221. Apical dominance is caused by

A abscisic acid in lateral bud
B cytokinin in leaf tip
C gibberellin in lateral buds
D auxin in shoot tip
Answer :   auxin in shoot tip
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222. Avena coleoptile tesdt to find out the quantity of growth promoting hormones was discovered by

A F.W. Went
B L.J. Oudus
C K.V. Thimann
D F. Skoog
Answer :   F.W. Went
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223. Cell elogation in internodel regions of the green plants takes place due to

A Ethylene
B Indoel acetic acid
C Cytokinin
D Gibberellins
Answer :   Gibberellins
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224. Motor or bulliform cells In Grasses shows

A Growth movement
B Tropism
C Nastic movement
D Turgor movement
Answer :   Turgor movement
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225. Dormancy of seed is broken by

A Auxin
B Gibberellins
C Ethylene
D Cytokinin
Answer :   Gibberellins
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226. "Foolish seeding" disease of rice led to the discovery of

A IAA
B GA
C ABA
D 2, 4-D
Answer :   GA
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227. Richmond-Lang effect is dut to

A Cytokinin
B Auxin
C ABA
D All of the above
Answer :   Cytokinin
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228. Growth curve is

A S-shapded
B Sigmoid
C L-shaped
D Both A and B
Answer :   Both A and B
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229. Plants bend toward the light because

A They need light for photosynthesis
B They need light for respiration
C Light attracts them
D Cell on the shaded side elongate more
Answer :   Cell on the shaded side elongate more
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230. Which of the following instrument can be used to record plant growth by seconds

A ARc auxanometer
B Arc indicator
C Space marker disc
D Crescograph
Answer :   Crescograph
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