11. D 12. C 13. B 14. A 15. A 16. D 17. D 18. C 19. D
1. (a) P : Erythrocyte
Q : Leucocyte
(b) (i) To transport oxygen from the lungs to the body tissue
(ii) Haemoglobin
(c) Cell P, erythrocyte, is filled with haemoglobin. Oxygen from the lungs diffuses into the red blood cells and combines with the haemoglobin to form oxyhaemoglobin.
Oxygen is carried to the body tissues in the form of oxyhaemoglobin. Upon reaching the tissues, oxygen readily detaches itself and diffuses into the body cells.
(d) Draw the 2 processes of phagocytosis from the Biology text book
(ii)Phagocytosis
(iii) Phagocytosis is carried out by neutrophil, a type of leucocyte.
The neutrophil will move towards a bacterium in an amoebic movement.
Upon coming into contact with the bacterium, a cup-shaped indentation is formed and the bacterium is taken into a vacuole where it is digested by lysosomes.
2. (a) To colour the xylem tissues
(b) 
(c) (i) Xylem
(ii) Elongated tube which runs continuously from the roots to the leaves.
(d) When water vapour evaporates from the leaves, a transpirational pull is exerted to draw up water along the xylem vessels.
Cohesive forces between the water molecules prevent the water column in the xylem vessels from breaking.
Adhesive forces between the water molecules and the xylem vessel wall prevent the water molecules from falling back.
As a result of these forces, water molecules are pulled towards the leaves.
(e) Water molecules from the soil are drawn into the root hairs through osmosis. A force exists to ‘pull’ the water from the roots to the xylem vessels. This force is called root pressure, which is responsible for pushing the water from the roots to the stem.
This explains the increase in water level in the tube after one day.
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