Plant Physiology This is a mesquite leaf that I plucked from a mesquite tree out
ID: 268310 • Letter: P
Question
Plant Physiology
This is a mesquite leaf that I plucked from a mesquite tree outside the EESAT building. Note that it has a distinctive bifurcation and compound pinnate structure. Also note that the leaflets I separated from the leaf show aberrant morphology and developed additional leaflets on the leaflets. If this development resulted from aberrant hormone distribution, the new leaflets likely correspond to localized increases in 10) A) Gibberellic acid C) Cytokinin B) Auxin D) Strigolactone E) Abscisic acid boundary between the material that will form the organ tissue, or cell, and that which will not. Explain how such a boundary may arise (2 points) and give an example of such a boundary in plants (1 point). will In the tissue surrounding the apical meristem, a local accumulation of determine where the next new leaf will form. 12) A) Ethylene B) Auxin C) CytokininD) Strigolactone Abscisic acidExplanation / Answer
10. Option B is correct.
Auxin is involved in leaflet initiation.
Leaflet formation occurs along the leaf margin where the auxin maxima is established.
11. There are several boundary-specific genes in plants such as LBD and CUC. These genes are expressed exclusively at the boundaries and prevent the growth.
For example, CUC2 is expressed at the sinus region and prevents the growth at the sinus. It also promotes auxin maxima establishment at the flanks which grow out into serration tips.
Examples of boundaries = Sepal boundaries, Stem-leaf boundary and boundary between two cotyledons.
12. Option B is correct.
Auxin is involved in the specification of the positioning of new primordia at the flanks of the meristem (RAM or SAM).