3.4.1- Haemoglobin

Question 1

Carbon dioxide helps haemoglobin to release o2 to rapidly respiring tissues. Explain how (2)

Answer 1

• Lowers affinity for o2

- Displaces dissociation curve to the right

Question 2

An increase in respiration in the tissues of a mammal affects the oxygen dissociation curve of haemoglobin and explain how (2)

Answer 2

Increase co2

Curve to right

Question 3

What is it meant by quaternary structure (1)

Answer 3

Number of polypeptide chains

Question 4

Explain how o2 is loaded, transported and unloaded in the blood (7)

Answer 4

• Heamoglobin carries oxygen/ oxyhaemoglobin
• In RBC’s
• Loading/uptake/association in lungs
• At high pp of 02
• Unloads into tissues
• Has a low pp of o2
• Unloading linked to higher co2 concentration

Question 5

In high pp of co2 the oxyhaemoglobin dissociation curve undergoes a change known as the Bohr shift.

Outline the benefits of the Bohr shift to actively respiring tissue (4)

Answer 5

• Actively respiring tissue needs more o2
• to release more energy (aerobic respiration)
• Actively respiring tissue makes more co2/ heamo involved in the transport of co2 so less is available to combine with o2

-Bohrn shift causes more o2 to be released

Question 6

What is the BOhr effect?

Answer 6

As partial pressure of carbon dioxide increases, the
conditions become acidic causing haemoglobin to
change shape. The affinity of haemoglobin for
oxygen therefore decreases, so oxygen is released
from haemoglobin. This is known as the Bohr effec

Question 7

Name the mechanism by which o2 enters the blood (1)

Answer 7

Diffusion

Question 8

Describe the role of haemoglobin in transporting oxygen around the body (4)

Answer 8

Haemoglonin has a high affinity for o2

o2 binds to heam at the lungs

Oxyheamoglobin

Oxygen is relased in tissues

Question 9

High concs of co2 in the blood reduce the amount of o2 transported by haemoglobin.
Name this effect and why it occurs (5)

Answer 9

Bohrs effect

Reduces affinity for oxygen

Less haem for o2 as co2 forms carbaminohaemoglobin

changes structure of heamogloobin

More o2 is released where needed (more respiration)

Question 10

Explain how changes in the shape of haemoglobin result in the S shaped oxyhaemoglobin dissaciayion curve for X (2)

Answer 10

When 1 molecule of oxygen binds to haemoglobin

It changes shape

This makes it easier for more oxygen molecules to bind to haemoglobin

Question 11

Explain why a shift to the right in a dissacation graph is beneficial for x (2)

Answer 11

y has a lower affinity for oxygen then x

Therefore o2 unloads from haemoglobin at a lower pp in respiring tissue

More o2 released for respiration

Question 12

Explain how o2 is loaded , transported and unloaded in the blood (6)

Answer 12

1. Haemoglobin carries o2 and has a high affinity for it to form oxyhaemoglobin
2. In red blood cells
3. Loading in lungs
4. at high p o2
5. Dissaciats at tissues
6. At low po2
7. Unloading linked to higher carbon dioxide concentration

Question 13

Haemoglobin is a protein with a quaternary structure

Explain what this means (1)

Answer 13

Has more than 1 polypeptide chain

Question 14

The haemoglobin in one organism may have a different chemical structure from the haemoglobin in
another organism. Describe how.

Answer 14

diff quaternary structure / number of polypeptides

Question 15

why llamas are better adapted to live in high mountains than horses.

Answer 15

1. Low partial pressure of oxygen in lungs;
2. (Llama) haemoglobin able to load more oxygen / (llama) haemoglobin saturated (at low / particular
   partial pressure of oxygen);
3. Higher affinity for oxygen;

Question 16

the relationship between the surface area to volume ratio of mammals and
the oxygen dissociation curves of their haemoglobins.

Answer 16

Smaller mammal has greater surface area to volume ratio;
Smaller mammal / larger SA:Vol ratio more heat lost (per unit body mass);
Smaller mammal / larger SA:Vol ratio has greater rate of respiration / metabolism;
Oxygen required for respiration so (haemoglobin) releases more oxygen / oxygen released more readily /
haemoglobin has lower affinity;