The salt content of the water can be measured very precisely using the conductivity method. Salinity can also be measured with a hand held refractometer. A refractometer measures the change of direction or bending of the light as it passes from air to water. Light moves slower in water than air. The more salt in the water, the slower the light moves. You can see the effect of light bending (refracting) as it passes from the water into the air by placing a pencil in a glass of water. The pencil appears to bend where it enters the water.
Red blood cells and haemoglobin. Oxygen is one of the substances transported with the assistance of red blood cells. The red blood cells contain a pigment called haemoglobin, each molecule of which binds four oxygen molecules.Oxyhaemoglobin forms.he curve shows that: 1  at relatively low oxygen concentrations there is uncombined haemoglobin in the blood and little or no oxyhaemoglobin, e.g. in body tissue. 2  at relatively high oxygen concentrations there is little or no uncombined haemoglobin in the blood; it is in the form of oxyhaemoglobin, e.g. in the lungs.
Introduction: Red blood cells. The purpose of red blood cells in the blood is to carry oxygen to body cells. The hemoglobin in red blood cells binds to oxygen received from the lungs, and these cells are circulated in the blood to all cells to supply needed oxygen.ed blood cells (also called RBCs or erythrocytes) carry oxygen from the lungs to the body's tissues and take carbon dioxide from the tissues back to the lungs. The red blood cells give blood its color.