2.50 explain how adaptations of red blood cells, including shape, structure and the presence of haemoglobin, make them suitable for the transport of oxygen

2.50 •adaptations of red blood cells for transporting oxygen

                  •small and biconcave, creating a large surface area for absorbing and releasing oxygen

                  •red blood cells have no nucleus, freeing up space for more haemoglobin, so they can carry more oxygen

                  •they contain haemoglobin, making it red, containing iron

                            •in the lungs haemoglobin reacts with oxygen, becoming oxyhemoglobin

                                      •the reverse happens to release oxygen to the cells