4.2 - Biodiversity Flashcards
Why we will never know for sure how accurate estimates of numbers of species are
- We will not be certain we have found all species on Earth
- We are discovering new sp. all the time
- evolution and speciation (the formation of new sp.) are continuing
- many sp. are endangered/ becoming extinct
Why estimates of species are likely to be lower than estimates
- not all species discovered yet
- many microscopic species are hard to see
- sampling might miss rare species
- organisms may be mistakenly identified as one when they are actually two different species
Sampling plants
- set area to be sampled
- use belt transect to sample
- use 50cmx50cm quadrants
- at regular 5m intervals
- identify plant species using keys
- record the presence/absence of sp. in each quadrant
- measure the % cover of each sp.
- Repeat this using several different transects for reliability
- To calculate biodiversity use Simpson’s diversity index
Sampling animals
- set grid to be sampled
- use random numbers to make grid coordinates to locate the areas you will randomly sample
- pick appropriate capture method CHOSE ONE e.g. sweep nets, pooters, pitfalls etc
- identify each sp. using a key
- count the numbers of each sp.
- Repeat this several times in each habitat, using the same technique each time
- To calculate biodiversity use Simpson’s diversity index
Why classification systems change over time
- scientific knowledge changes as new discoveries are made
- technological developments lead to new discoveries
- named technological development; e.g. microscopes, new DNA technology
- differences of opinion amongst biologists/scientists
Features of the five kingdoms
Animals = eukaryotes, multicellular, heterotrophic feeders, no cell walls,
Plants = eukaryotes, multicellular, autotrophic nutrition, cellulose cell walls,
Fungi = eukaryotes, mostly multicellular, saprotrophic feeders, chitin cell walls, reproduce with spores, have hyphae
Protoctists (misfits!) = eukaryotes, mostly single celled, have autotrophic and heterotrophic feeders, variety of different forms - DO NOT FIT INTO ANY OTHER KINGDOM!
Prokaryotes (bacteria) = prokaryotes (no nucleus - loop of naked DNA, no membrane bound organelles, smaller 70S ribosomes, respiration on mesosomes, smaller than eukaryotes, cell walls made of peptidoglycan (murein)
Why the appearance and anatomy of Fungi made their classification difficult for early taxonomists
- don’t move freely (like plants)
- hyphae resemble roots
- digest food (like animals) rather than photosynthesising
How Eubacteria (true bacteria) are different to Archaebacteria and eukaryotes
Eubacteria have:
- different cell membrane structures
- different flagella structures (not 9+2)
- naked DNA (not associated with histones)
- different mechanisms for DNA replication and RNA synthesis
The causes of variation
Genetic variation
- combination of alleles inherited will not be the same as any other individual (expect individuals made form asexual reproduction and identical twins)
- mutations can also cause genetic variation
Environmental variation
- any variation caused by any thing other than genetic differences,theenvironment causes e.g. scars, direction roots grown in response to water
Most variation is as a result of a combination of genetic and environmental factors
The forms of variation
Continuous
- no defined categories/distinct groups
- there is a range - any value is possible
- caused by genes and the environment
- quantitative (has to be measured rather than counted)
Discontinuous
- discrete categories with no intermediates
- caused by one (or very few) genes
- no (very little) environmental effects cause it
- qualitative
How any species has evolved to have any characteristic
- by natural selection
- mutations occur at random causing an individual to have ___________ (characteristic).
_________________ acts as a selection pressure causing competition between individuals - individuals with beneficial mutation for _____________ will be more likely to survive long enough to reproduce and pass on the mutated gene to its offspring over many
generations, the frequency of gene for __________ increases within the population
Speciation
- a population becomes separated or isolated
- allopatric speciation - geographical separation prevents interbreeding between individuals of the two populations e.g. river/mountain
- sympatric speciation - reproductive barriers which prevent interbreeding between individuals of the population e.g. sexual organs become incompatible, biochemical change prevents fertilisation
- mutations occur at random in (one of) the populations
- there may be different selective pressures in different environments
- the mutations may be beneficial which make survival more likely and therefore genes will be passed on (natural selection) in one population many small changes in the population over many generations
- populations to become so different they cannot interbreed and have become new
species.
Compare selective breeding with evolution
- both result from changes in allele frequencies
- selective breeding often faster than evolution
- both require selection of parents
- to pass alleles to offspring
- selective breeding involves artificial selection
- evolution involves natural selection
- man selective agent in selective breeding
- environment provides selective pressures in evolution
- selective breeding for benefit of man
- selective breeding may be detrimental to organism
How fossils provide evidence for evolution
- Fossils show that organisms have charged over time
- Methods such as carbon dating can be used to work out how old fossils are
- The oldest rocks contain the simplest species
- The fossil record shows many organisms that no longer exist but where intermediates between the oldest common ancestors and modern species
Molecular evidence for evolution
- DNA extracted from fossils can show similarities between organisms if they have a similar base sequence - implies they share a common ancestor
- Similar cytochrome C (protein needed for respiration) primary structure shows similarities between organisms - implies they share a common ancestor
