bio paper 2
homeostasis?
maintaining an internal stable condition by regulating conditions inside the bosy
what do receptors do
detect change
what do coordination centres do
interpret change and decides what needs to be done
nervous system
fast and precise
impulses travel through nerves
respond quickly
short lasting effects
endocrine system
effect cells containing correct receptors
released into bloodstream
longer lasting and more generalized
what is a negative feedback loop
when the body acts to counteract a change in the environment
what is the thermoregulatort centre
acts as a thermostat in the hypothalamus
body mechanisms to warm up?
vasoconstriction
stand hairs on end by contracting erector muscles
shiver
body mechanisms to cool down
vasodilation
relax erector muscles so hairs stay flat
sweat evaporates and takes heat energy
how does the body react to eating s high carb meal
inc of glucose in bloodstream detected in pancreas
insulin is released in order to tell liver and muscle dells to convert glucose to glycogen
how does the body react when glucose levels get to low
low levels of glucose is detected by the pancreas
glucagon is released to break down glycogen back into glucose
treatments for type 1 diabetes
inject insulin
excercise
control diet
why are type 2 diabetes caused
unhealthy causes cells to become unreactive to insulin therefore glucose is not absorbed
main treatment for type 2
low sugar diet
excercise
synapse
a gap in between two neurones where electrical impulses are converted to chemicals by neuro transmitters and diffuse across tje the gap rapidly
where is the thyroid gland
neck
produces thyroxine which regulates metabolism
growth and development
pituatary releases TSH
where is the adrenal gland
above the kidneys and releases adrenaline which increases heart rate
where is the pancreas
infront of the kidneys and releases insulin
puberty
development of secondary sex characteristics
ovulation
eggs travel along fallopian tubes into uterus ready to be fertilised
menstruation
breaking down of uterus lining that lasts 4 days
general monthly timeline
1-4 menstrustion
4-14 uterus lining starts to build up again
1day egg released from ovaries into uterus
14-28 maintain uterus lining
>28 menstrual cycle stops if egg is fertilised
>28 cycle repeats if no egg is fertlised
oestrogen
stimulate growth of uterus lining
progesterone
maintains uterus lining
Liutenising hormone
stimulates release of egg
follicle stimulating hormone
stimulates eggs to mature
what is stimulated and inhibited during pregnancy
fsh stimulates oestrogen and oestrogen inhibits fsh
oestrogen stimulates lh
progesterone inhibits fsh and lh
hormonal methods of comtraception
releases oestrogen or progesterone to inhibit fsh which stops egg maturing
the pill is progestoreone only for less side effects
contraceptive patch lasts weekly
injection lasts 2-3 months
implant 3years
iud-3+ years
physical methods
condoms trap sperm
female condoms trap sperm and protects against stds
diaghpram fits over cervix + spermicides
sterillisation via vasectomy or cutting fallopian tubes or abstinence
stages on ivf
women are giving fsh and lh
eggs are collected and fertillised by sperm
eggs are produced in an incubator
reinserted into uterus
pros in ivf
infertile couple have kids
cons
doesnt always work
emotionally upsetting
physically unpleasant
mutiple births
unused embryos destroyed
the brain and functions
cerebral cortex-controls concious activity opposite hemisphere controls opposite side
cerebellum-muscle coordination
medulla-unconcious activity
hypothalmus-regulates body temp
how is it studied
electrically stimulating brain to view a reaction
scanning the brain-ct scans xray
pet scans radioactive chemicals
mri scans magnetic fields
why treating the brain is so difficult
tumours
blunt trauma
infections
too complex
what does each part of the eye do
cornea- causes light to refract
iris-controls pupil dilation
lens-change shape to refract more or less light
fovea-single point on the retina where vision is the sharpest
retina-layer of receptors cone cells and rod cells
cone-all colours
rod cells-only black and white
iris reflex in bright and dark light
in bright light circular muscles contract and radial muscles relax to constrict
dark light circular muscles relax and radial muscles contract to dilate
what is accomodation
changing the shape of the lens in an eye to focus on a near or distant object
accomodation for close range
light has to be refracted a lot
lens needs to be short and fat
cilliary muscles contract inwards
suspensory ligaments slacken
accomodation for far range
light not refracted alot
cilliary muscles relax
suspensory ligaments become taut
lens become narrow
what is the name for longsightedness and why does it happen how fixed
hyperopia
image is formed behind the eye so cant focus on near images
glasses contain convex lenses
what is the name for shortsightedness why does it happen and how is it fixed
myopia
can see near images as far images are formed infront of the retina
concave lenses refract light outwards
what do kidneys do
filter blodd
remove waste
regulate ions and water
what do the kidneys selectively reabsorb
all glucose
some water
no urea
function of the hypothalmus
detects conc of water in bloodstream
negative feedback of adh
water too low
signal is sent to the pituatary gland to release adh
kidneys are less permeable to water and more of it is reabsorbed so less urine
water too high
signal is sent to the pituatary gland
to inhibit adh
kidneys are more permeable to water and less is reabsorbed so more urine is produced
main consequences of kidney failure
build up of urea
unable to regulate water and ion leveles
illness
what is dialysis
when blood is hooked up to a machine the blood come into contact with dialysis fluid seprated by a partially permeable membrane
properties of dialysis fluid
contains same conc of normal molecules as healthy blood
patients blood molecules diffuse out
new dialysis fluid always pumped
cons of dialysis
treatment is time consuming
expensive
can cause blood clots
what are auxins and what do they do in roots and shoots
auxins are a plant hormone that control growth in roots and shoots
shoots - grows toward light
roots - auxins inhibit growth
what is phototrophism
response to light
auxins accumulate on shaded side
cells become elongated and grow towards light
positively phototrophic
negatively geotrophic
what is gravitropism
response to gravity
auxins accumulate on lower side
growth is inhibited
top sode grows quicker and root curves down
negatively phototrophic
positively geotrophic
use of auxins
stimulate growth
kill weeds
use of gibberilins
controlling dormancy
inducing flowering
larger fruits
use of ethene
ripen fruit
1.transport before ripe
2.transport
3.ripen
what is dna
chemical that makes up the genetic material of all humans
what are genes
a small section of dna that tells the body to code for a specific protien
what are chromosomes
thin strands of dna coiled into a double helix
what is a genome
entire set of genetic material in an organism
what is an allele
alternative version of the same gene
what is a genotype
collection of alleles that we have
what is a phenotype
characteristics that are shown
what is polydactyl
when babies are born extra fingers or toes caused by a dominant allele
what is cystic fibrosis
sticky mucus is released in lungs and pancreas caused by a recessive allele
what is a carrier
dont have condition but contain copy of allele
what is embyro screening
looking at genes before they are implanted to check for disorders
pros
save money and reduce suffering
cons
implies disabled people are undesirable
could lead to design
what is natural selection and who was it made by
those with beneficial mutations are more likely to survive and pass on those genes
charles darwin
what is evolution
inheritance of certain characteristics in a population over multiple generations leading to a change in the species
what is acquired characteristics and who made it
a characteristic that is frequently used becomes stronger and unused genes dissapear
beneficial characteristics are passed onto offspring
made by lammarck
what is selective breeding and what are the benefits
breeding best plant or animals together so offspring has desired genes
bigger fruit
friendlier pets
more flowers
more meat on animals
drawbacks of selective breeding
reduces gene pool
potential inbreeding overtime causing inherited defects
susceptibpe to disease
what is genetic engeneering
taking a desirable gene out of an organism and placing it into another organism at an early stage
what is genetherapy
giving someone a healthy version of a gene to cure inherited problem but its hard to transfer and have to start during embryo stage
cons and pros of gm
more desirable characteristics
cured of inherited disease
dont know health implications
can change ecosystem in the wild
how to do gm
isolate gene that we want using enzymes
attach gene to a vector such as a virus and implant into organism
organism takes up vector carrying gene and starts producing protien
what is gradual replacement by minersls
teeth shells and bones decay slowly so are replaced by minerals and become rock like substances
what is a cast or impression
organism is burieed in soft materials and hardens leaving a gap with same shape as organims
footprint in ground
preservation
stuck in amber peat bogs are tar pots as there is no moisture or oxygen
reasons for extinction
environment changes too quickly
habitat cut down
new predator arrives
new disease
outcompeted by new species
process of tissue culture
tissue sample scraped from plant
tissue sample transferred to nutrient rich agar growth medium
samples develop into plantlets
plantlets placed in compost
uses of tissue culture
genetically identical
cheap
greater yield than cuttings
quic
steps of embyro cloning
egg cells are artificially fertilised by sperm both from best parents to form an embyro
embyro splits before cells become specialised
cloned embyros transplanted into mother
geneticslly identical
adult cell cloning
body cell taken from sheep A and dna is extracted egg cell is taken from sheep B and nucleus is removed DNA from sheep A is inserted into egg cell from sheep B
small electric shock to stimulate cell division
implanted into surrogate mother
offspring identical to sheep A
what are the eukaryotes
animal
plant
fungi
protist
what is a prokaryote
bacteria
propeties of animals
10 million species
multicellular
reproduce sexually
heterotrophs take energy from other animals
plants
300000 species
multicellular
autotrophs energy from the sun
function of fungi
mushroom multicellular
yeast unicellular
saprotrophs use enzymes to break down food and absorb nutrients
function of bacteria
unicellular
feed off other organisms
some are pathogens some are useful
what is the three domain system and who made it
carl woese
domain comes above kingdom
true bacteria
eukaryota
primitive archaea
classification and who made it
carl linnaeus
dead kings play cards on fat green stools
domain kingdom phylum class order family genus species
pros and cons of asexual
one parent needed so quick
clones
no variation so suscetible to disease
less chance of adaptation
pros and cons of sexual
variation
can adapt to condtitions
takes time and energy
requires 2 mates
meisosis process
replicate subcellular structures
line up centre of cell
chromosomes pulled apart
cytokinesis
chromosomes lined up in middle of cell
chromatids pulled apart
cytokinesis
4 genetically different off spring
what is speciation
results in the formation of a new species as the same species become so different they can no longer interbreed
what barriers cause speciation
physical new mountain formation
ecological same habitat with different ph
behavioural mating dances
difference between mrna and dna
shorter than dna
single strand
contains uracil instead of thyamine
transcription process
small section of dna is needed to be copied
rna polymerwse opens up double strand so template can be read
makes an mrna strand complimentary to dna bases
only small section is exposed at a time
rna polymerase detaches and mrna strand leaves nucleus
what is a codon
3 bases that code for an amino acid