(a) To what type of rock do each of specimens D,... | WAEC SSCE - Agricultural Science - 2000 (Practical)

Question 1 Report

(a) To what type of rock do each of specimens D, E, and F belong?

(b) State the types of weathering caused by each of specimens G, H, and l

(o) State three ways in which specimen D is important to agriculture

Answer

(a) Type of rock to which each specimen belongs

(b) Type of weathering caused by each specimen

Specimen G (earthworm) causes biological weathering (through its mechanical burrowing action).
Specimen H (water) causes chemical weathering and physical (mechanical) weathering.
Specimen I (ice block) causes physical (mechanical) weathering.

(c) Two ways by which each specimen causes weathering

Specimen G (earthworm): it burrows into and widens cracks in the rock, breaking it into smaller particles; the burrows also admit water and air which further speed up rock disintegration.
Specimen H (water): it dissolves soluble rock minerals and forms weak acids that chemically attack the rock; running water also drags rock particles which collide and wear against one another and the channel walls, breaking them down.
Specimen I (ice block): when water in rock cracks freezes to ice it increases in volume, and the pressure exerted widens the cracks until the rock splits; the movement of ice along a path also dislodges and drags away rock particles.

(d) Three ways in which specimen D (igneous rock) is important to agriculture

On weathering it breaks down to form soil, serving as the parent material of the soil.
It releases and supplies mineral nutrients such as calcium and potassium to the soil.
It is piled up to check erosion and is used to construct farm structures and access roads.

Answer Details

(a) Type of rock to which each specimen belongs

(b) Type of weathering caused by each specimen

Specimen G (earthworm) causes biological weathering (through its mechanical burrowing action).
Specimen H (water) causes chemical weathering and physical (mechanical) weathering.
Specimen I (ice block) causes physical (mechanical) weathering.

(c) Two ways by which each specimen causes weathering

Specimen G (earthworm): it burrows into and widens cracks in the rock, breaking it into smaller particles; the burrows also admit water and air which further speed up rock disintegration.
Specimen H (water): it dissolves soluble rock minerals and forms weak acids that chemically attack the rock; running water also drags rock particles which collide and wear against one another and the channel walls, breaking them down.
Specimen I (ice block): when water in rock cracks freezes to ice it increases in volume, and the pressure exerted widens the cracks until the rock splits; the movement of ice along a path also dislodges and drags away rock particles.

(d) Three ways in which specimen D (igneous rock) is important to agriculture

On weathering it breaks down to form soil, serving as the parent material of the soil.
It releases and supplies mineral nutrients such as calcium and potassium to the soil.
It is piled up to check erosion and is used to construct farm structures and access roads.

(a) To what type of rock do each of specimens D, E, and F belong? (b) State the types of weathering caused by each of specimens G, H, and l (c) Give two way...