1. Classification Classification systems consist of a hierarchy in which groups are contained within larger composite groups and there is no overlap.

3. Classification is a means of organising the variety of life based on relationships between organisms and is built round the concept of species. Principles of taxonomy The principles and importance of taxonomy. Classification systems consist of a hierarchy in which groups are contained within larger composite groups and there is no overlap. The phylogenetic groups are based on patterns of evolutionary history. A species may be defined in terms of observable similarities and the ability to produce fertile offspring. One hierarchy comprises Kingdom, Phylum, Class, Order, Family, Genus, Species. Candidates should be able to appreciate the difficulties of defining species and the tentative nature of classifying organisms as distinct species.

4. Classification is an attempt to impose a hierarchy on the complex and dynamic variety of life on earth. Classification systems have changed and will continue to change as our knowledge of the biology of organisms develops.

5. The identification, naming & grouping of species Currently we have identified and named less than 2 million different living organisms. It is estimated that there are approximately 14 million species currently living on earth. It is also estimated that over 99% of the species that have ever existed on earth, are now extinct.

6. Classification is the organisation of living organisms into groups based on accepted principles These groupings are not random and you need to understand the principles that scientists use to distinguish one type of organism from another.

7. What is a species? A species is the basic unit of classification. To be of the same species, the organisms must fulfill the following TWO criteria:

8. A species may be defined in terms of observable similarities and the ability to produce fertile offspring. Definition AQA. A species is an interbreeding group of organisms that produces viable and fertile offspring that share a common ancestry and are similar in terms of anatomy and biochemistry.

9. 1. They must be similar to one another but different from members of other species. Because they have similar genes, they share similarities: – Physically – Biochemically – Patterns of development – Immunological features – Occupy same ecological niche

10. 2. They are capable of breeding to produce living, fertile offspring Thus they are able to: – Maintain a population When a species reproduces sexually, genes will combine. These genes are referred to: – The same gene pool

11. SPECIES A species is a group of organisms that have similar characteristics [physiology, biochemistry, morphology and behaviour] that can interbreed to have fertile offspring.

12. Grouping Species together – Principles of Classification Note: Classification is the Grouping of organisms. The theory and practice of biological classification is called Taxonomy. There are two main forms of biological classification:

13. Artificial classification When observation is used to identify and compare similar (analogous) and different features. This is fairly superficial and is dependent on an individual’s viewpoint. This means that different people may divide the same organisms in different ways. The features that may be used in artificial classification include: size, colour, behaviour, number of legs.

14. Analogous features = have the same function but not the same evolutionary origins. E.g. the butterfly wing and the bird’s wing are analogous in terms of function but not anatomy (or evolutionary origin). Analogous features can include colour, size, number of legs, leaf shape etc.

15. Natural classification Based on evolutionary relationship between organisms and their ancestors. Species are classified into groups using shared features derived from their ancestors. Groups arranged in hierarchy – groups have no overlap but may be part of a larger composite group.

16. Relationships in a natural classification are based on homologous characteristics. Homologous characteristics have similar evolutionary origins REGARDLESS of their adult functions. E.g. the Pentadactyl Limb. Wing of a bird, the arm of a man and front leg of a horse all have same basic structure and all evolved from common ancestor = so are homologous.

17. homologous characteristics.

18. Taxonomy – Organisation of the groups of species The different classification groups are called taxa (plural, taxon is singular) and the study of classification groups and their positions in hierarchical order is called taxonomy. There are different levels of taxon. The lowest level is the species, which groups together all organisms of a single type that are capable of interbreeding and to produce fertile offspring. The classification system is based upon the evolutionary line of descent of the group members.

19. Linnaeus Binomial Scientists need to have a system to standardise naming of organisms across the world to make sense and organise them into manageable groups. 200 years ago, a Swedish botanist called Linnaeus devised a common system of naming organisms. By following the same conventions worldwide, it ensures that communication is more effective as it avoids confusion. Previously, the same organism might have a different name in one country than another. Species that are very similar to each other are placed in a larger group called a genus. For example, small cats are placed in the genus Felis. Within that group, there are several ‘cats’, including the domestic cat, Felis catus, the Europena wild cat, Felis silvestris, and the lynx, Felis lynx.

20. Notice the double-barrelled scientific name. It is called a binomial. All small cats have the same ‘first name’. This is the genus to which they belong. The last name is different for each cat and it is this that indicates the kind of Felis (cat) it is. All organisms are named in this way. These are the basic concepts of the binomial system: – Binomial names are based on Greek or Latin – Note that the binomial name is in Italics. – If your are writing in an exam, you can also Underline (e.g. Felis domestica). – Note the first name (the Genus – or Generic name) has an Upper case letter – Note the second name (the species – or specific name) has a lower case letter

21. Besides the cats mentioned above, there are other ‘cat-like’ mammals such as lions, tigers, cheetahs and leopards. The name of the lion is Panthera leo. It is in the genus Panthera. The cheetah, Acinonyx jubatus, is from a different genus. However, because these big cats and the smaller cats are quite similar, they are placed into one larger group, the family of cats – the Felidae. Cats are clearly different from dogs, yet there are similarities. They are both carnivorous mammals and so are grouped into the order Carnivora within the class Mammalia. Mammals belong to the phylum Chordata, which includes all the vertebrates. Finally, chordates belong to the kingdom Animalia – the animals.

22. Part of Animalia KINGDOManimal Animal PHYLUMChordate Arthropoda CLASSmammal Insect ORDERprimates carnivora dipteral FAMILYhominidaepongidaefelidae muscidae GENUSHomoPanFelis Musca SPECIESsapienstroglodytesdomesticaleodomestica

23. Write the name for the chimpanzee in the correct scientific format.

25. “Kindly Place Cover over fresh green sprouts” Kingdom (Kingdoms) Phylum (phyla) Class (Classes) Order (orders) Family (Families) Genus (Genera) Species

26. Long answer question Explain the principles biologists use to classify organisms into groups compared to older models.

27. Answer 1) Consider phylogeny [EVOLUTIONARY RELATIOSHIPS] Look at evolutionary lineage/history Find the point of divergence from a common ancestor Consider, genetic, biochemical, embryology, homology of anatomy Organisms are arranged in a hierarchy where large taxa (groups) are subdivided into smaller taxa (K, P, C, O, F, G,S) As groups get smaller the similarities between the species increase Each species is given a binomial name using the genus and species Older models of classification used observable features to group organisms

28. What are the five kingdoms? Kingdom Prokaryotae Organisms are either unicellular or filamentous (strands of cells). Examples include bacteria. In all cases: Cells lack true nuclei Cells have circular DNA Cells have no membrane bound organelles Cell walls are made of peptidoglycan

29. Five Kingdom ClassificationFive Kingdom Classification with video footage.video footage. The Amazing Diversity Of Living Systems Living organisms are subdivided into 5 major kingdoms, including the Prokaryotae (Monera), the Protoctista (Protista), the Fungi, the Plantae, and the Animalia. Student activity Use the information available to identify the kingdoms which the cell diagrams (not in any particular order)represent.

30. Kingdom Protoctista This group is very diverse and membership is often by exclusion from all other groups. Examples include Amoeba and Laminaria (giant brown seaweed). All protoctistans have eukaryotic cells. Some possess cell walls (non-cellulose), chlorophyll and can photosynthesise; others have no cell walls and are motile. Some are unicellular; others are composed of billions of cells.

31. Kingdom Fungi Fungi are also a diverse group, but have some common features including: A non-cellulose cell wall (this is often chitin) They are non-photosynthetic Eukaryotic cells (although hyphae can be multinucleated and not divided into separate cells). They secrete enzymes to digest organic materials outside their cells and absorb the products of digestion.

33. Kingdom Animalia All animals are: multicellular, have eukaryotic cells with no cell walls, develop from a blastocyst. Most animals: ingest their food into a digestive system, are motile.

34. Comparative anatomy

35. Kingdom Plantae All plants are multicellular, have eukaryotic cells with a cellulose cell wall and are photosynthetic. Examples include mosses, ferns, conifers, flowering plants.

36. Classification of three organisms from different kingdoms See table in notes.

37. : Classification is a human concept developed for convenience – thus many organisms don’t ‘like’ following such description

38. Questions 2. What are the 2 main things that all members of a species share? 3. What are the 3 features of a natural system of classification? 4. Rana temporaria is the frog found in Britain. The table below shows part of its classification. Give the most appropriate name for each of the blanks represented by the numbers 1-7.

39. Answers 2. They are similar to one another but different from other species. They are capable of breeding to produce living, fertile offspring. 3. It is based on the evolutionary relationships between organisms and their ancestors. It classifies species into groups, using shared characteristics derived from their ancestors. It is arranged in a hierarchy in which groups are contained within larger composite groups with no overlap.

40. 4. 1- phylum 2 – class 3 – order 4 – family 5 – Rana 6 – species 7- temporaria

41. Phylogeny – study of evolutionary relationships

42. PHYLOGENETIC TREE. All organisms share common ancestors – i.e. an organism through mutation developed two different species a long time ago. We call this a branch of evolution. The phylogeny of an organism reflects all the evolutionary branches that led up to its existence. We can look at these branches to determine how closely related two organisms are. The phylogenetic relationships of different species are usually represented by a tree-like diagram called a phylogenetic tree.

43. Which is the more informative tree? Look at where the branching occurs, this is where the two species diverged. The closer the branches, the closer the evolutionary relationship.

44. Questions The diagram shows the evolution of a group called the primates.

45. (a) Which primate evolved first? (1) (b) Name two primates that developed most recently from the same common ancestor as humans. (2)

46. The diagram shows an evolutionary tree for a group of animals called primates. The names of extinct animals are printed in italics e.g. Nycticeboides. The drawings show animals that are alive today.

47. (i) How many million years ago did Karanisia first appear? (1) (ii) During which geological period did the Apes and Monkeys begin to evolve? (1) (iii) Which group of primates alive today are the closest relatives of the Lorises? (1)

48. The diagram shows an evolutionary tree for humans based on a study of fossils.

49. When did Australopithecus afarensis first appear? (1) Which species was the direct ancestor of Paranthropus boisei? (1) Which species is most closely related to Homo habilis? (1) About 250 fossils of Homo erectus have been found. About 50 of these fossils have been found in China. A Chinese scientist has suggested the hypothesis that Chinese people evolved from Homo erectus. Most scientists do not agree with this hypothesis. Use the information above and information from the diagram to suggest two reasons why. (2)

50. Answers 5a. Lemur 5b. Gorilla and Chimpanzee 6a. 40 – 42 million 6b. Palaeocene 6c. Bush babies 7a. 3.75 million years ago 7b. Paranthropus aethiopicus 7c. Homo ergaster 7d. Homo erectus fossils found in other parts of the world (allow only 50 fossils found in China) (too many) gaps in fossil record Homo erectus on different branch of ‘tree’ or no evidence of other ‘humans’ developing from Homo erectus or no link shown between Homo erectus to Homo sapiens / modern humans diagram shows they are not closely related or (fossils show that) H. sapiens evolved from H. heidelbergensis / H. mauritanicus / H. ergaster

51. Difficulties in defining species Species are not fixed, they change and evolve over time. Some individuals may develop into a new species. Within a species there can be variation among individuals. All domestic dogs for example belong to the same species but artificial selection has led to a variety of different breeds. Many species are extinct and have left incomplete or no fossil records Some species rarely reproduce sexually Members of different groups of the same species may be isolates and so never meet and therefore do not interbreed Groups of organisms that are isolated may be classified as different species. These groups may turn out to be the same species when their ability to interbreed is tested. Some species are sterile.

52. Chihuahua and Great Dane

53. The mule problem A mule is the product of a horse and a donkey mating. Horses and donkeys are different species and the resulting mule will be sterile Horses have 64 chromosomes while donkeys have 62. This means that mules have 63 chromosomes. This is an odd number and therefore meiosis cannot form gametes.

54. Questions 8. Even where groups of extinct organisms have left fossil records, it is very difficult to distinguish between species. Suggest 2 reasons for this. 9. Suggest reasons why it is often difficult to classify organisms as distinct species. 10. From your knowledge of the events during meiosis 1, suggest a reason why the cells of a mule with their 63 chromosomes are unable to undergo meiosis and so cannot produce gametes. 11. Does the fact that fertile female mules occasionally occur make a mule a distinct species? Give reasons for your answer.

55. Answers Fossil records are normally incomplete and not all features can be observed and so comparisons between individuals are hard to make. Fossil records cannot reveal whether individuals could successfully mate. Species change and evolve over time, sometimes developing into different species. Fossil records are incomplete/ non-existent. Current classifications only reflect current scientific knowledge and, as this changes, so does the naming and classifying of organisms. During meiosis 1, chromosomes line up across the equator in homologous pairs. With an odd number of chromosomes, exact pairings are not possible. This prevents meiosis occurring in the normal way. No it does not. Only fertile female mules are known so interbreeding is impossible. The event is so rare it is considered abnormal and it would be wrong to draw conclusions from it. If a mule were a species, it would mean that the parents were the same species – however donkeys and horses are sufficiently different to be considered separate species.