7. genetics, population, evolution and ecosystems Flashcards
codominance
both outcomes can be expressed
sex linkage
genes found on the region of X or Y (sex) chromosomes
autosomal linkage
genes found not on sex chromosomes that do not assort independently during meiosis
if genes for tail length and scale colour in a species of newt are linked, the ratio will be different to if the genes were not linked
epistasis
when two genes on different chromosomes effect the same thing
define selection pressure
environment which encourages biased between alleles/phenotypes
increase the chance of specific phenotypes
founder effect
small no. of individuals from large population begin a new population
not all of the gene pool is present
allele frequency is completely different to previous population
genetic drift
very small population
alleles passed onto new population is completely due to chance
effects of selection pressures are minimised
physiological adaptation
biological processes in the body
anatomical adaptation
physical features
behavioural adaptations
the way an organism behaves
cons of farming
low species richness
harmful chemicals
succession
increases diversity of species
allele frequency
no. of times an allele appears in a gene pool
allopatric speciation
speciation which occurs due to geographical isolation
climax community
the stable community of organisms that exists at the final stage of
ecological succession
genetic drift
variation in allele frequency due to chance
sympatric isolation
a form of speciation that occurs when two populations within the
same area (not geographically isolated) become reproductively isolated
changes in allele frequency
gene pools separated
define population
a group of organisms of the same species that live in the same area and can interbreed
reason for change of efficiency of energy transfers as you move up a food chain
plants more difference in energy loss as there are more indigestable components of a plant
reason for loss energy transfer between parts of food chain
energy loss between trophic levels
respiration, heatloss
not all digested
excretion
what do decomposers do
break down dead/undigested material
ways farmers increase efficiency to livestock etc
simplify food web
remove pests - they can’t consume energy
use of pesticides to increase farming efficiency
gets into food chains
very effective
expensive
time consuming
biological agents to increase farming efficiency
natural predator (e.g. lady birds)
low maintenance
ethical
may disrupt ecosystems
