Fig. 1.1 is a diagram showing some body cells and parts of the human lymphatic andcirculatory systems.Fig 1.1(a) Capillaries allow blood to reach most cells in the body.(i) State the name of the process by which oxygen moves from A to Z as shown in Fig.1.1. [1](ii) Describe how some of the liquid in A moves to B in Fig. 1.1[ 2](iii) State one component of blood that remains inside the capillaries as the blood flowsfrom X to Y in Fig. 1.1. [1](b) Lymphatic vessels are similar in structure to veins.(i) Describe the structure of veins. [2](ii) Describe the role of the lymphatic vessel shown in Fig. 1.1.[2](c) Lacteals are another part of the lymphatic system.State where in the body lacteals are found and state their function. [2](d) In the lymphatic system, there are structures that contain large numbers oflymphocytes.(i) State the name of these structures.[1](ii) State the role of lymphocytes.[2]

(a) (i) The process by which oxygen moves from A to Z as shown in Fig.1.1 is called Diffusion. [1] (ii) Some of the liquid in A moves to B in Fig. 1.1 through a process called Filtration. This is driven by the hydrostatic pressure of the blood, which pushes fluid out of the capillaries and into the interstitial space. [2] (iii) One component of blood that remains inside the capillaries as the blood flows from X to Y in Fig. 1.1 is Red Blood Cells. [1]

(b) (i) Veins are blood vessels that carry blood towards the heart. They have a thin wall and a large lumen. They also have valves to prevent backflow of blood. [2] (ii) The role of the lymphatic vessel shown in Fig. 1.1 is to transport lymph, a fluid containing white blood cells, throughout the body. This helps in the removal of toxins and waste, and plays a crucial role in the immune response. [2]

(c) Lacteals are found in the small intestine, specifically in the villi. Their function is to absorb dietary fats that are not absorbed by blood capillaries. [2]

(d) (i) The structures that contain large numbers of lymphocytes in the lymphatic system are called Lymph Nodes. [1] (ii) The role of lymphocytes is to fight infections by producing antibodies, which neutralize foreign substances, or by directly attacking harmful cells. [2]