Life Science Notes 2 PDF

Evolution Definition. is the change in heritable characteristics of biological populations over successive...

Evolution Definition. is the change in heritable characteristics of biological populations over successive generations populations better L note : doesn't say anything about becoming or more complex ↳ Heritable characteristics (inherited via genes passed down from parents) ↳ Biological population (members of a single species living in a common place at a common time) ↳ Successive generations lover more than a single generation) organism's of survival adaptations : inherited characteristics that increase chance in its envoirment (structural, behavioural , Often results in an physiological) Lamark's Theory (1809) ↳ His theory assumed "inheritance of aquired characteristics ("Use it or lose it' 2) His ideas did not include genetic characteristics , so they could not be passed down (what you do isn't genetic) Darwin (1859) the HMS and collected hundreds of specimens and made A naturalist , he was invited aboard a voyage on Beagle extremely detailed observations Islands in 1831 - Darwin visited the Galapagos - On the Island Darwin found many finches, and he noticed there was variation between their beaks (shape and size) finches did ↳ Many not survive ↳ He thought the ones that did survive must be best adapted ↳ He developed a theory for the mechanism of evolution called Natural Selection Natural selection -. variation 1 exists within a population ↳ created by DWA mutations 2. Struggle for survival - often due to competition for resources (food space mates) , ,. Could be due to overpopulation but not always. 3 Selection - Some are better adapted to their envoirment and a re more likely to survive and reproduce generation population over time 4. Evolution - the advantageous characteristics a re passed on to the next leading to a change in the their 1 : those that a re less well adapted are less likely to survive and pass on characteristics  selection is sometimes referred to as "survival of the fittest Natural Note : Individuals do not adapt adaptations arise over successive generations , Fitness : The ability of an organism to survive and reproduce (pass on its genes Why Darwins Theory Was not initally, Accepted - Must people still believed that God made all animals/plants on earth - Insufficent evidence - the mechanism of inheritance/genes was unkown at the time. Genes and Variation The Basics: - Inside the nucleus is DWA-this is the instructions for us ! - DNA is arranged in chromosomes which come in pairs (in eukaryotes) - Each species has a different number of pairs of chromosomes.... we have 23 pairs control each feature these selections - genes sections of DNA - - Small -genes code for proteins - the building blocks of living things Variation! There alleles are different versions of the genes called - example there are two versions of the gene for tongue rolling one "says " you can roll your tongue , one " says can't you - - For ↳ Variation ! - This an example of a single-gene trait peak attached/detached widows ear lobes ↳ other examples - - , controlled byFor more alleles > lots of variation meaning they with - are Most traits are polygenic genes each many - - - colour ↳ Examples : height , eye Sources Of Variation Mutation : in the arrangement of bases in an individual gene a change - L > Mutations may happen at random by chance terrors in DNA replications - Mutagens : increase the likelihood of mutations : X-rays , ionising radiation, chemicals - Mutations may be positive , neutral , or negative ↳ Production of new/superior protein : : increase result in fitness (positive) ↳ Neutral Mutation : result : No change ↳ Production of inferior or no protein : result : fatal and /or disease causing I decrease in fitness-negative Sexual Reproduction - lasexual - offspring identical-variation only caused by mutations) - Gamete production : Random assortment of chromosomes and crossing over during meiosis population just the combinations Doesn't change the frequency of in the - - alleles Genotype Vs. Renotype has (it's genetic make-up) - Genotype : the combination on alleles an organism observed characteristic (physical/physiological / behavioural) may be affected by Phenotype : also - the envoirmental characteristics -Gene Pool : the collection of different genes within an interbreeding pool ↳ The bigger the genepool , the more diverse the population Genetic definition of evolution " - "a change in the relative frequency of alleles in a population - Natural selection works on phenotypes , but affects genotypes. Examples offvolution Example 1 : The peppered Moth The peppered - moth is a common insect in Britain with two forms : the dark form and the light form The form has small black specks been dusted with pepper - light just like it has > - variation (300 years ago most peppered moths were light form)  of before the industrial revolution ? Why ? What Type Moth was common colored peppered moths were common because their speckled white and black coloration comoflaged them -light litchen-covered trees , which thrived in clean air in the climate pre-industrial revolution against prevalent of Moth common after the industrial revolution ? Why? What type was - Dark coloured moths became more common after the revolution. Soot from industrial pollution darkened tree bark and killed light-colored lichens , making dark moths better camoflaged and less likely to be eaten by predators. How This Change Happened Using Natural selection 1 Variation : Within. the peppered moth population, there were both light and dark colored moths due to genetic variation 2 Selective In the Industrial Revolution , sout from pollution darkened tree bark , making dark moths harder for predators to see. Pressure : became visable While light moths more. Differential Survival 3 : Dark colored moths were less likely to be eaten , allowing them to survive and reproduce more successfully than light coloured moths. dark-coloured passed advantageous genes to their offspring the proportion of dark moths in the Reproduction moths their 4. : The time population over. 1 Because the wind is blowing center of UK inward toward the the areas in the center would have the more dark moths as the wind blows smoke towards them are also more dark moths in the major 1 There. ↓ cities , as during the industrial revolution they produced more smoke