Karteikarten
AS Cells Pt.2
Karten in diesem Stapel (54)
- 1Give 4 reasons why some vaccines don't eliminate a disease.- They fail to induce immunity.
- Individuals develop the disease just afte getting the vaccines, before immunity levels in their body are high enough.
- Antigenic variability of a pathogen makes it impossible to develop a vaccine.
- The pathogen 'hides' from the immune system eg) inside cells or in places out of reach eg) the instestines. - 2What does HIV stand for?Human immundeficiency disease.
- 3Label the 6 parts of a HIV virus.
- 4What does the HIV virus attack and what does this cause?Helper T cells, this means that the stumulation of B cells' divison doesn't happen.
- 5Even if the virus lays dormant what is the person still classed as?HIV positive.
- 6What is caused when replication takes place?AIDS (Acquired immunodefiency syndrome.)
- 7Give the 10 stages of HIV replication.1) Once infected the virus circulates in the blood stream.
2) A protein on the HIV virus attaches onto a CD4 protein.
3) Prtoein capsid fuses with the T cell membrane.
4) RNA & reverse transcriptase enter the t cell.
5) HIV reverse transriptase converts the virus' RNA to DNA.
6) Newly made DNA is mived to the helper t cell's nucleus where it's insterted into cell's DNA.
7) HIV DNA in nucleus creates mRNA using the cell's enzymes. This mRNA contains instructions for making new viral proteins.
8) mRNA passes out of the nucelus throuhg the nucelar pore and uses the cell's protein synthesis mechanisms to make HIV particles.
9) HIV particles break away from helper T cell with a piece of it's cell surface membrane surrounding them, which forms the lipid envelope. - 8Describe passive immunity and give an example.Produced by the introduction of antibodies from an outside source. No contact with contact with the pathogen or antigen is required and antibodies aren't produced by individuals themsleves so aren't replaced whne they break down, no memory cells are formed and so there's no lasting immunity.
Eg) Anti-venom given to snake bite victims. - 9Describe active immunity.Produced by stimulating the production of antibodies by individuals' own immune system. Direct contact with pathogen/antigen is required. Immunity takes time to develop and is geneally long lasting.
- 10Define natural and artifical active immunity.Natural - Individual becomign infected with disease under normal circumstances.
Artifical - The basis of vaccination. - 11Give 4 features of a successful vaccination process.- Economically available in large quantities.
- Few side effects.
- Means of producing, transporting and storing them must be available.
- Must be possible to vaccinate majority of population to achieve herd immunity. - 12Why are babies and infants sometimes not vaccinated?Because their immune sysem is not yet fully functional.
- 13What is best to achieve herd immunity and why?Giving the vaccine to everyone in a short period of time so that for a short period of time v few people have the disease and so transmission is interuptted.
- 14Give points on ethics with vaccines. (3)- Production and development of vaccines involves animals.
- Vaccines can have side effects which can have long-lasting effect.
- Concerns with testing vaccines on people as there's unknown health risks. - 15How does HIV kill?Indirectly. It infects the immune system and so it can't function normally, making those that are infected susceptible to other diseases which could be fatal.
- 16Give 2 reasons why antibiotics aren't effective against viruses like AIDS.- Viruses rely on host cells to carry out metabolic activities and therefore lack their own metabolic pathways and cell structure. Antibiotics therefore have no metabolic mechanisms or structures to disrupt.
- Viruses have a protein coat rather than a murein cell wall and so don't have a site for antibiotics to work. - 17Give the 5 features of a bacteria cell and their function.Cell Wall - Physical barrier that excludes certain substances and protects against mechanical damage and osmotic lysis.
Capsule - Protects bacterium from other cells and helps groups of bacteria to stick together for future protection.
Cell-Surface Membrane - Acts as a differentially permeable layer which controls the entry and exit of chemicals.
Circular DNA - Posses genetic material for the replication of the cells.
Plasmid - Possesses genes that may aid the survival of bacterium in adverse conditions eg) produces enzymes that break down antibiotics. - 18People with AIDS die because they're unable to produce an immune response to pathogens. Explain why this leads to death (3).- Susceptible to other diseases.
- Pathogens would replicate.
- Pathogens damage other cells and/or produce toxins. - 19Suggest why some pathogens may be considered unsafe (3).Pathogen used could become active.
Vaccinate people may develop other strain of disease.
Attenuated virus may actually become harmful. - 20Describe how you calculate the magnification of an image when given a scale bar.Divide real length of the bar by the measurement given at the bar.
- 21Suggest how the hinge region is important in allowing an antibody to bind to more than one antigen. (2)- 2 sites = 2 antigens can bind.
- The 2 antigens can be different distances from the antibody. - 22Give the order in which the following would be separated in a centrifuge. Cell walls, chloroplasts, mitochondria, nuclei and ribosomes.1. Cell Walls
2. Nuclei
3. Chloroplasts
4. Mitochondria
5. Ribosomes - 23What must you always include when defining a vaccination?That they're an injection of the weakened pathogen which stimulates the formation of antibodies.
- 24What do chloroplast use light to produce?Energy
- 25What does respiration need? What does this produce? What is this used for?O2
To produce ATP.
- Used in active transport. - 26When talking about osmosis in plant cells, why might there be a point where the cell no longer changes size?Because of the cell wall which is very strong and so prevents the osmotic effect.
- 27When investigating the stages of mitosis in a plant using a light microscope, explain why: a) a root tip was used. b) A stain was used. c) The root tip was firmly squished.a) Because it was carrying out mitosis.
b) So that the chromosomes will be visible.
c) To produce a thin layer so that the light can penetrate through. - 28Why might the results of this experiment be different on another occasion with a different garlic root tip? (2)- Different time of day.
- A different species mean there's a genetic difference. - 29When aren't chromosomes visible and why?In interphase and so they're in a diffused form and can't be seen as individual chromosomes.
- 30What is the role of extrinsic proteins? This is the answer you must always give.Cell recognition.
- 31For the beetroot permeability experiment: a) Give a suitable control. b) Why would this control be necessary? c) Why would you shake the test tubes every minute? d) Why were you instructed to pour the alcohol immediately from the test tube into a clean one? e) How would a decrease in temperature have affected these results? f) Despite working accurately, why might two students get different results?a) The number of beetroot disks in the alcohol.
b) To ensure it was only the concentration of alcohol that's affecting the leakage of pigment.
c) To ensure all the surface of the beetroot discs are in contact with the alcohol.
d) To ensure all the discs were in contact with the alcohol for the same amount of time.
e) Rate of diffusion would be lower as the molecules don't have as much kinetic energy.
f) They may have used different varieties of beetroot. - 32When talking about membranes and diffusion etc. what are very key things to mention?- Rate of diffusion.
- Permeability of the membrane.
- Whether the membrane has been disturbed and therefore damaged. - 33What should you do if you believe there's an anomaly?Repeat the experiment and then compare the results.
- 34At which point are substances considered to be inside the body?When they're absorbed into the blood.
- 35Give two ways in which fatty acids are important in the formation of cells.1) Used by cells in respiration which releases energy. More FA=more energy.
2) FA are sued to make phospholipids which are used in cell phospholipid bilayer membranes. More phospholipids=more membranes. - 36Give an advantage of presenting data as a percentage.It allows for an easier comparison.
- 37Give two possible limitations a conclusion can have.- Unrepresentative as there's no repeat.
- No control group. - 38What effect can alcohol have on a membrane? (2)Dissolves phospholipids and causes carrier and channel proteins to denature.
- 39Give 3 reasons why two of these different beetroot experiments may have produced different results?- Colorimeter may not have been calibrated properly.
- Beetroot may have been damaged when cutting.
- Test 1 and 2 may have used discs from different parts of the beetroot. - 40What effect would temperature have on the cell membrane?Increasing it would cause the channel and carrier proteins to denature and cause the phospholipids to dissolve.
- 41Suggest appropriate units the student should use to compare the distribution of stomata on leaves.Stomata per cm^3.
- 42Other than ensuring light can pass through, why else should specimen samples be very thin?So that there's only a single layer of cells and so no imposition.
- 43For 4 marks explain why a mutation results in a non-functioning protein.- Change to DNA base.
- Changes amino acid sequence.
- Changes tertiary structure due to change in position of bonds.
- This change in shape makes it non-specific etc., talk about complementary if it's an enzyme. - 44If a HIV can't attach to a T cell what 2 things can't it do?- Replicate
- Destroy the T cells. - 45How can you ensure that solution contain no oxygen?Put a layer of oil on top of the solution so that no oxygen is absorbed.
- 46Why may a pathogen rapidly entering a host cell mean that a vaccine is no longer effective? (2)Enters host cell before memory cells can respond.
Therefore no antibodies are produced to destroy cells. - 47Label the parts of a bacteria cell. (5)
- 48Does a TEM have a high or low resolution?High
- 49Give the order of units of measurement starting from cm to nm, what do you do to move down the chain each time?Cm
mm
Micrometers
nm
x 1000 - 50How do you work out which mitochondria has the least folds?The minotchondira with the fewest folds will have the lowst ratio of outer in inner membrane.
- 51List the ways in which substances can be transported. (4)- Active transport.
- Facilitated diffusion.
- Passive diffusion.
- Osmosis - 52Why must the antibodies in the ELISA test be monoclonal antibodies?Because the only bind to specific antigens.
- 53Why may levels of the HIV particles remain low for a certain period of time?Because it may lay dormant.
- 54—
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