Transport in Animals, Plants, Insects (3) Flashcards
what is the structure of the substance carrying oxygen in the blood in RBCs
A RBC contains molecules of haemoglobin, made of 4 sub-units. Each sub-unit is a conjugated polypeptide chain in an alpha helix, i.e. GLOBIN (protein) + HAEM (prosthetic group)
There are 2 alpha chains and 2 beta chains.
Haem has the same structure as chlorophyll (porphyrin ring, iron in the centre)
outline the route of the mammalian respiratory system
pharynx, larynx, glottis
trachea, bronchi, LUNGS: bronchioles, alveoli- squamous epithelium + capillary walls
explain the effect of light intensity on the rate of transpiration
- IN THE DARK- stomata close, drastically reducing the rate of transpiration
- once there is enough light to cause the STOMATA TO OPEN (which is quite low), increasing light intensity further has no effect
what are the types of circulatory system (+ characteristics)
OPEN blood or haemolymph/haemocoel bathes organs directly
- NO VESSELS*
- blood pumps at low pressure, circulation is slow, there is little control over direction of flow*
- INSECTS*
CLOSED a heart pumps blood through arteries, arterioles, capillaries (site of exchange), venules, veins and back to the heart i.e. in a continuous systems of vessels
- blood is pumped at high pressure by a muscular heart, producing rapid flow*
- CAPILLARIES: site of exchange between organs/tissues by fluid leaving/entering vessels (caps) for metabolites- O2, CO2, glucose, urea*
what is used to measure to volume of air moving in and out of the thorax in a human
a spirometer
due to low pressure (kPa) of blood in the veins why does it not pool
Semi-lunar valves in the veins close, negating/against the effect of gravity
what is symplast (1 mark)
The route taken by water as it moves through cells from cytoplasm of one cell to the cytoplasm of the adjacent cell through plasmodesmata.
what are the differences between PLASMA, TISSUE FLUID & LYMPH in terms of hydrostatic pressure, oncotic pressure, cells, proteins and fats
HYDROSTATIC PRESSURE high hydrostatic pressure at arterial end in blood plasma, low in tissue fluid + lymph
ONCOTIC PRESSURE more negative in blood plasma, less negative in tissue fluid + lymph
CELLS RBCs & WBCs in blood plasma, WBCs in lymph
PROTEINS plasma proteins in blood plasma, low in lymph
FATS present in lymph
what happens after the chloride shift in the lungs (3 marks)
At the lungs, hydrogen carbonate ions HCO3- re-enter RBCs and chloride ion Cl- leave the RBC to balance the charge.
HCO3- are reconverted to CO2 by the action of carbonic anhydrase.
CO2 DIFFUSES OUT + ENTERS THE ALVEOLI.
give four differences between structure for arteries capillaries and veins
COLLAGEN FIBRES:
A present, thick C absent V present, thin
ELASTIC + MUSCULAR FIBRES:
A present, thick C absent V present, thin
ENDOTHELIUM:
A present C present V present
VALVES:
A + C absent V semilunar valves at intervals
name the 7 parts of the root of a dicotyledonous plant
-VASCULAR BUNDLE in the middle to provide stability eg. against wind that pulls the plant -XYLEM ‘cross’ in the middle -PHLOEM (4 circles around the xylem) -ENDODERMIS around the vascular bundle -CORTEX(parenchyma) -EPIDERMIS -EXODERMIS containing ROOT HAIR
what is the outcome of Fick’s Law
the larger the area and the larger the difference in concentration and the thinner the surface, the faster the rate of diffusion
what is simple diffusion
when a substance goes through the phospholipid bilayer and does not need a protein carrier or channel (this would be facilitated diffusion)
what is the function of COLLAGEN and SMOOTH MUSCLE in artery+arteriole walls
collagen- thick outer layer** of **non-elastic** fibrous tissue to **prevent over-expansion** of vessel under **high pressure
smooth muscle- to allow narrowing of vessel lumen by contraction of muscle. Important for arterioles bc it controls blood flow + direction to capillaries eg. in thermoregulation- vasodilation due to adrenaline, endotherms conserving heat, fight/flight
what are the advantages and disadvantages of different circulatory systems
-open circulatory
- little control over direction of flow
- low pressure of flow
- low speed of flow
- no carriage of O2 in haemolymph (no separation or mixing)
outline the 4 stages involved in EXPIRATION
- diaphragm muscles relax and the diaphragm becomes dome-shaped
- the external intercostal muscles relax, the internal intercostal muscles contract, ribs and sternum move down and inwards
- volume of thorax (and therefore the lungs) is decreased, pressure in the lungs is increased above atmospheric pressure
- air flows out of thorax
what is the first link in the insect respiratory system chain
1
SPIRACLES are
- the* opening of the tracheae to the exterior.
- opened and closed by a sphincter (to prevent fungal infection, reduce water loss and regulate ventilation)*
- lined with fine hairs to (to reduce water loss and remove potential infection)*
what is the T wave
repolarisation of ventricle
+ they fill with blood
what is the vital capacity of lungs
the maximum volume of air that can be breathed in or out
what is the role of an artery+arteriole
to carry oxygenated blood from the heart to tissues under high pressure
(not oxygenated in pulmonary artery + umbilical cord)
give three adaptations that may be found in the stems+roots of hydrophytes + their effects
SMALL ROOTS; water can diffuse directly into the stem + leaf tissues; no need for root uptake
LARGE SURFACE AREA OF SUBMERGED PARTS i.e. stem+roots; maximises area** for **photosynthesis
LACK OF STRONG SUPPORTING STRUCTURE eg. xylem; plant supported by water
which cells and tissue line the airways in the mammalian respiratory system (the layers present)
(image of a bronchus)
INNERMOST: Ciliated columnar epithelia, which have goblet cells interspersed between them.
Cartilage, elastin and smooth muscle surround the epithelia.
Macrophages (phagocytes) are also present which ingest any bacteria that have entered the airways during breathing.
what are the three ways that water moves across leaf cells
APOPLAST pathway
SYMPLAST pathway
VACUOLAR pathway
give three adaptations that may be found in the leaves of hydrophytes + their effect
WIDE FLAT LEAVES; spread** across the water to **maximise SA exposed to light
VERY THIN/NO WAXY CUTICLE; conservation of water is unnecessary, a little wc can help water droplets roll off leaves, aiding stomatal gas exchange
MANY ALWAYS-OPEN STOMATA ON THE UPPER SURFACE OF THE LEAVES/inactive guard cells; no risk of loss of turgor to plant from water loss
label the diagram with tidal volume, vital capacity, total lung capacity, inspiratory reserve volume, expiratory reserve volume, residual volume, breathing rate
outline the route of insects’ respiratory system
spiracles, tracheae, branching of tracheae, tracheoles tracheal fluid, respiring cells
name the parts labelled on the diagram of the human thorax
nasal cavity, larynx, trachea, bronchiole, bronchus, pleural membranes, pleural cavity containing pleural fluid so that membranes slide over each other as we breathe, abdominal cavity, diaphragm, position of the heart, rib, intercostal muscles
what are the 3 factors that determine an organism’s need for a transport/circulatory system
SIZE
SA:VOL
METABOLIC ACTIVITY
what is the function of the bicuspid valve
LEFT-ATRIO VENTRICULAR VALVE
prevents back flow of blood from LV to LA during ventricular systole
what are the three ways in which capillaries are suited to their role
provide a very large SA for exchange of substances between the tissues and blood
total cross-sectional area of the capillaries is always greater than the arteriole supplying them, so rate of blood flow falls. relatively slow movement of blood through capillaries = more time for exchange by diffusion
walls are one endothelial cell thick, giving a thin layer for diffusion/short diffusion distance
what are the types of closed circulation
SINGLE circulation
DOUBLE circulation
what are the 3 mechanisms of movement of water in the xylem
- COHESION TENSION*
- ADHESION- CAPILLARITY*
- ROOT PRESSURE*
describe the apoplast pathway in the root cells to the xylem
what is the function of the aorta
takes oxygenated blood from the left ventricle to the body
give an overview of what the cardiac cycle
+ what is the time taken for each cycle
a sequence of events of a heart beat which pumps blood round the body
it has alternate contractions; systole and relaxations; diastole
these events occur simultaneously in the RHS and LHS
approx. 0.8 secs, tf approx. 80 BPM
what is the Bohr effect (4 marks)
THE BUFFERING OF PROTONS
- the protons are buffered by haemoglobin to prevent a change in pH of the RBCs. This forms haemoglobinic acid
- the binding of protons changes the tertiary structure of the Hb, lowering its affinity for oxygen (allosteric effect)
- O2 is able to dissociate more easily i.e. more will dissociate in the tissues.
name the respiratory surface in fish
gills
what is atrial fibrillation
arrhythmia: abnormal irregular rhythm from atria, ventricles lose regular rhythm
rapid electrical impulses are generated in the atria, they contract very fast/fibrillate but not properly: only some of the impulses are passed onto the ventricles
ventricular fibrillation = less blood supplied to tissues because no time to re-fill aria- ventricles contracting all the time
what is the function of valves in veins/venuoles
semi-lunar valves in the veins prevent backflow and pooling of blood (gravity) when blood is flowing against gravity eg. in the legs
blood flowing away from the heart pushes the valves closed, preventing it from flowing further away
what is the function of ELASTIC FIBRES and ENDOTHELIUM in artery+arteriole walls
- elastic fibres- allow expansion of vessel lumen to withstand high pressure from the heart. Elastic recoil maintains the high pressure + keeps smooth the blood flow.*
- endothelium- inner layer of cells are folded to allow increase in diameter of lumen*
where do contractions in the heart come from + which tissues make up the conduction system
the heart is myogenic i.e. its rhythmic contractions arise from within the cardiac muscle tissue itself (instead of neurogenic i.e. needing nervous impulses to contract)
- the conduction system is an intrinsic regulatory system composed of specialised tissues; 1. SA node, 2. AV node, 3. Bundle of His, 4. Purkinje fibres*
- it is capable of generating and distributing the electrical impulses that stimulate cardiac muscle to contract*
what is a co-transporter protein (1 mark)
A transmembrane protein (a carrier or channel) which transports two substances across the membrane.
name the respiratory surface of plants
CSM of spongy mesophyll cells (which is where air spaces are)
what is the advantage of pressure in double circulatory systems over single
-double circulatory systems maintain high pressure over both gas exchange surfaces- lungs and tissues
It can differentiate the pressure, so the LHS of the heart pumps blood at much higher pressure to the tissues than the RHS to the lungs. Pressure to pulmonary capillaires is much larger than to systemic capillaries.
explain the effect of humidity on the rate of transpiration (3 marks)
- As humidity of the air surrounding the plant increases, the concentration of water molecules in the air increases.
- The diffusion gradient between the inside of the leaf and the surrounding air decreases and the transpiration rate decreases.
- Eventually an equilibrium is reached and there is no water vapour loss from the leaf.
where does the heartbeat begin in the conduction system of the heart
Contraction starts at the sino-atrial node (SA node, also known as the pacemaker) which is embedded in the wall of the right atrium close to the entry of the vena cava
A wave of electrical excitation flows over both atria, causing them to contract
what are the 5 necessary properties of a respiratory surface for maximum rate of diffusion across it
- large SA 2. high/active blood supply 3. small diffusion distances/ thin 4. permeable 5. moist
what is bradycardia
SLOW heart rate below 60bpm evenly spaced
(can be due to high fitness levels causing the heart to beat slowly and efficiently)
may need an artificial pacemaker
what is the P wave
atrial systole
electrical charge/depolarisation spreads over both atria from SA node, causing atrial muscleto contract
explain why water moves through the plant
Due to the pull of transpiration
- Transpiration from the leaves/sub-stomatal air creates a water potential gradient with the cells in the leaf
- The ‘pull’ causes the movement of water across the leaf by the 3 pathways: apoplast, symplast, vacuolar
- The ‘pull’ from the water moving in the leaves causes the movement of water through the xylem by mass flow, due to the cohesion & adhesion tensions caused by H-bonds
- The ‘pull’ of the water from the xylem causes the movement of water across the cell of the root by the 3 pathways: a, s, v. The casparian strip in the endoderm causes the apoplast to join the symplast.
- Water moves by osmosis into the root hair cells from the soil. Water diffuses through cell walls into the apoplast pathway.
Water potential is very high (approx. -10kPa) because the soil solution is a very dilute solution of ions
name the 5 parts of the stem of a dicotyledonous plant
-PARENCHYMA in the middle -VASCULAR BUNDLES in a circle around the parenchyma (around edge in order to provide support and strength) -XYLEM on the inner side of the vascular bundle -PHLOEM on the outer side of the vascular bundle -CORTEX is the outer half of the stem -EPIDERMIS around the cortex
what are capillaries
microscopic blood vessels that link veins and arteries, forming an extensive networkt rhoguh all the tissues of the body
capillaries are 10µm in diameter
substances are exchanged through the capillary walls eg. O2, between the tissue cells and the blood
blood enters capillaries in organs from arterioles and is oxygenated. When it leaves to the venuoles it has less oxygen and more carbon dioxide/deoxygenated.
Describe the features of the TRACHEIDS
Spindle-shaped cells with large, bordered, hollow pits on the sides that allow the passage of water + minerals sideways to the living parts of the stem. (lateral movement of water)
The ends of the cells overlap so water moves up the stem.
outline the 4 stages involved in INSPIRATION
- diaphragm muscles contract the diaphragm flattens/lowers
- the external intercostal muscles contract, the internal intercostal muscles relax, ribs and sternum move upwards and outwards
- the volume of the thorax (and therefore lungs) is increased and the pressure in the lungs is decreased below atmospheric pressure
- air flows in
what is a hydrophyte
A plant that lives ; submerged in water of on the surface of water or at the edge of bodies of water
and do not have to conserve water
eg. water lilies
list the 4 stages of inspiration in fish
- mouth opens, floor of buccal cavity is lowered
- buccal cavity expands, volume increases, pressure decreases, water drawn in
- opercular valve is closed, operculum (covering of gills) is closed, cavity fills with water
- operculum moves outwards while closed, which pulls water in from buccal cavity
where are goblet cells found
in the ciliated epithelium of trachea, bronchi and larger bronchioles
what is the function of the pulmonary vein
delivers oxygenated blood from the lungs to the left atrium
what is the function of the inferior vena cava
delivers deoxygenated blood from the trunk and limbs to the right atrium
which 5 properties help the alveoli as a gas exchange surface
- permeable
- large surface area
- thin exchange surface
- moist
- steep conc. grad. between the blood and the alveolar air (maintained by: good blood supply + ventilation of the lungs)
list the 4 stages of expiration in fish
- mouth closes, floor of buccal cavity is raised
- buccal cavity becomes smaller, volume decreases, pressure increases
- opercular valve is open, operculum opens, water flows over gills and out of operculum
- gas exchange occurs between water and blood flowing through gills
how does 1. a large surface area and 2. a thin exchange surface enable the alveoli to be an effective site of gas exchange
The TSA of the alveoli and the numerous surrounding capillaries ensures rapid diffusion of a larger quantity of O2 gas from alveolar air into the blood (and vice versa for CO2)
T: alveolar walls are made of squamous epithelial cells (flat and thin), capillary walls made of endothelial cells which are flat and thin (cap walls are one cell thick)
Therefore the distance between the air in the alveoli and the blood in the capillaries is small.
Thinner the surface, higher the rate of diffusion.
where is squamous epithelium found in the mammalian respiratory system
alveoli (flattened epithelium in smaller bronchioles)
state the equation used in Fick’s Law
rate of diffusion = area of diffusion surface x difference in concentration / thickness of surface over which diffusion takes place
where is epithelium found in the thorax
- Ciliated epithelium in tracheae, bronchi and larger bronchioles*
- flattened epithelium in smaller bronchioles*
squamous epithelium in alveoli
why do the animal + plant transport systems differ
plants are less metabolically active than animals & tf have a much slower transport system ( + gases are transported by diffusion)
the transport sugar in plants is sucrose, which is less reactive than the transport sugar in animals, glucose
what is the transpiration pull
+ how is it measured
- the evaporation of water from the aerial parts of the plant eg. leaves/stomata
the rate of transpiration can be measured by a potometer, and is affected by many factors
what is the function of VEINS + VENUOLES
give three differences from arteries
to carry deoxygenated blood away from tissues to the heart
(pulmonary vein and umbilical vein are oxygenated)
blood goes from very small venuoles to larger veins, veins do not have a pulse, the blood pressure is low and they have valves
veins do not have to withstand high pressure but need a large capacity
skeletal muscle contraction aids blood flow in the veins
what is tissue fluid formed from
what is absent in tissue fluid
compare water potential with plasma
- formed from blood plasma.
- does not contain blood cells or plasma proteins (they are dissolved in fluid but not in plasma)
- wp plasma < wp tissue fluid
which creates an oncotic pressure that pulls water back into the plasma from tissue fluid
what is the second stage of the cardiac cycle
VENTRICULAR SYSTOLE; ventricles contract
ATRIAL DIASTOLE; atria are relaxed
- blood is pumped from left ventricle to aorta and from the right ventricle to pulmonary artery, semilunar valves are open*
- force/pressure of contractions closes atrio-ventricular valves so that there is no back flow*
give two additional structures features that may be found in a hydrophyte & their effect on the plant
SERENCHYMA CELLS; specialised parenchyma (packing) tissues in leaves, stems, roots. Air spaces are formed by apoptosis. Useful for buoyancy + easy transport of O2 to submerged tissues or in mud where O2 levels are low.
AIR SACS; enable leaves + flowers to float on the water
what sort of epithelium is found in the trachea, bronchi and bronchioles
ciliated epithelium
what is the third stage of the cardiac cycle
VENTRICULAR DIASTOLE; ventricles relax
Increased quantity of blood in aorta and pulmonary artery causes high pressure which closes semilunar valves
ATRIAL DIASTOLE; atria are relaxed
blood flows from atria to ventricles passively due to gravity + relaxed state of the ventricles
atrio-ventricular valves** are **pushed open
what is the function of the right ventricle
delivers deoxygenated blood from RHS of the heart to the lungs via the pulmonary artery
what is surfactant
a substance, similar to detergent, which reduces the surface tension of a liquid in which it is dissolved
outline the stages and changes and differences in pressure during the cardiac cycle
- think COMPARTMENTS, PRESSURE, VALVES*
1. PAT > PV atrial systole AV valves are open
2. PV > PAT PV > PAorta ventricular systole, atrial diastole blood travels down pressure gradient, blood does not flow back due to semi-lunar valves + chordae tendineae
3. PV < PAT PV < PAorta ventricular diastole semilunar valves shut
what is the advantage of speed of flow for double circulatory systems over single
double circulatory systems allow for more rapid flow over both gas exchange surfaces, which is important in mammals and birds (due to higher metabolic rate)
in single circulatory systems, eg. fish, blood is slowed down by both sets of capillaries- in the gills and then in the tissues- fish are ectotherms and therefore have a low metabolic rate, so this low speed of flow is sufficient
what is the difference between FOETAL Hb and ADULT (mother’s) Hb (5 marks)
+ what happens in the placenta
- In the placenta, the partial pressure of O2 is 8kPa compared to 13kPa in the lungs.
- at this partial pressure, the mother’s Hb will dissociate from/unload oxygen
foetal Hb has a much higher affinity for oxygen at low partial pressures (kPa) than the mother’s affinity. Therefore at the same partial pressure, it’s curve is to the left and above the mother’s curve.
Tf, at the placenta maternal Hb will dissociate from the oxygen whilst foetal Hb will associate with it.
The foetus is producing CO2 from its respiring tissues, which will diffuse into the capillaries of the mother. Due to the Bohr effect, there is further dissociation of O2.
what are the three stages of the cardiac cycle (2 marks)
STAGE 1: atrial systole
STAGE 2: ventricular systole, atrial diastole blood flowing out of ventricles
STAGE 3: ventricular diastole, atrial diastole blood flowing into ventricles
what is mass flow + hydrostatic pressure (1 mark each)
Bulk flow of fluid, due to hydrostatic pressure
which is the pressure exerted by a fluid at rest
state the components of the mammalian circulatory system that performs each of the following roles:
PUMP
MEANS OF MAINTAINING PRESSURE
TRANSPORT MEDIUM
EXCHANGE SURFACE
heart
aorta, arteries, (named artery), arterioles, smooth muscle, narrow lumen
blood plasma
capillary endothelium/walls
what happens in the resting muscle in an insect
tracheal fluid moves into the tracheoles, oxygen in the tracheoles dissolves in the fluid and diffuses into the cell
what is an ectopic heartbeat
extra heartbeats are out of the normal rhythm - altered rhythm eg. extra beat + long pause before next beat
what is the function of the left atrium
receives the oxygenated blood from the lungs via the pulmonary vein
which defining structure can be found in tracheae and bronchi
what is its function
rings of C-shaped cartilage
They provide support. It’s strong but flexible and therefore prevents the tracheae and bronchi from collapsing when breathing in and pressure decreases.
what are the advantages and disadvantages of different circulatory systems
-closed: double
- unidirectional flow through vessels
- high pressure of flow, different between lungs and tissues
- rapid speed of flow
- complete separation between 2 halves of heart (and oxy. and deoxy. blood)
what is the function of the tricuspid valve
RIGHT ATRIO-VENTRICULAR VALVE
prevents back flow of blood from RV to RA during ventricular systole
what is the first stage of the cardiac cycle
ATRIAL SYSTOLE; atria contract
VENTRICULAR DIASTOLE; ventricles are relaxed
blood flows into the ventricles from the atria, atrio-ventricular valves are open
how does Hb’s affinity for O2 change
Dependent on the LOADING TENSION
Hb has a high affinity for oxygen where the partial pressure of O2 (pO2/KPa) is high in the lungs.
Hb has a low affinity for oxygen where the partial pressure of O2 (pO2/KPa) is low in the tissues.
describe the process of the movement of water through the symplast pathway in the leaf + method of movement (6+1)
method of movement: water potential gradient
- Cytoplasm of one cell loses water to the sub-stomatal airspace
- This lowers the water potential (U)
- The cell pulls in more water from its neighbour, whose water potential is higher
- The water potential of this cell becomes lower
- (3+4 are repeated) This establishes a water potential gradient.
what is tachycardia
FAST heartbeat- over 100bpm, evenly spaced
(can be due to exercise, fever, fear, anger)
what do artery walls contain
COLLAGEN
ELASTIC FIBRES
SMOOTH MUSCLE
ENDOTHELIUM
what is the QRS wave and what happens just before
(BETWEEN P AND QRS: delay at AV node prevents overlap of atrial+ventricular systole)
ventricular systole: electrical charge/depolarisation spreads upwards over ventricles from the apex
what is the function of the superior vena cava
delivers deoxygenated blood from the head and neck to the right atrium
Describe the features of XYLEM VESSELS
Dead cells lined end to end whose horizontal walls have been broken down; water can travel in a continuous column
- Lined with rings/spirals of lignin, which keep the vessels open, especially when the transpiration pull exerts negative pressure on the walls.
- Lignin can also contain tannins, which are bitter and deter herbivores.
how is carbon dioxide carried in the blood (+ formula)
After being released by respiring tissues, it is carried in 3 ways:
- 5% dissolved in plasma
- 10% carried by haemoglobin, forming carbaminohaemoglobin
- 85% combines with H2O to form carbonic acid by the enzyme carbonic anhydrase in the RBCs. Carbonic acid dissociates to form hydrogen carbonate ions (HCO3-) and H+ protons.
CO2 + H2O ⇔ H2CO3 ⇔ HCO3- + H+
carbonic anhydrase (CO2 + H2O)
what is the advantage of not mixing oxy/deoxy blood in double circulatory systems over single
double circulatory system has 2 completely separate parts. Therefore efficiency of oxygen distribution is higher.
Important for mammals and birds which have a higher metabolic rate (amphibian+reptile allow mixing of blood in the heart before it is pumped out)
what is O2 consumption/O2 uptake
the rate at which an organism uses up oxygen eg. number of dm3 used per minute (dm3/min-1)
explain the effect of temperature on rate of transpiration (3 marks)
- Increasing temperature increases the kinetic energy of all molecules.
- Tf an increase in temperature will increase the transpiration rate, assuming the concentration of water molecules in the air is lower than in the leaf.
- Very high temperatures will cause the stomata to close, which will cause the rate of transpiration to reduce.
what is the definition of hydrostatic pressure
the pressure exerted by the fluid at rest eg. water
explain why there is a steep concentration/diffusion gradient between the blood and alveolar air and how this enables the alveoli to be a more effective exchange surface
Is it maintained by ventilation of the lungs
Inhalation delivers high concentration of O2 into the airsacs so maintaining its concentration high in the lungs. Exhalation removes carbon dioxide from the airsacs so maintaining its concentration low in the lungs.
and good blood supply through the numerous capillaries around the alveoli.
The blood delivers a high concentration of CO2 from respiring tissues to the capillaries in the lungs. The blood moves O2 away from the lungs by its constant flow, tf maintaining a low concentration in the capillaries. O2 diffuses from the alveoli to the blood and vice versa for CO2. Greater the conc, higher the rate of diffusion.
How does water leave the leaf + create the transpiration pull (4 marks)
MOVEMENT of WATER VAPOUR in the SUB-STOMATAL AIRSPACE
- Water potential of atmosphere is lower < Water potential of the sub-stomatal airspace
- Tf if the stomata are open, water diffuses out of the stomatal pores
- Water potential* of the *sub-stomatal air space* is *lower < Water potential* of the *cell walls* of the *spongy mesophyll cells
- Water diffuses into* the *sub-stomatal air space* *down the water potential gradient* from the *surrounding mesophyll cells
what is the next part of the insect respiratory system after spiracles
2
TRACHEA, they…
- carry air into the body*
- are lined with spirals of chitin which keeps them open when bent or pressed (like cartilage in mammals)*
- are impermeable to O2, CO2*
what happens in a contracting muscle in an insect
aerobic respiration is not sufficient for oxygen demands, anaerobic respiration produces lactic acid, which accumulates.
water potential of cell decreases and becomes lower than the water potential of tracheole
tracheal fluid drains into the respiring tissue from the tracheoles, delivers dissolved oxygen
tracheole becomes air-filled, which increases diffusion of O2 into the cell from the steeper concentration gradient from air in tracheole
what is the function of the chordae tendineae
prevent atrio-ventricular valves inverting and therefore prevents back flow of blood during ventricular systole
how does gas exchange occur
by simple diffusion over a respiratory surface
what is the definition of osmotic pressure
a hydrostatic pressure caused by a difference in the amounts of solutes between solutions that are separated by a semi-permeable membrane
(oncotic pressure is the part of the osmotic pressure produced by colloids i.e. proteins and large molecules)
name the 4 parts of the leaf of a dicotyledonous plant
-MIDRIB OF LEAF, which is the main vein of the leaf. Smaller, more numerous branching veins spread through the leaf for transport and support -VASCULAR BUNDLE in middle of midrib of leaf helps to support the structure of leaf -PALISADE MESOPHYLL the main photosynthetic tissue, on flat parts of leaf -XYLEM nearer flat side -PHLOEM nearer the raised part of midrib of leaf
what is the movement of the wave of excitation
SA node ⇒ atria contract ⇒ AV node ⇒ bundle of His ⇒ Purkyne fibres ⇒ ventricles contract ⇒ diastole
how does being permeable and moist enable the alveoli to be an effective gas exchange surface
P: O2 and CO2 are non-polar and can diffuse across the phospholipid bilayer of cell membranes
M: water lines the airsacs and is mixed with lung surfactant, which breaks the surface tension of water to allow the airsacs to expand during inhalation.
This allows the gases to dissolve and diffuse across the walls.
describe how water moves across a leaf via the symplast pathway (4 marks)
- water moves through the cytoplasm*
- cytoplasm of adjacent cells is connected by plasmodesmata (strands of cytoplasm)*
- there is resistance to flow (due to organelles)- less water flows through this pathway than apoplast*
explain the pressure changes that occur once blood leaves the ventricles
+ importance
blood pressure fluctuates in the heart due to contractions/pumping
the arteries close to the heart have a lot of elastic tissue, which allows the walls to stretch when blood leaves the heart.
as blood moves out of the aorta, the pressure in the aorta begins to decrease
the elastic recoil of the walls helps to maintain blood pressure in the aorta
the further the blood moves along the arteries, the more the pressure decreases because there is an increase in the total cross sectional area of the arteries (and fewer fluctuations)
It is important to maintain a pressure gradient between the aorta and arterioles, so that blood keeps flowing towards the tissues
what is the role of lymph
- to drain excess fluid
- to take up cell debris + large particles
- to combat bacteria using white cells
- to take up fatty products of digestion from small intestine
explain cohesion tension in the xylem
As water molecules move up the xylem, they attract neighbouring molecules by cohesion tension due to intermolecular hydrogen bonds between the polar water molecules- pull water up 100m in giant redwood + sequioa trees.
(water lost from the mesophyll cells in the leaves is replaced by water in the xylem due to the water potential gradient between the cells)
what is the xylem
a mainly non-living vascular tissue composed of vessel elements (elongated, hollow, dead cells) and tracheides packed between parenchyma cells
why do plants need a transport system
what is the exception
SIZE : large plants have a small SA:Vol therefore, diffusion is too slow for the movement of substances eg. sucrose/water, throughout the plant/to respiring or photosynthesising cells. Tf transport system/bulk transport necessary.
CO2 + O2 : required for photosynthesis + respiration, rely entirely on diffusion (however, specialised exchange surfaces exist in the tissues concerned)
name the respiratory surface in insects
tracheoles
describe how water moves across a leaf cell via the apoplast pathway (5 marks)
- Through the cellulose cell walls. Path of least resistance (no organelles/cellular structure impeding). 90% of water travels via this pathway
- Cellulose fibres of the cell wall have channels between them where water can flow freely by cohesion tension.
- As water evaporates into the sub-stomatal airspace from one cell, cohesive forces between water molecules due to their hydrogen bonds pulls water from spaces in the walls of adjacent cells.
what is a vascular tissue
a plant tissue that transports nutrients and water through the organism (comparable to veins and arteries in animals). Two types: xylem and phloem
explain what occurs in double closed circulation
PULMONARY CIRCULATION: RHS of heart pumps deoxygenated blood to the lungs via the pulmonary artery. Oxygenated blood then enters the LHS from the pulmonary vein.
SYSTEMIC CIRCULATION: LHS of the heart pumps the blood to the tissues via the aorta. Deoxygenated blood enter the RHS via the vena cava.
what is the function of the right atrium
receives deoxygenated from the body via the vena cava
what are insect bodies covered in
an exoskeleton of chitin and a layer of waxy cuticle to reduce water loss. Therefore they are impermeable to gases
what is biomass
the dry (organic) mass of living organisms, usually measured at a trophic level e.g. producers in a food chain
describe the innermost layer of the mammalian respiratory system (5 marks)
Lined with CILIATED COLUMNAR EPITHELIUM, interspersed with mucus-secreting goblet cells.
The goblet cells secrete mucus, which traps microorganisms and dust particles in the inhaled air, preventing entry to the alveoli.
The cilia on the surface of the epithelial cells beat the mucus. Cilia move mucus upwards, away from the alveoli, to the throat, where it is swallowed. This prevents entry to the alveoli and prevents subsequent lung infection.
what structures are there in the xylem that help the function of the xylem
The walls of the vessel elements are strengthened by lignin spiralling in the lumen, which is waterproof and provides structural support against the pull of transpiration (and therefore the collapse of vessel elements). The xylem vessels are surrounded by thick-walled parenchyma, which store food and tannin deposits (a bitter chemical that prevents herbivores digesting the plant).
what is mass flow
mass flow = the movement of a fluid in bulk in one direction
A heart pumps blood, moving it quickly to all parts of the body.
what is the function of the pulmonary artery
takes deoxygenated blood from the right ventricle to the lungs
describe the second layer of the mammalian respiratory system (2 parts, each 3 marks)
IN THE WALLS surrounding the epithelium
Elastic fibres- help the process of breathing out. -When the lungs inflate (breathing in), the elastic fibres are stretched. The fibres recoil to push air out (exhaling).
Smooth muscle- allows the diameter of the airway to be controlled. -Smooth muscle relaxes, widening the tube, during exercise. This gives less resistance to airflow, allowing air to move in and out of the airways more easily for increased delivery of oxygen/removal of carbon dioxide.
explain what occurs in single closed circulation
SINGLE circulation
blood passes through the heart once in each circulation eg. FISH, the heart pumps deoxygenated blood to the gills where gases are exchanged, oxygenated blood goes to the rest of the body/tissues from the gills directly, deoxygenated blood then returns to the heart
why does the diameter of a tree increase during the day and decrease at night
+ how is it measured
DAY: cohesive tension forces are higher during the day
There is less tension in the xylem at night because the rate of transpiration is low.
DENDROGRAPH
outline the route of the fish respiratory system
Buccal cavity- GILLS (a gill arch holds many gill filaments. On each filament there are many lamellae) Water passes over the lamellae to the opercular cavity.
what are the advantages and disadvantages of different circulatory systems
-closed: single
- unidirectional flow through vessels
- pressure of flow is higher than open, but no differentiation between gills and tissues
- speed of flow is relatively rapid
- oxygenated blood flows directly to tissues from gills; no separation/mixing
what is a sieve tube element (1 mark)
the cells of the phloem that allow movement of sap up and down the plant, from the source to the sink
what is the function of the semilunar valves
prevent back flow of blood from aorta + pulmonary artery during ventricular diastole due to the force of gravity
what is the chloride shift (2 marks)
Hydrogen carbonate ions HCO3-* diffuse out of the RBCs. In order to balance the negative ions leaving, *_chloride ions Cl_- enter the RBC.
(in the tissues)
describe the vacuolar pathway of the movement of water in a leaf (5 marks)
Movement of water through the vacuoles- takes water from apoplast pathway, therefore less water follows this pathway.
Through the established water potential gradient, water in the vacuoles of cell 1 will cross:
Vacuole of cell 1, Tonoplast of cell 1, Cell membrane of cell 1, Cell wall of cell 1, Cell wall of cell 2, Cell membrane of cell 2, Tonoplast of cell 2, Vacuole of cell 2
Therefore individual cells can absorb water from the apoplast pathway. Method of movement: water potential gradient + osmosis.
what effect does the presence of increased CO2 have on curve + pO2
The presence of increased CO2 shifts the Hb-oxygen dissociation curve to the right + down
therefore, at the same partial pressure of O2 (pO2) the dissociation of O2 from Hb increases and the % saturation of Hb with O2 decreases.
Therefore more O2 is made available for the respiring cells.
what is the function of the left ventricle
delivers oxygenated blood from LHS of the heart to the body via the aorta
why does the first contraction not continue to the ventricles
what is the second stage in the conduction system of the heart
A non-conducting layer/septum of connective tissue exists between atria/ventricles that prevents conduction, except for a second node: atrio-ventricular node (AV node) (there is a time delay here)
From here, impulses travel down the bundle of His along the interventricular septum and along specialised Purkinje fibres, that fan out and up from the apex of the ventricles. This causes them to contract from the apex upwards and push the blood out through the aorta and pulmonary artery.
explain adhesion tension- capillarity in the xylem
Water molecules are attracted to the walls of the xylem vessels due to adhesive forces.
(can create frictional drag)
what is the function of the xylem
transport of water and nutrients throughout plants
from the roots to the shoots and leaves
support
how is oxygen transported in the blood
Up to 4 molecules of oxygen can be carried by one molecule of haemoglobin
deoxyhaemoglobin Hb + 4O2 ⇔ HbO8 oxyhaemoglobin
The first molecule binds with difficulty, to an allosteric site, changing the tertiary structure. Each molecule is loaded progressively more easily.
summarise the ventilation of the lungs
INSPIRATION is an energy-requiring process where air is drawn in, diaphragm flattens/lowers and volume of the lungs increases.
EXPIRATION is a passive process where air is expelled from the thorax, the diaphragm becomes more dome-shaped and the volume of the lungs decreases.
what is the purpose of a circulatory system
- to move substances eg. O2, carbon dioxide and digestive products around the body
- to allow movement of substances around the body by mass flow which is more rapid than diffusion alone
- to allow transport of substances from exchange surfaces with large surface areas (eg. lungs) and the alimentary canal (the small intestine) to the rest of the body
- for delivery: waste products are removed from the cells and excreted; hormones are delivered to target cells; heat is redistributed in endotherms
where are elastic fibres found
in the walls of the trachea, bronchi, bronchioles and alveoli (everywhere)
