SOIL - Jamb Biology Past Questions and Answers

Question 11:

• JAMB 1983

28 g soil sample was heated to a constant weight of 24 g. When further heated to red hot and cooled, it weighed 18 g. What is the percentage of humus in the soil?

A. 22.2
B. 55.6
C. 75.0
D. 25.0
E. 35.7

Question 12:

• JAMB 1984

Erosion can be reduced along shape by

A. Ridging across slope
B. Ridging up slope
C. Ridging down slope
D. Crop rotation
E. Bush fallowing system

Question 13:

• JAMB 1984

If a handful of soil is shaken with water and left to settle, the soil particles will settle from light to heavy particles as follows

A. Humus, clay, silt, sand, stones
B. Humus, silt, clay, sand, stones
C. Humus, clay,silt, stones, sand
D. Humus, sand, silt, clay, stones
E. Clay, humus, silt, sand, stones

Question 14:

• JAMB 1984

Denitrifying bacteria in nature liberate gaseous nitrogen directly from

A. Ammonium salts
B. Soil nitrates
C. Thunderstorms
D. Soil nitrites
E. Plant and animal proteins

Question 15:

• JAMB 1984

Leaching is

A. Washing away of humus from the soil surface
B. Reducing of soil aeration by pressure
C. Soil erosion by means other than rainfall
D. Loss of organic matter due to exposure to direct sunlight
E. Washing out chalk and limestone from upper layers of by heavy rains