Biology 110

Plant Growth and Development: overview

Development - a change in structure over time

• Examples in plants

Growth - an increase in size

• Indeterminant growth in contrast to determinant growth
• Mechanisms: cell division and expansion (elongation)

Meristems are regions where growth takes place

• Primary growth - apical meristems
• Secondary growth - cambium

Hormones (plant growth substances) are chemical messengers active at very low concentration whose only function is to influence growth and development. They often work in combination.

• Promoters

Auxin (IAA)

Gibberellins (GA)

Cytokinins (CK)

• Inhibitors

Ethylene

Abscisic acid (ABA)

• Cellular mechanism of hormone action (a model)

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