Which of the following pathways shows the correct direction of blood flow through a double circulatory system, starting from the site of gas exchange in the lungs?
lungs→left side of heart→body organs→right side of heart\text{lungs} \rightarrow \text{left side of heart} \rightarrow \text{body organs} \rightarrow \text{right side of heart}lungs→left side of heart→body organs→right side of heart
lungs→right side of heart→body organs→left side of heart\text{lungs} \rightarrow \text{right side of heart} \rightarrow \text{body organs} \rightarrow \text{left side of heart}lungs→right side of heart→body organs→left side of heart
lungs→left side of heart→right side of heart→body organs\text{lungs} \rightarrow \text{left side of heart} \rightarrow \text{right side of heart} \rightarrow \text{body organs}lungs→left side of heart→right side of heart→body organs
lungs→body organs→left side of heart→right side of heart\text{lungs} \rightarrow \text{body organs} \rightarrow \text{left side of heart} \rightarrow \text{right side of heart}lungs→body organs→left side of heart→right side of heart
82 exam-style questions on OCR GCSE Biology 2.1 Supplying the cell, covering 2.1.1 Transport across cell membranes, 2.1.2 Mitosis and the cell cycle, 2.1.3 Importance of cell differentiation, and 2.1.4 Stem cells. Each one has a worked solution and a mark scheme showing where the marks go.