Diversity, Classification and Variation

ethan vincent
Mind Map by , created over 2 years ago

A level Biology (Topic 4 ) Mind Map on Diversity, Classification and Variation, created by ethan vincent on 04/18/2017.

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ethan vincent
Created by ethan vincent over 2 years ago
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Diversity, Classification and Variation
1 Meiosis and Genetic Variation
1.1 Gametes
1.1.1 Sperm Cells
1.1.2 Egg cells
1.1.3 Haploid Number
1.1.4 Random Fertilisation Increased genetic diversity
1.2 Meiosis


  • 1) Before meiosis starts, the DNA unravels and replicates so there are two copies of each chromosome, called chromatids. 2) The DNA condenses to form double-armed chromosomes, each made from two sister chromatids. The sister Chromatids are joined in the middle by a centromere. 3) Meiosis 1 (first division) chromosomes arrange themselves into homologous pairs. 4) These homologous pairs are then separated, halving the chromosome number. 5) Meiosis II (second division) the pairs of sister chromatids that make up each chromosome are separated (the centromere is divided) 6) Four haploid cells (gametes) that are genetically different from each other are produced
1.2.1 Cell Division
1.2.2 Chromatids
1.2.3 Centromere
1.2.4 Meiosis I Chromosomes arranges themselves into homologous pairs
1.2.5 Chromatids cross over during Meiosis I
1.2.6 Meiosis II Centromere divides
1.2.7 Daughter Cells
1.3 Genetic Variation
1.3.1 Cells are genetically different
1.3.2 Crossing over
1.3.3 Chromatids with different alleles
1.3.4 Independent Segregation Each homologus pair is made up of two chromosomes Maternal Paternal when the pairs are separated it's completely random which chromosome ends up in each daughter cell. Shuffling of chromosomes leads to genetic variation in any potential offspring Different combinations of maternal and paternal chromosomes
1.4 Mutations
1.4.1 Errors in cell division
1.4.2 Chromosome mutations lead to inherited conditions
1.4.3 Non- disjunction Failure of the chromosome to separate properly
2 Mutations
2.1 Mutations are changes to the base sequence of DNA
2.1.1 Substitution One base is substituted
2.1.2 Deletion One base is deleted
2.2 Degenerate nature of DNA
2.2.1 Not all substitution mutations will result in a change to the amino acid sequence of the protein.
2.2.2 Deletions will always lead to changes in amino acids
2.2.3 Shift in all base triplets after it
2.3 Mutagenic agents increase the rate of mutation
2.3.1 Ionising radiation
3 Genetic Diversity and Natural Selection
3.1 Lots of different alleles means a high genetic diversity
3.1.1 Alleles Different versions of the same gene
3.2 Genetic Diversity
3.2.1 Number of different alleles of genes in a species or population
3.2.2 Genetic diversity within a population is increased Mutations in the DNA forming new alleles Different alleles being introduced into a population when individuals from another population migrate into them and reproduce Gene flow
3.2.3 Genetic bottlenecks Founder effect Initial colony is very small so the genetic diversity is low Amish Reduce genetic diversity Large number of organisms within a population die before reproducing
3.3 Natural Selection
3.3.1 Increases advantageous alleles within a population
3.3.2 Some mutations can produce beneficial alleles that can help the organism survive
3.3.3 Differential reproductive success within a population
3.3.4 Individuals that have alles that are beneficial will be more likely to survive, reproduce and pass on their genes (including the beneficial allele)
3.3.5 Greater proportion will have the beneficial allele
3.3.6 And so they will be more likely to survive, reproduce and pass on their alleles
3.3.7 The frequency of the alle increases over generations
3.3.8 over generations this leads to evolution as the advantageous alleles become more common within the population
3.4 Adaptations
3.4.1 Behavioural Way the organism acts that increases its chances of survival.
3.4.2 Physiological Processes inside the organisms body that increases its chances of survival
3.4.3 Anatomical Structural features of an organism's body that increases its chances of survival
4 Investigating Selection
4.1 Directional Selection
4.1.1 Indiviuals with alleles for characteristics of an extreme type are more likely to survive and reproduce.
4.1.2 Response to and environmental change
4.1.3 Antibiotic Resistance
4.2 Stabilising Selection
4.2.1 Individuals with alleles for characteristics towards the middle of the range are more likely to survive and reproduce
4.2.2 Environment isn't changing
4.2.3 Reduces range of possible characteristics
4.2.4 Human birth weight
5 Classification of Organisms
5.1 Phylogeny
5.1.1 Evolutionary history of organisms How closely organisms are related
5.1.2 Ancestors
5.1.3 Phylogenic tree First branch is the common ancestor to all family members
5.2 Taxinomy
5.2.1 Science of classification
5.2.2 Taxon
5.2.3 Domain Kingdom Phylum Class Order Family Genus Species
5.2.4 Drunk Kangaroos Punch Children On Family Game Shows
5.2.5 A species is a group of similar organisms able to reproduce to give fertile offspring
5.3 Binomial Naming System
5.3.1 Nomenclature (naming system)
5.3.2 First part of an organisms name is the genus Second part is the species
5.4 Courtship Behaviour
5.4.1 Species specific
5.4.2 Allows species to recognise each other and prevents interbreeding
5.4.3 Can be used to classify organisms
5.4.4 Male butterflies use chemicals to attract females
6 Biodiversity
6.1 Variety of organisms living within an area
6.2 Habitat
6.2.1 Place where and organism lives
6.3 Community
6.3.1 All the populations of different species in a habitat
6.4 Local Biodiversity
6.4.1 The variety of species living in a small habitat
6.5 Global Biodiversity
6.5.1 Variety of species on Earth
6.6 Index of Diversity
6.6.1 Species richness Number of different species in a community
6.6.2 N= Total number of organisms of all species { = 'Sum of' n= Total number of organisms of one species
6.6.3 Higher the number the more diverse the area is
6.7 Agricultural Practices
6.7.1 Can reduce biodiversity
6.7.2 Woodland Clearance
6.7.3 Reduces Shelter, food source and habitat
6.7.4 Hedgerow removal
6.7.5 Pesticides
6.7.6 Herbicides
6.7.7 Monoculture