3.4.1-Mass Transport Animals

Question 1

1. Describe the structure of haemoglobin. Why do we say it has quaternary structure? (Q2 Jan 2011)

Answer 1

It is a protein made of 4 polypeptide chains (two alpha chains and two beta chains)
Each polypeptide chain has a heme group which is where the oxygen molecule binds.
(One haemoglobin molecules can hold up to 4 oxygen molecules)

It has a quaternary structure because it is made of more than 1 polypeptide chain

Question 2

1. Write an equation to show the reversible reaction between haemoglobin and oxygen

Answer 2

Haemoglobin + oxygen  oxygaemoglobin

Hb + 4O2  Hb(O2)4

Question 3

nnotate this graph stating where oxygen is loaded and unloaded and wh

Answer 3

1. Annotate this graph stating where oxygen is loaded and unloaded and why (Q7 June 2010)

Question 4

1. Give the formula for calculating the percentage saturate of haemoglobin with oxygen

Answer 4

Percentage saturate of haemoglobin with oxygen = Oxygenated haemoglobin x 100
Maximum saturation

Question 5

5. How does the binding of the first oxygens to haemoglobin affect the affinity of haemoglobin? (Use the term tertiary structure in your answer)

Answer 5

• 1 Oxygen molecule binds to haemoglobin;
• This alters tertiary structure of Hb;
• Uncovers second binding site for haem group to bind to;
• This increases the affinity of Hb to Oxygen (so it’s easier for the 2nd and 3rd molecules of oxygen to bind)
• This is called cooperative binding

Question 6

6. Sketch a curve on the graph above to show what happens when carbon dioxide levels increase (sh

Answer 6

curve on the graph above to show what happens when carbon dioxide levels increase (shown in red)

Question 7

Organisms which are adapted to permanently live at high altitude (BIOL2 Q2 Jan 2011)

Answer 7

Shift to the left

Allows oxygen to be LLLLOADED even at low partial pressures of oxygen

Question 8

Humans who have gone to live at high altitude (and thus have a higher number of red blood cells than humans who live at sea level) (BIOL2 Q4 Jan 2010)

Answer 8

Shift to the right

Allows oxygen to be RRRRELEASED to respiring cells so that organisms can maintain a high metabolic rate

Question 9

Large mammal with small SA:Vol ratio

BIOL2 June 2010 Q7

Answer 9

Shift to the left
These organisms lose very little heat due to their small SA:Vol ratio. Therefore they do not require a high rate of respiration and muscle contraction to keep them warm. So their rate of respiration is low

So curve shifted to the left to so haemoglobin hoLLLLLds onto the oxygen

Question 10

Small mammal with large SA:Vol ratio

BIOL2 June 2010 Q7

Answer 10

Shift to the right
These organisms lose a lot of heat due to their large SA:Vol ratio. Therefore the high rate of respiration and muscle contraction generate heat to keep them warm. This requires a high rate of respiration

So curve shifted to the right means that oxygen is RRRRELEASED to respiring cells

Question 11

Foetal haemoglobin

Answer 11

Shift to the left

The curve shifted to the left so foetal haemoglobin has a higher affinity for oxygen than adult haemoglobin

This means that at the same partial pressure of oxygen, the adult haemoglobin can unload oxygen and the foetal haemoglobin can LLLLLOAD oxygen

Question 12

Myoglobin

Answer 12

Myoglobin
Shift to the left

Myoglobin is found in muscles  The curve shifted to the left so myoglobin has a higher affinity for oxygen than normal haemoglobin

This means that at the same partial pressure of oxygen, the haemoglobin can unload oxygen and the myoglobin can LLLLOAD oxygen

This allows myoglobin to act as a ‘store’ of oxygen

Question 13

Heart

Answer 13

Name of organ Name of blood vessel entering organ Name of blood vessel leaving organ
Heart From the lungs = pulmonary vein
From the body = vena cava To the lungs = pulmonary artery
To the body = aorta

Question 14

Liver

Answer 14

From the heart = Hepatic artery

From the small intestine = hepatic portal vein Hepatic vein

Question 15

Kidney

Answer 15

Renal artery Renal vein

Question 16

1. Where in the body is blood at lowest pressure?

Answer 16

In the veins and in particular at the top of the vena cava near the heart

Question 17

What is the function of the coronary arteries

Answer 17

To supply blood to the heart muscle

Question 18

1. Label the parts of the heart, including where each vein/artery comes from or goes to)

Answer 18

1. where each vein/artery comes from or goes to)

Pressure and volume changes and associated valve

Question 19

1. What is the equation for cardiac output? (include units)

Answer 19

Cardiac output (cm3min-1) = stroke volume (cm3) x heart rate (min-1)

Question 20

1. Re arrange the equation to calculate stroke volume and heart rate

Answer 20

Stroke volume (cm3) = Cardiac output (cm3min-1) / heart rate (min-1)
Heart rate (min-1) = Cardiac output (cm3min-1) / Stroke volume (cm3)

Question 21

How else can you calculate heart rate?

Answer 21

1. Heart rate = 60 / time taken for one cardiac cycle

Question 22

Look at the graph below

Answer 22

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Question 23

This graph shows the left side of the heart. Add a line to show the pressure in the right ventricle (

Answer 23

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Question 24

1. Draw a diagram of a cross section of an artery, arteriole and a vein (or insert a picture). Label the epithelium, elastic layer, muscle layer and outer layer.

Answer 24

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Question 25

Describe and explain the function of each layer. (use mark scheme Jan 2011, Q8c, June 2010 Q2 a

Answer 25

Elastic tissue
• Elastic tissue stretches when pressure is high (during ventricular systole)
• Recoils during ventricular diastole
• This evens out pressure (so that pressure surges are reduced) and maintains smooth blood flow

Muscle

• Muscle contracts;
• This reduces the diameter of the lumen (this is called vasoconstriction)
• This reduces the amount of blood that can flow through the vessel (and increases the pressure)

Epithelium
• the epithelium is smooth
• This reduces friction so that there is less resistance and reduced chance of blood clots

Question 26

structure of capillaries and the importance of capillary beds as exchange surfaces.
1. Draw and label a diagram of a capillary bed. Annotate the diagram with a description of how the structure helps the function. (Jun 2010 Q2d)

Answer 26

• Large/increase in (total) cross sectional area / friction / resistance;
• This means that there is MORE TIME for exchange of substances between the capillaries and their surrounding cells

Question 27

Describe how tissue fluid is formed and how it returns to the circulatory system (June’11 Q6b & Jan‘10

Answer 27

• At the arterial end:
o The Hydrostatic pressure is higher in the capillary than the tissue fluid
o The hydrostatic pressure is higher than the osmotic pressure
o Therefore water (and substances dissolved in water) are forced out of the capillaries and into the tissue fluid
• At the venous end
o The hydrostatic pressure is much lower in the capillary (due to loss of fluid) than at the arterial end
o The total water potential is lower in the capillary at the venule end than at the arterial end (and also lower in the capillary than in the tissue fluid) due to large soluble proteins which remain in the blood vessel
o Therefore the osmotic pressure (pulling water in) is greater than the hydrostatic pressure
o So water is returns to the capillary from the tissue fluid by OSMOSIS
• Excess water in the tissue fluid is taken up by the lymph capillaries which return it to the circulatory system at the subclavian vein

Question 28

1. What causes the high hydrostatic pressure at the arterial end of the capillaries?

Answer 28

Contraction of the ventricles

Question 29

Explain why people who lack protein in their diet often accumulate tissue fluid which leads to swelling

Answer 29

• The lack of protein means that the water potential (in capillary) is not as low as it should be (it is less negative)
• Therefore the water potential gradient is reduced;
• Therefore more tissue fluid is formed at arteriole end (because more water leaves the capillaries and moves into the tissue fluid)
• And less water is absorbed from the tissue fluid into the blood capillary by osmosis