1. Unit B1 – Influence on Life
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Unit B1 – Influence on Life
(EdExcel)

2. Topic 1 - Classification
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Topic 1 - Classification

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

4. Classification
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How would you construct a key to classify these organisms?

5. Classifying organisms
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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
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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 Organisms are classified using the following levels:
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Organisms are classified using the following levels:
Kingdom
Phylum
Class
Order
Family
Genus
Species

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

9. The 5 Kingdoms The 5 Kingdoms that organisms are classified by are:
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The 5 Kingdoms that organisms are classified by are:
Animalia
Plantae
Fungi
Protoctista
Prokaryotes
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?
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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
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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?
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Vertebrates
Invertebrates

13. Differences between vertebrates
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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
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Wasp – “vespula germanica”
Human – “homo sapien”
Dog – “Canis lupus familiaris”
Carolus Linnaeus,
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.

15. Reproduction between species
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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 Ways in which sharks and dolphins are similar:
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Ways in which sharks and dolphins are similar:
Ways in which sharks and dolphins are different:

17. Problems with classifying species
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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
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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. Deep sea volcanic vents
Extreme environments
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Mountains
Deep sea volcanic vents
The Arctic

24. Evolution
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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 ( )

25. The “Evolution Tree” Family Hylobatidae (Lesser Apes)
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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
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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
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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. Words – offspring, resistance, killed, antibiotics, reproduce
A smaller example
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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!!
Bacteria
No effect!!
Penicillin
Words – offspring, resistance, killed, antibiotics, reproduce

29. An example – the peppered moth
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An example – the peppered moth

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

31. Environmental differences
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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”.
Variation due to inheritance only
Variation due to environment only
Variation due to a bit of both

32. Words – species, mutations, mountain, gene, ancestors, reproducing
Geographic isolation
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Different species can be formed by “geographic isolation”, for example, consider an African elephant:
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

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

34. Genes, Chromosomes and DNA
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35. Sexual Reproduction
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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?
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“Allele” XX XY
Girl
Boy

37. Boy or Girl?
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Mother
Son
Daughter
Father

38. Key words Genotype Phenotype Allele Dominant Recessive Homozygous
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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. What would the offspring have?
Eye colour
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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. X X Eye colour BB bb Bb Bb (FOIL)
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Example 1: A homozygous brown-eyed parent and a blue-eyed parent:
Example 2: 2 heterozygous brown-eyed parents BB bb Bb Bb X X
Parents: B b B b B b
Gametes:
(FOIL) Bb Bb Bb Bb BB Bb bB bb
Offspring:
All offspring have brown eyes
25% chance of blue eyes

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

42. Another method – the “Punnett Square”
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Another method – the “Punnett Square”
Example 3: A heterozygous brown-eyed father and a blue-eyed mother: B b B b Bb bb
Father
Mother

43. Example questions
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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. X X X Inherited diseases Ff Cc cc Ss
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1) Cystic fibrosis – a disease that causes thick and sticky mucus to coat the lungs, gut and pancreas. It’s caused by recessive alleles: Ff X
2) Huntingdon's disease – a disease of the nervous system that causes shaking and eventually dementia. It’s caused by a dominant allele: Cc cc X
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: Ss X

45. Family Pedigree Charts
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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?