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PCA - PLANT GROWTH REGULATORS EXAM
QUESTIONS AND ANSWERS 2025
1-naphthalenacetic acid (NAA) - Auxins - ...ANSWER...
✔ ✔Used as a rooting agent to stimulate root
development in cuttings and tissue cultures
2, 4-D - Auxins - ...ANSWER... ✔ ✔Used as a
herbicide, primarily used for broadleaf weed control. It
may also be used to regulate the growth of citrus plants
3-indoleacetaldehyde acid (IAId) - Auxins - ...ANSWER...
✔ ✔Playing a crucial role in the biosynthesis of IAA
within plants and microorganism. It is involved in various
aspects of plant growth and development, including cell
elongation, root initiation, and responses to
environmental cues.
3-indoleacetic acid (IAA) - Auxins - ...ANSWER... ✔
✔Is the most common auxin class phytohorme and
plays vital roles in plant growth and plant development.
processes, such as cell division, cell expansion, cell
differentiation and fruit development.
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3-indolepyruvic acid (IPA) - Auxins - ...ANSWER... ✔
✔Is a crucial intermediate in the biosynthesis of IAA in
plants. It plays a key role in various plant
developmental processes, including root development
and lateral root formation.
Indolebutanoic acid (IBA) - Auxins - ...ANSWER... ✔
✔Is used on many crops and ornamentals to promote
growth and development of roots, flowers, and fruits;
and to increase crop yields. Growers find it more
effective and efficient than its natural courtparts
because plants cannot break it down as quickly.
GA4GA7 - Gibberellins - ...ANSWER... ✔
✔Primarily stimulate growth, particularly stem
elongation and seed germination.
GA3 - Gibberellins - ...ANSWER... ✔ ✔Promote stem
elongation, seed germination, and fruit development.
GA3 can increase fruit size and improve fruit shape in
crops like apples and grapes.
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CPPU - Cytokinins - ...ANSWER... ✔ ✔Is used to
promote plant cell division. This compound has been
used to increase embryogenic potential by inducing
somatic embryogenesis, assist in plant callus production
and investigate effects on plant biomass growth.
Kinetin - Cytokinins - ...ANSWER... ✔ ✔Promotes cell
division and growth in plants. It's primarily used in tissue
culture to induce cell division and promote shoot
regeneration, often in conjunction with auxins.
Ethephon - Ethylene / Ethylene releasers - ...ANSWER...
✔ ✔Used to promote fruit ripening, abscission, flower
induction, and other responses. Ethephon is registered
for use on a number of food, feed, and nonfood crops,
greenhouse nursery stock, and outdoor residential
ornamental plants, but is used primarily on cotton.
Ethylene - Ethylene / Ethylene releasers - ...ANSWER...
✔ ✔Primarily influencing fruit ripening, leaf
senescence, and abscission. It is a major regulator if
stress responses.
Abscisic Acid (ABA) - Inhibitors / Retardants -
...ANSWER... ✔ ✔It promotes dormancy in seeds and
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buds, triggers abscission of leaves and fruits, and plays
a crucial role in stress tolerance, particularly drought
and salinity. ABA also influences seed germination,
seedling development, and stomatel closure.
Ancymidol - Inhibitors / Retardants - ...ANSWER... ✔
✔A gibberellin biosynthesis inhibitor, used to control
plant height and promote compact growth in various
container-grown plants. It reduces internode elongation,
resulting in shorter, bushier plants.
Carbanyl - Inhibitors / Retardants - ...ANSWER... ✔
✔Is a chemical used to kill a variety of insect.
Insecticides conatining carbaryl are available over the
counter for residential use, mainly in the form of liquids,
sprays, and dusts.
Chlormequat - Inhibitors / Retardants - ...ANSWER...
✔ ✔Primarily used to control stem height, reduce
loding in cereal crops, and improve plant habit and
flowering in ornamentals. It works by inhibiting
gibberellin biosynthesis, which reduces cell elongation
and promotes thicker, sturdier stalk.
PCA - PLANT GROWTH REGULATORS EXAM
QUESTIONS AND ANSWERS 2025
1-naphthalenacetic acid (NAA) - Auxins - ...ANSWER...
✔ ✔Used as a rooting agent to stimulate root
development in cuttings and tissue cultures
2, 4-D - Auxins - ...ANSWER... ✔ ✔Used as a
herbicide, primarily used for broadleaf weed control. It
may also be used to regulate the growth of citrus plants
3-indoleacetaldehyde acid (IAId) - Auxins - ...ANSWER...
✔ ✔Playing a crucial role in the biosynthesis of IAA
within plants and microorganism. It is involved in various
aspects of plant growth and development, including cell
elongation, root initiation, and responses to
environmental cues.
3-indoleacetic acid (IAA) - Auxins - ...ANSWER... ✔
✔Is the most common auxin class phytohorme and
plays vital roles in plant growth and plant development.
processes, such as cell division, cell expansion, cell
differentiation and fruit development.
,2|Page
3-indolepyruvic acid (IPA) - Auxins - ...ANSWER... ✔
✔Is a crucial intermediate in the biosynthesis of IAA in
plants. It plays a key role in various plant
developmental processes, including root development
and lateral root formation.
Indolebutanoic acid (IBA) - Auxins - ...ANSWER... ✔
✔Is used on many crops and ornamentals to promote
growth and development of roots, flowers, and fruits;
and to increase crop yields. Growers find it more
effective and efficient than its natural courtparts
because plants cannot break it down as quickly.
GA4GA7 - Gibberellins - ...ANSWER... ✔
✔Primarily stimulate growth, particularly stem
elongation and seed germination.
GA3 - Gibberellins - ...ANSWER... ✔ ✔Promote stem
elongation, seed germination, and fruit development.
GA3 can increase fruit size and improve fruit shape in
crops like apples and grapes.
,3|Page
CPPU - Cytokinins - ...ANSWER... ✔ ✔Is used to
promote plant cell division. This compound has been
used to increase embryogenic potential by inducing
somatic embryogenesis, assist in plant callus production
and investigate effects on plant biomass growth.
Kinetin - Cytokinins - ...ANSWER... ✔ ✔Promotes cell
division and growth in plants. It's primarily used in tissue
culture to induce cell division and promote shoot
regeneration, often in conjunction with auxins.
Ethephon - Ethylene / Ethylene releasers - ...ANSWER...
✔ ✔Used to promote fruit ripening, abscission, flower
induction, and other responses. Ethephon is registered
for use on a number of food, feed, and nonfood crops,
greenhouse nursery stock, and outdoor residential
ornamental plants, but is used primarily on cotton.
Ethylene - Ethylene / Ethylene releasers - ...ANSWER...
✔ ✔Primarily influencing fruit ripening, leaf
senescence, and abscission. It is a major regulator if
stress responses.
Abscisic Acid (ABA) - Inhibitors / Retardants -
...ANSWER... ✔ ✔It promotes dormancy in seeds and
, 4|Page
buds, triggers abscission of leaves and fruits, and plays
a crucial role in stress tolerance, particularly drought
and salinity. ABA also influences seed germination,
seedling development, and stomatel closure.
Ancymidol - Inhibitors / Retardants - ...ANSWER... ✔
✔A gibberellin biosynthesis inhibitor, used to control
plant height and promote compact growth in various
container-grown plants. It reduces internode elongation,
resulting in shorter, bushier plants.
Carbanyl - Inhibitors / Retardants - ...ANSWER... ✔
✔Is a chemical used to kill a variety of insect.
Insecticides conatining carbaryl are available over the
counter for residential use, mainly in the form of liquids,
sprays, and dusts.
Chlormequat - Inhibitors / Retardants - ...ANSWER...
✔ ✔Primarily used to control stem height, reduce
loding in cereal crops, and improve plant habit and
flowering in ornamentals. It works by inhibiting
gibberellin biosynthesis, which reduces cell elongation
and promotes thicker, sturdier stalk.
