biology topic 4

types of passive transport

diffusion osmosis facilitated diffusion

water potential

tendency of water to move by osmosis distilled water has the highest water potential

calculate water potential

water potential= turgor pressure + osmotic potential

role of ATP in active transport

ATP binds to carrier protein providing enough energy for protein to change shape

how does ATP release energy

ATP is phosphorylated to form ADP

features of effcient gas exchange surfaces

large surface area

thin or short distance

steep conc gradient

spiracles

openings on bodies surface

tracheae

large tubes in body tissue supported by rings to prevent collapse

tracheoles

smaller branches dividing off the tracheae

how are insects adapted for gas exchange

spiracles can be opened or closed to regulate diffusion

muscles in trachea allow mass movement of air in

tracheoles are highly branched

gills

made of filaments and supported by arches

lamellae

folds that cover the filaments

countercurrent

water and blood flow in opposite directions so water is next to blood of a low O2 conc

how are plant leaves adapted for gas exchange- SA

spongy mesophyll layer provides large surface area

how are plant leaves adapted for gas exchange- W

waxy cuticle is impermeable to pass preventing water loss

how are plant leaves adapted for gas exchange- G

lenticels allow gases to enter and leave

left side of heart

aorta pulmonary vein semilunar vlaves bicuspid valve

right side of heart

pulmonary artery vena cava tricuspid

which side of ventricle is thicker

left side

arteries

thick muscular walls

elastic tissue

narrow lumen

veins

thin walls

valves to prevent backflow

less muscle

capillaries

walls are one cell thick

very narrow

numberous and highly branched

cardiac diastole

heart is relaxed

blood enters atria

atrioventicluar valves open

blood moves into ventricles

atrial systole

atria contract

blood moves into venticles

ventricular systole

ventricles contract

atrioventicular valves close

semilunar valves open

blood moves into arteries

myogenic

hearts contraction is from the muscle itself rather than by nerve impulses

sinoatrial node

wall of right atrium

atrioventricular node

between atria

heart contracts pt 1

SAN initates and spreads impulse across atria so they contract

heart contracts pt 2

AVN receives, delays, and conveys impulse to bundle of his

heart contracts pt 3

impulse moves to purkinje fibres which branch across ventricles so they contract

why does impulse need to be delayed

if impulse spread from atria or venticles there wouldnt be enough time for atrial systole to complete

ECG

graph showing amount of electrical activity in the heart

P-wave

shows atrial systole caused by SAN

QRS complex

shows venticular systole

T-wave

shows systole as the ventricles repolarise

main components of blood

erythrocytes

leucocytes

plasma

structure of erythocytes

biconcave shape no nucleus has haemoglobin

function of leucocytes

help fight disease

why does blood clot

prevent blood loss

prevent entry of bacteria

help in repair

process of blood clotting pt 1

platelets release thromboplastin in response to damage

process of blood clotting pt 2

causes prothrombin to change to thrombin

rocess of blood clotting pt 3

turns souble fibrinogen to insoluble fibrin

causes of atherosclerosis

if endothelium is damaged blood clots causing cells salts cholesterol to build up and form a plaque

how does atherosclerosis affect health

risk of heart attack, stroke

factors increasing risk of atherosclerosis

age genetics smoking alcohol obesity cholesterol

how does partial pressire of O effect binding

partial pressure increases so affinity increases

bohr effect

partial pressure of CO2 increases so more acidic so shape of haemaglobin changes so affinty for O2 decreases

oxyhaemaglobin curve

further left higher affinity for O2

difference between myoglobin and haemaglobin

one haem group

higher affinity for O2

found in muscle cells with high metabolic needs

difference between foetal and adult haemaglobin

foetal has high O2 affinity

tissue fluid

substance containing glucose amino acids O2 supplying to cells and removing waste material

hydrostatic pressure

higher at arterial end of capillary then venous end

oncotic pressure

changing water potential of the capilliares as water moves out

how is tissue fluid formed

blood is pumped through increasingly small vessels hydrostatic pressure is higher than oncotic so fluid moves out of capillaries

excess tissue fluid

removed through vessels into the lymphatic system and returned to blood near heart

function and structure of xylem -length

long continous columns made of dead tissue

function and structure of xlyem -pits

pits allow water to move sideways between vessels

function and structure of xlyem -strength

thickened providing structural support

function and structure of phloem- sieve

sieve tubes transport sugars around plant

function and structure of phloem- companion cells

companion cells for active transport of sugars into tubes

function and structure of phloem- cytoplasm

cytoplasms linked by plasmodesmata allowing flow of substances between cells

apoplastic pathway

water moves through cell walls and intercellular spaces by mass flow

pathway can be used until casparian strip

symplastic pathway

osmosis through root hair cells

water moves through cytoplasm

water must be actively transported to cells to start

cohesion tension theory

water molecules form hydrogen bonds so they stick together

surface tension also causes this effect

as water is lost through transpiration more can be drawn up the stem

how does root pressure affect water movement

high mineral content gives root low water potential

strong osmotic flow into roots

creates weak push effect moving water from roots to stem

temp effect on rate of transpiration

higher temp increases random motion and evaporation so higher rate of transpiration

light effect rate of transpiration

higher light intensity increases rate of photosynthesis so stomata open increasing rate of transpiration

humidity effect on rate of transpiration

water content is high reducing conc gradient decreasing rate of transpiration

mass flow hypothesis of translocation

sugar loaded into sieve tubes by active transport

lower water potential so water moves in from xylem

hydrostatic pressure causes sugars to move

evidence for mass flow hypothesis

sap released when a stem is cut so must be pressure in phloem

higher sucrose content in leaves then roots

evidence against mass flow hypothesis

not all solutes move at same speed

direction movement in sieve tubes