IB DP Biology A1.2 Nucleic acids Exam Style Questions HL Paper 1
IB DP Biology A1.2 Nucleic acids Exam Style Questions HL Paper 1
IB DP Biology A1.2 Nucleic acids Exam Style Questions HL Paper 1 at IITian Academy focus on a specific topic or type of questions asked in actual exam. Questions are based on new syllabus for first assessment of 2025.
A1.2 Nucleic acids Topics : RNA & DNA Structure, Antiparallel, Complementarity, Directionality, Nucleosome, Hershey-Chase, Radioisotopes, Chargaff
Question
▶️Answer/Explanation
Question
The image displays a DNA profile generated through gel electrophoresis. What might be present in each band?
A. DNA fragments with the same number of base pairs
B. Several complete DNA molecules of different lengths
C. A complete DNA molecule with a specific charge
D. One DNA strand with a particular base sequence
▶️Answer/Explanation
Ans. A
DNA fragments with the same number of base pairs will appear in the same band on an electrophoresis gel:
Explanation
In gel electrophoresis, DNA fragments move through a gel at different rates depending on their size. Smaller fragments move faster than larger fragments. DNA fragments of the same size move the same distance and form a band. The darkness of the band indicates the amount of DNA in that position.
How to determine the size of DNA fragments
To determine the size of DNA fragments in a sample, compare the location of the bands in the sample to a DNA ladder. The DNA ladder contains fragments of known sizes.
Staining the gel
To see the DNA fragments, the gel is stained with a DNA-binding dye and exposed to ultraviolet light. The dye causes the DNA to glow.
Question
The Human Genome Project completed the sequencing of the human genome in 2003. What could have been a source for the entire human genome?
A. The contents of a red blood cell
B. The nucleus and mitochondria of a skin cell
C. The nucleus and acrosome of a sperm cell
D. The nucleus and ribosomes of any somatic cell
▶️Answer/Explanation
Ans. B
The nucleus and mitochondria of a skin cell has source for the entire human genome.
The Human Genome Project (HGP) sequence was a combination of DNA samples from multiple people:
One person with blended ancestry: The majority of the sequence came from one person, with 70% of the original reference sequence coming from their DNA.
19 other people: The remaining 30% of the sequence came from 19 other people, mostly of European ancestry.
White blood cells from two male and two female donors: Each donor provided a separate DNA library.
The HGP also sequenced the genomes of other organisms, including the bacterium E. coli, yeast, fruit fly, the nematode worm C. elegans, and the mouse.
The HGP used two new DNA sequencing technologies to generate the complete genome sequence:
- PacBio HiFi DNA sequencing method: Can read about 20,000 letters with nearly perfect accuracy
- Oxford Nanopore DNA sequencing method: Can read up to 1 million DNA letters at a time, with modest accuracy
Question
Which are two proteins that assist in the unwinding and separation of DNA strands during replication?
A. Helicase and DNA polymerase III
B. DNA gyrase and DNA polymerase I
C. Helicase and DNA primase
D. Single-strand binding protein and DNA gyrase
▶️Answer/Explanation
Ans:D
Question
Which statement applies to tRNA?
A. There is at least one type of tRNA that combines with each known amino acid.
B. One type of tRNA can combine with all of the known amino acids.
C. tRNA carries out its main role within the nucleus.
D. tRNA is produced by the process of translation.
▶️Answer/Explanation
Ans:A
Question
The graph shows results of an experiment by Hershey and Chase in 1952 in which bacteria were infected with a mixture of virus particles labelled with either \({ }^{32} \mathrm{P}\) or \({ }^{35} \mathrm{~S}\). A suspension of the infected bacteria was agitated with a blender, and samples collected from the suspension were centrifuged to record the percentage of isotope remaining on the outside of the cells.
What do curves X and Y represent?
▶️Answer/Explanation
Ans:B