Question

As with all multicellular organisms, homeotic genes in plants control morphogenesis (how the tissues and organs of the plant are arranged). in maize plants, the homeotic gene knotted1 (abbreviated kn1) maintain the indeterminate state of shoot apical meristems. in wild-type maize plants, kn1 is expressed at high levels in the shoot apical meristem, but is expressed at low levels in leaves. in some mutant maize plants, kn1 is expressed at high levels in leaves. in those plants, outgrowths or knots of adventitious shoot meristems (shoot meristems that appear in abnormal locations on the leaves) form. use this information to determine which of the following statements are true. select the four statements that are true.
a. expression of the kn1 gene in shoot apical meristem cells produces a protein involved in the maintenance of shoot apical meristems.
b. in wild-type maize plants, the kn1 gene is mostly expressed in shoot apical meristem cells.
c. in mutant maize leaves, the kn1 gene is mostly not expressed.
d. leaves of the mutant maize plants produce more kn1 protein than leaves of wild-type maize plants.
e. both the wild-type and mutant maize leaves have the same morphology.
f. in wild-type maize plants, the kn1 gene is present in shoot apical meristem cells, but not in leaf cells.
g. in wild-type maize plants, the kn1 gene is expressed diferentially in shoot apical meristem cels and leaf cells.

Answer 1

Answer:

a. True

b. True

c. False

d. True

e. False

f. False

g. True

Explanation:

The homeotic genes refer to evolutionarily conserved genes that modulate the development of different structures in organisms of the same groups (in this case, plants).  Moreover, homeobox genes are genes that encode transcription factors involved in the regulation of development in eukaryotic organisms. The knotted1 (kn1) gene is a plant homeobox gene is a member of the kn1 homeobox (knox) gene family, which is responsible for maintaining indeterminacy and preventing cellular differentiation. In maize, kn1 plays a key role in maintaining the cells of the shoot apical meristem in an undifferentiated state, being mainly expressed in shoot meristems during postembryonic stages of shoot development. It has been observed that maize mutant plants where kn1 is ectopically expressed (i.e., in tissues in which this gene is not normally expressed) exhibit proximal-distal patterning defects.