Biology Unit 1 Revision

1. -Diet -Disease -Drugs -Nerves -Hormones -Adaption -Environmental Change -Biomass -Decay and the Carbon Cycle -Genetic Variation -Evolution Biology Unit 1 Revision

2. DIET • Balanced Diet-the right balance of different foods in the right proportions. • If unbalanced will become malnourished – overweight or underweight. Metabolic Rate – the rate at which all chemical reactions are carried out in the cells of the body. Measured in joules per minute. Affected by: -proportion of muscle to fat. -Amount of activity you do. -Inherited factors. SAT FAT – increases cholesterol MONO-UN – little effect on cholesterol POLY-UN – lowers cholesterol Cholesterol level is affected by inherited factors. Deficiency diseases such as scurvy (vitamin C), beriberi or anaemia. Type 2 Diabetes, arthritis, heart disease

3. DISEASE BODY RESPONSE IMMUNISATION CULTURING MEDICINE • External – skin, mucus in lungs, blood clotting, acid in stomach, tears contain enzymes. • Internal-WBCs: • Ingest • Produce antibodies specific to pathogen. • Produce antitoxins to counteract the toxins. • Vaccinations immunise people. (eg, MMR, HPV, tetanus). • An inactive or dead form of the pathogen stimulates the WBCs to produce the specific antibodies. • When you are infected in the future they will remember how to produce the antibody and so respond MORE RAPIDLY. • Painkillers such as paracetemol relieve symptoms but do not kill the pathogen. • Antibiotics kill the bacteria, but must be specific. • Bacteria can mutate to be a resistant strain. • Eg: MRSA has developed due to natural selection– we need to develop new ones. • Used for investigating disinfectants and antibiotics. • Petri dishes etc. must be sterilised first. • Inoculating loops must be sterilised then used to transfer. • Lid secured with tape. • School – 25oC to keep safe from harmful cultures. • Labs – higher temps for more rapid growth. BACTERIA VIRUSES Reproduce rapidly and produce toxins. Live and reproduce inside cells. -Damage cells when they reproduce. Semmelweis found that hand washing helps to prevent the spread of infection. • Reproduce rapidly. • Produce toxins which make us feel ill. • Can be treated with antibiotics (eg penicillin). • Can develop resistant strains if antibiotics are overused.

4. Drugs – Changethe chemical processes in people’s bodies • Legal drugs have much worse an overall impact than illegal drugs • Cannabis causes mental illness in some people. • As they change chemical processes people become dependent or addicted and suffer withdrawal symptoms without them. • Performance enhancing drugs are prohibited by sporting regulations, (however some are legal). • Statins lower the risk of heart and circulatory diseases. • Thalidomide was developed as a sleeping pill, however was used to treat morning sickness. This resulted in babies being born with severe limb abnormalities. • More recently thalidomide has been used to treat leprosy. • Misuse of illegal drugs such as ecstasy, cannabis and heroin will adversely affect the heart and circulatory system. • New drugs are tested for TOXICITY, EFFICIENCY AND DOSE. • In the lab, they test using CELLS, TISSUES AND LIVE ANIMALS. • In clinical trials, healthy volunteers and patients are given very low doses of the drug. If it is safe they will find the optimum dose. • A placebo is a dummy drug which does not contain the drug. • A double blind trial is where the patient nor the doctor know which is the placebo. • Eg. Stimulants boost bodily functions such as HR and anabolic steroids stimulate muscle growth.

5. A synapse is a junction between two neurones – a chemical is released that causes an impulse to be sent along the next neurone. Nerves Reflex actions are automatic and rapid – they involve sensory, relay and motor neurones. An effector is either a MUSCLE contracting or a GLAND secreting a substance

6. Human Hormones Hormones are secreted by glands and transported to their target organs via the bloodstream • Internal conditions that are controlled are: • WATER CONTENT (lost via lungs, sweat and excess lost in kidneys in urine) • ION CONTENT (lost in sweat and excess lost in kidneys in urine) • TEMPERATURE (for enzymes) • BLOOD SUGAR LEVELS (so cells have constant energy supply) CONTRACEPTIVES – inhibit FSH production – oral (oestrogen and progesterone) – at first large amounts of oestrogen but these had bad side effects – now lower dose of oestrogen or are progesterone only IVF – FSH and LH given to stimulate egg mature – eggs collected – fertilised by father’s sperm, develop into embryos – inserted back into uterus

7. Plant hormones • Shoots – grow towards light – against gravity • Roots – grow towards moisture – direction of force of gravity. • Auxin controls phototropism and gravitropism. • Plant hormones are used in agriculture as weed killers and rooting hormones.

8. Environmental change and adaptations • Living organisms can be used as indicators of pollution. -Lichens for air pollution – concentration of sulphur dioxide -Invertebrate animals for water pollution used as concentration indicators of dissolved oxygen. • Enviro change can also be measure using non-living indicators such as oxygen levels, temp and rainfall. • An ecosystem is all the enviro factors and all the plants an animals living in those conditions. • A habitat is a place within an ecosystem where a particular type of organism can live. Animals compete for: -Food -Mates -Territory Plants compete for: -Light -Space -Water -Nutrients Extremophiles live in environments that are very extreme. Eg. Tolerant to high levels of salt, high temps or high pressures.

9. biomass Decay and the carbon cycle The decay process releases substances that plants need to grow The energy made in physs is stored in the substances that make up plant cells Micro-organisms digest materials faster in warm, moist, aerobic conditions The amounts of material and energy contained in biomass at each stage is REDUCED because: -some is lost in organism’s waste -respiration supplies all energy for processes (eg. Movement). This is transferred to surroundings as heat. In a stable community processes that remove materials are balanced by processes that return materials Materials are constantly cycled round

10. Sexual reproduction – the joining (fusion) of male and female gametes. Mixture of genetic info from 2 parents leads to… VARIETY IN OFFSPRING! • Chromosomes, found in the cell nucleus, contain many genes. A gene is a section of DNA, which carries coding for a particular protein. • Different genes control the development of different characteristics of an organism. • Many genes are needed to carry all the genetic information for a whole organism. • Different characteristics come from: -Genes -Conditions developed in (environment) -Or both Asexual reproduction – no fusion of gametes and only 1 individual parent. No mixing of genetic info so no genetic variation. Genetically identical individuals are clones. Issues concerning cloning and genetic engineering: Genetic variation

11. Cuttings can be taken from older plants. Rooting hormone used and planted. Quick and cheap Embryo transplant – splitting apart cells from developing embryo before become specialised – transplant into uterus of host mum. Tissue culture – using small groups of cells from part of plant Genes transferred to cells of animal etc. at AN EARLY STAGE IN DEVELOPMENT New genes transferred to crop plants Egs of GM crops include: -resistant to insect attack -resistant to herbicides. Electric shock used to make cell divide to form embryo Cloning techniques Genetic engineering Adult cell cloning

12. When new forms of gene result from mutation there may be relatively rapid changes in a species if environment changes Natural selection: -Individual organisms within particular species show wide range of variation -Characteristics most suited to environment more likely to survive and breed successfully. -These genes then passed on to offspring Darwin’s theory states that all species evolved from simple life forms that developed > 3 billion years ago Evolution Darwin’s theory of evolution by natural selection is most widely accepted. Lamarck theory – changes occur in organism during lifetime can be inherited (not the case in vast majority of inheritance) Gradually accepted because: -Challenged idea that god made everything. -Insufficient evidence at time -Mechanism of inheritance and variation not known until 50 years later