Plant Growth Flashcards
Define meristem
Meristems are confined regions of growth in plants composed of undifferentiated cells undergoing active cell division and thus capable of indeterminate growth
Plant growth is generally indeterminate. What is indeterminate growth?
Cells continue to grow indefinitely throughout the life of the plant producing any number of extra structures or tissues from the meristem
State plants have totipotent cells
Meristems are analagous to totipotent stem cells in animals allowing plants to regrow structures or even form entirely new plants containing cells that are totipotent
What is apical meristem?
Apical meristems occur at shoot and root tips and are responsible for primary growth (i.e. plantlengthening)
What are lateral meristems?
Lateral meristems occur at the cambium and are responsible for secondary growth (i.e. plantwidening / thickening)
How does the apical meristem cause growth of the plant?
Growth at these regions is due to a combination of cell enlargement )cells absorb nutrients and water and therefore increase in volume and mass) and repeated cell division to produce more cells (mitosis and cytokinesis)
Root meristems are responsible for? (Differentiation of the dividing meristem gives rise to a variety of structures for plant growth)
Root meristems are responsible for growth and extension of the root.
Shoot meristems creates cells responsible for? (Differentiation of the dividing meristem gives rise to a variety of structures for plant growth)
Shoot meristems creates cells responsible for shoot growth, but also create groups of cells that will develop into flowers and leaves.
How does mitosis occur in the growth of stem and leaves while maintaining a meristem.
With each division, some cell remains in the meristem (and continue to undergo cell division to produce more cells) while the other cells increase in size and differentiates as they get displaced from the meristem region
Apical meristems create additional meristems including? And what does each give rise to?
protoderm (forms epidermis), procambium (forms vascular tissue) and ground meristem (forms pith, cortex and mesophyll)
What is leaf primordia.
Young leaves produced at the sides of the shoot apical meristem. They appear as small bumps known as leaf primordia.
What plays a large role in determining which type of specialised tissue develops from unspecialised plant cells?
Chemical influences
What are axillary buds?
Axillary buds are shoots which are inactive and left behind as regions of meristems at the junction or node of the stem and base of the leaf when the shoot apical meristem grows and forms leaves.
What is the function of auxin?
- It initiates the growth of roots
- Influences the development of fruits
- Regulates the development of leaf
The most abundant auxin is? And what are the effects?
The most abundant auxin is indole-3-acetic acid (IAA)
IAA has a range of effects, among which elongation of cells in the stems is the most important effect.
Where is auxin produced?
Auxins (IAA) are produced by the shoot apical meristem
What is the role of auxin in apical dominance?
The production of auxins additionallypreventsgrowth inlateral (axillary) buds, this is known asapical dominance
What determine whether the axillary bud will develop.
The relative ratio of cytokinins and auxins determine whether the axillary bud will develop.
What is cytokinins?
cytokinins is a plant hormone produced in the root which promotes axillary bud growth.
What is the need of apical dominance?
Apical dominance ensures that a plant will use its energy to grow up towards the light in order to outcompete other plants
What happens when distance between the terminal bud and axillary bud increases?
As the distance between the terminal bud (where apical meristem is situated) and axillary bud increases, the inhibition of the axillary bud by auxin diminishes
What is the hormone gibberlins?
Gibberellins are another category of hormones that contribute to stem elongation
What is Tropism?
tropism is a plant growth response to external stimuli in which the stimulus direction
determines the direction of the growth response.
What controls tropism?
Plant uses hormones to control the growth of stems and roots. Hormones control both the growth are rate of growth.
What is phototropism?
Directional growth of plant in response to a unidirectional light source
What is gravitropism?
Directional growth in response to gravitational forces
