Ans: (a)
289. Hormone promoting maleness in flowering plants is
     (a) Indole Acetic Acid
     (b) Kinetin
     (c) Cytokinin
     (d) Gibberellin
Ans: (d)
290. Two tall plants, each being a hybrid and carrying a recessive factor for dwarfness are crossed. What proportion of
     their offspring will be dwarf?
     (a) 50%
     (b) 25%
     (c) 75%
     (d) 100%
Ans: (b)
291. An inherited characteristic which does not appear in one generation but can appear in the next is called
     (a) dominant
     (b) recessive
     (c) homozygous
     (d) heterozygous
Ans: (b)
292. Maize is attacked by
     (a) Phytophthora
     (b) Pythium
     (c) Ustilago
     (d) Puccinia
Ans: (c)
293. Diseases in plants can be caused by
     (a) virus
     (b) bacteria
     (c) fungi
     (d) All the above
Ans: (d)
294. Necrosis is a symptom which is recognised by
     (a) pattern colouration on leaves
     (b) little leaves
     (c) out growth
     (d) death of tissues
Ans: (d)
295. Fusarium causes the wilting of the cotton plants by
     (a) clogging the vessels
     (b) producing toxic substance
     (c) causing necrosis of roots
     (d) killing the leaves
Ans: (b)
296. The best and easy method of control of crop pests is by
     (a) crop rotation
     (b) chemicals
     (c) quarantine
     (d) biological control
Ans: (a)
297. The spores of Puccinia formed on the leaves of wheat are called
     (a) Basidiospores
     (b) Ascidiospores
     (c) Uredospores
     (d) Pycnospores
Ans: (c)
298. Plant diseases are spread by
     (a) insects
     (b) man
     (c) wind
     (d) All the above