Which statement explains why dissolved food molecules are transported from the small intestine to body cells?
They provide oxygen for respiration and carbon dioxide for growth.
They provide substrates for respiration and materials for growth.
They remove urea from respiration and water from growing tissues.
They remove mineral ions from cells and oxygen from growing tissues.
42 exam-style questions on Edexcel GCSE Biology 8.1 Exchange surfaces and diffusion, covering 8.1.1 Introduction to exchange and transport, 8.1.2 Alveoli adapted for gas exchange, 8.1.3 Factors affecting rate of diffusion, and 8.1.4 Rate of diffusion using Fick's law. Each one has a worked solution and a mark scheme showing where the marks go.