dc2 q flashcards
1
Q
2.2 give structural differences between dna structure and mrna structure
A
- DNA has deoxyribose, mRNA has ribose;
- DNA has thymine, mRNA has uracil;
- DNA long, mRNA short;
- DNA is double stranded, mRNA is single
stranded; - DNA has hydrogen bonds, mRNA has no
hydrogen bonds
2
Q
3.6 name two features of hiv particles that are not found in bacteria
A
Reverse transcriptase
Capsid
3
Q
6.1 explain a peroperty of iron ions to carry out their role in red blood cells
A
charged/polar
part of haem(oglobin);
binds/associates/loads (with) oxygen
forms oxyhaemoglobin
transports oxygen
4
Q
8.1 Suggest why the number of E. coli cells per mm3 in each culture after 24 hours might
have been lower if the student had not used a sterilised pipette. Explain your answer.
A
Unknown/new/different
microorganisms/pathogens/microbes/bacteria
(introduced);
2. (these bacteria) use food/space
5
Q
9.1 Gas exchange for the fetus occurs in the placenta (line 3).
Describe how the composition of blood in the pulmonary artery of a fetus is different
from the composition of blood in the pulmonary artery of its mother
Give one reason for this difference.
A
Fetal blood has more oxygen
gas exchange occurs in the
placenta
6
Q
9.2 Explain how a fetus is protected against the pathogens that infect its mother during
pregnancy (lines 5–6).
Do not give details of an active immune response in the mother.
A
antibodies (from mother) are
complementary/bind specifically
To pathogens/antigens crossing the
placenta;
Giving passive immunity
7
Q
9.3 Suggest how vaccinating as many babies as possible protects the UK population
against pathogens such as measles viruses and tetanus bacteria
Protection against measles
Protection against tetanus
A
herd immunity to reduce
spread;
No herd immunity
8
Q
9.4 Suggest why there has been a recent increase in the number of children catching
measles
A
Reduced vaccination (in children)
virus has mutated;
9
Q
9.5 Explain why giving children more than one tetanus vaccination develops good
immunity against tetanus
A
(Production of) more memory cells;
2. (So) higher concentration of antibodies (in
blood)
10
Q
4.3 Describe how the scientist will use information from the colorimeter and her calibration
curve to determine the pO2 in a sample of lugworm blood.
A
1) (Measure light) absorption/transmission;
2. Interpolate/draw line to curve/line then to pO2
11
Q
7.1 differences between DNA and Trna molecules
A
1) Deoxyribose v ribose
2) Double stranded v single stranded
3) Many nucleotides v few
4) Thymine base v uracil base
5) Linear v clover leaf (strucutre)
6) Does not bind to amino acid v does bind to amino acid
7) No exposed bases v anticodon
12
Q
1.1 name the type of bond between complementary base pairs
adjacent nucleotide in a dna strand
A
- Hydrogen (bonds);
- Phosphodiester (bonds);
13
Q
1.3 Describe two differences between the structure of a tRNA molecule and the
structure of an mRNA molecule.
A
- tRNA is ‘clover leaf shape’, mRNA is linear;
- tRNA has hydrogen bonds, mRNA does not;
- tRNA has an amino acid binding site, mRNA
does not; - tRNA has anticodon, mRNA has codon;
14
Q
1.4 In a eukaryotic cell, the structure of the mRNA used in translation is different from
the structure of the pre-mRNA produced by transcription.
Describe and explain a difference in the structure of these mRNA molecules.
A
- mRNA fewer nucleotides
Pre-mRNA more nucleotides
mRNA has no introns/has (only) exons
Pre-mRNA has (exons and) introns; - (Because of) splicing;
15
Q
2.2 Describe how HIV is replicated.
A
- Attachment proteins attach to receptors on helper
T cell/lymphocyte; - Nucleic acid/RNA enters cell;
- Reverse transcriptase converts RNA to DNA;
- Viral protein/capsid/enzymes produced;
- Virus (particles) assembled and released (from
cell)
16
Q
4.4 Describe how a gene is a code for the production of a polypeptide. Do not include
information about transcription or translation in your answer.
A
- (Because) base/nucleotide sequence;
- (In) triplet(s);
- (Determines) order/sequence of amino acid
sequence/primary structure (in polypeptide);
17
Q
6.1 Give the pathway a red blood cell takes when travelling in the human circulatory
system from a kidney to the lungs.
A
- Renal vein;
- Vena cava to right atrium;
- Right ventricle to pulmonary artery;
18
Q
6.3 Tissue fluid is formed from blood at the arteriole end of a capillary bed.
Explain how water from tissue fluid is returned to the circulatory system.
A
- (Plasma) proteins remain;
- (Creates) water potential gradient
Reduces water potential (of blood) - Water moves (to blood) by osmosis;
- Returns (to blood) by lymphatic system
19
Q
9.4 Describe the roles of anti-human EPO antibody and anti-mouse antibody with enzyme
attached (lines 14−16) in producing a positive result for EPO in the ELISA test.
Role of anti-human EPO antibody
Role of anti-mouse antibody with enzyme attached
A
- (Anti-human EPO antibody) attaches/binds to
EPO/antigen (in plastic well); - (Anti-mouse antibody) attaches/binds to anti-
human antibody; - Substrate is added, enzyme causes colour
change/product (is positive result)
20
Q
9.5 Some people object to using monoclonal antibodies in testing programmes.
Use information in the passage to suggest why
A
Ethics of/welfare issues with using
mice/goats/animals;
21
Q
3.1 Describe how a phagocyte destroys a pathogen present in the blood.
A
- Engulfs;
- Forming vesicle/phagosome and fuses with
lysosome; - Enzymes digest/hydrolyse;
22
Q
3.2 Give two types of cell, other than pathogens, that can stimulate an immune response.
A
- (Cells from) other organisms/transplants;
- Abnormal/cancer/tumour (cells);
- (Cells) infected by virus;
23
Q
3.4 What is the role of the disulfide bridge in forming the quaternary structure of an
antibody?
A
Joins two (different) polypeptides;
24
Q
4.1 Eukaryotic cells produce and release proteins.
Outline the role of organelles in the production, transport and release of proteins from
eukaryotic cells.
Do not include details of transcription and translation in your answer.
A
- DNA in nucleus is code (for protein);
- Ribosomes/rough endoplasmic reticulum
produce (protein); - Mitochondria produce ATP (for protein
synthesis);
4 Golgi apparatus package/modify;
OR
Carbohydrate added/glycoprotein produced by
Golgi apparatus;
5 Vesicles transport
OR
Rough endoplasmic reticulum transports; - (Vesicles) fuse with cell(-surface) membrane;
25
6.1 Describe how mRNA is produced from an exposed template strand of DNA.
1. (Free RNA) nucleotides form complementary
base pairs;
2. Phosphodiester bonds form;
3. By (action of) RNA polymerase;
26
6.2 Define the term exon.
The sequence of DNA present in mature messenger RNA, some of which encodes the amino acids of a protein
27
2a Use your knowledge of phagocytosis to describe how an ADC enters and kills the tumour cell.
Cell ingests/engulfs the antibody/ADC
Lysosomes fuse with vesicle/phagosome (containing ADC);
Lysozymes breakdown/digest the antibody/ADC to release the drug
28
2b Some of the antigens found on the surface of tumour cells are also found
on the surface of healthy human cells.
Use this information to explain why treatment with an ADC often causes side effects.
ADC will bind to non-tumour/healthy cells
Cause death/damage of non-tumour/healthy cells
29
3a Describe how the human immunodeficiency virus (HIV) is replicated once
inside helper T cells (TH cells).
RNA converted into DNA using reverse transcriptase
DNA incorporated/inserted into (helper T cell) DNA/chromosome/genome/nucleusDNA transcribed into (HIV m)RNA
(HIV mRNA) translated into (new) HIV/viral proteins
30
4a Describe how a phagocyte destroys a pathogen present in the blood
Engulfs
Forming vesicle/phagosome and fuses with lysosome
Enzymes digest/hydrolyse
31
5a Explain how HIV affects the production of antibodies when AIDS develops in a person
1.less/no antibody produced
2. (Because HIV) destroys helper T cells;
Accept ‘reduces number’ for ‘destroys’
3. (So) few/no B cells activated / stimulated
32
In Europe, viruses have infected a large number of frogs of different species. The viruses are closely related and all belong to the Ranavirus group.
Previously, the viruses infected only one species of frog.
6(a) Suggest and explain how the viruses became able to infect other species of frog.
Mutation in the viral DNA/RNA/genome/genetic material
Altered (tertiary structure of the) viral attachment protein
Allows it/attachment protein/virus to bind (to receptors of other species);
33
6c Determining the genome of the viruses could allow scientists to develop a
vaccine.
Explain how.
(The scientists) could identify proteins (that derive from the genetic code
(They) could (then) identify potential antigens (to use in the vaccine
34
6d Describe how the B lymphocytes of a frog would respond to vaccination against Ranavirus.
You can assume that the B lymphocytes of a frog respond in the same way as B lymphocytes of a human.
B cell (antibody) binds to (viral) specific/complementary receptor/antigen
B cell clones
Plasma cells release/produce (monoclonal) antibodies (against the virus
(B/plasma cells produce/develop) memory cells
35
7 What is a monoclonal antibody?
(Antibodies with the) same tertiary structure
OR
identical/cloned plasma cells/B cells/B lymphocytes;
36
b After a disease is diagnosed, monoclonal antibodies are used in some medical treatments.
Give one example of using monoclonal antibodies in a medical treatment
Block antigens/receptors on cells;
37
c Describe the role of antibodies in producing a positive result in an ELISA test.
(First) antibody binds/attaches /complementary (in shape) to antigen;
(Second) antibody with enzyme attached is added;
(Second) antibody attaches to antigen;
(Substrate/solution added) and colour changes;
38
8a Describe and explain the role of antibodies in stimulating phagocytosis.
Bind to antigen
(Antibodies) cause clumping/agglutination
39
9 Explain how the treatment with antivenom works and why it is essential to use passive immunity, rather than active immunity
(Antivenom/Passive immunity) antibodies bind to the toxin/venom/antigen and (causes) its destruction;
Active immunity would be too slow/slower;
40
e During vaccination, each animal is initially injected with a small volume of venom. Two weeks later, it is injected with a larger volume of venom.
Use your knowledge of the humoral immune response to explain this vaccination programme.
B cells specific to the venom reproduce by mitosis;
(B cells produce) plasma cells and memory cells
The second dose produces antibodies (in secondary immune response) in higher concentration and quickly
41
11 Describe how phagocytosis of a virus leads to presentation of its antigens.
1)phagosome/vesciles fuse with lysosome
2)virus destoryed by lysosome
3)peptide/antigen from virys are displayed on the cell membrane
42
b Describe how presentation of a virus antigen leads to the secretion of an antibody against this virus antigen.
1)helper t cell/th cell binds to the antigen
2)this helper t/th cell stimulates a specific b cell
3)b cell does
43
12 What is an antigen?
1)foreign protein
2)that stimulates an immune response/production of antibody
44
12b What is an antibody
1)a protein/immunoglobin specific to an antigen
2)produced by b cells
45
13 In the UK, children are vaccinated against this disease. Describe how vaccination can lead to protection against bacterial meningitis
1.
Antigen / epitope on surface of N. meninigitidis / bacterium binds to surface protein / surface receptor on a (specific / single) B cell.
2. (Activated) B cell divides by mitosis / produces clone;
If answered in context of T cell, allow (Activated) T cell releases cytokine.
3. (Division) stimulated by cytokines / by T cells;
If answered in context of T cell, allow (Cytokine) stimulates production of plasma cells;
4. B cells / plasma cells release antibodies;
5. (Some) B cells become memory cells;
6. Memory cells produce plasma / antibodies faster
46
14 a When a vaccine is given to a person, it leads to the production of antibodies against a disease-causing organism. Describe how.
1.vaccine contains antigen from pathogen
2. Macrophage presents antigen on its surface;
3. T cell with complementary receptor protein binds to antigen;
4. T cell stimulates B cell;
5. (With) complementary antibody on its surface;
6. B cell secretes large amounts of antibody;
7. B cell divides to form clone all secreting / producing same
antibody.
47
14 b Describe the difference between active and passive immunity.
1.active involves memory cells passive does not
2. Active involves production of antibody by plasma cells /
Active involves memory cells, passive does not;
memory cells;
3. Passive involves antibody introduced into body from outside /
named source;
4. Active long term, because antibody produced in response to
antigen;
5. Passive short term, because antibody (given) is broken down;
6. Active (can) take time to develop / work, passive fast acting.
48
3(a) Describe the structure of DNA.
1)polymer of nucleotides
2)each nucleotide fromed from deoxyribose , a phopshate group and an inorgnaic nitorgnous base
3)phosphodiester bonds
4)double helix
5)hydoegn bonds between at and cg
49
4.
(a) Describe how a phosphodiester bond is formed between two nucleotides within a DNA molecule.
1)condesnation reaction
2)between phopshate and deoxyribose
3)catalysed by dna polymerase
50
c Name the protein associated with DNA in a chromosome.
histone
51
d In the process of semi-conservative DNA replication, the two strands within a DNA molecule are separated. Each then acts as a template for the formation of a new complementary strand.
Describe how the separation of strands occurs.
1)dna helicase
2)breaks hydrogen bonds between base pairs
52
5.
(a) Describe the role of DNA polymerase in the semi-conservative replication of DNA.
1)join adjacent dna nuceltodies
2)catalyses condensation reaction
3)Catalyses formation of) phosphodiester bonds (between adjacent nucleotides);
53
6a Name the two scientists who proposed models of the chemical structure of
DNA and of DNA replication
watson and crick
54
(b) Name the enzyme used in this DNA replication.
dna polymerase
55
c
1. the role of the single-stranded DNA fragments
1. Template;
2. Determines order of nucleotides/bases
56
2. the role of the DNA nucleotides
Forms complementary pairs / A – T, G - C
57
b Give two features of DNA and explain how each one is important in the semi-conservative replication of DNA.
Weak / easily broken hydrogen bonds between bases allow two strands to separate / unzip;
Two strands, so both can act as templates;
Complementary base pairing allows accurate replication
58
8a Describe the role of two named enzymes in the process of semi- conservative replication of DNA.
(DNA) helicase causes breaking of hydrogen/H bonds (between DNA strands);
DNA polymerase joins the (DNA) nucleotides
Forming phosphodiester bonds
59
Describe the function of each of these enzymes.
DNA helicase
DNA polymerase
1)DNA helicase – (unwinding DNA and) breaking hydrogen bonds / bonds between chains / bases / strands;
2. DNA polymerase – joins (adjacent) nucleotides OR forms phosphodiester bond / sugar-phosphate backbone;
60
d
Contrast the structures of ATP and a nucleotide found in DNA to give two differences.
1)ATP has ribose and DNA nucleotide has
2
deoxyribose;
2. ATP has 3 phosphate (groups) and DNA
nucleotide has 1 phosphate (group);
3. ATP – base always adenine and in DNA nucleotide base can be different / varies;
61
62
Name the type of bond between complimentary base pairs
Hydrogen binds
63
Name the type of bond between adjacent nucleotides in a dna strand
Phosphodiester bond
64
Describe the srturvutr of dna
Double helix
Deoxyribose sugar
At gc complimentary base pairings
Polymer of nucleotides
Phosphodiester bonds between nucleotides
65
Describe bio a phosphodiester bind is formed between two nucleotides within dna molecules
Condensation reaction
Between phosphate. and sugar
Catalysed by dna polymerase
66
Role of single stranded dna fragment
Template determines order of bases
67
Role of dna nucleotides
Forms complimentary pairs
68
Why arrows in opposite direction in dna replication
Dna has anti parallel strands
Shape of nucleotides are different
Enzymes have active sites in specific shapes
Only substrates with complimentary shapes
69
Why new nucleotides can only be added in a 5’ to 3’ direction
-dna polymerase
Specific
Only complimentary w 5’ ends
Shapes of 5’ and 3’ ends are different
70
Describe two differences between the structure of tRNA and mRNA
tRNA is a c,over shaped mRNA is linear
tRNA gas anticodon and mRNA has codon
71
In a eukaryotic cell, the structure of the mRNA used in translation is different from the structure of the pre-mRNA produced by transcription
Describe and explain a difference in the structure of these mRNA molecules
Ore mRNA has more nucleotides because of splicing
72
Describe how one amino acid is added to a polypeptide that is being
formed at a ribosome during translation.
tRNA brings one specific amino acid
Anticodon on tRNA binds to codon on mRNA
Amino acids join by condensation reactions
73
Describe how mRNA is produced from an exposed template strand of dna
Nucleotides form complimentary base pairs
Phosphodiester bonds form
By rna polymerase
74
Describe how mRNA is formed by transcription in eukaryotes.
Double helix unwind by dna helicase
Free rna joins nucleotides exposed dna bases on template strand
Rna nucleotides compiled,mentally base pairs join
Dn polymerase joins sugar phosphate backbones through condensation reaction creating phosphodiester binds
Rna to mRNA due to slicing where intro s are removed
75
In a eukaryotic cell, the base sequence of the mRNA might be different from the sequence of the pre-mRNA.
Introns
Removal of them by splicing
76
Two types of molecules from which ribosomes is made
Rna and protein
77
(1) (b) Describe the role of a ribosome in the production of a polypeptide. Do not
include transcription in your answer.
mRNA. Ines to ribosomes
2 codons
tRNA with anticodons bind
Peptide binds between 2 amino acids
Moves mRNA along to next codon
78
What is degenerate
More than one codon binds to single amino acids
79
Describe how a polypeptide is formed by translation of mRNA
mRNA attaches to ribosomes
Anticodons binds to come mRNA codons
Brings spec amino acids
Amino acids join by peptide binds
Atp
tRNA released
Ribosomes move along mRNA to form the polypeptide
80
What is the proteome of a cell?
All the proteins that a cell can produce
81
Starting with mRNA in the cytoplasm, describe how translation leads to the production of a polypeptide.
Do not include descriptions of transcription and splicing in your answer.
mRNA binds to ribosomes tRNA brings amino acids
Anticodon binds to codon
Ribosomes moves a,one to next codon
Amino acid joins by peptide binds
82
Describe how mRNA is produced in a plant cell.
H bonds broken spreading strands
Temp,ate strand
Comp base pairing
Pre mRNA formed
Splicing
83
How hiv is replicated
-attachment protein attach to receptors on t helper cells
-nucleui. Acids /rna enters the cell
Reverse transcriptase converts rna to dna
-viral protein produced
-virus assembled and released from the cell
84
Use your knowledge on phagocytosis and describe how an add enters and kiss the tumour cell
Cell engulfs adc
Lysosomes fuse
Lysozymes hydrolysisw and release drug from adc
85
Some of the antigens found on the surface of tumour cells are also found on the surface of healthy human cells
Explain why treatment with an adc often causes side effects
Can bind to healthy human cells causing damage to them
86
Suggest two further investigations that should be done before adc is tested on human breast cancer patients
Test on other mammals
Test diff concs
87
Describe how the human immunodeficiency virus (HIV) is replicated once
inside helper T cells (TH cells).
1)rna converted to dna by reverse transcriptase
2)dna inserted into t helper cell
3)dna trasncribed into rna
4) trasnslated into new hiv
88
Describe how a phagocyte destroys a pathogen present in the blood.
1)pathogen releases chemicals which attract phagocyte towards ur
2)phagocyte engulfs pathogen
3)vesicle fuses a lysosomes
4)ohagolyssomes
5)lysozymes,es catalyse hydrolysis of pathogen
89
Give two types of cell, other than pathogens, that can stimulate an immune
response.
Cancerous cells
Cells from other organisms
90
What is the role of the disulfide bridge in forming the quaternary structure of an antibody?
Joining two polypeptide chains
91
Explain how HIV affects the production of antibodies when AIDS develops in a person.
Fewer antibodies produced
As kills t helper cells
So b cells less differentiated
92
In Europe, viruses have infected a large number of frogs of different species. The viruses are closely related and all belong to the Ranavirus group.
Previously, the viruses infected only one species of frog.
(a) Suggest and explain how the viruses became able to infect other species of frog.
Mutation in viral dna
Altered tertiary structure of viral attachment protein
Allows to bind to other species
93
Determining the genome of the viruses could allow scientists to develop a
vaccine.
Explain how.
Identity the protein that could identify the potential antigen
94
Describe and explain the role of antibodies in stimulating phagocytosis.
Do not include details about the process of phagocytosis.
Agglutination -antibody antigen bind complexes
95
Explain how the treatment with antivenom works and why it is essential to use passive immunity, rather than active immunity.
Active immunity too slow
Antibodies bind to toxin and causes its destruction
96
During vaccination, each animal is initially injected with a small volume of venom. Two weeks later, it is injected with a larger volume of venom.
Use your knowledge of the humoral immune response to explain this vaccination programme.
-b cells specific to venom reproduced by mitosis
-b cells produce plasma and memory cells
-second dose produce antibodies faster and higher conc
97
Describe how phagocytosis of a virus leads to presentation of its antigens.
Phagosome fuses with lysosomes
Lysozymes hydrolyse it
Antigen from virus displayed in cell membrane
98
Describe how presentation of a virus antigen leads to the secretion of an antibody against this virus antigen.
-helper T cells binds to antigen
-stimulates spec b cells
-b cell clones
-forms plasma cells that release antibodies
99
Bacterial meningitis is a potentially fatal disease affecting the membranes around the brain. Neisseria meningitidis (Nm) is a leading cause of bacterial meningitis.
(a) In the UK, children are vaccinated against this disease. Describe how vaccination can lead to protection against bacterial meningitis.
+antigen binds to surface protein on cell
-b cell divides by mitosis
-releases cytokines
-stimulate clonal expansion
-differentiate b cells to plasma cells which secrete antibodies
-b cells memory cells
100
When a vaccine is given to a person, it leads to the production of antibodies against a disease-causing organism. Describe how.
-vaccine contains antigen from pathogen
-macrophage presents antigen on its surface
-T cells complimentary receptor protein binds to antigen
-T cells stimulate b cell
-complimentary antibody in its surface
-b cells secrete large amounts of antibody
-b cells divide to form clone secreting same antibody
101
Describe the difference between active and passive immunity
Active -gain antibodies from self
Long term
Memory cell
No antibody exposure
Passive -gain antibodies elsewhere
Antibody exposure
No memory cells
Short term
102
Give the pathway a red blood cell takes when travelling in the human circulatory system from a kidney to the lungs.
Do not include descriptions of pressure changes in the heart or the role of heart valves in your answer.
Renal vein
Ven cava to right atrium
Right ventricle to pulmonary artery
103
Tissue fluid is formed from blood at the arteriole end of a capillary bed.
Explain how water from tissue fluid is returned to the circulatory system.
Plasma protein remains
Creates water potential gradient
Water moves to blood by osmosis
Returns to blood by lymphatic system
104
Explain how an arteriole can reduce the blood flow into capillaries.
Muscle contracts
Constructs lumen
105
blood vessel carrying blood at the lowest
blood pressure.
Vena cava
106
At P on the diagram above, the pressure in the left ventricle is increasing. At this time, the rate of blood flow has not yet started to increase in the aorta.
Semi lunar valve closed
Bc pressure in sorta is higher than in ventricle
107
At Q on the diagram above there is a small increase in pressure and in rate of blood flow in the aorta.
Explain how this happens and its importance.
Elastic recoil
Maintains blood pressure
108
Describe the advantage of the Bohr effect during intense exercise.
Releases co2 when respiring in tissues
Disassociate of o2 when high po2
109
owever, the graph above shows that the pCO2 in air breathed out did not show a large increase during the exercise.
Suggest one physiological change that would cause this result. Explain how the physiological change would allow for the removal of the increase in the volume of carbon dioxide produced.
Inc in breathing rate
Similar pco2 per breath
110
A heart attack is caused by a lack of glucose and oxygen being delivered to cardiac muscle via the coronary arteries. The overuse of EPO can increase the risk of a heart attack.
Causes blood to thicken
Slows blood flow
111
Describe and explain the effect of increasing carbon dioxide concentration on the dissociation of oxyhaemoglobin.
Decreases Haemoglobin affinity for o2
Increasing acidity and decreasing ph
112
Explain how valve A in Figure 1 maintains a unidirectional flow of blood.
Pressure in left atrium higher than in ventricle causing valves to open
Pressure in left ventricle is higher than if atrium causing valve to close
113
Name the blood vessels that carry blood to the heart muscle.
Coronary arteries
114
(a) Binding of one molecule of oxygen to haemoglobin makes it easier for a second oxygen molecule to bind.
Explain why.
Binding of first oxygen changes tertiary structure
Uncovers another iron
115
Explain the role of the heart in the formation of tissue fluid.
Contraction of ventricles produce high blood pressure
Forces water out of capillaries
116
Lymphoedema is a swelling in the legs which may be caused by a blockage in the lymphatic system.
Suggest how a blockage in the lymphatic system could cause lymphoedema.
Excess tissue fluid cannot be reabsorbed
117
Explain how changes in the shape of haemoglobin result in the S-shaped (sigmoid) oxyhaemoglobin dissociation curve for HbA.
First oxygen binds causing h2 to change shape
Allows more o2 to bind easily
