longer answers PAPER 1 Flashcards
1
Q
how do pregnancy tests work?
A
- the part you wee on has mobile antibodies to HCG with blue beads attached
- the test strip has stationary antibodies as they are stuck onto the strip
- HCG binds to the antibodies on the blue beads
- the urine moves up the stick carrying the hormone and the beads
- the beads and HCG bind to the antibodies on the strip
- the beads get stuck on the strip making it have 2 blue lines
2
Q
how are monoclonal antibodies made?
A
- inject a mouse with the chosen antigen
- B-lymphocytes are taken from the mouse
- B-lymphocyte is fused with a tumour cell to form a hybridoma
- this divides quickly to produce lots of clones that produce monoclonal antibodies
3
Q
what is the lytic pathway?
A
- virus binds to a host cell and injects its genetic material
- virus is replicated using the host cells resources
- to produce more viral genetic material
- produced viral proteins
- new virus assemble
- host cell is lysed
4
Q
what is the lysogenic pathway?
A
- the injected genetic material is incorporated into the DNA of the host cell
- viral genetic material gets replicated along with the host cell
- virus is dormant and no new virus is made
- a trigger causes the virus to leave the genome and enter the lytic pathway
5
Q
describe how an electrical impulse is transmitted between 2 neurones
A
- the electrical impulse travels to the end of the neurone
- this triggers the release of neurotransmitters in vesicles across a synapse
- they bind to the receptor molecule at the post synaptic neurone
- a new electrical impulse is generated
6
Q
describe how a doctor might determine if a baby is growing as expected
A
- measure head circumference every month
- find the percentile on percentile chart for their age
- measurements shouod increase along or around the same percentile
7
Q
describe how changes in DNA sequence can affect the individuals and how the sequencing of a person’s genome could influence medical treatments
A
- DNA has 4 bases
- changes in DNA are mutations which results in different alleles for these genes
- affects the phenotype of a person causing variation
- by sequencing DNA you can identify genetic diseases and the risk of developing them
- by knowing a disease can develop it allows the person to modify their lifestyle to reduce the risk
- HGP determined the location of the genes which lead to a better understanding of diseases
- so people can take preventative medicines and doctors can provide personalised medicines
8
Q
some antibiotics are no longer effective in killing pathogens, using natural selection explain why
A
- there is VARIATION in pathogen population of the trait that is resistant to antibiotics
- causes pathogen to be immune due to RANDOM MUTATIONS
- antibiotics being used is a selective pressure so some die but some survive as they have the RESISTANT allele
- these pathogens reproduce and multiple where they pass on the GENE to their offspring
9
Q
Explain how DNA can be extracted from fruit
A
- mix cold water, a teaspoon of salt, 10ml of detergent in a beaker
- mash fruit with skin off and add it to the solution in the beaker
- the detergent breaks down cell membrane to release DNA
- the salt will make DNA stick together
- add enzyme protease to mixture as protease breaks down proteins in cell membrane
- filter mixture using filter paper and funnel to get big insoluble bits of cell out
- add cold ethanol to the solution as DNA is insoluble in ethanol and wait 10 mins
- DNA will start to appear as a white precipitate that can be fished by a glass rod
10
Q
Describe the stages of protein synthesis
A
- RNA polymerase binds to non-coding DNA located in front of gene
- RNA polymerase produces complementary mRNA strand from coding DNA of the gene
- mRNA attaches to reibosome
- the coding by base triplets (codons) in mRNA for a specific amino acid
- transfer of amino acids to ribosome by tRNA
- amino acids link together to form polypeptides and fold in a specific shape for its function
11
Q
what are the main stages of genetic engineering?
A
- genes from chromosomes are cut out using restriction enzymes
- restriction enzymes are also used to cut the vector (usually bacterial plasmid) into which the genes will be placed
- ligase enzyme is used to attach the sticky ends of the gene and the vector together to produce a GMO
- the vector is placed into another organism in its early stages so the desired gene moves into its cells and causes the organism to grow with the desired characteristics
FOR PLANTS ONLY: vector is put into meristematic cells which can then produce identical copies of the modified plant
12
Q
how is genetic modification used to artificially produce insulin?
A
- remove a plasmid from a bacterial cell
- cut open the plasmid with restriction enzymes
- locate and remove human insulin gene using the same restriction enzymes
-the DNA is combined with the plasmid using ligase enzymes - bacteria are incubated with the new recombinant plasmid
- bacteria will take up the plasmid and start to produce insulin
13
Q
Explain why a bomb calorimeter gives a more accurate value than the normal equipment for burning food
A
- because the system is sealed as it has a life
- there is less heat loss
- and the stirrer distributes the heat evenly
- and all of the food burns
14
Q
describe how to introduce a gene for insect resistance into crop
A
- genes are cut out from Bacillus thuringiensis using restrictive enzymes and are re-inserted into crop using ligase
- the crop will then produce a toxin that kills insects that eat the crop
- so less crop gets eaten by insects
- so crop yield increases and profits
15
Q
how to grow plant tissue culture
A
- remove tissue (explant) from plant
- place tissue on sterile nutrient medium where they grow into an undifferentiated callus
- add plant hormones to the medium. these cause the callus to differentiate into tiny plantlets with roots and shoots
- put plantlets in soil in humid greenhouse
16
Q
how to grow animal tissue culture
A
- remove tissue (explant) from animal
- cut into small pieces
- digest connective tissue with enzymes to separate cells
- grow cells in nutrient medium where they divide
- cells are often stored by freezing in liquid nitrogen
17
Q
how to clone by embryo splitting?
A
- embryo forms naturally by sexual reproduction
- embryo can be split into individual cells which will multiply into individual embryos and can be implanted into surrogate mothers to produce multiple clones
- they will be clones of each other but not genetically identical to their parents
18
Q
what are the advantages of biological control?
A
- the pest cannot become resistant
- if well chosen the control agent is specific to the pest
- avoids using chemical pesticides which can leave harmful residues and kill useful organisms
19
Q
what are the disadvantages of biological control?
A
- biological control doesnt get rid of the pest completely
- the control agent may become a pest itself
20
Q
what are the advantages of fertilisers?
A
- contain nutrients like nitrates and phosphates that help grow the plant well
- increases crop yield providing more food for people
- good way to use animal waste (manure) from farms
21
Q
what are the disadvantages of fertilisers?
A
- excess fertilisers can pollute waterways causing eutrophication
- artificial fertilisers are expensive to make
- artificial fertilisers can reduce soil biodiversity
22
Q
what are the benefits of genetic engineering?
A
- able to mass produce hormones in microorganisms
- improved growth rate so improved yield
- crops with extra vitamins can be produced in areas where they are difficult to obtain
- greater yield can help solve world hunger which is a bigger issue due to population growth
23
Q
what are the disadvantages of genetic engineering?
A
- GM crops are infertile and might spread to wild plants which would causes infertility in other species
- nobody knows the effect of GM crops on human health
- GE in plants could lead to GE in humans so leads to designer babies
- pose a selective pressure which could lead to resistance in other species
24
Q
what are the benefits of selective breeding?
A
- possible to greatly increase yield by selectively breeding only individuals that have higher food mass or higher quality
- individuals can be bred to be resistant to a certain disease which increases crop yield
25
what are the disadvantages of selective breeding?
- lack of genetic variation could wipe out whole population
- selecting advantageous characteristics could lead to severe health problems in offspring
- ethical issues as animal will have lower quality of life is selectively bred for certain characteristics
