Biodiversity Flashcards
Genetic diversity, adaptation, species and taxonomy, Biodiversity and investigating diversity
What is a Habitat?
- place where an organism lives
- normally characterised by the physical conditions and the types of other organisms present
What is a niche?
An organisms role in an ecosystem
What is species richness?
- Count of the number of species present in a community
- Doesn’t take into account how many of each there is.
- more species present, the richer the habitat
(Observe and record the species present in a habitat
Samples should be taken
Visual surveys should be taken, to ensure that nothing is missed)
What is index of diversity?
mathematical measure of diversity that takes into account total number of organisms, number of species and how many of each species there are
What is species diversity?
Number of different species and the number of individuals of each species within a community.
What is a community?
All the living organisms present in an ecosystem at a given time.
What is an ecosystem?
All the living and non-living components of a particular area.
What is Genetic diversity?
- Variety of alleles that are possessed by individuals of a population
- Genetic diversity is a factor enabling natural selection to occur
What is a population?
A group of individuals of the same species occupying a particular geographic area.
Principles of natural selection in the evolution of populations
Random mutation can result in new alleles of a gene.
• (Many mutations are harmful but, in certain environments,) the new allele of a gene might benefit its possessor, leading to increased reproductive success.
• The advantageous allele is inherited by members of the next
generation.
• As a result, over many generations, the new allele increases in
frequency in the population.
Types of natural selection that alter allele frequency in a population?
Directional and stabilising selection
What is directional selection?
where individuals with alleles for characteristics of an extreme type are more likely to survive & reproduce. Could be in response to an environmental change
Example of directional selection
antibiotic resistance in bacteria
Explain Directional selection with antibiotic-resistant bacteria
- Some individuals in a population have alleles that give them resistance to an antibiotic.
- When population is exposed to antibiotic, bacteria without resistant allele will be killed
- Resistant bacteria survive (have a selective advantage) & reproduce without competition, passing on allele that gives antibiotic resistance to offspring
- Increases frequency of this antibiotic-resistant allele in subsequent generations - becomes widespread in bacterial population
Describe directional selection graph
Y axis = number of individuals
X axis = antibiotic resistance
Bell shape. Mean shifts right in offspring (higher antibiotic resistant individuals in population)
What is stabilising selection?
- where individuals with alleles for characteristics towards the middle of the range are more likely to survive and reproduce
- having alleles on both extremes of population leads to less chance of survival to pass on these alleles, so frequency of these alleles is reduced.
Example of stabilising selection
Human birth weights
Explain stabilising selection with human birth weights
- Babies born with extremely high or low birth weights are less likely to survive due to complications during birth & infancy
- Therefore less likely to pass on their alleles
- average organisms more likely to survive & pass on their alleles to offspring, so increasing frequency of these alleles
Describe stabilising selection graph
Y axis = number of individuals
X axis = weight of baby
High bell shape, weight of human babies tend to shift towards middle of the range
Adaptations help organisms do?
survive in their environment
Types of adaptations?
Behavioural adaptations, physiological adaptations & anatomical adaptations
What are behavioural adaptations?
Ways an organism acts to increase chances of survival e.g. autumn migration of swallows from UK to Africa to avoid food shortages in UK winter
What are physiological adaptations?
Processes inside an organism’s body that increase its chance of survival e.g. brown bears hibernate over winter. They lower their metablic rate, this conserves energy so they don’t need to look for food in months when it’s scarce
What are anatomical adaptations?
Structural features of an organism’s body that increase it’s chances of survival e.g. whales have a thick layer of blubber (fat) which help them keep warm in cold sea
Explain what is meant by a species
two organisms that are able to reproduce and produce fertile offspring
Explain what is meant by a phylogenetic group?
group of organism that have a common ancestory
What is necessary for sucessful mating?
Courtship behaviour
How are organisms identified?
Binomal naming system
Explain binomal naming system
It has 2 parts. Generic and specific name.
Generic - the genus to which the organisms belongs
specific - species to which an organism belongs
How to write organism’s binomal name in exam?
names must be underlined and first letter of generic name capitalised and first letter of specific name in lower case
What do members of the same species share?
similar physical, biochemical and behavioural characteristics
When does courtship behaviour take place?
Before mating
Steps involved in courtship behaviour
- Recognise members of the same species
- Identify a mate capable of breeding
- Form a pair bond
- Synchronise mating
- Become able to breed
Courtship behaviour: why must organisms be able to recognise their own species?
because only members of the same species can produce fertile offspring
Courtship behaviour: why must they be able to identify a mate capable of breeding?
because both partners need to be sexually mature, fertile receptive to mating
Courtship behaviour: why must they be able to form a pair bond?
for successful mating and raising of offspring
Courtship behaviour: why must they sychronise mating?
- females of most species can only produce eggs at specific and few times in a year
- so synchronise mating takes place when there is maximum probability of sperm and egg meeting
Courtship behaviour: becoming able to breed?
by bringing a member of the opposite sex into a physiological state that allows breeding to occur
Explain Courtship process
- Animals use signals to communicate with possible mate
- Chain of actions between male and female
- Chain of actions are the same for all memebers of a species (but differ for memembers of other species)
- Individuals recognise that partner is the same species and may be prepared to mate
What is classification?
the process of naming and organising organisms into groups based on their characteristics
What’s a taxon?
Phylogenetic classification uses a hierarchy where smaller groups are placed within larger
groups, with no overlap between groups. Each group is a taxon (plural taxa)
Plural of taxon
Taxa
What are the 3 domains?
Eukarya, Bacteria & Archaea
Features of Bacteria?
- absence of membrane bound organelles (mitochondria & nuclei)
- unicellular (although not always)
- Ribosomes smaller (70S) than those in eukaryotes
- Cell walls made of murein
- single loop of naked DNA made up of nucleic acids (no Histones)
What are Archaea?
single-celled prokaryotes that were originally classified as bacteria (they resemble them)
How does Archaea differ from bacteria?
genes and protein synthesis more similar to eukaryotes
- membranes contain fatty acid chains attached to glycerol by ETHER linkages
- no murein in cell walls
- more complex form of RNA polymerase
What are Eukarya?
group of organisms made up of 1 or more eukaryotic cells.
Features of Eukarya?
cells possess memebrane-bounded organelles (e.g. mitochondria, chloroplast)
- membranes contain fatty acid chains attached to glycerol by ESTER linkages
- some have cell walls, those that do don’t contain murein
- riosomes larger (80S) than in bacteria & Archaea
What are the 5 kingdoms?
don’t need to know - check spec
Prokaryotae Protoctista Fungi Plantae Animalia
8 Levels of taxonomy
Domain Kingdom Phylum Class Order Family Genus Species (Did King Phillip Come Over For Good Soup?)
Trend down the hierarchy ( Domain - Species) ?
As you move down the hierarchy, there are more groups at each level but fewer organisms in each group. Organisms in each group become more closely related
- Hierarchy ends with species - this group contains only 1 type of organism (e.g. humans, dogs, E.coli)
What’s phylogeny?
study of evolutionary history of groups of organisms
What’s biodiversity?
variety of living organisms
Index of diversity calculation
d= N(N-1) / (sum of)n(n-1) N = total number of organisms n = total number of organisms of each species
How do agriculture ecosystems reduce biodiversity and the number of species present?
- Humans select for particular characteristics
- Therefore reduces no. of alleles & therefore genetic diversity of population
- Farmland is typically used for only a single species & so fewer individuals of other species can survive there
Biodiversity can be measured in terms of what?
Species diversity
Genetic diversity
Ecosystem diversity (range of different habitats)
how does selective breeding by farmers reduce biodiversity?
- any particular area can only support a certain biomass
- if most area taken up by 1 species favoured by farmer, less space avaiable for other species
- many other species have to compete for little space and resources available, even if some adapt some will not.
How do pesticides reduce index of species diversity?
- makes species compete for light, mineral ion, water and food (resources) required by the farmed species
- overall effect is a reduction in species diversity
What is deforestation?
clearing forests for agriculture or buildings
How does deforestation reduce biodiversity?
Loss of habitat Destruction of species Change in microclimate Animals move away to habitats they are worse adapted to Disruption of complex food webs
Why is index of diversity a good measure of biodiversity?
It takes into account both species richness and evenness
Gives an idea of the number of each species relative to population size
Small and large populations are treated differently
Why is species of richness not as good of a measure of biodiversity as index of biodiversity is?
doesn’t take into account the number of individuals of each species
Not sufficient data to measure diversity alone
techniques used to maintain biodiversity?
- use hedgerows instead of fences
- intercropping (growing different crops in the same area)
- reducing the use of herbicides & pesticides
- preserving wetlands instead of draining these for farming use
High index of biodiversity means what?
- Indicates a diverse habitat
- Many different species live there
- Small change to environment may only affect one species
- If this species is only small population, then only a small proportion of the habitat is effected
- Total effect on the habitat would be small
- Tends to be stable habitat
Low index of biodiversity means what?
- Suggests it is dominated by few species
- Small change to the environment may affect one of the major species
- Could damage or destroy the whole species
- Small change would have a very large impact on the environment
- Much less stable environment
How are farmers encouraged to practice management techniques for biodiversity?
financial incentives
Why is maintaining biodiversity very important?
if biodiversity is reduced the global living systems become increasingly unstable and we all rely on the global system for food & other resources
Five ways farming reduces biodiversity?
- Monoculture - fewer food sources, fewer ecological niches
- removal of woodland and hedgerows - fewer food resources, fewer ecological niches
- filling in ponds, draining marsh and wetlands - fewer food resources, fewer ecological niches
- pesticides - fewer food resources, they eat pests, impact on food chain
- pollution - toxin from bacteria can poison organisms
What 2 key things increase biodiversity? (Key terms)
- Lots of food sources
- Lots of ecological niches
What’s an ecological niche?
the role and position a species has in its environment; how it meets its needs for food and shelter, how it survives, and how it reproduces
Genetic diversity within, or between species, can be made by comparing what?
- the frequency of measurable or observable characteristics
- the base sequence of DNA
- the base sequence of mRNA
- the amino acid sequence of the proteins encoded by DNA and mRNA.
Discuss Comparison of observable characteristics in genetic diversity
- Genetic diversity traditionally measured by observing characteristics of organisms
- method based on fact that each observable characteristic is determined by a gene or genes
Limitations of comparing observable characteristics as a measure of genetic diversity
- characteristics coded for by more than one (POLYGENIC), they vary continously
- characteristics modified by environment (environmental factors e.g. diet affects height in humans)
How are DNA differences investigated today instead of by observable characteristics?
directly observing DNA sequences, made possible by advances in gene technology made over recent years
What’s sampling?
- when a small, random group of individuals within a population is selected and studied carefully
- you can then multiply up the numbers of individual species found to give an estimate for the entire habitat.
Number of samples in sampling?
- Number of samples should be sufficient to give an accurate measure of the number of species in habitat and relative abundance
- If two areas are being compared, the same number of samples should be taken at each
How to do random sampling?
- Taking samples at regular distances
- Use random numbers to plot co-ordinates
- Select co-ordinates from a map and use GPS to find the exact location
Standard deviation formula
(In notes)
sum of( measured value from sample - mean value) squared / total number of values in sample - 1.
All over a square root
Whats is standard deviation?
measure the deviation of the data from the mean value - assumes the data fits a normal distribution
Why is standard deviation more useful than range?
- tells you about the values either side of the mean
- it’s more useful than using range because the values is not affected by OUTLIERS (results that don’t fit trend)
Describe significant and insignificant difference in a graph with standard deviation
If error bars overlap (the values) there is no significant difference
If they don’t overlap, shows a sig difference
What’s normal distribution?
- Bell shaped curve
- shows continuous variation
- average (mean, mode & median) is in the middle
Discuss the P value (significant & not significant difference)
If P < (or equal to) 0.05 results are significantly different
- means there’s a less than 5% probability that results are due to chance
If P > (or equal to) 0.05 results are NOT significantly different
- means there’s a greater than 5% probability that results are due to chance
What does the t-test show?
- statistical test that compares the mean and standard deviation of two samples to see if there is a significant difference between them (to see if results are due to chance)
Comparison of DNA base sequences in genetic diversity?
- gene technology allows us to read base sequence of any organism
- can accurately determine exact order of nucleotides on DNA
- can use these techniques to examine evolutionary relationships between species
What does two organisms with similar DNA mean? (evolution)
- when one species give rise to another during evolution, DNA will be similar
- due to mutations, sequence of nucleotide bases in DNA of new species will change
- species closely related will show more similarity in their DNA than those more distantly related.
Comparison of base sequence of mRNA in genetic diversity
- base sequence of mRNA is complementary to those on DNA from which they were made
- can measure DNA diversity & therefore genetic diversity by comparing base sequence of mRNA
Comparison of amino acid sequences in proteins in genetic diversity?
- sequence of AAs in proteins determined by mRNA which is determined by DNA.
- GD can therefore be measured by comparing amino acid sequences
- how similar AA sequence is of the same protein in 2 species will reflect how closely related they are
- similarities are found by counting number of similarities & differences
How does woodland clearance reduce biodiversity?
- done to increase farmland
- directly reduces number of trees & no. of different tree species
- destroys habitats, losing shelter & food source (fewer ecological niches, fewer food sources)
How does hedgerow removal reduce biodiversity?
- increases area of farmland by turning lots of small fields into fewer larger fields
- reduces ecological niches, fewer food sources
How do pesticides reduce biodiversity?
- chemicals that kill pests that feed on crops
- reduces biodiversity by DIRECTLY killing pests
- any species that feed on pests will lose a food source
How do herbicides reduce biodiversity?
- chemicals that kill unwanted plants (weeds)
- reduces plant diversity & could reduce food source for organisms that feed on plant
How does monoculture reduce biodiversity?
- when farmers have fields containing 1 plant.
- single type of plant reduces biodiversity and will support fewer organisms (as a food source or a habitat), this reduces biodiversity
Examples of conservation schemes
- giving legal protection to endangered species
- creating protected areas. they restrict further development like agriculture development
state three comparisons of genetic diversity that scientists use to classify organisms
- base sequence of DNA
- base sequence of mRNA
- amino acid sequence of proteins
list three features of a phylogenetic system of classification
- based on evolutionary relationships between organisms and their ancestors
- it classifies species into groups using shared characteristics derived from their ancestors
- it’s arranged in a hierarchy in which groups are contained within larger composite groups with no overlap
suggest reasons why it is often difficult to classify organisms as distinct species
species change and evolve over time, sometimes developing into different species.
There is considerable variety within a species.
Fossil records are incomplete/non-existent.
Current classifications only reflect current scientific knowledge and as it changes, so does naming and classifying of organisms.
Even where groups of extinct organisms have left fossil records, it is very difficult to distinguish different species. Suggest two reasons why
- fossil records are normally incomplete and not all features can be observed (there’s no biochemical record) and so comparisons between individuals are hard to make
- fossil records can never reveal whether individuals could successfully mate
Forest is cleared to make more land available for agriculture. After the forest was clear the species diversity of insects in the area decreased. Explain why
- decrease in the variety of plants
- fewer habitats/niches
- fewer food SOURCES
(fewer species of herbivores so few species of carnivores)
(aspect of agriculture killing insects e.g. machinery/pesticides)
define a hierarchy
- groups within groups
- no overlap (between groups)
define a phylogenic group
- organisms grouped according to evolutionary relationships/common ancestry
Points in a graph sometimes joined with straight lines rather than with a smooth curve. Explain why
- cannot predict
- intermediate values not known
Explain why there might be a time lag in desirable allele (e.g. resistant to pests) being shown
- initially, only organisms have desirable allele
- individuals with favourable allele will have more offspring
- takes many generations for favourable mutation/allele to be most common allele of this gene
what is a genetic bottleneck?
occurs when a population is greatly reduced in size, limiting the genetic diversity of the species
- e.g. due to environmental events such as famines, earthquakes, floods, fires, disease, and droughts or human activities
Give three ways in which courtship behaviour increases the probability of successful mating?
- Ensure that two individuals are off the same species
- stimulates synchronised mating therefore gametes are released together
- Ensure the individuals are of sexual maturity
- Two mates can form a pair bond therefore raising the sound more successfully together.
- recognition and attraction of a mate of the opposite sex
Mutation is one cause of genetic variation in organisms.
Give two other causes of genetic variation.
- . crossing over
2. independent assortment/segregation
