EdExcel Unit B1 – Influence on Life

1. EdExcel Unit B1 – Influence on Life 05/01/2020 This PowerPoint supports Topic 1 (Classification) from the 2011 EdExcel Biology Unit 1 module W Richards

2. Topic 1 - Classification

3. Classification 05/01/2020 The world is populated by millions of different species of animals and plants…

4. Classification 05/01/2020 How would you construct a key to classify these organisms?

5. Classifying organisms 05/01/2020 All organisms are classified into groups. For example: Organism What is the main difference between these? Plants Animals Vertebrates Invertebrates Amphibians Birds Reptiles Fish Mammals These 5 are called “classes” – what’s the difference between each of these classes? How would you decide, for example, if a whale is a mammal or a fish?

6. Classifying fungi, bacteria, algae and viruses 05/01/2020 Fungi are not classed as plants as they have no _______ and no cell wall, so they have their own ____. Bacteria have no _____ and so they are in the “prokaryote kingdom” Algae have features of both plants and _____ and are placed in the “protoctist” kingdom. Viruses are regarded as ____ so they have no kingdom. Words – non-living, nuclei, chloroplasts, kingdom, animals

7. Classification Kingdom Phylum Class Order Family Genus Organisms are classified using the following levels: Species

8. Classification Kingdom - Animalia Phylum - Chordata Class - Mammalia Order - Carnivora Family - Canidae Genus - Canis Consider, for example, a dog: Species – C. lupus

9. The 5 Kingdoms Animalia Plantae Fungi Protoctista Prokaryotes The 5 Kingdoms that organisms are classified by are: Multicellular, don’t have cell walls or chlorophyll Multicellular, have cell walls and chlorophyll Multicellular, have cell walls but no cholophyll Unicellular, have a nucleus Unicellular, have no nucleus

10. The Virus – Living or non-living? • Is a virus alive? • It contains genes • It can reproduce • Is a virus not alive? • It can only reproduce within a host • It has no metabolism Overall, scientists class them as non-living

11. Vertebrates Vertebrates are organisms with backbones and they are all members of the phylum “chordata”, meaning “organism with a supporting rod running the length of the body”. Some examples:

12. Vertebrate or invertebrate? 05/01/2020 Vertebrates Invertebrates

13. Differences between vertebrates • Vertebrates have a number of significant differences. Describe how each of the following species: • Absorb oxygen • Reproduce • Regulate their body temperature

14. Naming Species – The Binomial System 05/01/2020 Human – “homo sapien” Dog – “Canis lupus familiaris” Wasp – “vespula germanica” I invented the modern system of naming species. I did this so that species would have the same name in every language and so that we would have a greater ability to study and conserve different species. Carolus Linnaeus, 1707-1778

15. Reproduction between species 05/01/2020 A “species” is defined as when organisms reproduce with each other to produce fertile offspring. Different species can sometimes mate and have offspring but they would be infertile. Some examples: Mule Liger Zebroid Geep

16. Similar Species 05/01/2020 Ways in which sharks and dolphins are similar: Ways in which sharks and dolphins are different:

17. Problems with classifying species 05/01/2020 Ring species – these two different types of gull can breed with the same other gulls but not with each other, so are they the same species? Hybridisation – sometimes different species can interbreed and produce fertile offspring (unlike the geep) – so which species is the offspring?

18. Adaptation 05/01/2020 Organisms are ADAPTED to the habitat they live in. In other words, they have special features that help them to survive. Some examples:

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23. Extreme environments 05/01/2020 Mountains The Arctic Deep sea volcanic vents

24. Evolution 05/01/2020 Evolution is the theory of slow, continual change of organisms over a very long time. All living things on the Earth have supposedly developed from the first simple life forms that arrived 3,000,000,000 years ago. Charles Darwin (1809-1882)

25. The “Evolution Tree” 05/01/2020 Family Hylobatidae (Lesser Apes) Family Hominidae (Great Apes) Subfamily Ponginae Subfamily Hominidae Tribe Panini Tribe Homini Tribe Gorillini Gibbons Orangutans Chimpanzees Gorillas Humans

26. Evolution 05/01/2020 • The main evidence for my theory came from fossil records. However, these records didn’t exist when I came up with my theory. Also, there was little evidence about how species evolved so few people believed my ideas. • These days scientists understand that the process that causes evolution is called “Natural selection” and it works like this:

27. Natural Selection 05/01/2020 1) Each species shows variation and they “overpopulate” – they produce more offspring than will survive to adulthood: • There is competition within each species for food, living space, water, mates etc Get off my land • The “better adapted” members of these species are more likely to survive – “Survival of the Fittest” Harsh Yum • These survivors will pass on their better genes to their offspring who will also show this beneficial variation. The “smaller-necked” giraffe will eventually die out.

28. A smaller example 05/01/2020 Bacteria Penicillin Bacteria provide evidence for Darwin’s theory by showing the same natural selection to become immune to antibiotics: • Mutation – some strains of bacteria can develop _______ to the antibiotics. • The non-resistant bacteria are _____ by the _______. • The resistant bacteria _______ and pass on their mutations to their ______. Don’t use antibiotics unless you need to!! No effect!! Words – offspring, resistance, killed, antibiotics, reproduce

29. An example – the peppered moth 05/01/2020

30. Variation Ways in which they are the same Ways in which they are different Variation means “differences within a species. For example, consider some of the people in your class: Would you class these variations as “continuous” or “discontinuous”?

31. Environmental differences Some of this variation is due to our parents, but some of it is due to our upbringing and the environment in which we live – this is called “Environmental variation”.

32. Geographic isolation • Elephants are separated by a geographic feature e.g. a _________ • Elephants on each side of the mountain have different ______ in their _____ pool • Their _______ die out and the offspring are so genetically removed that they’re incapable of ________ with each other – they’re now different ________ Words – species, mutations, mountain, gene, ancestors, reproducing Different species can be formed by “geographic isolation”, for example, consider an African elephant:

33. Validating New Evidence Peer review Publishing findings in a scientific journal Scientific conferences Whenever new evidence is discovered it always has to be validated by the scientific community, for example by:

34. Genes, Chromosomes and DNA 05/01/2020

35. Sexual Reproduction 05/01/2020 The human egg and sperm cell contain 23 chromosomes each. When fertilisation happens the gametes fuse together to make a single cell called a ZYGOTE. The zygote has 46 chromosomes (23 pairs).

36. Boy or Girl? 05/01/2020 X Y X “Allele” XX XY Girl Boy

37. Boy or Girl? 05/01/2020 Daughter Mother Son Father

38. Key words 05/01/2020 Genotype Phenotype Allele Dominant Recessive Homozygous Heterozygous • This allele determines the development of a characteristic • The characteristic caused by the genotype • This allele will determine a characteristic only if there are no dominant ones • This word refers to a pair of chromosomes being made of two different alleles of a gene • The genetic make up in a nucleus • This word refers to a pair of chromosomes being made of two of the same alleles of a gene • An alternative form of a gene

39. Eye colour 05/01/2020 In eye colour the brown eye allele is dominant, so we call it B, and the blue eye is recessive, so we call it b: BB Bb bb Homozygous brown-eyed parent Heterozygous brown-eyed parent Blue-eyed parent What would the offspring have?

40. Eye colour 05/01/2020 Bb BB bb Bb B B b b B b B b Bb Bb Bb Bb BB Bb bB bb Example 1: A homozygous brown-eyed parent and a blue-eyed parent: Example 2: 2 heterozygous brown-eyed parents X X Parents: Gametes: (FOIL) Offspring: All offspring have brown eyes 25% chance of blue eyes

41. Eye colour 05/01/2020 Bb bb b b B b bb Bb Bb bb Example 3: A heterozygous brown-eyed father and a blue-eyed mother: Equal (50%) chance of being either brown eyed or blue eyed.

42. Another method – the “Punnett Square” 05/01/2020 Example 3: A heterozygous brown-eyed father and a blue-eyed mother: Father Mother

43. Example questions 05/01/2020 1) In mice, white fur is dominant. What type of offspring would you expect from a cross between a heterozygous individual and one with grey fur? Explain your answer with a genetic diagram. 2) A homozygous long-tailed cat is crossed with a homozygous short-tailed cat and produces a litter of 9 long-tailed kittens. Show the probable offspring which would be produced if two of these kittens were mated and describe the characteristics of the offspring (hint: work out the kitten’s genotype first).

44. Inherited diseases 05/01/2020 X Ff Ff X Cc cc X Ss Ss 1) Cystic fibrosis – a disease that causes thick and sticky mucus to coat the lungs, gut and pancreas. It’s caused by recessive alleles: 2) Huntingdon's disease – a disease of the nervous system that causes shaking and eventually dementia. It’s caused by a dominant allele: 3) Sickle cell anaemia – a disease that alters the shape of red blood cells, thereby reducing their oxygen capacity, causing weakness and anaemia. It’s caused by recessive alleles:

45. Family Pedigree Charts 05/01/2020 Consider the following chart of the offspring and grandchildren between two sickle-cell anaemia carriers: Key: = male = female = S allele = s allele Q. Describe the genotype and the phenotype of each of the grandchildren. Also, which member of this family has got sickle-cell anaemia?

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