Explain PCR temperature cycles, primers and thermostable polymerase, and how gel electrophoresis separates DNA fragments.
Tę umiejętność sprawdza 26 zadań wzorowanych na arkuszach IB z lat 2022–2026.
A thermocycler follows the temperature programme shown. What is the purpose of holding the mixture at stage X? A. To expose the templates by melting hydrogen bonds B. To permit primers to anneal at the lowest temperature C. To allow the thermostable polymerase…
A thermocycler repeats DNA strand separation, primer binding and strand extension. Which change correctly connects the primer-binding and extension stages? A. The temperature rises from the annealing range towards the polymerase’s extension temperature B. The…
DNA fragments move through an agarose gel from the wells shown. Which deduction is supported? A. P travelled furthest and represents smaller DNA fragments than Q B. Q is positively charged and moves toward the negative electrode C. Q must have a lower…
DNA fragments begin in wells near the negative electrode of the gel shown. Which fragment would move farthest towards the positive electrode during the same run? A. 7 kb, positively charged B. 3 kb, negatively charged C. 9 kb, negatively charged D. 1 kb,…
Why does a PCR protocol use two designed DNA primers? A. They identify the ends of the target and provide sites for extension B. They digest all DNA outside the target C. They prevent complementary strands from ever pairing D. They replace the proofreading…
A PCR protocol repeatedly heats DNA to separate its strands. Why can a heat-stable bacterial DNA polymerase remain useful through many cycles? A. It prevents the DNA strands from separating B. It replaces the need for a template strand C. It produces the…
Outline evidence that the gene transfer worked.
A hypothetical assay uses reverse-transcription PCR to distinguish HIV variants at two variable regions, R and S. Five primer pairs give the fragment sizes below. The all-variant product confirms viral material; a variant has one R and one S category. Lane1 is…
A DNA sample is separated by gel electrophoresis. What do the DNA fragments forming one narrow band have in common? A. Approximately the same number of base pairs B. Necessarily the same sequence at every base C. Opposite electrical charges D. Each must be one…
When a voltage is applied across an agarose gel, why do DNA fragments migrate towards the anode? A. Their negatively charged phosphate backbones are attracted to the positive electrode B. Their phosphate groups are positively charged at the electrophoresis pH…
Deduce whether the gel supports successful transformation, giving a reason.
Predict a suitable source of DNA for the negative control, giving a reason.
State the lane number for the control lacking template DNA.
Deduce whether the primers are shorter or longer than the amplified DNA, giving a reason.
Explain why the temperature changes within each cycle.
Predict the result if fewer cycles are completed.
State the lane number for the control lacking template DNA.
Deduce whether the primers are shorter or longer than the amplified DNA, giving a reason.
Explain why the temperature changes within each cycle.
Predict the result if fewer cycles are completed.
In PCR, a pair of primers is chosen to flank a selected DNA segment. What does this choice determine? A. Which region is amplified B. Which enzyme separates strands by hydrolysing DNA C. Which RNA codons are translated D. Which bases are removed from the…
In PCR, a pair of primers is chosen to flank a selected DNA segment. What does this choice determine? A. Which region is amplified B. Which enzyme separates strands by hydrolysing DNA C. Which RNA codons are translated D. Which bases are removed from the…
State one technique that can detect viral genetic material.
State one technique that can detect viral genetic material.
(i) Describe the structure of a nucleosome. (ii) Explain what holds the two DNA strands together. (iii) Outline how tandem-repeat regions are used in DNA profiling.
Nucleic acids underlie inherited biological variation. (a) Draw and label one RNA nucleotide. (b) Describe how DNA profiling can be used to investigate paternity. (c) Explain why human adult heights vary.
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