Effect of Acid Rain on Germination

Effect of Acid Rain on Germination

A seed is formed from the ovule of a flower as a result of

fertilisation, and is then dispersed from the parent plant. If the

seed lands in a suitable place, it will germinate. Germination is the

growth of the embryo inside the seed, eventually growing into a mature

plant.

CONDITIONS NEEDED FOR GERMINATION

OXYGEN - is used for aerobic respiration, which provides the energy

for many chemical changes involved in the food reserves and making the

new cytoplasm and cell walls of the growing seedling.

TEMPERATURE - a rise in temperature speeds up most chemical reactions,

including those taking place in living organisms. Germination,

therefore occurs more rapidly at high temperatures (up to about 40

degrees centigrade). Above 45 degrees centigrade, the enzymes are

denatured and the seedlings would be killed. Below 0-5 degrees

centigrade, germination may not start at all.

WATER - before the changes necessary for germination take place, the

seed must absorb water. The water which reaches the embryo and

cotyledons is used to:

* Activate the enzymes in the seed

* Help the conservation of starch to sugar, and proteins to amino

acids

* Transport the sugar in solution from the cotyledons to the growing

regions

WHAT HAPPENS DURING GERMINATION?

A typical seed stores carbohydrates, lipids and proteins. It also

stores minerals and vitamins. As a result of 'imbibition' (the initial

uptake of water by a seed) and osmosis (water travels from cell to

cell in the seed by osmosis) the embryo becomes hydrated and this

activates enzymes. The enzymes then break down the food reserves the

seed needs for growth.

Proteases

[IMAGE]Proteins Amino acids

Carbohydrases

[IMAGE]Polysaccharides Sugars

Amylase Maltase

[IMAGE][IMAGE]Starch Maltose Glucose

Lipases

[IMAGE]Lipids Fatty Acids + Glycerol

The soluble products of digestion then go to the growth regions of the

embryo, enabling the seed to grow.