Everything Life Sciences Grade 10

use water in special chambers in their body to give their bodies support. This use of water

pressure to provide body form, and enable movement is called ahydrostatic skeleton. Plants

grow upright and keep their shape due to the pressure of water (turgor pressure) inside the

cells.

Transport medium: water transports substances around the body. For example, water is the

main constituent of blood and enables blood cells, hormones and dissolved gases, elec-

trolytes and nutrients to be transported around the body.

Lubricating agent: water is the main constituent of saliva which helps chewing and swallow-

ing and also allows food to pass easily along the alimentary canal. Water is also the main

constituent of tears which help keep the eyes lubricated.

Solvent for biological chemicals: the liquid in which substances dissolve is called a solvent.

Water is known as the universal solvent as more substances dissolve in water than in any

other liquid.

Medium in which chemical reactions occur: all chemical reactions in living organisms take

place in water.

Reactant: water takes place in several classes of chemical reactions. During hydrolysis reac-

tions, water is added to the reaction to break down large molecules into smaller molecules.

Water can also be split into hydrogen and oxygen atoms to provide energy for complex

chemical reactions such as photosynthesis.

Temperature Structure and support Lubrication

Figure 2.1:

(Attribution: ??)

Sweating helps

human bodies

cool down.

Jellyfish and worms use a

hydrostatic (water

pressure) skeleton to

keep their body shape.

Water helps

maintain the

upright structure

of plants.

Water is an important

lubricant in the eye.

Minerals DUMMY

Dietary minerals are the chemical elements that living organisms require to maintain health.

In humans, essential minerals include calcium, phosphorous, potassium, sulfur, sodium,

chlorine and magnesium.

Macro-elements(macro-nutrients) are nutrients that are required in large quantities by living

organisms (e.g carbon, hydrogen, oxygen, nitrogen, potassium, sodium, calcium, chloride,

magnesium, phosphorus and sulfur).

26 2.3. Inorganic compounds