DP Biology (first assessment 2025)

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Question SPM.2.HL.TZ0.10

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Date May Specimen-2023 Marks available [Maximum mark: 15] Reference code SPM.2.HL.TZ0.10
Level HL Paper 2 Time zone TZ0
Command term Describe, Explain, Outline Question number 10 Adapted from N/A
10.
[Maximum mark: 15]
SPM.2.HL.TZ0.10

Changes in the form of biological molecules lead to changes in their function.

(a)

Outline the role of UV radiation as a mutagen.

[4]

Markscheme
  1.  affects/damages/causes change in oncogenes/errors in DNA repair;
  2.  UV radiation might alter complementary base pairing/break hydrogen bonds/fuse bases;
  3.  double helix may uncoil;
  4.  strands may separate/break;
  5.  DNA sequence may be altered/DNA bases may re-connect to different bases after separating;
  6.  DNA strand may break into pieces / fragments of DNA may be lost;
(b)

Explain how the function of DNA is linked to its molecular structure.

[7]

Markscheme
  1.  DNA base sequence provides information;
  2.  gene expression / genes provides a template for the construction of a protein;
  3.  transcription occurs / mRNA is built using DNA as a template;
  4.  DNA nucleotide structure described/sugar and phosphate and base;
  5.  polymer of nucleotides makes a DNA strand;
  6.  DNA has two anti-parallel strands;
  7.  complementary base pairs/A pairs with T and C with G;
  8.  strands linked by hydrogen bonding between bases;
  9.  double helix shape / helix held by hydrogen bonds;

Accept points in clearly labelled diagram

(c)

Describe the use of gene knockout technology in research.

[4]

Markscheme
  1.  gene knockout technology is a genetic engineering technique/intentional alteration in the sequence of a  gene;
  2.  making a gene inactive;
  3.  using site specific nucleases / CRISPR;
  4.  researcher observes changes in phenotype of organism;
  5.  allows researcher to determine function of the gene;
  6.  entire library of knockout organisms exists;
  7.  made available to researchers;

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