15)When a new leaf grows on a stem, the vascular system A) is present in the pri
ID: 269639 • Letter: 1
Question
15)When a new leaf grows on a stem, the vascular system
A) is present in the primordia and expands with the new leaf
B) grows up from the pre-existing vascular system and into the new leaf
C) starts within the new leaf and cells differentiate down toward the pre-existing vascular system
D) Dividing cells in the new leaf push down through the stem toward the preexisting vascular system
E) Hormone gradients trigger a line of apoptosis/programmed cell death to from the new vascular strand
12)In the tissue surrounding the apical meristem, a local accumulation of __________________ will determine where the next new leaf will form.
11)Formation of a distinct organ, tissue or cell type requires a 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).
10)his 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
A) Gibberellic acid B) Auxin C) Cytokinin
D) Strigolactone E) Abscisic acid
1)In the shade avoidance response, PIF transcription factors promote the expression of cell elongation genes because the low ratio of red:far red light converts Pfr to Pr such that Pfr is not present to target PIF for ubiquitination and degradation, AND gibberellic acid promotes ubiquitination and degradation of DELLA repressors, which otherwise bind to and inhibit PIF transcription factors.
A) TRUE B) FALSE C) WHAAAAAT?
2)In a classic experiment, Ian Sussex carefully separated a leaf primordia from the adjacent apical meristem. What was observed?
A) The leaf developed normally
B) The leaf primordia transitioned into a second apical meristem
C) The leaf primordia grew out as branch
D) The leaf grew out as needle-like structure instead of a flat blade
E) The leaf primordia transitioned to a flower primordia
Explanation / Answer
Answer 15) When a new leaf grows on a stem, the vascular system is present in the primordial and expands with the new leaf.
Answer 12) Auxin
Answer 10)Auxin
Answer 1) False
Answer 2)The leaf primordia transitioned into a second apical meristem
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