Question bank
Practice IB Biology D1 1 Dna Replication questions by syllabus topic with past-paper context, marks, difficulty and question previews on Eduninja.
Question 1
Organisms often release chemicals when attacked as part of their defence system. Scientists studied lima bean plants (Phaseolus lunatus) infested with either an armyworm, Spodoptera exigua, or a herbivorous mite, Tetranychus urticae. Both organisms feed on lima bean leaves, causing the leaves to release chemicals.
Question 1(c)
Identify the process that was used to amplify the targeted genes.
PCR Accept RT-PCR.
Question 1
A polymerase chain reaction (PCR) was performed to amplify a small amount of DNA. Eight tubes were prepared as shown in the table. The tubes were placed in a thermal cycler with the temperatures shown in the diagram and run for 25 cycles. The image shows the result of gel electrophoresis on the eight samples.
Question 1(a)
State the number of the tube used as a control without DNA.
8;
Question 1(b)
Deduce, with a reason, whether the primers are smaller or larger than the amplified DNA.
smaller than DNA because it is further away from well;
Question 1(c)
Explain the reason for changing the temperature during each cycle.
a. (heat/ \(94^{\circ} \mathrm{C}\) ) separates/denatures the DNA strands / breaks hydrogen bonds; b. (cooling \(/ 55^{\circ} \mathrm{C}\) ) allows primers to bind to the DNA strand / annealing (of primers); c. (heating/ \(72^{\circ} \mathrm{C}\) ) allows for DNA elongation OR (heating \(/ 72^{\circ} \mathrm{C}\) ) allows Taq polymerase to synthesize new strands; Mp a. do not accept denaturing of enzymes or proteins, they must say DNA Mp a,b and c OWTTE 2 max
Question 1(d)
Predict the result that would be obtained if fewer cycles were used in this PCR process.
a. bands of DNA much lighter/thinner OR no bands of DNA visible; b. fewer copies of DNA; Mp b. OWTTE 1 max
Question 5
What is the function of the primers in the polymerase chain reaction (PCR)? To separate the two strands of DNA To bind to the complementary strands of DNA To determine the region of DNA that will be copied To activate the Taq DNA polymerase
C
Question 6
How is the sequence of DNA conserved? A. Unwinding of the double helix by helicase during DNA replication B. Separation of sister chromatids to opposite poles during mitosis C. Transcription into complementary RNA for protein synthesis D. Complementary base pair matching during DNA replication
D
Question 6
Which diagram(s) illustrate(s) semi-conservative replication of DNA?
B
Question 2
Over 50 years ago, Meselson and Stahl investigated the mechanism of DNA replication. They transferred a rapidly growing population of Escherichia coli from a growth medium containing only \({ }^{15} \mathrm{~N}\) to a growth medium with only \({ }^{14} \mathrm{~N}\). DNA samples were centrifuged at high speed in a salt density gradient. In the original published research, DNA molecules of the same density appear as a band in the UV absorption photographs as shown. Generations
Question 2(a)
The density of the DNA band at generation 0 is 1.724 and the density of the dark band of DNA at generation 4.1 is 1.710. Estimate the density of the DNA band at generation 1.0.
1.717
Question 2(b)
Describe the nitrogen composition of the DNA band in the E. coli at generation 1.0.
half \({ }^{14} \mathrm{~N}\) and half \({ }^{15} \mathrm{~N}\) OR one/new strand \({ }^{14} \mathrm{~N}\) and one/old strand \({ }^{15} \mathrm{~N}\) OR half labelled Must indicate equal quantities eg: 50 \% of each or 1 strand of each.
Question 2(c)
Explain the pattern shown in generation 3.0.
a. «as replication is semi-conservative» each new strand is built on parental/old/template strand b. generation 3 shows DNA that is mostly made of \({ }^{14} \mathrm{~N}\) c. when E. coli replicates, half of its new DNA must always contain \({ }^{14} \mathrm{~N}\) when growing in an \({ }^{14} \mathrm{~N}\) growth medium d. every new generation of E. coli always has a smaller proportion of «labelled» \({ }^{15} \mathrm{~N}\) in its DNA «than the previous generation» e. each new generation has half the amount of \({ }^{15} \mathrm{~N}\) in previous generation Accept answers in an annotated diagram. Do not give a mark for "semi-conservative". 3 max
Question 2(d)
This experiment was designed to demonstrate whether replication was semi-conservative or conservative. Distinguish between semi-conservative replication and conservative replication.
a. «daughter» DNA is half parental b. one strand of the «daughter» «daughter» DNA is all parental DNA is new OR all «daughter» DNA is new c. both strands of parental DNA both strands of parental DNA are separated remain together Table format not required. 2 max
Question 7
Which sequence of DNA would be suitable in DNA profiling? A. ---ATTCGTGAATCAGCC--- B. ---ATTCGTGAATTTGCC--- C. ---ATTCGTGATTGCAGC--- D. ---ATTCGTGATTCGTGA---
D
Question 7
What is the reason for Taq DNA polymerase being used in the polymerase chain reaction (PCR)? A. It does not denature at high temperatures. B. It produces Okazaki fragments more rapidly. C. It allows translation to proceed rapidly. D. It works efficiently with helicase in PCR.
A
Question 7
The diagram shows a gel electrophoresis apparatus. What can be deduced from the diagram? X is the smallest fragment. Y is positively charged. X is moving towards the cathode. Y travels at the greatest rate.
A
Question 7
The DNA profile from a paternity test shows six profiles. Who is the child's father? mother
B