BIOLOGY [5 Mark Question Answer]

We can conserve soil by following these few steps as :
a. Afforestation: The planting of more trees to conserve soil is called afforestation. Hie roots of plants and trees hold the soil particles together and thus prevent the washing away of the soil by flowing water and strong winds.
b. Terrace farming: In hilly areas, cutting steps of same height on the sides of a steep mountain slopes restricts the flow of water carrying top soil with it.
c. Land should not be left barren for long as the dry soil gets eroded easily.
d. Crop rotation : Different crops should be grown in a given area each season. It helps in reducing the loss of nutrients from the soil.
e. Trees should be planted at short distance in desert areas and also around the fields to reduce the effect of wind.

Soil erosion is the process of sweeping away of the top fertile layer of the soil profile. The various factors responsible for it are:
a. rain – as in mountain areas
b. wind – as in desert areas
c. deforestation – i.e. cutting down of trees
d. over grazing by animals – it leaves the land barren and prone to erosion.
e. unscientific agricultural practices by humans
E. mining, construction, housing etc. by humans.

Draw a neatly labelled diagram showing the different layers of soil.
Answer;
A soil profile shows three layer and the bedrock (parental rock) as observed in a vertical section of soil as :
a. A-horizon (Top soil): It is the uppermost layer and contains humus and is soft and porous. It is the most fertile layer.
b. B-horizon (Sub soil): Below the A-horizon is B-horizon. It contains sand, silt and clay. It is rich in minerals and iron oxide. Roots of tall plants can reach the subsoil.
c. C-horizon: It consists of lumps of parent rock material.
d. Bed rock : It lies below the C-horizon and has unweathered parent rock from which soil is formed. It provides a base to the upper three horizons.

Soil is regarded as one of the most important natural resources because life on earth indirectly depends on soil. Some of its uses are :
a. Plants need soil to grow for support, water and minerals.
b. Soil is a rich source of metals like iron, calcium, aluminium, magnesium etc. which are used in industries.
c. It is a source of clay used for making bricks, pottery and porcelain.
d. Soil helps to store the underground water.