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BIO 274-01
Exam 4
Name ___________________
Multiple Choice (3 pts each)
1.
a.
b.
c.
d.
All of the following are a function of roots except
absorption of water and nutrients
converting light energy to chemical energy
conduction of absorbed minerals
anchoring plant in the soil
2.
a.
b.
c.
d.
All of the following are true about fibrous root systems except
have several main roots
are denser than tap roots
develop from the radicle only
all of the above are true
3.
a.
b.
c.
d.
Adventitious roots are defined as
roots that have several main roots that form a dense mass of roots
roots that have one main root from which lateral roots branch
roots that do not arise from another root or the embryo
none of the above are true
4.
a.
b.
c.
d.
Climbing vines have
a tap root system
a fibrous root system
both a and b
an adventitious root system
5.
a.
b.
c.
d.
The root cap functions to
protect the root
provide nutrients to the root
is located at the tip of the root
both a and c
6.
a.
b.
c.
d.
The epidermis
anchors the plant in the soil
converts sunlight to chemical energy
is the reproductive structure of the plant
none of the above
7. All are true about the quiescent center except
a. it is located in the center of the RAM
b. it is the zone where root initials are maintained
c. it is characterized by low mitotic activity
d. it originates from the embryo proper
8.
a.
b.
c.
d.
Primary roots are formed in the
embryo only
from the lower tier of the embryo
from the hyphophysis
both b and c
9.
a.
b.
c.
d.
The hyphophesis
is the uppermost cell of the suspensor
undergo’s divisions that result in the QC
produces lateral roots
both a and b
10. Growth of lateral roots is triggered by
a. ethylene
b. gibberellic acid
c. auxin
d. none of the above
---------------------------------------------------------------------------------------------------------Short Answer
11. The RAM differentiates into three primary meristems. What are they and what
develops from each one? (6 pts)
Protoderm - epidermis
Ground meristem - cortex
Procambium – xylem, phloem
12. The root has three zones of development. List and describe them. (6 pts)
Root apical meristem – zone of cell division
Region of elongation – no cell division, rapid growth by elongation
Region of maturation – zone of differentiation, cells complete differentiation into
specialized cells
13. What is the “quiescent center? The QC is analogous to what zone in the SAM?
(6 pts)
The QC is located in the center of the RAM, it is the zone where root initials are
maintained. It is analogous to the central zone of the SAM.
14. What determines the identity of a cell (specialized function) in the root? (5 pts)
The location of the cell in the root.
15. What will happen if you use a laser to destroy cells in the cortical layer? (6 pts)
The cells of the adjacent layers will invade the empty space and assume the cell division
patter of cortical initials.
16. Where is growth of lateral roots initiated? Why do these roots only develop in the
late cell elongation, early cell differentiation zones? (5 pts)
In the pericycle, this is the zone where cells are differentiated enough to have a specific
function.
17. How do plant hairs differ from lateral roots? (5 pts)
Plant hairs are found on root epidermis, lateral roots originate from the pericycle.
18. Complete the following table. (6 pts)
Gene Mutation
Phenotype of Plants with Mutation
Fass (fs)
Enlarged roots resulting from enlarged
vascular cylinder and multiple cortical
layers
Superroot (sur1) Several lateral and adventitious roots;
produces greater levels of auxins
HOBBIT (HBT)
Interference with cell division and cell
type specification; root cap cells and
Proposed Function of Gene
a.
b.
Gene required for the maintenance of
cell division and acquisition of the
QC cells cannot be maintained
differentiated state
a. regulates cell growth
b. regulates auxin production
19. Mutations in the HOBBIT (HBT) gene interfere with what two functions in
Arabidopsis roots? (5 pts)
Cell division and cell type specification.
20. The HBT gene encodes a homolog of the CDC27 subunit of the Anaphase Promoting
Complex. What is the specific function of this complex? (5 pts)
Cell cycle progression, it degrades proteins to allow M phase progression.
21. SCR and SHR encode what type of regulatory proteins. What is the function of these
genes? (6 pts)
GRAS-type transcription factors required for asymmetric division of ground tissue stem
cells and endodermis specification.
22. What phenotype is observed in plant that have a mutation in the rml1 and rml2
genes? (4 pts)
Very short primary roots, lateral roots that do not elongate.