Topic 4 Flashcards
species definition
a group of organisms with similar morphology, physiology and behaviour which can interbreed to produce fertile offspring and are reproductively isolated from other species
what is the disadvantage of using DNA analysis to identify species
cannot say whether 2 populations can interbreed to produce fertile offspring
population def
a group of interbreeding individuals of the same species found in an area
ecological niche
the way an organism exploits its environment
what are behavioural adaptations
actions by organisms which helps them survive and reproduce
what are physiological adaptations
features of the internal workings of an organism that helps them survive and reproduce
example of physiological adaptation
changes in internal biochemical functioning of an organism in response to an altered environmental stimulus
what are anatomical adaptations
a physical or structural adaptation- internal or external
e.g. cacti have spines
natural selection
change in environment (selective pressure) = change in selective pressures acting on population
allele previously selectively neutral now adv
organisms with allele more likely to survive and reproduce
offspring more likely to have allele so it becomes more common in population
evolution def
a change in allele frequency in a population over time
for natural selection to lead to evolution, there must be genetic variation in the population
what is a gene pool
consist of all the alleles of the genes present in a population
Hardy Weinberg Equation: working out allele frequencies
frequency of homozygous dominant individuals (p squared)
+
frequency of heterozygous individuals (2pq)
+
frequency of homozygous recessive (q squared)
what does the ability of a population to adapt to new conditions depend on?
- size of selection pressure
- size of gene pool
- reproductive rate
biodiversity def
the variety of species that belong to every different group of organisms
measuring helps focus conservation efforts to vulnerable habitats and species
what is the binomial system for naming organims
1st part of name: genus: shared by all closely related species
2nd part: defines particular species in the genus
where can scientific findings be reported
scientific journals
conference papers
internet
adv peer review
detect invalid claims
adds weight to valid claims
what is phenotype result of
interactions between genotype and environment
observable traits
sources of genetic variation
meiosis - independent assortment + crossing over
random mutations - change base sequence of DNA in organisms cells, creating new alleles which adds to the gene pool and increases variation
how can molecular changes in genetic variation be detected
electrophoresis of proteins: 2 alleles at a single locus produce slightly different protein products
how to measure biodiversity
- species evenness
2. species richness
how to calculate species richness
count number of species present in a given habitat
disadvantage
takes no account of population size of each species
what are areas of particularly high biodiversity known as
biodiversity hotspots
how to measure genetic diversity within a species
directly- DNA sequencing to determine the bases in a segment of DNA, thus determining what alleles are present
indirectly- DNA cut into fragments and separated using electrophoresis. Different alleles identified because they produce fragments of different lengths
differences : plant and animal cells
Plant: rigid cell wall and contains chloroplasts; animal cells do not
function of chloroplasts
site of photosynthesis- sun energy used to make storage molecules - starch is found in storage vacuoles in cytoplasm (amyoplasts)
plant adaptations
big and strong
building tall structure
disadvantage plants growing big and strong
can take long time to reach maturity
must be strong enough to hold own weight and withstand wind
how do plants build tall structures
- produce strong cell walls out of cellulose
- build columns and tubes from specialised cells
- stiffin some of these specialised cells with polymer LIGNIN
characteristics of cellulose
in plant cell walls
polysaccharide polymer of glucose made up of B- glucose units 1,4 glycosidic bond- long, unbranched molecule forms bundles (microfibrils)
Microfibrils
strong as LOTS OF hydrogen bonds between cellulose
would in helical arrangement around cell and stuck with polysaccharide glue
successive layers of microfibrils laid down at angles to one another, forming a composite structure
polysaccharide glue holding microfibrils together
composed of short, branched polysaccharides - pectins and hemicelluloses
short polysaccharides bind to:
- surface of cellulose
- each other and hold cellulose microfibrils together
what are pectins
component of middle lamella (region between cell walls and adjacent cells)
act as cement; holds cells together
why is cell wall so strong (2)
arrangement of cellulose microfibrils within a matrix of hemicelluloses and reinforced pectins
Microfibrils laid down at diff angles so strong and flexible
How to cross the cell wall
narrow fluid filled channels - plasmodesmata cross the cell walls, making the cytoplasm of one cell continuous with the cytoplasm of the next.
cell walls fully permeable to water and solutes
xylem vessels
form tubes for water and mineral transport + stiffened cell walls help support plant
sclerenchyma fibres
columns of these cells with their stiffened cell walls provide support
phloem sieve tube cells
form long tubes for transport of organic solutes (sugars, amino acids).
advantages of millennium seed bank
- collecting small sample of seeds is unlikely to damage wild population
- seeds small and easy to store
- seeds can survive in desiccated state for years
what happens when seeds collected
identification verified
seeds cleaned and dried and stored at -20
1month after placed in cold storage, sample taken out and germinated on agar plates to ensure seeds survive
germination tested every 10 years
if falls below 75% then seeds grown to produce new seed sample
what can seed collections be used for
research
habitat restoration
species reintroduction
what do studbooks do
shows history and location of all captive animals of that species in all places which are cooperating in an overall breeding plan
what can studbook records be supported by
cytogenetic techniques- looking at chromosome structures and molecular biology: studying nature of genes
important because studbook data may be incomplete and can reveal how closely related individuals are
