Transcript Slide 1
Evolution and Classification Biodiversity Biodiversity is a measure of: Define the term species: The number of species per square km ____________as one moves from the ________to the __________ Give two examples of environments that have high levels of biodiversity Extinction of organisms has been occurring since life began, what is it about current extinctions that is so worrying to scientists? What are the three main causes of extinction? 1. 2. 3. What additional factors threaten species? 1. 2. 3. Why might the loss of plant species in the rainforest be a serious problem for humans? Describe what is meant by a genetic bottleneck: Define species conservation: Evolution Evolutionar theory is the process by which new ________are formed from ______________ ones over a very _______period of time. This theory was established by _______________ Charles Darwin accumulated ___________ for his theory of __________ whilst travelling around the world on a 5 year voyage on HMS Beagle. Whilst visiting the _____________ __________ he studied small birds called ____________. The islands were relatively recently formed and so any species must have reached there from the ___________ 600 miles away. ___________ are unable to fly long distances so Darwin suggested that one ______________ of finch flew over with the help of prevailing winds. There were no other birds on the islands so there was a large supply of___________ for the finches. _________ noticed that each island’s finch had a different ______ and that each beak was _____________ to a different food type e.g. insects, seeds, fruit. Darwin proposed that over time different species of _______ developed from a single common ________ and that the type of beak developed over time to become specialised to feed on a particular food source. This is an example of adaptive ___________ Darwin’s Finches Draw diagrams below to show some of the beak shapes that evolved from the common finch ancestor Bud and fruit eating finch Leaf eating finch E.g. Vegetarian tree finch Grub eating finch E.g. Cactus ground finch Insect eating finch E.g. Warbler finch Tool using finch E.g. Wood pecker finch Natural selection Natural selection is the process that drives evolution A population refers to a group of individuals from the same species. In any population there is _______________ Individuals within a _________________ have the potential to produce large numbers of __________________ yet the number of _______________ stays the same from one _________________ to the next. Naturals selection states that: - there is variation between _______________ -there is ___________________ between members of the same species to survive. - the ‘fittest’ organisms (those with the most favourable characteristics) survive and _______ - the genes for these favourable characteristics are __________by the offspring Using the idea of natural selection explain how modern tigers may have evolved to have sharp teeth If members of a species are isolated from each other and can’t interbreed they can become different species. Using the idea of natural selection explain how this could occur Fossil record 1, What is palaeontology? 2,What is a fossil and how are they formed? 3, Label the below diagram with the following words Strata , Oldest rock, Youngest rock, Oldest fossil, Youngest fossil 4, The layer labelled A was dated using radiometric dating as 500 million years old, how old are the fossils likely to be in this layer? 5. What is predicted by Darwin’s theory but not found in the fossil record? 6. How do creationists explain this absence? Eldridge and Gould came up with a theory that evolution occurs in rapid bursts, species remain unchanged for millions of years before changing rapidly and turning into a new species within a few thousand years 7, Why does this explain why there is few intermediate species in the fossil record? Unfavourable conditions cause species to move to better conditions. Species that cannot move die out. This is happening to the polar bear at the moment as the melting of the polar ice caps is causing it’s habitat to change and it can no longer survive there. 8, Give another example of a species that is under threat due to a change in it’s environment 9, Mass extinction occurs when a _________proportion of known species go extinct within a __________time period. 10, Give two examples of major mass extinctions • • 11, What are the two main theories of how the dinosaurs became extinct? Evolutionary history shows that biodiversity has gone through several ____________ due to mass extinctions followed by _____________of new species Taxonomy Taxonomy is the scientific study of the ____________of living organisms. Classification places ________upon the diversity of life, classification _____ living organisms into _________of a manageable size. Scientists classify organisms based on their _______________relationship, to identify this relationship scientists look for ____________and _________________ Scientists examine: Physical similarity - DNA composition - The Bonobo Chimpanzee is the closest living relative to humans. How could a scientist decide that humans are more closely related to chimps than to cows? All organisms are now in a______________system. A hierarchical system is one where _______ groups are divided into __________groups. The hierarchal system used to characterise living things has seven levels reach level is a taxon. Complete the below table to show the taxons, descriptions and examples from the classification hierarchy King Phil Came Over For Great Sausages or think of your own! K_______P__________C________O__________F__________G_________S_________ Taxon Description Kingdom Example Animalia Organisms become more closely related A grouping of similar orders Order Family A group of species that are closely related. Homo sapiens Explain why humans are called Homo sapiens in the binomial system What is an advantage of having the binomial system used worldwide? Protoctista Fungi Plantae The Five Kingdom Classification System Prokaryotae Animalia Kingdom Phylum Class Features of Selected Animal Phyla (Textbook p. 34-35) Phylum: Annelid Annelids include earthworms, lugworms, leeches Body structure: Annelids have a segmented .............., visibly seen externally as rings. The body is divided internally into septa and filled with..................... (hydrostatic skeleton). They have a thin permeable.................. and a closed........................... system. The brain and ...................... system are very primitive. Phylum: Arthropod includes insects, spiders, crustaceans, centipedes and millipedes The arthropod body is divided into........................; the body includes a head, thorax and ..................................; legs are paired and ......................; spiders have .... pairs of legs; crustaceans have ........... pairs of legs, centipedes and millipedes have many pairs of legs. Arthropods have open .................................... systems; They have a hard exoskeleton that is made of ........................ (for support, prevention of .....................loss, protection of internal organs, protection from ............................) Why could it be a disadvantage for an arthropod to have an exoskeleton? ................................................................................................ Insects have..... pairs of legs, a head with antennae and compound eyes. In terrestrial insects, gas exchange takes place in the.................., aquatic species have gills; many insect species have...................for flight. Phylum: Chordate (vertebrate), includes 5 classes: Fish have scales, fins and g................, eggs are fertilised externally in water. Amphibians have moist ...................; jelly coated eggs (e,g. frogspawn), eggs are fertilised externally in.........................; juveniles (e.g. tadpoles) have gills, adults have ................... Reptiles have dry scaly ...................; they have ....................... for gas exchange; fertilised eggs are laid on land and protected by a leathery ............................ Birds have a body covered by ...................... and can usually fly; they have lungs and lay eggs with hard ......................... Mammals give birth to live..................... ; they have lungs and feed their young on ....................; this class includes the marsupials e.g. kangaroos, their young develop in a................... and the placentals – young develop in the ............... and are nourished via the placenta. Pentadactyl limb- evidence for common ancestry Homologous features – A feature that has ___________functions in different organisms but is ____________ in structure so may have had a common origin. An example is the pentadactyl limb The pentadactyl limb has five digits and is found in four classes of terrestrial vertebrates, amphibians, reptiles, birds and mammals. The structure is basically the same in all classes however the limbs have adapted for different functions. Give the functions of the pentadactyl limb in each of the following organisms Bat Cat – Horse – Whale – Humans - Some features appear to be homologous but are not. Sometimes animals have common features that are not due to them coming from a common ancestor but to both adapting to a similar ____________, e.g. dolphins and sharks both have similar fore limbs (fins) but are not at all related. These structures are ______________, performing the same function but ___ derived from a common ancestor. Both these species have adapted independently to their environment. This is an example of ______________ evolution. Explain why the wings of a bat and the hands of a human are said to be homologous while the wings of a bird and an insect are said to be analogous Biochemical techniques used to confirm evolutionary relationships Amino acid sequence analysis Separation of chemical substances DNA base sequence analysis. In order to work out quantitatively how closely organisms are related DNA analysis is used . DNA strands are extracted from the two species and then mixed and analysed. Humans and chimps share 97.6% DNA and humans and rhesus monkeys have 91.1% of DNA in common.