The Examiner's Verdict

The May/June 2024 suite of papers for IGCSE Combined Science presents a balanced yet demanding assessment. Paper 43 (Extended Theory) stands out as a rigorous test of chemical structures, physiological adaptations, and multi-step physics calculations. While the basic recall questions remain accessible, the differentiator lies in the application questions where students must integrate mathematical processing with precise scientific vocabulary.

Where the Marks Were Won and Lost

High-scoring candidates demonstrated exceptional precision in the physics components, successfully navigating the speed-time graphs and executing exact formulas like \( Q = It \) and \( v = f\lambda \). However, significant marks were lost in the structured chemistry questions. Specifically, drawing the poly(ethene) molecule with the correct continuation bonds and specifying exact conditions for catalytic cracking tripped up many. In biology, candidates struggled to articulate the adaptation of capillaries beyond simply stating 'thin walls', missing the crucial explanation of a 'short diffusion distance'.

Top Examiner Pitfalls to Avoid

  • The 'Covalent Bond' Misconception in Boiling: When explaining why oxides of nitrogen have low boiling points, many candidates wrongly claimed that covalent bonds are broken. Examiners look for the explicit mention of overcoming weak intermolecular forces instead.
  • Neglecting Unit Conversions: In Paper 43 Question 9, calculating time in hours from charge required converting seconds to hours. A large proportion of students left their answers in seconds, losing the final mark.
  • Incomplete Polymer structures: Omitting the open-ended single bonds (continuation lines) on both sides of polymer drawings continues to be a common source of lost marks.

Revision and Exam Strategy

To secure a Grade A*, candidates should focus heavily on the overlapping practical skills tested in Paper 63, which carry a significant weight. Master the identification tests for cations (e.g., iron(II), ammonium) and anions (sulfate, nitrates). For physics, practice multi-step calculation paths and ensure every numerical answer features its correct unit (such as \( \Omega \) for resistance). In chemistry, prioritize memorizing the exact general formulas for alkanes and alkenes along with industrial conditions for cracking.

Predictions for Upcoming Series

Given the minimal coverage of Gas exchange in humans and Electrochemistry in this theory series, future papers are highly predicted to contain detailed structured questions on alveoli adaptations and electrolysis equations (specifically at the anode and cathode with state symbols).