Question 19N.3.HL.TZ0.9
| Date | November 2019 | Marks available | [Maximum mark: 6] | Reference code | 19N.3.HL.TZ0.9 |
| Level | HL | Paper | 3 | Time zone | TZ0 |
| Command term | Explain, Identify, State | Question number | 9 | Adapted from | N/A |
The figure represents a section of DNA.
Identify the first triplet of nucleotides of each of the three reading frames in the 5’ to 3’ direction.
[1]
«frame 1 =» ATG
«frame 2 =» TGC ✔
«frame 3 =» GCC
All three required.
Order of frames is not relevant.
Do not accept RNA, e.g. AUG.
Open reading frames have start and stop codons. State one other characteristic of open reading frames.
[1]
continuous stretch of codons «between start and stop codon»
OR
can contain introns
OR
sufficient nucleotides to code for a polypeptide chain ✔
Explain how marker genes are used in genetic modification.
[3]
a. «marker genes» are attached to target genes and inserted into bacteria/host cells ✔ OWTTE
b. «marker genes» confirm that the target gene has been successfully integrated into the genome/ plasmid ✔
c. «marker genes» for antibiotic resistance/fluorescence ✔
d. antibiotic is added to the media used to grow the bacteria
OR
UV light is used «to detect fluorescence» ✔
e. genetically modified bacteria will survive
OR
successful transgenic organisms will fluoresce
OR
allow researchers to identify the bacteria that have been modified ✔
State one physical method that could be used to introduce a gene into a plant.
[1]
electroporation
OR
microinjection
OR
biolistics/gene gun/gunshot ✔