Biodiversity Flashcards
What is genetic diversity?
Number of different alleles of genes in a population
What are alleles and how do they arise?
Variations of a particular gene
Arise by mutation
Explain the importance of genetic diversity
Enables natural selection to occur
As in certain environments, a new allele of a gene might benefit its possessor
By resulting in a change in the polypeptide (protein) coded for that positively changes its properties
Giving possessor a selective advantage
What is evolution?
Change in allele frequency over many gens occurring through natural selection
Explain the principles of natural selection in the evolution of populations
Mutation can cause new alleles
Organism has a selective advantage
Posessors more likely to reproduce
Advantageous allele is inherited by next generation
Allele frequency increases
Describe 3 types of adaptations
Anatomical - structural / physical features that increase chance of survival
Physiological - processes / chemical reactions that increase chance of survival
Behavioural - ways in which an organism acts that increase chance of survival
What is a species?
A group of organisms that can (interbreed to) produce fertile offspring
Suggest why 2 different species are unable to produce fertile offspring
Different species have different chromosome numbers
So homologous pairs cannot form → meiosis cannot occur to produce gametes
Explain why courtship behaviour is a necessary precursor to successful mating
Allows recognition of members of same species → so fertile offspring produced
Allows recognition / attraction of opposite sex
synchronises mating
Indicates sexual maturity / fertility
Establishes a pair bond to raise young
Describe a phylogenetic classification system
Species arranged into groups, called taxa, based on their common ancestors and relationships
Hierarchy - small groups within larger with no overlap
Name the taxa in the hierarchy of classification
1.Domain (largest / broadest)
2. Kingdom
3. Phylum
4. Class
5. Order
6. Family
7. Genus
8. Species (smallest)
How is each species universally identified?
binomial consisting of the name of its genus and species, eg. Homo sapiens
Suggest an advantage of binomial naming
Universal so no confusion as many organisms have more than one common name
How can phylogenetic trees be interpreted?
Branch point = common ancestor
Branch = evolutionary path
If two species have a more recent common
ancestor, they are more closely related
What is biodiversity?
Variety of living organisms
Can relate to a range of habitats,
What is a community?
All populations of different species that live in an area
What is species richness?
A measure of the number of different species in a community
What does an index of diversity do?
Describes the relationship between:
1. The number of species in a community (species richness)
2. The number of individuals in each species (population size)
Suggest why index of diversity is more useful than species richness
Also takes into account number of individuals in each species
List the steps involved in calculating an index of diversity
- Calculate the total number of organisms (N), if not given
- Multiply N by (N - 1)
- For each species, multiply the number of organisms (n) by (n - 1)
- Addupallthevaluesofn(n-1)togetΣn(n-1) 5. DivideN(N-1)byΣn(n-1)
Describe how index of diversity values can be interpreted
High → many species present (high species richness) and species evenly represented
Low → habitat dominated by one / a few species
Explain how some farming techniques reduce biodiversity
Removal of woodland and hedgerows, use of herbicides to kill weeds - Reduces variety of plant species, so fewer habitats and niches
and less variety of food sources
Use of pesticides to kill pests, predator population of pest decreases
Explain the balance between conservation and farm
Conservation required to increase biodiversity
Give examples of how biodiversity can be increased in areas of agriculture
Reduce use of pesticides
Growing different crops in the same area (intercropping)
Using crop rotation of nitrogen fixing crops instead of fertilisers
How can genetic diversity within or between species be measured?
Comparing frequency of measurable or observable characteristics
Comparing base sequence of DNA
Comparing base sequence of mRNA
Comparing amino acid sequence of a specific protein encoded by DNA and mRNA
Explain how comparing DNA, mRNA and amino acid sequences can indicate relationships between organisms within a species and between species
More differences in sequences → more distantly related / earlier common ancestor
As mutations (change in DNA base sequences) build up over time
More mutations cause more changes in amino acid sequences
Explain the change in methods of investigating genetic diversity over time
Early estimates made by inferring DNA differences from measurable or observable characteristics
○ Many coded for by more than one gene → difficult to distinguish one from another
○ Many influenced by environment → differences due to environment not genes
● Gene technologies allowed this to be replaced by direct investigation of DNA sequences
Explain how data should be collected when investigating variation within a species quantitatively
Collect data from random samples
○ Use a grid / divide area into squares
○ Use a random number generator to obtain random coordinates
Use same method of measurement each time
Use a large sample size / measure a large number of organisms → so representative of population
Calculate a running mean and sample until number becomes (fairly) constant
(Where applicable) ensure sampling is ethical → must not harm organism / must allow release
unchanged
