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Biology Synoptic Essays
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Biology Synoptic Essays
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Biology Synoptic Essayshe importance of interactions between cells and between organisms
viruses
- bind to receptor so they can enter, viral rna to dna, translation, assembly, budding
- important so that viruses can replicate and pass on alleles to next generation
- cells prevent viral antigens, so that t and b cells can stimulate immune response, organism
survives
immune system
- phagocytosis
- th activation
- tc activation
- b cell activation
- important so antibodies produced, agglutination and neutralisation
- important so memory cells = acquired immunity, prevents symptoms on second infection
mass transport in plants
- companion cells a/t sugars to phloem, water in from xylem
- hydrostatic pressure means sugars move to sink
- cells in sink using sugars
- important so sugars source to sink
- sugars from p/s in leaves can be transported to other parts, used for resp so energy for
growth and protein synthesis, increases biomass
courtship behaviour
- rituals between males and females of same species
- involves chain of actions, calls and responses between male and female
- important so identify same species to produce fertile offspring, alleles passed to next gen
,- identifies receptive females so successful reproduction
- forms pair bond so raise offspring successfully
- synchronisation of mating
nutrient cycles
- bacteria fix nitrogen, forms nitrates
- plants absorb for protein synthesis, consumed by animals
- death means saprobionts decompose
- important so nitrogen-containing compounds passed between organisms and eventually
returns to soil
- mutualistic bacteria interact w/ plants to fix more nitrogen for more growth, bacteria get
glucose and aa
the importance of the control of movement in cells and organisms
control of heart rate
- SAN sends WOD across atria, contract, so blood moves to ventricles
- AVN pause, important so blood completely empties from atria
- AVN sends signal down bundle of his, to apex
- up purkinje fibres so ventricles contract
- septum insulated so contract from bottom up, controls contraction of v from bottom up so
that max blood pumped out
mass transport in animals
- valves control movement of blood
- av opens when p(a>v) so blood can flow to v, close when p(v>a) prevents backflow
- semi lunar opens when p(v>artery) to allow flow, closes vice versa to prevent backflow
- important so that all blood moves to lungs to get oxygenated and all delivered to tissues so
more terminal electron acceptor so more ATP so more energy
, - veins have valves to prevent backflow so deox blood at extremities can be oxygenated,
prevents tissue death as co2 removed
nerve impulses
- sodium potassium pump maintains negative resting potential
- membrane impermeable to sodium and permeable to K so polarised
- stimulus means membrane permeable to Na, influx means depolarisation
- permeability to Na decrease, K increase so K out, repolarise
- pump resets, refractory period means permeability to ions low so cannot generate another
a/p
- important so that at resting potential, cannot depolarise unless stimulus, controlled
response
- also refractory period means unidirectional impulse and separated impulses
photosynthesis
- electrons from photolysis move down electron carrier chain
- H+ pumped into thylakoid space
- impermeable so H+ accumulates
- impermeability important as means conc grad set up
- controlled as can only flow down ATP synthase, so KE from H+ used to make ATP
meiosis
- synapsis means hom chrom pairs, means chiasmata form, independent assortment
- important for variation
- spindle attaches at centromere to pull to opposite poles, important so chrom number
halved
- movement of chromosomes to equator, independent assortment of chromatids
- pulled apart so chromatids separated
- important to produce gametes with full set of chromosomes, but with haploid number
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