Growth and Development in Plants Flashcards
(24 cards)
What is the definition of development in living organisms?
Changes that occur in an organism starting from its beginning till its death.
Development includes aspects such as morphogenesis, differentiation, and maturation.
What are the three stages of cellular growth?
- Cell Division
- Cell Enlargement
- Cell Differentiation
These stages involve increasing the number and size of cells, as well as their specific functions.
What characterizes the growth curve of organisms?
An S-shaped sigmoid growth curve.
The growth curve includes a lag phase, log phase, and stationary phase.
What happens during the Lag Phase of the growth curve?
Initial slow growth.
What occurs during the Log Phase of the growth curve?
Rapid maximum growth.
What is the Grand period of growth?
Total time of fastest growth.
How can growth be quantitatively measured?
- Increase in length (stem/root)
- Increase in area or volume (leaves/fruits)
- Increase in cell number (e.g., yeast, bacteria)
Auxanometer can be used to measure the growth rate of shoot length.
What external factor is essential for photosynthesis?
Light.
What is the optimal temperature range for plant growth?
28–30°C.
What is the effect of water deficiency on plant growth?
Inhibits growth.
What role do mineral nutrients play in plant growth?
Required for metabolic processes; deficiency retards growth.
What are phytohormones?
Organic substances produced in small quantities that influence plant growth.
Name a major class of plant hormones.
- Auxins
- Gibberellins
- Cytokinins
- Ethylene
- Abscisic Acid
These hormones regulate various growth processes in plants.
What is the function of auxins in plants?
Promote cell elongation, apical dominance, delay leaf fall.
What do gibberellins promote in plants?
Stem elongation, break dormancy, induce parthenocarpy.
What is the role of cytokinins?
Promote cell division, inhibit apical dominance, prevent aging.
What does ethylene do in plants?
Promotes ripening, senescence, abscission, increases cell width.
What is the function of abscisic acid?
Induces bud/seed dormancy, senescence, inhibits germination, closes stomata.
What are practical applications of growth regulators?
- Induce seedless fruits
- Enable early flowering
- Promote seed germination
- Inhibit sprouting in storage (e.g., potatoes, onions)
Growth regulators can significantly enhance agricultural practices.
Define differentiation in plants.
Cells develop specialized structure/function.
What is dedifferentiation?
Differentiated cells regain the ability to divide.
What is redifferentiation?
Dedifferentiated cells specialize again to perform specific functions.
What are characteristics of woody plants?
- Perennial
- Hard stem
- Includes trees, shrubs, vines
- Growth rings show age
Types include deciduous and evergreen.
What defines herbaceous plants?
- Soft, green, flexible stems
- Mostly annuals/biennials
- Top dies in unfavorable season; regrows from seeds or roots.
