JAMB Biology Past Questions & Answers - Page 297

1,481.

Viruses are regarded as non-living because they

A.

can niether reproduce asexually nor sexually

B.

cannot survive in their respective enviroments

C.

 do not possess characteristics that can be transmitted from one generation to the next

D.

can neither respire nor excrete

Correct answer is D

No explanation has been provided for this answer.

1,483.

Atmospheric nitrogen is directly replenished in nature through

A.

the activities of denitrifying bacteria

B.

the breakdown of ammonium salts in the soil

C.

the activities of nitrifying bacteria

D.

the activities of nitrogen-fixing bacteria in root nodules

E.

egestion, death and decay

Correct answer is A

The nitrogen in the soil is converted to atmospheric nitrogen by the process of DENITRIFICATION. This is done by the action of denitrifying bacterias eg several species of Pseudomonas.

1,484.

The origin of mineral particles in the soil is

A.

humus

B.

 water

C.

micro-organisms

D.

weathered rock

E.

organic matter

Correct answer is E

No explanation has been provided for this answer.

1,485.

Water retention is highest in soils which are rich in

A.

sand, poor in humus and devoid of clay

B.

clay and sand, but poor in humus

C.

clay and humus, but poor in sand

D.

clay, poor in humus and devoid of sand

E.

sand and humus, but poor in clay

Correct answer is C

Clay Soil can hold more total water than most other soil types.