Page 82 - Biology_F5

Cytology

Water as solvent (c) Water found in humours of the eye
Water is a universal solvent; it readily helps to maintain the eye’s shape.
dissolves other substances, hence it is (d) The mammalian foetus is supported
used for the following purposes: and protected by an amniotic fluid,
(a) For transportation of various which is largely water.
substances from one part of the body (e) Water provides support (habitat) to
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to another. These are carried by blood aquatic organisms, such as fish.
and other fluids in solution form.
(b) For removal of metabolic wastes, such
as nitrogenous waste products. These Other functions
excretory wastes are removed from the Other functions of water include the
body in the form of solution in water. following:
(a) It controls body temperature in
mammals. Evaporation of sweat from
Water as a lubricant
Due to its viscosity property, water takes the body surface has the cooling effect.
part in lubricating body parts, which (b) It is an agent for dispersal of seeds,
slide past each other. It makes various larvae, and male gametes of animals
lubricating fluids in the body; example: and lower plants, such as bryophytes.
mucus, which aids in movement in (c) In mammals, fluids in the inner ear are
animals, such as snails. It also lubricates important for hearing and balance.
internal parts, such as gut walls in animals.
The synovial fluid (which lubricates joints
of vertebrates) and pleural fluid (which Exercise 1.16
lubricates lungs).
1. Explain the role of water in plants
Supporting role of water and animals.
The supporting role of water is made clear
in the following examples: 2. Water is universal solvent.

(a) In animals, such as annelids and Substantiate.
nematodes, water exerts a hydrostatic 3. Explain the properties of water.
pressure which helps to support and
maintain their structure. This is known
as the hydrostatic skeleton.
(b) Osmotic influx of water into plant
cells generates turgor pressure which
supports herbaceous (non-woody)
plants. The turgor pressure also
supports primary growth in woody
plants.

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