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B1 Biology Checklist Specification 2011 Specification Point B1.1.1 Diet and exercise What makes up a healthy diet Describe what each of the components are needed for in the body e.g. carbs for energy Malnourishment is too much (obesity) or too little (e.g. starvation) Deficiency diseases e.g. anorexia and diabetes type 2 The energy balance in the body and how diet and exercise can affect it Metabolic rate varies according to exercise and genetic factors Inherited factors also affect our health e.g. Cholesterol People who exercise regularly are usually healthier than people who take little exercise. B1.1.2 How our bodies defend themselves against infectious diseases Microbes that cause infectious disease are called pathogens. Bacteria and viruses may reproduce rapidly insidethe body and may produce toxins. Viruses damage the cells in which they reproduce. The body has different ways of protecting itself against pathogens e.g. the skin White blood cells help to defend against pathogens by: ingesting pathogens, producing antibodies and producing antitoxins The immune system of the body produces specific antibodies to kill a particular pathogen. This leads to immunity from that pathogen. Semmelweiss and his links with handwashing and reducing disease It is difficult to develop drugs that kill viruses without also damaging the body’s tissues. Pathogens mutate, producing resistant strains. Painkillers don’t get rid of pathogens Roles of antibiotics in treatment, and not successful against viruses Strains of bacteria, e.g. MRSA, have developed resistance as a result of natural selection due to overuse Mutations of pathogens produce new strains. Need to develop new treatments How a vaccine works e.g. MMR How to culture microbes properly in petri dishes to avoid contamination + keep safe (e.g. incubation) In school and college laboratories, cultures should be incubated, at a maximum temperature of 25 °C B1.2.1 The nervous system Nervous system allows body response to environment Receptors detect stimuli (changes in the environment) e.g. eyes Info from receptors passes along cells (neurones) in nerves to the brain. The brain coordinates the response. Reflex actions Role of receptors, sensory neurones, motor neurones, relay neurones, synapses and effectors in simple reflex actions. B1.2.2 Control in the human body Internal conditions that are controlled include: water content, ion content, temp and blood sugar Hormones released from glands to help control body e.g. sex hormones Roles of FSH, LH and oestrogen in menstrual cycle Roles of oestrogen and progesterone in the contraceptive pill and how oestrogen alone leads to side effects so often combined or progesterone only Role of LH and FSH in IVF B1.2.3 Control in plants Plants are sensitive to environment e.g. light and moisture Plants produce hormones to coordinate and control growth. Auxin controls phototropism and gravitropism (geotropism). Unequal distribution of auxin leads to uneven growth on one side Plant growth hormones are used in agriculture and horticulture as weed killers and as rooting hormones. B1.3.1 Drugs Why and how new drugs are developed to be effective and safe The use of trials including double blind and use of placebos Use of statins to reduce risk of heart disease The problems with thalidomide and how it can be used today Misuse of illegal drugs and its effects on the body and society Links of cannabis with mental health Addiction, stimulants and depressants Legal vs. illegal drugs Use of performance enhancing drugs B1.4.1 Adaptations Plants often compete with each other for light, space, water and nutrients Animals often compete with each other for food, mates and territory Organisms, including microorganisms have features (adaptations) that enable them to survive in the conditions in which they normally live Extremophiles may be tolerant to high levels of salt, high temperatures or high pressures SRR 2011 B1 Biology Checklist Specification 2011 Animals and plants may be adapted for survival in the conditions where they normally live, eg deserts, the Arctic Animals and plants may be adapted to cope with specific features of their environment, eg thorns, poisons and warning colours to deter predators B1.4.2 Environmental change Changes in the environment affect the distribution of living organisms Animals and plants are subjected to environmental changes. Such changes may be caused by living or non-living factors such as a change in a competitor, or in the average temperature or rainfall Living organisms can be used as indicators of pollution: lichens + invertebrates Environmental changes can be measured using non-living indicators such as oxygen levels, temperature and rainfall B1.5.1 Energy in biomass Radiation from the Sun is the source of energy for most communities of living organisms (photosynthesis in green plants and algae) The biomass at each stage in a food chain is less than it was at the previous stage. The biomass at each stage can be drawn to scale and shown as a pyramid of biomass The amounts of material and energy contained in the biomass of organisms is reduced at each successive stage in a food chain e.g. lost in respiration B1.6.1 Decay processes Living things remove materials from the environment for growth + other processes and returned through death and decay Materials decay because of digestion by microbes (most active when warm, moist and aerobic conditions) In a stable community the materials are constantly cycled B1.6.2 The carbon cycle The constant cycling of carbon is called the carbon cycle Describe the processes which add carbon to the atmosphere and those that take the carbon away B1.7.1 Why organisms are different Genetic info is carried by genes, which are passed on in the sex cells (gametes) from which the offspring develop The nucleus of a cell contains chromosomes (made up of genes, made up of DNA) Different genes control the development of different characteristics of an organism (allele = different version of the same gene) Variation can be genetic (combination of genes inherited) or environmental or both B1.7.2 Reproduction 2 forms of reproduction: sexual and asexual New plants can be produced quickly and cheaply by taking cuttings from older plants. These new plants are genetically identical to the parent plant Modern cloning techniques include: tissue culture, embryo transplants, adult cell cloning In genetic engineering, genes from the chromosomes of humans and other organisms can be ‘cut out’ using enzymes and transferred to cells of other organisms Genes can also be transferred to the cells of animals, plants or microorganisms at an early stage in their development so that they develop with desired characteristics Concerns about GM crops include the effect on populations of wild flowers and insects, and uncertainty about the effects of eating GM crops on human health B1.8.1 Evolution Darwin’s theory of evolution by natural selection The theory of evolution by natural selection was only gradually accepted because: it challenged creationism, insufficient evidence at the time, mechanism of inheritance + variation not understood at the time Other theories, including that of Lamarck, are based mainly on the idea that changes that occur in an organism during its lifetime can be inherited Studying the similarities and differences between organisms allows us to classify living organisms into animals, plants and microorganisms, and helps us to understand evolutionary and ecological relationships Where new forms of a gene result from mutation there may be relatively rapid change in a species if the environment changes SRR 2011