JAMB Agricultural Science Past Questions & Answers - Page 48

236.

The correct sequence in the processes of crop improvement is

A.

Introduction → selection → breeding

B.

Breeding → selection → introduction

C.

Breeding → introduction → selection

D.

Introduction → breeding → selection

Correct answer is A

The correct sequence in the process of crop improvement is Introduction → selection → breeding.

 

 

237.

The characteristic symptoms of mosaic disease of crops is usually observed on

A.

Roots

B.

Leaves

C.

Stems

D.

Fruits

Correct answer is B

The characteristic symptoms of mosaic disease are usually observed on leaves. The disease is characterized by leaves that are mottled with yellow, white and light or dark green spots and streaks (in other words, a mosaic of colors).

238.

Which of the weeds is dispersed by wind?

A.

Pig weed (Boerhavia diffusa)

B.

Goat weed (Ageratum conizoides)

C.

Hause thorns (Acanthospermum hispidum)

D.

Tridax (Tridax procumbeus)

Correct answer is D

Tridax procumbeus is dispersed by wind.

239.

Gummosis disease of citrus is caused by

A.

Aphids

B.

Fungi

C.

White flies

D.

Bacteria

Correct answer is B

Gummosis disease of citrus is caused by Phytophthora fungi.

240.

Callosobruchus maculates is a common pest of

A.

Maize

B.

Cowpea

C.

Rice

D.

Millet

Correct answer is B

Callosobruchus macualatus is a species of beetles known commonly as the cowpea weevil or cowpea seed beetle.