Section 4 - Biodiversity Flashcards
What is a population?
Group of individuals of the same species that live in the same place and can interbreed.
How does the reproductive success of individuals affect allele frequency?
Random gene mutations lead to new alleles in a gene pool
New alleles allow individuals to survive and reproduce
Offspring inherit the new allele
Over generations new advantageous allele will increase
What is gene pool?
The variety of alleles in a population
What is directional selection?
Environmental favours individuals at one extreme of the bell curve
Individuals outside of mean will have phenotype for suited to new conditions
(Mean value changes)
What is stabilising selection?
If environmental conditions remain stable, individuals with phenotypes closet to mean are favoured.
Individuals more likely to pass alleles onto next generation.
Individuals with extreme phenotypes are less likely to survive
(Mean stays the same)
What is classification?
The grouping of organisms
What is taxonomy?
The theory and practice of biological classification
What is a species?
A group of organisms which have similar characteristics are able to breed to produce fertile offspring
What is the system for naming species?
The Binomial system
What two categories identifies organisms using the binomial system?
The generic name: genus (capital and underlined)
The specific name: species (underlined)
What is courtship behaviour?
A necessary precursor to successful mating
What factors are included in courtship behaviour?
Species recognition
Attracting a mate that’s capable of breeding
Pair bond formation
Synchronisation of mating
What are the advantages of courtship behaviour?
Individuals can:
- recognise sexually mature members of their species of the opposite sex
- synchronise mating
- form a pair bond
- successfully breed
What are the 8 groups in the classification hierarchy?
largest to smaller
- Domain
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
What is artificial classification?
Divides organisms according to differences that are useful at the time
(colour, size, number of legs, leaf shape)
What is phylogenetic classification?
- Based upon evolutionary relationships
- Classifies species into groups with shard features derived from ancestors
- Arranges groups into hierarchy
What are the 3 domain types?
Bacteria
Archaea
Eukarya
What is the domain, bacteria?
Single-celled prokaryotes
- Absence of membrane-bound organelles
- Unicellular
- Ribosomes are smaller (70s) than eukaryotes
- Cell walls are present (murein)
- Single loop of naked DNA
What is the domain, archaea?
Single-celled prokaryotes
- Genes and protein synthesis
- Membranes contain fatty acid chains attached to glycerol by ester linkages
What is the domain, eukarya?
Organisms made up of one or more eukaryotic cell
-Cell possess membrane-bound organelles
-Membranes containing fatty acid chains attached to glycerol by ester linkages
Ribosomes are larger (80s)
What is phylogeny?
The evolutionary relationship between organisms
In a phylogenetic diagram what is at base of the tree?
The oldest species
What are one thing that all members of a species have?
They are capable of breeding to produce offspring which are themselves fertile
What are 3 features of a phylogenetic system of classification?
Based on evolutionary relationships between organisms and their ancestors
Classifies species into groups using shared characteristics from their ancestors
Arranged in a hierarchy with no overlap
Why is it important for species recognition in courtship?
Ensures mating only takes place between members of the same species as only they can produce fertile offspring
What is a way species may use courtship behaviour to determine which species it is most closely related to?
The courtship display that most closely resembles that of the first species is likely to be the closest relative.
What is species diversity?
The number of different species and the number of individuals of each species within any one community
What is genetic diversity?
The variety of genes possessed by the individuals that make up a population of a species.
What is ecosystem diveristy?
The range of different habitats
What is species richness?
The number of different species in a particular area at a given time
How do you measure index of diversity?
d= N(n-1)/ Zn(n-1)
d= index of diversity N= total number of organisms of all species n= total number of organisms of each species Z= the sum of
Why is it more useful to calculate a species diversity index than just to record the number of species present?
It measures both number of species and number of organisms
Takes account of species that are only present in small numbers
What are the rules for naming species in the binomial system?
Generic specific
Generic: genus (capital letter)
Specific: species (lower case)
Both underlined
What is the name for the practice of biological classification?
Taxonomy
What is the different between phylogenetic and artificial classification?
Phylogenetic: DNA sequences
Artificial: characteristics
What is the difference between species richness and species diversity?
Species diversity: how many of each species
Species richness: how many different species
Why is it important to increase yield of agricultural ecosystems?
To provide more for the growing population
- a nation needs food security
Increases employment opportunities
Affordable food
How is yield increased in agriculture?
Use fertilisers (pesticides, herbicides)
Selective breeding
Use of machinery
What are the consequences of intensive farming on ecosystems?
Cause damage to land Can kill beneficial insects/ plants Creates polluted run-off and polluted ecosystems Decrease species diversity Reduces biodiversity
What conservation measures can be introduced in farming to increase species diversity?
Maintain or build hedgerows Crop rotation Stop draining ponds Reduce the use of pesticides Use intercropping (crop rotation with nitrogen fixing crops)
Why is there a reduction in species diversity when a forest is replaced by grassland for sheep?
Forests have many habitats for many species
Grasslands have single layer, fewer habitats, fewer species, lower species diversity
Why would draining ponds have a great effect on biodiversity than removing a hedgerow?
Ponds provide habitat for wide range of species
(unlikely to find alternative habitat)
Ponds source of food and water
Hedgerow species have larger range of alternative habitats
Other sources of food and shelter
Fewer species likely to be lost
How can the base sequence of mRNA be used to investigate diversity?
mRNA is complementary to base sequence on DNA so can be used to measure genetic diversity
How can amino acid sequences in proteins be used to investigate diversity?
Sequence of amino acid in a protein is determined by DNA of the organism
Comparing 2 species- more similar the sequences, more closely related they are/
What does sampling involve?
Taking measurements of individuals, selected from the population of organisms which is being investigated
What is sampling bias?
The selection process may be biased because investigators may be making unrepresentative choices, either deliberately or unwittingly.
What is chance in sampling?
Even if sampling bias is avoided, the individuals chosen, by pure choice, may not be representaive
What is an effective method of random sampling?
- Divide are into a grid of numbered lines
- Use random numbers to obtain a series of coordinates
- Take samples at the intersection of each pair of coordinates
How will using a large sample size remove chance from sampling process?
More individuals selected, smaller the probability chance will influence result and less influence anomalies will have
What is interspecific variation?
Differences between speices
What is intraspecific variation?
Differences within the same species
What is discontinuous variation?
Variables are assigned to clearly defined categories or distinct groups
(e.g. sex, colour, blood group)
Data presented by bar graph
What is continuous variation?
Full range of variables between 2 extreme values
(e.g. height, weight, length, size)
Data presented in normal distribution= bell shaped
What is standard deviation?
A measure of the width of the curve.
Gives an indication of the range of values either side of the mean
What term can be used to describe the difference between 2 populations?
Variation
What are 2 ways scientists can ensure index of diversity is representative of a habitat?
Random
Large sample size
Why does diversity decrease when farmers use large fields?
Large field has highest proportion of centre with the lowest diveristy
What is an advantage and disadvantage to a farmer replanting hedges on farmland?
Advantage: provides habitat for predators of pests.
Reduces crop loss to pests.
Disadvantage: less land to grow crops
Farmer makes less profit
What are the principles which biologists use to classify organisms into groups?
Hierarchical
Members of a group have features in common
Reflects evolutionary biology
DNA
How is information on amino acid sequences used to construct phylogenetic tree?
Those with similar sequences are more closely related
Greater the differences, more distance
What is an advantage and disadvantage of using amino acid sequences to construct a phylogenetic tree?
Advantage: present in all organisms, quantifiable
Disadvantage: no timing of events, can’t include prokaryotes
What is a hierarchy?
Group within group
No overlap
What are 3 ways in which courtship behaviour increases the probability of successful mating?
Attracts same species
Stimulates mating
Recognition of opposite sex
What are 3 features of a phylogenetic system of classification?
Evolutionary relationship
Shared characteristics with ancestors
Arranged into hierarchy in which groups are contained within larger groups with no overlap
