In a clinical study of human monozygotic (identical) twins who were separated at birth and raised in completely different geographical and socio-economic environments, researchers measured several physiological and biochemical characteristics. Which of the following traits would be expected to show 100% concordance (showing identical phenotypes in both twins) regardless of their different environments?
Serum immunoglobulin G (IgG) antibody profile against specific viral pathogens
Red blood cell rhesus (RhD) antigen status
Resting systolic blood pressure
Clinical severity of abdominal symptoms following lactose ingestion
97 exam-style questions on OCR GCSE Biology 5.1 Inheritance, covering 5.1.1 The genome, 5.1.2 Environment and phenotype, 5.1.3 Variants and mutations, 5.1.4 How genetic variants influence phenotype, 5.1.5 Asexual and sexual reproduction, 5.1.6 Haploid and diploid, 5.1.7 Meiotic cell division, 5.1.8 Single gene inheritance, 5.1.9 Predicting single gene crosses, 5.1.10 Sex determination, 5.1.11 Multiple gene inheritance, and 5.1.12 Development of our understanding of genetics. Each one has a worked solution and a mark scheme showing where the marks go.