(b) light
     (c) sound
     (d) gravity
Ans: (d)
259. The geotropism of the roots that makes them grow towards gravity is said to be
     (a) positive
     (b) negative
     (c) neutral
     (d) oblique
Ans: (a)
260. The rate of growth of plants can be measured by a/an
     (a) manometer
     (b) auxanometer
     (c) photometer
     (d) thermometer
Ans: (b)
261. Polyploid wheat does not normally show an increase in
     (a) size
     (b) vigour
     (c) length of the life cycle
     (d) resistance to desease
Ans: (c)
262. Chlorosis is the phenomenon where leaves have
     (a) more chlorophyll
     (b) less chlorophyll
     (c) no chlorophyll
     (d) patches of chlorophyll
Ans: (c)
263. The plants will stop growing if the shoot tip is cut off because
     (a) shoot tip produces growth hormones
     (b) shoot tip contains meristematic cells
     (c) shoot tip is the growing part
     (d) the plant dies
Ans: (a)
264. Cutting and layering are the methods of plant propagation usually referred to as
     (a) asexual reproduction
     (b) sexual reproduction
     (c) vegetative reproduction
     (d) gardening
Ans: (c)
265. Plantain is
     (a) a tree
     (b) an annual herb
     (c) a perennial herb
     (d) a shrub
Ans: (c)
266. The tallest tree in the world ‘Sequoia’ is found in
     (a) UK
     (b) USA
     (c) former USSR
     (d) China
Ans: (b)
267. Chemical substances that called have effect on growth of plants are called
     (a) enzymes
     (b) catalysts
     (c) hormones
     (d) pesticides
Ans: (c)
268. Plants grown in darkness show
     (a) stout stem
     (b) long internodes