1
Q
What are the distinguishing features of eukaryotic cells?
A
● Cytoplasm containing membrane-bound organelles
● So DNA enclosed in a nucleus
2
Q
Describe the general structure of eukaryotic cells
A
Check online for answer
3
Q
Describe the structure of the cell-surface membrane
A
Hydrophilic phosphate heads - attracted to water
Hydrophobic tails - repelled from water
Phospholipid bilayer
4
Q
Describe the function of the cell-surface membrane
A
● Selectively permeable → enables control of passage of substances in / out of cell
● Molecules / receptors / antigens on surface → allow cell recognition / signalling
5
Q
Describe the structure of the nucleus
A
Nuclear envelope
- Double membrane
- Has nuclear pores
Nucleoplasm
Nucleolus
Protein/histone-bound, linear DNA
- Chromatin = condensed
- Chromosome = highly condensed
6
Q
Describe the function of the nucleus
A
● Holds / stores genetic information which codes for polypeptides (proteins)
● Site of DNA replication
● Site of transcription (part of protein synthesis), producing mRNA
● Nucleolus makes ribosomes / rRNA
7
Q
Describe the structure of a ribosome
A
● Made of ribosomal RNA and protein (two subunits)
● Not a membrane-bound organelle
8
Q
Describe the function of a ribosome
A
Site of protein synthesis (translation)
9
Q
Describe the function of rER and sER
A
Rough
● Ribosomes on surface synthesise proteins
● Proteins processed / folded / transported inside rER
● Proteins packaged into vesicles for transport eg. to Golgi apparatus
Smooth
● Synthesises, processes, transports and packages lipids & carbohydrates
● Eg. cholesterol and steroid hormones
10
Q
Describe the function of lysosomes
A
● Release hydrolytic enzymes (eg. lysozymes)
● To break down / hydrolyse pathogens or worn-out cell components
11
Q
Describe the function of Golgi apparatus and Golgi vesicles
A
Golgi apparatus
● Modifies protein, eg. adds carbohydrates to produce glycoproteins
● Modifies lipids, eg. adds carbohydrates to make glycolipids
● Packages proteins / lipids into Golgi vesicles
● Produces lysosomes (a type of Golgi vesicle)
Golgi vesicles
● Transports proteins / lipids to their required destination
● Eg. moves to and fuses with cell-surface membrane
12
Q
Describe the structure of mitochondria
A
Outer membrane
Cristae - inner membrane fold
Matrix - small 70s ribosomes and circular DNA
13
Q
Describe the function of mitochondria
A
● Site of aerobic respiration
● To produce ATP for energy release (from respiratory substrates)
● Eg. for protein synthesis / vesicle movement / active transport
14
Q
Describe the structure of chloroplasts in plants and algae
A
Double membrane
Stroma containing:
- Thylakoid membrane
- 70s ribosomes
- Circular DNA
- Starch granules + lipid droplets
Lamella
Grana
15
Q
Describe the function of chloroplasts in plants and algae
A
● Pigments eg. chlorophyll absorb light energy for photosynthesis
● To produce organic substances eg. carbohydrates / lipids
16
Q
Describe the structure of the cell wall in plants, algae and fungi
A
● Composed mainly of cellulose (a polysaccharide) in plants / algae
● Composed of chitin (a nitrogen-containing polysaccharide) in fungi
17
Q
Describe the function of the cell wall in plants, algae and fungi
A
● Provides mechanical strength to cell
● So prevents cell changing shape or bursting under pressure due to osmosis
18
Q
Describe the function of the cell vacuole in plants
A
● Maintains turgor pressure in cell (stopping plant wilting)
● Contains cell sap → stores sugars, amino acids, pigments and any waste chemicals
19
Q
Describe how eukaryotic cells are organised in complex multicellular
organisms
A
Tissue
Group of specialised cells with a similar structure working together to perform a specific function, often with the same origin
Organ
Aggregations of tissues performing specific functions
Organ system
Group of organs working together to perform specific functions
20
Q
What are the distinguishing features of prokaryotic cells?
A
● Cytoplasm lacking membrane-bound organelles
● So genetic material not enclosed in a nucleus
21
Q
Compare and contrast the structure of eukaryotic and prokaryotic cells
A
Eukaryotic
- Has membrane-bound organelles eg. mitochondria, endoplasmic reticulum
- Has a nucleus containing DNA
- DNA is long & linear
& associated with histone proteins
- Larger (80S) ribosomes (in cytoplasm)
- Cell wall only in plants, algae and fungi containing cellulose or chitin
-Plasmids / capsule never present (sometimes flagella)
- Larger overall size
Prokaryotic
- No membrane-bound organelles
- No nucleus, DNA free in cytoplasm
- DNA is short and circular and not associated with proteins
- Smaller 70s ribosomes
- Cell wall in all of them containing murein
- Plasmids, flagella and a capsule sometimes present
- Much smaller
22
Q
Explain why viruses are described as acellular and non-living
A
● Acellular - not made of cells, no cell membrane / cytoplasm / organelles
● Non-living - have no metabolism, cannot independently move / respire / replicate / excrete
23
Q
Describe the general structure of a virus particle
A
- Nucleic acid (DNA or RNA) enclosed by a
protective capsid (protein coat) - Attachment proteins allow attachment /
binding to receptors on specific host cells - No cytoplasm, ribosomes, cell wall,
cell-surface membrane etc. - Some viruses also surrounded by a lipid
envelope, eg. HIV
24
Q
Describe the difference between magnification and resolution
A
● Magnification = number of times greater image is than size of the real (actual) object
○ Magnification = size of image / size of real object
● Resolution = minimum distance apart 2 objects can be to be distinguished as separate objects
(level of detail)
25
Compare the principles and limitations of optical microscopes, transmission electron microscopes and scanning electron microscopes
In the order optical 1), TEM 2) and SEM 3)
1) Light focused using glass lenses
2) Electrons focused using
electromagnets
3)Electrons focused using
electromagnets
1) Light passes through specimen, different structures absorb
different amounts & wavelengths
2) Electrons pass through specimen, denser parts absorb more and appear darker
3) Electrons deflected / bounce off specimen surface
1) Generates a 2D image of a cross-section
2) Generates a 2D image of a cross-section
3) Generates a 3D image
of surface
1) Low resolution due to long wavelength of light
2) Very high resolution due to short wavelength of electrons
3) High resolution due to short wavelength of electrons
1) Can’t see internal structure of organelles or ribosomes
2) Can see internal structures of organelles and ribosomes
3) Can’t see internal structures
1) Specimen = thin
2) Specimen = very thin
3) Specimen does not need to be thin
1) Low magnification (x 1500)
2) High magnification (x 1,000,000)
3) High magnification (x 1,000,000)
1) Can view living organisms 2) Can only view dead / dehydrated specimens as uses a vacuum
3) Can only view dead / dehydrated specimens as uses a vacuum
1) Simple preparation
2) Complex preparation so
artefacts often present
3) Complex preparation so
artefacts often present
1) Can show colour
2) Does not show colour
3) Does not show colour
26
Describe how to convert between different units
m
mm
um
nm
going down each x1000, going up divide by 1000
27
Describe how the size of an object viewed with an optical microscope can be measured
1. Line up (scale of) eyepiece graticule with (scale of) stage micrometre
2. Calibrate eyepiece graticule - use stage micrometre to calculate size of divisions on eyepiece graticule
3. Take micrometre away and use graticule to measure how many divisions make up the object
4. Calculate size of object by multiplying number of divisions by size of division
5. Recalibrate eyepiece graticule at different magnifications
28
Describe and explain the principles of cell fractionation and ultracentrifugation as used to separate cell components
1. Homogenise tissue / use a blender
● Disrupts the cell membrane, breaking open cells to release contents / organelles
2. Place in a cold, isotonic, buffered solution
● Cold to reduce enzyme activity
○ So organelles not broken down / damaged
● Isotonic so water doesn’t move in or out of organelles by osmosis
○ So they don’t burst
● Buffered to keep pH constant
○ So enzymes don’t denature
3. Filter homogenate
● Remove large, unwanted debris eg. whole cells, connective tissue
4. Ultracentrifugation - separates organelles in order of density / mass
● Centrifuge homogenate in a tube at a low speed
● Remove pellet of heaviest organelle and respin supernatant at a higher speed
● Repeat at increasing speeds until separated out, each time the pellet is made of lighter organelles (nuclei → chloroplasts / mitochondria → lysosomes → ER → ribosomes)
29
Summarise the stages of the cell cycle in eukaryotic cells (simple)
Stage 1- Interphase
● DNA replicates semi-conservatively (S phase)
○ Leading to 2 chromatids (identical copies) joined at a centromere
● Number of organelles & volume of cytoplasm increases, protein synthesis (G1 / G2)
Stage 2 - Mitosis
● Nucleus divides
● To produce 2 nuclei with identical copies of DNA produced by parent cell
Stage 3 - Cytokinesis
● Cytoplasm and cell membrane (normally) divide
● To form 2 new genetically identical daughter cells
30
Describe in detail the process of mitosis
Stage 1 - Prophase
● Chromosomes condense, becoming shorter / thicker so visible
○ Appear as 2 sister chromatids joined by a centromere
● Nuclear envelope breaks down
● Centrioles move to opposite poles forming spindle network
● Spindle fibres start to attach to chromosomes by their centromeres
Stage 2 - Metaphase
● Spindle fibres attach to chromosomes by their centromeres
● Chromosomes align along equator
Stage 3 - Anaphase
● Spindle fibres shorten / contract
● Centromere divides
● Pulling chromatids (from each pair) to opposite poles of cell
Stage 4 - Telophase
● Chromosomes uncoil, becoming longer / thinner
● Nuclear envelopes reform = 2 nuclei
● Spindle fibres / centrioles break down
31
Why do some eukaryotic cells not undergo the cell cycle?
● Within multicellular organisms, not all cells retain the ability to divide (eg. neurons)
● Only cells that do retain this ability go through a cell cycle
32
Explain the importance of mitosis in the life of an organism
Parent cell divides to produce 2 genetically identical daughter cells for:
● Growth of multicellular organisms by increasing cell number
● Replacing cells to repair damaged tissues
● Asexual reproduction
33
Describe how tumours and cancers form
Mitosis is a controlled process so:
● Mutations in DNA / genes controlling mitosis can lead to uncontrolled cell division
● Tumour formed if this results in mass of abnormal cells
○ Malignant tumour = cancerous, can spread (metastasis)
○ Benign tumour = non-cancerous
34
Suggest how cancer treatments control rate of cell division
● Some disrupt spindle fibre activity / formation
○ So chromosomes can’t attach to spindle by their centromere
○ So chromatids can’t be separated to opposite poles (no anaphase)
○ So prevents / slows mitosis
● Some prevent DNA replication during interphase
○ So can’t make 2 copies of each chromosome (chromatids)
○ So prevents / slows mitosis
35
Describe how prokaryotic cells replicate
Binary fission:
1. Replication of circular DNA
2. Replication of plasmids
3. Division of cytoplasm to produce 2 daughter cells
○ Single copy of circular DNA
○ Variable number of copies of plasmids
36
Describe how viruses replicate
Being non-living, viruses do not undergo cell division.
1. Attachment proteins attach to complementary receptors on host cell
2. Inject viral nucleic acid (DNA/RNA) into host cell
3. Infected host cell replicates virus particles:
a. Nucleic acid replicated
b. Cell produces viral protein / capsid / enzymes
c. Virus assembled then released
37
Describe the fluid-mosaic model of membrane structure
● Molecules free to move laterally in phospholipid bilayer
● Many components - phospholipids, proteins, glycoproteins and glycolipids
38
Describe the arrangement of the components of a cell membrane
● Phospholipids form a bilayer - fatty acid tails face inwards, phosphate heads face outwards
● Proteins
○ Intrinsic / integral proteins span bilayer eg. channel and carrier proteins
○ Extrinsic / peripheral proteins on surface of membrane
● Glycolipids (lipids with polysaccharide chains attached) found on exterior surface
● Glycoproteins (proteins with polysaccharide chains attached) found on exterior surface
● Cholesterol (sometimes present) bonds to phospholipid hydrophobic fatty acid tails
39
Explain the arrangement of phospholipids in a cell membrane
● Bilayer, with water present on either side
● Hydrophobic fatty acid tails repelled from water so point away from water / to interior
● Hydrophilic phosphate heads attracted to water so point to water
40
Explain the role of cholesterol (sometimes present) in cell membranes
● Restricts movement of other molecules making up membrane
● So decreases fluidity (and permeability) / increases rigidity
41
Suggest how cell membranes are adapted for other functions
● Phospholipid bilayer is fluid → membrane can bend for vesicle formation / phagocytosis
● Glycoproteins / glycolipids act as receptors / antigens → involved in cell signalling / recognition
42
Describe how movement across membranes occurs by simple diffusion
● Lipid-soluble (non-polar) or very small substances eg. O2, steroid hormones
● Move from an area of higher concentration to an area of lower conc., down a conc. gradient
● Across phospholipid bilayer
● Passive - doesn’t require energy from ATP / respiration (only kinetic energy of substances)
43
Explain the limitations imposed by the nature of the phospholipid bilayer
● Restricts movement of water soluble (polar) & larger substances eg. Na+ / glucose
● Due to hydrophobic fatty acid tails in interior of bilayer
44
Describe how movement across membranes occurs by facilitated diffusion
● Water-soluble / polar / charged (or slightly larger) substances eg. glucose, amino acids
● Move down a concentration gradient
● Through specific channel / carrier proteins
● Passive - doesn’t require energy from ATP / respiration (only kinetic energy of substances)
45
Explain the role of carrier and channel proteins in facilitated diffusion
● Shape / charge of protein determines which substances move
● Channel proteins facilitate diffusion of water-soluble substances
○ Hydrophilic pore filled with water
○ May be gated - can open / close
● Carrier proteins facilitate diffusion of (slightly larger) substances
○ Complementary substance attaches to binding site
○ Protein changes shape to transport substance
46
Describe how movement across membranes occurs by osmosis
● Water diffuses / moves
● From an area of high to low water potential (ψ) / down a water potential gradient
● Through a partially permeable membrane (phospholipid bilayer)
● Passive - doesn’t require energy from ATP / respiration (only kinetic energy of substances)
47
Describe how movement across membranes occurs by active transport
● Substances move from area of lower to higher concentration / against a concentration gradient
● Requiring hydrolysis of ATP and specific carrier proteins
48
Describe the role of carrier proteins and the importance of the hydrolysis of ATP in active transport
1. Complementary substance binds to specific carrier protein
2. ATP binds, hydrolysed into ADP + Pi, releasing energy
3. Carrier protein changes shape, releasing substance on side of higher concentration
4. Pi released → protein returns to original shape
49
Describe how movement across membranes occurs by co-transport
● Two different substances bind to and move simultaneously via a co-transporter protein (type of carrier protein)
● Movement of one substance against its concentration gradient is often coupled with the movement of another down its concentration gradient
50
Describe an example that illustrates co-transport
Absorption of sodium ions and glucose (or amino acids) by cells lining the mammalian ileum:
1 ● Na+ actively transported from epithelial cells lining ileum to blood (by Na+ /K+ pump)
● Establishing a concentration
gradient of Na+
(higher in lumen than epithelial cell)
2 ● Na+ enters epithelial cell down its concentration gradient with glucose against its concentration gradient
● Via a co-transporter protein
3 ● Glucose moves down a concentration gradient into blood via facilitated diffusion
51
Describe how surface area, number of channel or carrier proteins and differences in gradients of concentration or water potential affect the rate of movement across cell membranes
● Increasing surface area of membrane increases rate of movement
● Increasing number of channel / carrier proteins increases rate of facilitated diffusion / active transport
● Increasing concentration gradient increases rate of simple diffusion
● Increasing concentration gradient increases rate of facilitated diffusion
○ Until number of channel / carrier proteins becomes a limiting factor as all in use / saturated
● Increasing water potential gradient increases rate of osmosis
52
Explain the adaptations of some specialised cells in relation to the rate of transport across their internal and external membranes
● Cell membrane folded eg. microvilli in ileum → increase in surface area
● More protein channels / carriers → for facilitated diffusion (or active transport - carrier proteins only)
● Large number of mitochondria → make more ATP by aerobic respiration for active transport
53
What is an antigen?
● Foreign molecule / protein / glycoprotein / glycolipid
● That stimulates an immune response leading to production of antibody
54
How are cells identified by the immune system?
● Each type of cell has specific molecules on its surface (cell-surface membrane / cell wall) that identify it
● Often proteins → have a specific tertiary structure (or glycoproteins / glycolipids)
55
What types of cells and molecules can the immune system identify?
1. Pathogens (disease causing microorganisms) eg. viruses, fungi, bacteria
2. Cells from other organisms of the same species (eg. organ transplants)
3. Abnormal body cells eg. tumour cells or virus-infected cells
4. Toxins (poisons) released by some bacteria
56
Describe phagocytosis of pathogens (non-specific immune response)
1) Phagocyte attracted by chemicals / recognises (foreign) antigens on pathogen
2) Phagocyte engulfs pathogen by surrounding it with its cell membrane
3) Pathogen contained in vesicle / phagosome in cytoplasm of phagocyte
4) Lysosome fuses with phagosome and releases lysozymes (hydrolytic enzymes)
5) Lysozymes hydrolyse / digest pathogen
Phagocytosis leads to presentation of antigens where antigens are displayed on the phagocyte cell-surface membrane, stimulating the specific immune response (cellular and humoral response).
57
Describe the response of T lymphocytes to a foreign antigen (the cellular response)
T lymphocytes recognise (antigens on surface of) antigen presenting cells eg. infected cells, phagocytes presenting antigens, transplanted cells, tumour cells etc.
Specific helper T cells with complementary receptors (on cell surface) bind to antigen on antigen-presenting cell → activated and divides by mitosis to form clones which stimulate:
● Cytotoxic T cells → kill infected cells / tumour cells (by producing perforin)
● Specific B cells (humoral response - see below)
● Phagocytes → engulf pathogens by phagocytosis
58
Describe the response of B lymphocytes to a foreign antigen (the humoral response)
B lymphocytes can recognise free antigens eg. in blood or tissues, not just antigen presenting cells.
1. Clonal selection:
○ Specific B lymphocyte with complementary receptor (antibody on cell surface) binds to antigen
○ This is then stimulated by helper T cells (which releases cytokines)
○ So divides (rapidly) by mitosis to form clones
2. Some differentiate into B plasma cells → secrete large amounts of (monoclonal) antibody
3. Some differentiate into B memory cells → remain in blood for secondary immune response
59
What are antibodies?
● Quaternary structure proteins (4 polypeptide chains)
● Secreted by B lymphocytes eg. plasma cells in response to specific antigens
● Bind specifically to antigens forming antigen-antibody complexes
60
Describe the structure of an antibody
Diagram must show:
Antigen
Antigen binding site
Variable region
Constant region
Disulfide bridges
Light and heavy polypeptide chain
61
Explain how antibodies lead to the destruction of pathogens
● Antibodies bind to antigens on pathogens forming an antigen-antibody complex
○ Specific tertiary structure so binding site / variable region binds to complementary antigen
● Each antibody binds to 2 pathogens at a time causing agglutination (clumping) of pathogens
● Antibodies attract phagocytes
● Phagocytes bind to the antibodies and phagocytose many pathogens at once
62
Explain the differences between the primary & secondary immune response
● Primary - first exposure to antigen
○ Antibodies produced slowly & at a lower conc.
○ Takes time for specific B plasma cells to be stimulated to produce specific antibodies
○ Memory cells produced
● Secondary - second exposure to antigen
○ Antibodies produced faster & at a higher conc.
○ B memory cells rapidly undergo mitosis to produce many plasma cells which produce specific antibodies
63
What is a vaccine?
● Introduction (eg. injection) of antigens → could be from attenuated (dead / weakened) pathogens
● Stimulating formation of memory cells
64
Explain how vaccines provide protection to individuals against disease
1. Specific B lymphocyte with complementary receptor binds to antigen
2. Specific T helper cell binds to antigen-presenting cell and stimulates B cell
3. B lymphocyte divides by mitosis to form clones
4. Some differentiate into B plasma cells which release antibodies
5. Some differentiate into B memory cells
6. On secondary exposure to antigen, B memory cells rapidly divide by mitosis to produce B plasma cells
7. These release antibodies faster and at a higher concentration
65
Explain how vaccines provide protections for populations against disease
● Herd immunity - large proportion of population vaccinated, reducing spread of pathogen
○ Large proportion of population immune so do not become ill from infection
○ Fewer infected people to pass pathogen on / unvaccinated people less likely to come in contact with someone with disease
66
Describe the differences between active and passive immunity
Active immunity
● Initial exposure to antigen eg. vaccine or primary infection
●Memory cells involved
●Antibody produced and secreted by B plasma cells
●Slow; takes longer to develop
●Long term immunity as antibody can be produced in response to a specific antigen again
Passive immunity
●No exposure to antigen
●No memory cells involved
●Antibody introduced from another organism eg. breast milk / across placenta from mother
●Faster acting
●Short term immunity as antibody hydrolysed (endo/exo/dipeptidases)
67
Explain the effect of antigen variability on disease and disease prevention
● Antigens on pathogens change shape / tertiary structure due to gene mutations (creating new strains)
● So no longer immune (from vaccine or prior infection)
○ B memory cell receptors cannot bind to / recognise changed antigen on secondary exposure
○ Specific antibodies not complementary / cannot bind to changed antigen
68
Describe the structure of a HIV particle
Diagram should include:
Lipid envelope
RNA
Reverse transcriptase
Capsid
Attachment protein
69
Describe the replication of HIV in helper T cells
1. HIV attachment proteins attach / bind to receptors on helper T cell
2. Lipid envelope fuses with cell-surface membrane, releasing capsid into cell
3. Capsid uncoats, releasing RNA and reverse transcriptase
4. Reverse transcriptase converts viral RNA to DNA
5. Viral DNA inserted / incorporated into helper T cell DNA (may remain latent)
6. Viral protein / capsid / enzymes are produced
a. DNA transcribed into HIV mRNA
b. HIV mRNA translated into new HIV proteins
7. Virus particles assembled and released from cell (via budding)
70
Explain how HIV causes the symptoms of acquired immune deficiency syndrome (AIDS)
● HIV infects and kills helper T cells (host cell) as it multiplies rapidly
○ So T helper cells can’t stimulate cytotoxic T cells, B cells and phagocytes
○ So B plasma cells can’t release as many antibodies for agglutination & destruction of pathogens
● Immune system deteriorates → more susceptible to (opportunistic) infections
● Pathogens reproduce, release toxins and damage cells
71
Explain why antibiotics are ineffective against viruses
● Viruses do not have metabolic processes (eg. do not make protein) / ribosomes
● Viruses do not have bacterial enzymes / murein cell wall
72
What is a monoclonal antibody?
● Antibody produced from genetically identical / cloned B lymphocytes / plasma cells
● So have same tertiary structure
73
Explain how monoclonal antibodies can be used in medical treatments
● Monoclonal antibody has a specific tertiary structure / binding site / variable region
● Complementary to receptor / protein / antigen found only on a specific cell type (eg. cancer cell)
● Therapeutic drug attached to antibody
● Antibody binds to specific cell, forming antigen-antibody complex, delivering drug
74
Explain how monoclonal antibodies can be used in medical diagnosis
● Monoclonal antibody has a specific tertiary structure / binding site / variable region
● Complementary to specific receptor / protein / antigen associated with diagnosis
● Dye / stain / fluorescent marker attached to antibody
● Antibody binds to receptor / protein / antigen, forming antigen-antibody complex
75
Explain the use of antibodies in the ELISA (enzyme-linked immunosorbent assay) test to detect antigens
Example method 1 (direct ELISA):
1. Attach sample with potential antigens to well
2. Add complementary monoclonal antibodies with enzymes attached → bind to antigens if present
3. Wash well → remove unbound antibodies (to prevent false positive)
4. Add substrate → enzymes create products that cause a colour change (positive result)
Example method 2 (sandwich ELISA):
1. Attach specific monoclonal antibodies to well
2. Add sample with potential antigens, then wash well
3. Add complementary monoclonal antibodies with enzymes attached → bind to antigens if present
4. Wash well → remove unbound antibodies (to prevent false positive)
5. Add substrate → enzymes create products that cause a colour change (positive result)
76
Explain the use of antibodies in the ELISA test to detect antibodies
Example method (indirect ELISA):
1. Attach specific antigens to well
2. Add sample with potential antibodies, wash well
3. Add complementary monoclonal antibodies with enzymes attached → bind to antibodies if present
4. Wash well → remove unbound antibodies
5. Add substrate → enzymes create products that cause a colour change (positive result)
77
Suggest the purpose of a control well in the ELISA test
● Compare to test to show only enzyme causes colour change
● Compare to test to show all unbound antibodies have been washed away
78
Suggest why failure to thoroughly wash the well can result in a false positive in the ELISA test
● Antibody with enzyme remains / not washed out
● So substrate converted into colour product
79
Suggest some general ethical issues associated with the use of vaccines and monoclonal antibodies
● Pre-clinical testing on / use of animals → potential stress / harm / mistreatment
○ But animals not killed & helps produce new drugs to reduce human suffering
● Clinical trials on humans → potential harm / side-effects
● Vaccines → may continue high risk activities and still develop / pass on pathogen
● Use of drug → potentially dangerous side effects
80
Suggest some points to consider when evaluating methodology relating to the use of vaccines and monoclonal antibodies
● Was the sample size large enough to be representative?
● Were participants diverse in terms of age, sex, ethnicity and health status?
● Were placebo / control groups used for comparison?
● Was the duration of the study long enough to show long-term effects?
● Was the trial double-blind (neither doctor / patient knew who was given drug or placebo) to reduce bias?
81
Suggest some points to consider when evaluating evidence and data relating to the use of vaccines and monoclonal antibodies
● What side effects were observed, and how frequently did they occur?
● Was a statistical test used to see if there was a significant difference between start & final results?
● Was the standard deviation of final results large, showing some people did not benefit?
● Did standard deviations of start & final results overlap, showing there may not be a significant difference?
● What dosage was optimum? Does increasing dose increase effectiveness enough to justify extra cost?
● Was the cost of production & distribution low enough?
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