7 - Inheritance & Ecology Flashcards
What’s a population
A group of organisms of the same species, living in the same habitat at the same time
What’s a community
All the populations of different species living in the same habitat at the same time
What’s an ecosystem
A community, plus all the non living (abiotic) conditions of their environment.
What are abiotic conditions
Non-living
Eg temperature and pH
What are Biotic conditions
Living features
Eg inter/intraspecific competition, predation, food supply, disease
Describe and explain how succession works (5m)
- colonisation by pioneer species
- pioneer species change the environment eg forms soil
- environment becomes more suitable for new species
- increase in biodiversity
- to climax community
How could you do sampling
- use a grid
- get random coordinates using a random number generator
- count number in quadrat
- large sample and calculate average number per quadrat
- calculate the total number (mean number x no. Of quadrats)
Give two features of a climax community
- same species present over long time
- abiotic factors constant over time
What are 3 actions to achieve balance between conservation and breeding
- provide less food to the species so their populations don’t grow large enough to cause competition
- do not breed similar animals as they share the same habitat and food so will compete
- keep the species in separate areas as they occupy the same habitat
Describe the mark release re capture method
- capture the sample, mark and release
- leave time for species to disperse before second sample
- population = (no. in first sample x no. in second sample) /no. recaptured (in 2nd sample)
Describe the equation for calculating population in the mark release recapture method
(Total No. in first sample x total no. In second sample) divided by no. Marked in 2nd sample
Repeated at least 10 times
What is interspecific competition
- biotic factor
- competition between different species
- for limited resources eg food
What is intraspecific competition
- biotic factor
- competition between the same species
- for resources & a mate to reproduce
What is predation
Interaction between predators and prey
How does conservation effect succession
- climax community is prevented
- so wider variety of habitats
- so higher species diversity
What are the assumptions made in proportional sampling
- they know the size of the area where a population lives
- the organisms are evenly distributed
What are the assumptions made in mark release recapture
- there’s enough time for organisms to distribute themselves
- no migration
- no births or deaths
What is an autosome
Any chromosome that isn’t a sex chromosome
What’s the typical ratio for dihybrid crosses when crossing over occurs
9:3:3:1
What’s the typical ratio for dihybrid crosses when crossing over does not occur
3:1
In genetic crosses why are observed phenotypes not the same as expected ratios
- small sample size
- fertilisation of gametes is random
What’s the hardy Weinberg equation
P^2 + 2pq + q^2 = 1
p+ q = 1
What does each letter stand for in the hardy Weinberg equation
p = frequency of dominant allele
q = frequency of recessive allele
P2 = frequency of homozygous dominant genotype
2pq = frequency of heterozygous genotype
q2 = frequency of homozygous recessive genotype
What is a homologous pair of chromosomes
Two chromosomes that carry the same genes
Describe Allopatric speciation
- geographical isolation eg mountains or rivers
- Separate gene pools, no interbreeding
- Mutations create genetic variation in each population
- Different selection pressures act on each population
- Leading to natural selection of different favourable alleles
- Different survival and reproductive success
- Leads to change of frequencies over many years
- Members of different populations cannot interbreed
- New species arise from existing species
Describe directional selection eg antibiotic resistance
- Selection pressure act on one side of the mean
- one extreme phenotype more likely to survive and produce organisms with the gene for resistance
- mean Phenotype changes
Describe stabilising selection, e.g. human birthweights
- stable environment
- Selection and pressure act either side of the mean
- Both extremes of phenotype less likely to survive and produce eg very small or very large
- mean Phenotype remains the same
Describe disruptive selection
- Selection against the mean
- both extremes of phenotypes are favoured
- Could result in two separate species
What is speciation?
The development of a new species from an existing species when population can cannot interbreed
Describe Sympatric speciation
- Population in the same area
- Individuals reproductively isolated due to different mating seasons or different courtship behaviour
- different selection pressures
- Lead to change of allele frequencies within gene pools
- Members of different populations cannot interbreed
- New species arise from existing species
What is a niche
The role of a species within a habitat eg where it eats or what it eats
