Plant Growth and Development for NEET UG
Plants grow throughout their lives, and five main hormones control when they grow, flower, ripen and shed leaves. Light and temperature act as signals too.
BiologyClass 1178 MCQs2 lessons12 flashcards3 memory tricks
Practise Plant Growth and Development free
What you'll learn
- Plant growth
Describe the phases of growth and the difference between arithmetic and geometric growth. - Plant growth regulators
Match each plant hormone to its main effects and uses.
Memory tricks
Auxin from the shoot tip suppresses side buds. Removing the tip lets lateral buds grow, which is why hedges are trimmed.
Ethylene is a gaseous hormone that promotes ripening. Ethephon releases ethylene and is used to ripen fruit evenly.
Abscisic acid closes stomata during water stress, keeps seeds and buds dormant, and opposes gibberellins.
Try 3 NEET-style questions
Q1. Auxins help to prevent fruit and leaf drop at early stages, but they
- always prevent all abscission
- cause bolting in cabbage
- promote the abscission of older, mature leaves and fruits
- close stomata during drought
Show answer
Answer: (3) promote the abscission of older, mature leaves and fruits
Auxins prevent fruit and leaf drop at early stages but promote abscission of older, mature leaves and fruits.
Q2. More than 100 gibberellins have been reported from fungi and higher plants. They
- are all gases
- are all derivatives of adenine
- are produced only by fungi
- are all acidic, and GA₃ was the first discovered and is the most intensively studied
Show answer
Answer: (4) are all acidic, and GA₃ was the first discovered and is the most intensively studied
There are more than 100 gibberellins (GA₁, GA₂, GA₃ and so on). All are acidic. GA₃ was one of the first discovered and remains the most intensively studied.
Q3. Plant growth is generally indeterminate (open) mainly because
- plants never stop growing in size or number of cells, in all parts
- plants have no hormones
- plants have meristems that keep dividing throughout life
- plant cells are larger than animal cells
Show answer
Answer: (3) plants have meristems that keep dividing throughout life
Meristems at certain locations retain the capacity to divide and self-perpetuate, so plant growth continues throughout life (open form of growth).
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