paper review - weak spots Flashcards
how to convert:
mm to um
um to nm
X 1000 for each
/1000 to reverse
how is stem rust fungus transmitted
- wind borne spores
- host crops leave infected fragments in soil
how do plants become infected by stem rust fungus
- water allows spores to germinate and produce hyphae which enter through the stomata
- enzymes like cellulase digest plant cells so fungus can absorb nutrients as it grows into the mycelium and surrounds tissues
pathogenic effects of SRF
- depletes nutrients eg glucose
- weakens stem
- affects vascular tissue therefore transpiration is reduced
- when pustules burst more spores are released
binomial name of stem rust fungus
puccinia (genus) graminis (species)
centriole definition and structure
organelle made up of microtubules which allow the separation and movement of DNA/organelles etc
centromere definition
the section of a chromosome which is attached to another via microtubules
how skin protects against pathogens
- keratin in skin forms a physical barrier
- has a lack of receptors for pathogens to attach to
why might organisms not cause illness
- enzymes can kill pathogens / break them down
- competition with other flora in body
- may not be enough to cause infection
- may not be pathogenic
name two gram negative bacteria
e. coli and salmonella
name a gram positive bacteria
staphylococcus
features of endotoxins
- released from gram negative
- lipopolysaccharide
- released from dead bacteria
- later effect
features of exotoxins
- released from gram positive and negative
- proteins
- released from living bacteria
- earlier effect
explain oxygen dissociation curve for foetuses
- foetal has to have higher affinity for oxygen - picks it up more easily to make oxygen from the mother
- graph moves to the left
- higher at even low partial pressure
explain the bohr shift for ODC
- shifts to right, lower affinity for 02 - tends to unbind very easily
- when there is a high CO2 concentration
- gives 02 away easily so cells have lots of 02 for respiration
- happens in exercise
how does size of animals relate to ODC
- larger/slower animals have higher affinity for oxygen
- smaller animals have larger sa:v and so loses heat more easily - needs higher metabolic rate
- therefore needs more respiration and to release 02 more easily
why are birds able to increase biodiversity
- birds are pollinators
- can carry seeds
- waste provides mineral ions
how are seed banks used
- variety of seeds from each species
- low temp, dry
- reduced 02, airtight
- test seeds for viability
structure of collagen
- 3 polypeptide chains in a triple helix structure
- held by many h bond to join polypeptides together
what is atherosclerosis
build up of cholesterol in the blood that can cause clots to form
atherosclerosis steps
- endothelium damage - cholesterol deposited, build up under endothelium and form an atheroma (bulge)
- blood pressure increases - narrow artery, loses elasticity and blood flow
- can break through endothelium and form plaques
- platelets/wbcs collect and can form clot
blood vessel structure
- smooth inner endothelium
- elastic muscle with high pressure recoil
- vasoconstriction and dilation
- collagen for strength against pressure
why are men more at risk for atherosclerosis
- males are more likely to smoke
- oestrogen limits amount of cholesterol that enters blood
age and atherosclerosis
- exposed to more risk factors such as diet over time
- less active
what is tissue fluid
water substance containing glucose, amino acids, oxygen and other nutrients
supplies them to cells and removes waste
how is tissue fluid formed
hydrostatic pressure is greater than oncotic pressure so fluid diffuses out of capillaries and then can exchange substances with cells
what happens to excess tissue fluid
enters the lymphatic system as lymph in vessels and returned to blood near heart
what are ips cells
induced pluripotent stem cells
- turning multipotent stem cells into pluripotent by inserting a gene
types of potency cells
unipotent
multipotent
pluripotent
totipotent
how potency decreases
as a foetus develops it creates cells that differentiate less
- toti- can create the placenta
- neurones have no potency
making ips cells
- took a (pluri) mouse embryo cell with 24 key genes
- transfer each gene to a different human fibroblast (multi)
- observe cells that become pluri - eg oct4 sox2
- culture and transplant into patient
how do ips cells know what to differentiate into?
cells around send signals to ips cells and it tells them what to differentiate into
plasma proteins and tissue fluid
plasma protiens cannot move out of capillaries - too large
increases oncotic pressure
how do macrophages present antigens to t helper cells
- antigen is on the membrane on a macrophages MHC
- the antigen bind to the CD4 receptor of a t helper cell
blood clotting cascade
- exposed collagen, platelets adhere and form a plug
- prostaglandins are released to constrict vessels and blood flow
- clotting factor thromboplastin released
- calcium and vitamin k convert prothrombin into thrombin
- this converts fibrinogen into fibrin forming a mesh on RBCS
role of tissue fluid
delivers nutrients to respiring cells as it is faster than diffusion - is faster
insect gas exchange
enter through spiracles
tracheas reinforced with chitin
develop into smaller tracheoles
rapid diffusion pathway to respiring muscles
use abdomen to force gas exchange
fish breathing process
- mouth opens and operculum closes and bulges out
- volume in buccal cavity increases, pressure decreases so water enters
- mouth closed, operculum open, water forced over gills
fish gas exchange
water flows over gills, O2 in water into capillary
higher O2 concentration in water, diffusion gradient over gill plate
constant pathway
why do mammals need specialised gas exchange systems
- low sa:v
- endotherms so very active
- high respiration rate to maintain temp
- higher need for O2
how leaves are adapted for plant exchange
spongy mesophyll - large surface area, air pockets for diffusion, moist so gases dissolve
have rapid diffusion
action of guard cells
daytime - turgid and outer wall expands more, opens the stomata
water floods in via potassium ion pump, K+ actively transported in and malate formed - increase water potential
night - closed to reduce water loss via trainspiration
lenticels
gaps in the back of trees to exchange gases
xylem structure
low pressure
vessels strengthened with lignin
impermeable to water so die - no organelles
bordered pits
phloem structure
- transports sucrose and amino acids
- bi-directional through seive tube elements
- less dense cytoplasm, connected to companion cells which have many mitochondria for active transport
translocation via mass flow
source to sink
- sucrose moves into STE via active transport
- low water potential - water in via osmosis
- increased hydrostatic pressure- gradient to sink and removed when converted to starch
- high water potential, water out
central vs peripheral nervous system similarities and differences
similarities - both have neurones and synapses
differences - P has sympathetic and parasympathetic, only P have sensory and motor input, only C processes information
uses of the sympathetic nervous system
- fight or flight reflex
- speeds heart rate, dilates airways to lungs, stimulates adrenal glands
- aim to increase availability of O2 and glucose
uses of the parasympathetic nervous system
- rest and digest
- has the opposite effect
- will reverse the work of parasympathetic
what kills gram positive bacteria
bacteriacidal such as penicillin because it can break down the cross links in peptidoglycan cell wall
