investigating diversity Flashcards
define selection
when better adapted species survive and reproduce
define genetic diversity
number of different alleles of genes in a population
define evolution
change in frequency of alleles over many generations in a population
define population
groups of individuals of same species that live in same place and interbreed
directional selection
selection favours individuals with extreme features
stabilising selection
selection favours individuals with modal trait
give 4 ways of investigating genetic diversity
DNA base sequence
mRNA base sequence
amino acid sequence
observable characteristics
what can you conclude about genetic diversity when comparing DNA base sequences
the closer the DNA base sequences are between two groups, the more closely related they are
key thing to remember when analysing mitochondrial DNA
zygote only contains the mitochondria of the egg and none from the sperm- only maternal mitochondrial DNA present in a zygote
There is no crossing over that occurs in mtDNA so the base sequence can only change by mutation
why is only maternal mitochondrial DNA present in a zygote
zygote only contains the mitochondria of the egg and none from the sperm- only maternal mitochondrial DNA present in a zygote
why is mRNA analysis easier than DNA analysis
mRNA is easier to isolate from cells as it is found in the cytoplasm
whereas DNA in the nucleus so it is harder to isolate
how does mRNA analysis work
mRNA is collected and used as template to make cDNA (complementary DNA)
this cDNA is complementary to the mRNA template
the cDNA is copied, complementary strand made which is then the same as the mRNA template strand
cDNA only contains exons, no introns
give the difference between cDNA and original DNA in the nucleus
cDNA has no introns, only exons
DNA has introns and exons
describe how amino acid sequence is analysed
one protein is selected e.g haemoglobin
the amino acid sequence of this protein is compared between organisms to see if they match
why is it likely that closely related species will have same amino acid sequence
as amino acid sequence of proteins evolves more slowly than DNA
name the 2 types of sampling
systematic
random
advantage of random sampling
prevents bias
disadvantages
of systematic sampling
bias- may choose area with fewer or more species
what is meant by species abundance
number of individuals of that species
describe method using quadrats to measure species abundance
- create a grid with 2 tape measures
- generate 2 co-ordinates with random generator
- place quadrat at co-ordinate
- count number of individuals in each quadrat
- do 10x
- calculate mean
- multiply mean by whole area of grid
what is species density
how many individuals of that species there are per unit area
how to calculate species density
number of individuals in all quadrats is divided by the total area of all the quadrats
e.g. 107 bluebells were found across 50 quadrats that are 1m2 each
the species density would be 107/50 = 2.14 individuals per m2
limitation of quadrats
can only be used for sessile and immobile species (eg. plants and slow-moving animals)
what is standard deviation
a measure of the spread of data around the mean
what does small standard deviation mean
results lie close to the mean
what does a big standard deviation mean
results are more spread out, further from mean
how to know if results are significantly different or not
overlap between standard deviations= no significant difference
no overlap between standard deviations= significant difference
define gene pool
the collection of genes in a species
define evolution
the formation of new species from pre-existing species over time,
due to changes to gene pools from generation to generation
what must happen for evolution to happen
the old and new species must be reproductively and genetically isolated from one another- no longer exchange of genes between them
