Topic 9.3: Growth in plants Flashcards
Definition of meristem
Tissues of undifferentiated cells capable of indeterminate growth
Types of meristematic tissue
a) Apical - Responsible for plant lengthening (Shoot apex + Roots)
b) Lateral - Responsible for plant thickening (Vascular / Cork)
Apical growth process
Auxins produced by the shoot apical meristem promotes growth via elongation and division
Plant hormone responsible for plant growth
Auxin (IAA)
Effect of auxin in shoots and roots
a) Stimulate cell elongation
b) Inhibit cell elongation
How to maintain a concentration gradient of auxin in plant tissue?
By using auxin efflux pumps, the direction of plant growth is determined.
How does auxin influence cell growth?
By changing the pattern of gene expression
a) Activates a H+ pump in the plasma membrane, causing secretion of H+ into cell wall
b) Decrease in pH causes cellulose fibers within the cell wall to loosen
Tropism definition
Growth or turning movement in response to a directional stimulus
Phototropism in shoots (enhancer)
a) The dark side of the shoot elongates and shoots grow towards the light
b) The lower side of the shoot elongates and roots grow away from the ground
Function of micropropagation
Produce large numbers of identical plants from undifferentiated meristematic tissue
Process of micropropagation
a) Undifferentiated shoot apex is selected from a stock plant and sterilized
b) Explant is grown on a sterile nutrient agar gel
c) Explant is treated with auxin to stimulate shoot and root development
d) Once the root and shoot are developed, the cloned plant is transferred to soil
Benefits of micropropagation
a) Rapid bulking (Desirable traits)
b) Virus free strains
c) Preservation of endangered species
