Summary

Summary - Unit 3 - Organisms exchange substances with their environment

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Institution
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Here are a bunch of flashcards I made for the whole topic chapter 7 of the A-level Biology Pearson textbook. These flashcards are questions that I use to test my memory and see how much I can remember since A-level Biology is a very content-heavy subject. I have written this based on information fr...

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Uploaded on October 16, 2023
Number of pages 18
Written in 2023/2024
Type Summary

111.what is the structure of Hb?
● Protein with a quaternary structure

2.what is the role of Hb?
● Transport O2
● Readily associate with O2 at the surface where gas exchange takes place
● Readily dissociate from O2 at those tissues requiring it

3.why do different Hb’s have different affinities ?
● Different Hb’s have different AA seq, diff tertiary + quaternary structure and hence
different O2 binding properties

4.When is O2 loaded?
● Loaded in regions with a high partial pressure of O2 (e.g. alveoli)

5.when is O2 unloaded?
● Unloaded in regions of low partial pressure of O2 (e.g. respiring tissues)

This is shown on the oxyhaemoglobin dissociation curve

,4.describe the cooperative nature of O2 binding
● The cooperative nature of O2 binding to Hb is due to the Hb changing shape
when the first O2 binds.
● This makes is easier for subsequent O2’s to bind

5.what is the Bohr effect
● When a high CO2 conc causes oxyhaemoglobin curve to shift to right
● Affinity for O2 decreases bec the acidic CO2 changes shape of Hb slightly
● Hb has a lower affinity for O2

6.what happens if there is a low partial pressure of CO2?
● Curve shifts left
● There is an increased affinity for O2
● Hb releases O2 less readily

7.what happens if there is a high partial pressure of CO2?
● Curve shifts right
● There is a decreased affinity for O2
● Hb releases O2 more readily

8.Why do llamas have Hb that has a higher affinity for
O2 than human Hb?
● They live in areas of high altitudes, where there is a
low partial pressure of O2
● Curve of llama shifted to left, so Hb has an increased
affinity for O2 + Hb releases O2 less readily

9.why do doves need more O2?
● Faster metabolism, so needs more O2 for
respiration to provide energy for contracting
muscles
● Curve shifts to right
● Hb has lower affinity for O2
● Hb releases O2 more readily

, 10.Describe the advantage of the Bohr effect during intense exercise.
● Increases dissociation of O2
● For aerobic resp at tissues/ muscles/cells
● Anaerobic resp delayed at tissues/ muscles/cells
● So less lactate at tissues/ muscles/cells

Circulatory system

1.what is a double circulatory system?
● When blood passes through the heart 2x in each circuit
● There is one circuit which delivers blood to lungs and one which delivers blood to
rest of body

2.why does blood flow through lungs at a lower pressure?
● To prevent damage to capillaries in alveoli + also reduces the speed at which the
blood flows, enabling more time for gas exchange

3.why does the oxygenated blood from lungs then travel back through the heart
to be pumped out at a higher pressure to the rest of the body?
● To ensure that blood reaches all respiring cells in body

KEY BLOOD VESSELS

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