Mass Transport

Question 1

Why do Humans/Mammals require a Specialised Transport System?

Answer 1

Multicellular organisms therefore have large diffusion distances and high demand

need a transport system to deliver nutrients and remove waste from all cells

transport system in humans/mammals called Circulatory System

Circulatory System made of heart, blood vessels, blood (heart pumps blood, blood vessels carry blood, blood carries nutrients/waste)

Question 2

Why is the transport system in mammals called a double circulatory system?

Answer 2

The heart pumps twice, the blood goes through the heart twice – generates enough pressure to supply all body cells

Question 3

Why is the transport system in mammals called a closed circulatory system?

Answer 3

Blood is transported in blood vessels – helps to maintain pressure and redirects blood flow

Question 4

Layout of Circulatory System

Answer 4

heart pumps blood which is carried in arteries which flow into arterioles which flow into capillaries which then are carried in venules then veins back to the heart

Artery to Arterioles to Capillaries to Venules to Veins

Artery/Arterioles carry blood away from the heart
(arterioles are small arteries)

Capillaries are the site of exchange (nutrients out, waste in)

Veins/Venules return blood back to the heart

Question 5

Heart

Answer 5

Job is to pump blood around the body (delivers nutrients to cells and remove waste)

made of 4 muscular chambers (2 atria, 2 ventricles)

atria pumps blood to ventricles, ventricles pump blood out of heart (R to lungs, L to body)

ventricles thicker then atria (has to pump blood further)

left ventricle has a thicker muscular wall then right ventricle, therefore has stronger contractions, so can generate higher pressure and pump the blood further around the body

Question 6

Blood vessels of the heart

Answer 6

Artery takes blood away from the heart, vein returns blood to the heart

Vena Cava supplies R atrium (with deoxygenated blood from body)

Pulmonary Vein supplies L atrium (with oxygenated blood from lungs)

R ventricle supplies Pulmonary Artery (deoxygenated blood to lungs)

L ventricle supplies Aorta (oxygenated blood to body)

Question 7

Job of valves in heart

Answer 7

Ensure one way flow of blood, no backflow

(blood flows from atria to ventricles to arteries)

2 sets of valves: Atrio-ventricular Valve & Semi-lunar Valve

AV valve = between atria and ventricles

SL valve = between ventricles and arteries

Question 8

When are AV valves open or closed?

Answer 8

Open = pressure in atria greater than pressure in ventricles,
Closed = pressure in ventricles greater than pressure in atria

Question 9

When are SL valves open or closed?

Answer 9

Open = pressure in ventricles greater than pressure in arteries
Closed = pressure in arteries greater than pressure in ventricles

Question 10

Describe the processes of the cardiac cycle

Answer 10

Filling Stage = atria relaxed, ventricles relaxed, AV valve open, SL valve closed

Atria Contracts = the SAN located in the R atrium initiates the heart beat and sends the impulse across both atria making them contract, this pushes all the remaining blood into the ventricles so it becomes full

Ventricles Contract = the AVN picks up the impulse, delays it (stops the atria and ventricles contracting at the same time, so the atria empties and the ventricles fill), sends the impulse down the septum in the Bundle of His, then at the apex the impulse goes up both walls of the ventricles in the purkine fibres, so the ventricles contract from the base upwards, pushing the blood up thru the arteries, when the ventricles start to contract the AV valve closes then the SL valve opens and blood leaves the heart

Ventricles Relax = the SL valve closes then the AV valve opens and filling starts

Question 11

Formula for Cardiac Output

Answer 11

CO = Stroke Volume x Heart Rate

stroke volume = volume of blood pumped out of the heart in one beat

heart rate = number of beats per minuted

Cardiac Output = volume of blood pumped out of the heart in one minute

Question 12

Coronary Heart Disease

Answer 12

high blood pressure damages lining of coronary artery

fatty deposits/cholesterol builds up beneath the lining, in the wall = Atheroma

the atheroma breaks thru the lining forming a Atheromatous Plaque on the lining, in the lumen

this causes turbulent blood flow

a blood clot (thrombus) forms

this block the coronary artery

therefore less blood flow to the heart muscle

less glucose and oxygen delivered

the heart muscle cannot respire

so it dies (myocardial infarction)

Question 13

Risk Factors of CHD

Answer 13

Age, gender, ethnicity

Saturated fats (increases LDL, LDL deposits cholesterol in the arteries to form atheroma)

Salts (increases blood pressure – lowers water potential of the blood so it holds the water)

Smoking (nicotine = increase HR and makes platelets more sticky – blood clot, carbon monoxide = permanently blocks haemoglobin)

Obesity and Lack of Exercise

Question 14

Role of Arteries/Arterioles

Answer 14

Generally carry oxygenated blood away from the heart

For example, Coronary Artery to the heart muscle
or Renal Artery to kidneys

exception = Pulmonary Artery carries deoxygenated blood to the lungs

Question 15

Role of Veins/Venules

Answer 15

generally carry deoxygenated blood back to the heart

for example, Coronary Vein from heart or Renal Vein from kidneys

exception 1 = Pulmonary Vein carries oxygenated blood back to the heart
exception 2 = Hepatic Portal Vein carries deoxygenated blood from the digestive system to the liver (for filtering)

Question 16

Structure of Arteries/Arterioles

Answer 16

Narrow lumen = maintains pressure

Lining made of epithelial cells = smooth lining to reduce friction

Thick wall = withstand pressure

Elastic tissue in the wall,

Ventricles contract – elastic tissue stretches to withstand pressure
Ventricles relax – elastic tissue recoils to maintain pressure and smooth outflow

smooth muscle in the wall (particularly in arterioles),

smooth muscle contracts – lumen narrows and arteriole constricts
smooth muscle relaxes – lumen widens and arteriole dilates

collagen in wall - prevents the artery from tearing

Question 17

Structure of Veins/Venules

Answer 17

wide lumen = ease of blood flow

lining made of squamous epithelial cells = smooth lining to reduce friction

thin wall = vein can be squashed by skeletal muscle pushing blood back to the heart

valves in lumen = prevents backflow of blood

Question 18

Function of Capillaries

Answer 18

Site of exchange
3 locations,

With Alveoli, takes in O2 and removes CO2

With Microvilli, takes in glucose/amino acids/monoglyceride and fatty acids/vitamins/minerals

With All Cells, deliver nutrients and remove waste

Question 19

Adaptation of Capillaries

Answer 19

many small capillaries = large surface area

thin wall, one cell thick, squamous epithelial cells = short diffusion distance

pores between cells = allows fluid to move in and out

narrow lumen = increase diffusion time and decrease diffusion distance

Question 20

Content of Blood

Answer 20

main component = Plasma (fluid)

plasma carries,

Cells = red blood cells, white blood cells, platelets

Solutes = nutrients, waste, protein

Question 21

How does exchange occur between Capillaries & All Cells

Answer 21

by mass flow

fluid moves out of the blood in the capillaries carrying the nutrients

fluid moves back into blood in the capillaries carrying the waste

(fluid in the blood called plasma, fluid surrounding cells called tissue fluid, fluid in lymph system called lymph)

Question 22

How is tissue fluid formed and returned to circulatory system

Answer 22

at the start of the capillary (arterial end) there is a build up hydrostatic pressure

this pushes fluid out of the capillary via the pores

the fluid carries the nutrients with it

the fluid surrounds the cells, this is called tissue fluid

at the finish of the capillary (venous end) the fluid moves back in by osmosis

the capillary has low water potential due to the presence of proteins (too large to move out of capillaries)

any excess tissue fluid is picked up by the lymph system and deposited in the vena cava

Question 23

Why does high blood pressure cause accumulation of tissue fluid

Answer 23

increases hydrostatic pressure, so more tissue fluid is formed – not as much can be returned to the circulatory system

Question 24

Why does diet low in protein cause accumulation of tissue fluid?

Answer 24

the water potential in the capillary is not as low as normal, so not as much fluid can move back into the capillary by osmosis

Question 25

Blood Pressure changes along the Circulatory System

Answer 25

Arteries = - highest pressure (connects directly with heart/ventricles) - pressure fluctuates (increases when ventricles contract which causes the elastic tissue to stretch, decreases when ventricles relax which causes the elastic tissue to recoil) - overall decrease in pressure due to friction Arterioles = large decrease in pressure due to increase in total cross-sectional area (ensures pressure is not to high to damage capillaries) Capillaries = pressure here is called hydrostatic pressure (decreases due to a loss in fluid) Venules/Veins = blood under low pressure

Question 26

Job of Red Blood Cells

Answer 26

found in humans/mammals (animals) carries haemoglobin haemoglobin carries oxygen

Question 27

Structure of Haemoglobin

Answer 27

globular protein (soluble & specific 3d shape) quaternary structure made of 4 polypeptide chains (2α, 2β) each chain carries a haem group each haem group carries Fe2+ each Fe2+ carries an O2 therefore, each haemoglobin carries 4 lots of O2

Question 28

Job of Haemoglobin

Answer 28

load oxygen in the lungs and deliver it to the respiring tissues

Question 29

What is Affinity?

Answer 29

The level of attraction haemoglobin has to oxygen (high affinity = strong attraction, low affinity = weak attraction)

Question 30

Role of haemoglobin in oxygen transport

Answer 30

haemoglobin has High Affinity in the lungs – due to high partial pressure of oxygen and low partial pressure of carbon dioxide, so haemoglobin loads/associates oxygen in the lungs and becomes saturated (full) the haemoglobin is transported in the blood in the red blood cell at the respiring tissues, haemoglobin has Low Affinity – due to low partial pressure of oxygen and high partial pressure of carbon dioxide, so oxygen is unloaded/dissociated/delivered and haemoglobin becomes unsaturated

Question 31

Relationship between O2 Partial Pressure & Affinity/Saturation of Haemoglobin?

Answer 31

positive correlation as O2 partial pressure increases, affinity/saturation of haemoglobin increases the correlation is not linear but is curved (produces a s-shaped, sigmoid curve called Oxygen Dissociation Curve) middle portion of ODC has a steep gradient so when respiring tissues change from resting to active and partial pressure of O2 falls, there is a large drop in affinity, so more O2 would be delivered to the respiring tissues

Question 32

Relationship between CO2 Partial Pressure & Affinity/Saturation of Haemoglobin

Answer 32

negative correlation as CO2 partial pressure increases, affinity/saturation of haemoglobin decreases this occurs at the site of respiring tissues = the carbon dioxide lowers the pH of the blood, makes the haemoglobin change shape, so oxygen is released, lowering affinity. this shifts the ODC to the right, called the bohr shift. benefit = more oxygen delivered to respiring cells

Question 33

How does a Fetus receive oxygen?

Answer 33

From mother's blood, oxygen dissociates from mother's haemoglobin and associates with fetal haemoglobin in the placenta – fetal haemoglobin has a higher affinity compared to mother's haemoglobin

Question 34

Affinity of Organisms in a Low Oxygen Environment?

Answer 34

has a high affinity, curve to the left, therefore it can readily associate oxygen at the low oxygen partial pressures

Question 35

Affinity of Active Organisms

Answer 35

has a low affinity, curve to the right, therefore more oxygen can be unloaded to meet the cell's demand for more respiration

Question 36

Affinity of Small Organisms?

Answer 36

have a large surface area to volume ratio, lose a lot of heat, needs to respire to generate heat, therefore has a low affinity, curve to the right, so unloads enough oxygen for the cells demand of more respiration

Question 37

What are the Exchange & Transport Systems in Plants

Answer 37

exchange systems = leaf and root leaf to absorb light and CO2 for photosynthesis roots to absorb water and minerals transport systems = xylem and phloem xylem transports water and minerals phloem transports glucose/sugars xylem transports in one direction from roots to leaves, phloem transports in both directions

Question 38

Job of the Roots

Answer 38

absorb water and minerals absorbs water by osmosis absorbs minerals by active transport plants need water for photosynthesis, cytoplasm hydration, turgidity of cells plants need magnesium, nitrate, phosphate (magnesium to make chlorophyll, nitrate to make amino acids, phosphate to make phospholipids/ATP/DNA)

Question 39

Function of the Xylem

Answer 39

transport water and minerals from roots, up the plant, to the leaves

Question 40

Structure of the xylem

Answer 40

long continuous hollow tube (no resistance to water flow) narrow lumen wall made out of lignin lignin: strong, waterproof, adhesive wall contains pits/pores (water and minerals can leave)

Question 41

How does water move up the xylem?

Answer 41

loss of water at the leaves (transpiration) water moves from the top of the xylem into the leaf by osmosis (transpirational pull) this applies TENSION to the column of water in the xylem the column of water moves up as one as the water particles stick together, COHESION this is is the cohesion-tension theory it is supported by capillary action, adhesion and root pressure (capillary action = water automatically moves up narrow lumen of xylem) (adhesion = water particles stick to lignin in wall of xylem) (root pressure = water absorbed at the roots pushes the column of water up slightly by hydrostatic pressure)

Question 42

Why does the diameter of a tree decrease during the day?

Answer 42

more light and higher temperature increase rate of transpiration increase transpirational pull water pulled up xylem by cohesion-tension because the water particles stick to the wall of the xylem (adhesion) the walls of the xylem are pulled inwards

Question 43

Structure of leaves

Answer 43

Upper layer called Upper Epidermis Waxy cuticle on upper epidermis (barrier to reduce water loss) Beneath the upper epidermis are Palisade Cells palisade cells are were photosynthesis takes places beneath palisade cells are Spongy Mesophyll Cells are loosely packed leaving air spaces to allow ease of gas exchange lower layer called Lower Epidermis

Question 44

Adaptation of palisade cells for photosynthesis

Answer 44

located near top of leaf, closer to light large size, large surface area for light thin cell wall, short diffusion distance for carbon dioxide contains many chloroplasts, site of photosynthesis large vacuole, pushes chloroplast to the edge of the cell closer to light

Question 45

Structure of chloroplast

Answer 45

organelle for photosynthesis has double membrane contains discs called thylakoids thylakoids contain chlorophyll stack of thylakoids called granum thylakoids surrounded by a fluid called stroma

Question 46

How does Exchange occur in Leaves

Answer 46

lower epidermis of leaf contains pairs of cells called Guard Cells when turgid, guard cells form an opening called Stomata gas exchange occurs via the stomata In Day, plant photosynthesises and respires, CO2 moves in for photosysnthesis and O2 moves out (some is used in respiration) At Night, plant only respires, O2 moves in for respiration and CO2 moves out

Question 47

What is Transpiration?

Answer 47

loss of water vapour from the leaf via the stomata

Question 48

How does Transpiration occur?

Answer 48

moist lining of spongy mesophyll cells evaporate forming water vapour water vapour builds up in air spaces if water vapour concentration is high enough & stomata is open, water vapour diffuses out

Question 49

Factors that increase the rate of transpiration

Answer 49

light = more light, more stomata open, increase surface area for transpiration temperature = more temperature, more evaporation (increase water vapour concentration and more kinetic energy wind = more wind, maintains the concentration gradient humidity = less humidity, less water vapour in the surrounding air, increase in water vapour concentration gradient

Question 50

What is a Potometer?

Answer 50

apparatus used to measure rate of transpiration

Question 51

Principle of potometer?

Answer 51

as transpiration occurs from the leaves, the plant will pull up more water from the potometer by cohesion-tension causing the bubble to move towards the plant the more water lost by transpiration, the more water taken up, the further the bubble moves

Question 52

Measuring Rate of Transpiration

Answer 52

rate of transpiration = volume of transpiration divided by time for volume of transpiration, distance bubble moved x cross-sectional area of tube (πr2)

Question 53

How to set up a potometer?

Answer 53

choose healthy leaf and shoot cut shoot underwater and connect to potometer underwater (prevents air bubbles entering/blocking xylem) ensure potometer is air tight and water tight

Question 54

What does a potometer actually measure?

Answer 54

measures rate of water uptake as a result of water loss from plant (water loss can be due to: transpiration, photosynthesis, making cells turgid, loss from potometer)

Question 55

Function of Phloem?

Answer 55

transport organic material (e.g. Sucrose) up and down a plant

Question 56

Structure of phloem?

Answer 56

made of 2 parts (Sieve Tube with Companion Cells alongside)

Question 57

How does phloem transport organic material like sucrose?

Answer 57

by principle of Mass Flow (mass flow of water carries the sucrose) Sucrose loaded into Phloem at Source Hydrogen Ions (H+) actively transported from companion cells into source therefore, H+ diffuses back into companion cells from source as they do, they pull in sucrose with them by co-transport sucrose then diffuses into sieve tube this lowers the water potential of sieve tube so water follows by osmosis this water will carry the sucrose by hydrostatic pressure (mass flow) Sucrose unloaded from Phloem at Sink sucrose moves out of phloem/sieve tube into sink by diffusion water follows by osmosis