AQA As Biology Paper 1 2025 Mark Scheme Pdf

Download the official AQA AS Level Biology Paper 1 mark scheme for the June 2025 exam (7401/1). This is the final examiner-approved marking guide used during standardisation, providing full answers, detailed marking points, and guidance on how marks are awarded.

The mark scheme includes complete solutions for all questions. For example, Question 1 confirms key biological terms such as amine and carboxyl groups, peptide bonds, and identifies serine correctly (page 5). It also provides the full calculation for antibody structure, with the correct answer of 450 amino acids per heavy chain (page 5). Question 2 outlines ATP structure (adenine, ribose, and three phosphates) and explains hydrolysis and phosphorylation processes (page 6).

Extended answers are fully detailed, such as semi-conservative DNA replication (Question 3, page 7), including helicase activity, complementary base pairing, and phosphodiester bond formation. The mark scheme also includes full solutions for genetic code questions (page 8), biodiversity and uncertainty calculations (page 9), and lung function analysis with the correct percentage decrease of 42.5% (page 10).

Later sections provide examiner-approved explanations for plant transport (sucrose and mass flow hypothesis, pages 12–13), membrane structure and permeability experiments (pages 14–16), and natural selection in antibiotic resistance (page 17). It also includes key examiner principles such as error carried forward (ECF), level-based marking, and acceptable alternative answers to ensure consistent grading.

This resource is essential for understanding how to gain full marks, structure precise answers, and avoid common mistakes. Fully updated for the 2025/2026 academic year and optimised for instant download on markscheme.net.

This mark scheme is essential for Year 12 students preparing for AQA AS Biology exams and Year 13 students reinforcing core foundational topics for A-Level Biology. It is especially valuable for students aiming for top grades by understanding exactly how examiners award marks.

Teachers and tutors use this mark scheme to standardise marking, deliver accurate feedback, and model high-quality answers. It is also ideal for independent learners and retake students who want clear, step-by-step solutions and insight into examiner expectations.