning they cannot be immunised against the other two.
      • 1.10: Dealing with Disease - Vaccination and herd immunity protects individuals and society against the effects of disease; the treatment of disease has changed as our understanding of immunity and antibiotics has increased.
        • Some disease have been eradicated completely from the world thanks to global immunisation and destruction campaigns by the UN and WHO. Smallpox (1979) and rinderpest (2011) have been declared extinct, campaigns against polio, yaws, GWD and malaria  are ongoing, and two former programs targeting hookworm and yellow fever were failures. Five more diseases are possible targets - measles, mumps, rubella elephantis and cysticercosis.
      • 1.8: Changing Pathogens - If a pathogen changes by mutation, the new strain may spread rapidly; some bacteria have developed resistance to anti-biotics by natural selection (eg. MRSA). This means that anti-biotics have no effect on them, meaning they are a huge killer.
        • NOTE: An outbreak within a country is known as an EPIDEMIC (eg. Measles); An international outbreak is a PANDEMIC (eg. MERS, Swine flu).
    • 2. Coordination and Control
      • 2.1: Responding to Change - The nervous system allows animals to react to surroundings and coordinates behaviour; receptors detect external stimuli; electrical impulses pass to the brain along neurons; the brain coordinates responses.
      • 2.2: Reflex Actions - Reflex actions are rapid responses to a stimulus; they bypass the brain and conscious CNS to increase reaction times.
        • NOTE: The C(entral) N(ervous) S(ystem) is the collective of nerves running along the spine, neck and brain, connecting all the nerves in the body.
      • 2.3: Hormones - The menstrual cycle takes 28 days with ovulation about 14 days into the cycle; the cycle is controlled by three hormones - FSH, Oestrogen; LH
      • 2.4: Artificial Control - Contraceptive pills contain oestrogen and/or progesterone to inhibit FSH; FSH can be given to a woman to help her produce eggs.
      • 2.5: Controlling Conditions - It is important that internal conditions of the body (the Core) are kept within certain limits; the nervous system, hormones and glands control this; water and mineral ion content as well as temp and blood sugar level are all carefully controlled.
      • 2.6: Hormones and Plant Growth - Plants respond to light (phototropism), gravity (geotropism) and moisture; shoots grow towards light and away from gravity's pull; roots grow towards gravity and water; hormones such as auxin cause these changes by lengthening or shortening one side of the plant; plant hormones have uses in agriculture and horticulture.
      • 2.7: Using Hormones - It is evaluate the advantages and disadvantages of using hormones to control fertility; the incorrect use of plant hormones can damage the enviromnment.
    • 7. Evolution
      • 7.1: Theories of Evolution - All species of living organisms have evolved from simple life forms, starting over 4 billion years ago; Darwin's theory states that evolution takes place by natural selection and 'survival of the fittest' (although this was Spencer's idea).
      • 7.3: Natural Selection - Natural selection works because only the healthiest, best adapted animals survive to breed and produce offspring; Adaptations occur because of mutated genes, sometimes giving the mutant a greater advantage.
        • NOTE: Darwin and Spencer knew nothing of genetics and DNA, which would not be fully comprehended for another 100 years, but knew that Lemarck's idea of inherited characteristics was visibly wrong and therefore something else must be causing evolution.
      • 7.4: Classification and Evolution - Organisms can be classified into groups and families by comparing their similarities and differences; Classification helps to highlight evolutionary and ecological relationships
        • NOTE: Living organisms today are either single-celled (Bacterial) or multi-cellular (Eukaryota). Eukaryota can be roughly classed into five kingdoms: Plants, Animals, Fungi, Protozoa and Protoctista, with Animals being the dominant and only sentient life-forms.
      • 7.2: Acceptance of Darwin's Ideas - 'On The Origin of Species' and later 'The Descent of Man' both proved contraversial, provoking much opposition from critics, supporters of Lemarck, and above all, many far-right Church groups (although some liberals such as Baden Powell were supportive).
        • NOTE: Darwin was publicly challenged in the 1860 Oxford debate, with T.H. Huxley, ****** and Brodie on one side and Richard Owen, the Bishop of Oxford Samuel Wilberforce and FitzRoy (the Captain of the Beagle, who had invited Darwin in the first place) against, made famous by Wilberforce's quip asking Huxley whether he was descended from apes on his mother's side or his father's.
        • NOTE: Darwin was even denied a knighthood because of dissent among Queen Victoria's clerical advisers when his name was mooted for the honouts list.
  • 1.8: Changing Pathogens - If a pathogen changes by mutation, the new strain may spread rapidly; some bacteria have developed resistance to anti-biotics by natural selection (eg. MRSA). This means that anti-biotics have no effect on them, meaning they are a huge killer.
    • NOTE: An outbreak within a country is known as an EPIDEMIC (eg. Measles); An international outbreak is a PANDEMIC (eg. MERS, Swine flu).
  • 7.2: Acceptance of Darwin's Ideas - 'On The Origin of Species' and later 'The Descent of Man' both proved contraversial, provoking much opposition from critics, supporters of Lemarck, and above all, many far-right Church groups (although some liberals such as Baden Powell were supportive).
    • NOTE: Darwin was publicly challenged in the 1860 Oxford debate, with T.H. Huxley, ****** and Brodie on one side and Richard Owen, the Bishop of Oxford Samuel Wilberforce and FitzRoy (the Captain of the Beagle, who had invited Darwin in the first place) against, made famous by Wilberforce's quip asking Huxley whether he was descended from apes on his mother's side or his father's.
    • NOTE: Darwin was even denied a knighthood because of dissent among Queen Victoria's clerical advisers when his name was mooted for the honouts list.

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