Mass Transport In Animals

Question 1

What is haemoglobin

Answer 1

-A group of chemically similar molecules found in different organisms
-it is a protein with a quaternary structure and it carry’s oxygen in red blood cells

Question 2

Describe the loading, transport and unloading of oxygen in relation to the
oxyhaemoglobin dissociation curve

Answer 2

Areas with low partial pressure of oxygen (respiring tissues):
● Haemoglobin has a low affinity for O2
● So haemoglobin unloads and dissociates oxygen more readily
● So % saturation of haemoglobin with oxygen is low

Areas with high partial pressure of oxygen (gas exchange surfaces):
● Haemoglobin has a high affinity for O2
● So O2 readily loads / associates with Hb
● So % saturation of haemoglobin with oxygen is high

Question 3

The oxyhaemoglobin dissociation curve also shows co operative binding
What is co operative binding

Answer 3

1. Binding of first oxygen changes quaternary structure of haemoglobin slightly
2. This uncovers Haem group binding sites, making further binding of oxygens easier

Question 4

What is the Bohr effect

Answer 4

Effect of CO2 concentration on dissociation of oxyhaemoglobin → curve shifts to right

Question 5

Explain the advantage of the Bohr effect (eg. during exercise)

Answer 5

More dissociation of oxygen → faster aerobic respiration / less anaerobic respiration → more ATP produced

Question 6

Explain effect of CO2 concentration on the dissociation of oxyhaemo

Answer 6

1. Increasing blood CO2 eg. due to increased rate of respiration
2. Lowers blood pH (more acidic)
3. Haemoglobin has a lower affinity for oxygen as shape quaternary structure changes slightly
4. So more unloading of oxygen
   to respiring cells at a given pO2

Question 7

Describe the Bohr effect at high partial pressure of carbon dioxide at respiring tissues and low partial pressure of CO2 at gas exchange surfaces

Answer 7

High
Curve shift to right,decreased affinity and therefore unloads more oxygen
Low
Curve shift to left,higher affinity therefore uploads more oxygen

Question 8

Explain why different types of haemoglobin can have different oxygen
transport properties

Answer 8

● Different types of Haemoglobin are made of polypeptide chains with slightly different amino acid sequences
● Resulting in different quaternary structures → different affinities for oxygen

Question 9

Humans have a what so blood passes through the heart twice in each circuit where one circuit delivers blood to the lungs and another to the rest of the body

Answer 9

A double circulatory system

Question 10

What are the arteries and veins in the heart and function

Answer 10

Hearts Arteries
-pulmonary artery,-taking deoxygenated blood to lungs
aorta-sending oxygenated blood to the body
Hearts veins
-pulmonary vein-receiving oxygenated blood from lungs
-vena cava-receiving deoxygenated blood from the body

Question 11

What are the 2 main artery and vein involved with the lungs

Answer 11

Pulmonary artery
Pulmonary vein

Question 12

What is the 2 artery and vein involved with the kidneys and function

Answer 12

Renal artery=takes oxygenated blood to the kidneys
Renal vein=takes deoxygenated blood away from the kidneys to vena cava

Question 13

What is a coronary artery

Answer 13

The supply the cardiac muscle on the heart with oxygenated blood

located on surface of the heart, branching from aorta

Question 14

What are the 4 chambers of the heart

Answer 14

Right atrium and left atrium, at the top
Left ventricle and right ventricle at the bottom

Question 15

Suggest why the wall of the left ventricle is thicker than that of the right

Answer 15

● Thicker muscle to contract with greater force
● To generate higher pressure to pump blood around entire body

Question 16

What is the structure of ventricles and how it relates to its function

Answer 16

-thicker muscular walls to enable contraction
This creates high blood pressure to enable blood to flow longer distances

Question 17

Describe how blood is travelled round the heart by the 4 main blood vessels-hint veins=atrium

Answer 17

-pulmonary artery carries deoxygenated blood from the right ventricle to the lungs to become oxygenated
-pulmonary vein carries oxygenated blood from the lungs To the heart to the left atrium
-aorta carries oxygenated blood from the left ventricle to the rest of the body
-vena cava carries deoxygenated blood from the body into the right atrium

Question 18

What is the valve In the aorta and pulmonary artery

Answer 18

Semi lunar valve

Question 19

What are the valves between atria and ventricles

Answer 19

Atrioventricular valves

Question 20

What are the atrioventricular valves found In the right and left side

Answer 20

Right side=tricuspid
Left side=bicuspid

Question 21

What is the function of valves

Answer 21

-they open when the pressure is higher behind the valve
-they close when the pressure is higher in front of the valve
-prevent back flow of blood

Question 22

What is the function of the septum

Answer 22

-separates the oxygenated and deoxygenated blood
-it maintains high concentration of oxygen in oxygenated blood to maintain concentration gradient

Question 23

Explain how the structure of the arteries relate to their function

Answer 23

Function: carry blood away from heart at high pressure
-thick smooth muscle tissue-can contract to maintain blood flow and blood pressure
- thick elastic tissue - can stretch as ventricles contact and recoil as ventricles relax to maintain high blood pressure
-thick wall- withstand high pressure to stop bursting
-smooth/folded endothelium-reduces friction and can stretch
Narrow lumen- maintain high pressure

Question 24

Explain how the structure of veins relate to their function

Answer 24

Function - carry blood back to heart at lower pressure
-valves-prevent back flow of blood
- thin elastic and muscle tissue as the blood pressure is lower
-wider lumen - less resistance to blood flow

Question 25

Explain how the structure of arterioles relate to their function

Answer 25

Function- direct blood to capillaries -thicker smooth muscle layer to: -contracts- narrows lumen which reduces blood flow to capillaries -relaxes-widens lumen- increases blood flow into capillaries -thinner elastic layer as the pressure a lower as further from heart and ventricles

Question 26

Describe the capillary structure and how that is important to its function

Answer 26

-thin walls - one cell thick- layer of endothelial cells- reduces diffusion distance -capillary bed is a large network of branched capillaries so increased surface area for diffusion -small diameter/narrow lumen - reduces blood flow rate so more time for diffusion -pores in walls between cells- allows larger substances through

Question 27

What are the 3 stages of the cardiac cycle

Answer 27

-diastole -atrial systole -ventricular systole

Question 28

Describe the diastole stage of the cardiac cycle

Answer 28

-both atria and ventricles relax - volume increases pressure decreases -blood enters via the pulmonary vein and vena Cava -semi lunar valves forced shut by pressure when pressure in arteries exceed pressure in ventricles -Atrioventricular valves open when pressure in atria exceeds pressure in ventricles -pressure increases in the atria as blood is flowing in

Question 29

Describe the atrial systole stage

Answer 29

-atria muscle walls contract decreasing the volume but increasing pressure -causes atrioventricular valves to open when pressure in atria exceeds pressure in ventricles -blood to flow into the ventricles -ventricular muscles are relaxed Semi lunar valves remain shut

Question 30

Describe the ventricular systole stage

Answer 30

-atria is relaxed and walls of ventricles contract increasing pressure and volume decreases -as pressure rises atrioventricular valves close to prevent back flow when pressure in ventricles exceeds pressure in atria - semi lunar valves open when pressure in ventricles exceeds pressure in arteries -blood is pushed out the ventricles into the pulmonary artery and aorta

Question 31

What is the equation of the cardiac output

Answer 31

Heart rate x stroke volume

Question 32

What is tissue fluid

Answer 32

A fluid containing water and oxygen ad other small molecules that leaves the blood plasma and bathes the tissues

Question 33

Explain the formation of tissue fluid

Answer 33

-higher hydrostatic pressure inside capillaries due to contraction of ventricles -forcing water and dissolved substance out of capillaries -large plasma proteins remain in capillary

Question 34

Not all the tissue fluid is absorbed by osmosis Where doe the rest the tissue fluid go

Answer 34

Into the lymphatic system and eventually drains back into the bloodstream near the heart

Question 35

What is the affinity if oxygen of organisms that live in environments with low and high concentration of oxygen and explain the dissociation curve

Answer 35

Low concentration of oxygen-Haemoglobin has a higher affinity for oxygen so dissociation curve shifts to the left High concentration of oxygen - haemoglobin has lower affinity for oxygen as higher oxygen demand so dissociation curve shifts to right

Question 36

Explain the return of tissue fluid to the circulatory system

Answer 36

At the venule end of capillaries 1. Hydrostatic pressure reduces as fluid leaves capillary (also due to friction) 2. Due to water loss an increasing concentration of plasma proteins lowers water potential in capillary below that of tissue fluid 3. Water enters capillaries from tissue fluid by osmosis down a water potential gradient 4. Excess water taken up by lymph capillaries and returned to circulatory system through vein

Question 37

Suggest and explain causes of excess tissue fluid accumulation

Answer 37

Low concentration of plasma proteins ○ Water potential in capillary not as low → water potential gradient is reduced ○ So more tissue fluid formed at arteriole end / less water absorbed at venule end by osmosis ● High blood pressure → high hydrostatic pressure

Question 38

Describe precautions that should be followed when performing a dissection -Required practical 5

Answer 38

● Cover any cuts with a waterproof dressing ● When using a scalpel, cut away from body onto a hard surface ● When using a scalpel, use a sharp blade ● When using a scalpel, carry with blade protected / pointing down ● Wear disposable gloves and disinfect hands / wash with soap ● Disinfect surfaces / equipment ● Safe disposal - put gloves / paper towels / organ in a separate bag / bin to dispose ● If poisonous chemicals / toxins involved, work in a well ventilated environment

Question 39

Suggest an ethical consideration when dissecting animals RP 5 - dissection

Answer 39

● Morally wrong to kill animals just for dissection ● So use animals for dissection that have already been killed (humanely) for meat

Question 40

Describe how you could prepare a temporary mount of a piece of plant tissue for observation with an optical microscope - RP 5 dissection

Answer 40

1. Add a drop of water to glass slide 2. Obtain a thin section of specimen and place on slide 3. Stain (eg. with iodine / potassium iodide to view starch) 4. Lower coverslip at angle using mounted needle without trapping air bubbles

Question 41

What are the rules of scientific drawing?

Answer 41

✓ Look similar to specimen / image, draw all parts to same scale / relative size ✓ No sketching / shading - only clear, continuous lines ✓ Include a magnification scale (eg. x 400) ✓ Label with straight, uncrossed lines

Question 42

Describe the structure of haemoglobin

Answer 42

● Protein with a quaternary structure ● Made of 4 polypeptide chains ● Each chain contains a Haem group containing an iron ion (Fe2+)

Question 43

Suggest the importance of a double circulatory system

Answer 43

● Prevents mixing of oxygenated / deoxygenated blood -So blood pumped to body is fully saturated with oxygen for aerobic respiration ● Blood can be pumped to body at a higher pressure (p ○ Substances taken to and removed from body cells quicker / more efficiently

Question 44

Describe the general pattern of blood circulation in a mammal

Answer 44

1. Deoxygenated blood in right side of heart pumped to lungs; oxygenated returns to left side of heart 2. Oxygenated blood in left side of heart pumped to rest of body; deoxygenated returns to right side of heart

Question 45

Look at this: Explain how graphs showing pressure or volume changes during the cardiac cycle can be interpreted, eg. to identify when valves are open / close

Answer 45

valves closed ● Pressure in [named] artery higher than in ventricle ● To prevent backflow of blood from artery to ventricles SL valves open ● When pressure in ventricle is higher than in [named] artery ● So blood flows from ventricle to artery AV valves closed ● Pressure in ventricle higher than atrium ● To prevent backflow of blood from ventricles to atrium AV valves open ● When pressure in atrium is higher than in ventricle ● So blood flows from atrium to ventricle

Question 46

How can heart rate be calculated from cardiac cycle data?

Answer 46

Heart rate (beats per minute) = 60 (seconds) / length of one cardiac cycle (seconds)