Final answer:
FLD (Flowering Locus D) promotes flowering in Arabidopsis by participating in the epigenetic regulation of genes necessary for flowering. Epigenetic modifications alter gene expression to inhibit flowering in new seedlings and enable flowering following cold exposure through vernalization.
Step-by-step explanation:
In Arabidopsis, FLD (Flowering Locus D) is a deacetylase enzyme known for its role in stimulating flowering in the plant. The correct answer to the student's question, 'Which of the following is TRUE?' with respect to FLD's function is b) FLD promotes flowering. This is because FLD is involved in the epigenetic regulation of flowering, acting to deacetylate histones and therefore promoting the expression of genes necessary for flowering.
Epigenetic modifications in Arabidopsis consist of changes in the histone proteins associated with DNA, which can alter gene expression. New seedlings express the Flowering Locus C (FLC) gene, which inhibits flowering and is associated with specific histone modifications that prevent flowering. After exposure to cold temperatures, a process known as vernalization, the FLC expression is reduced due to changes in epigenetic marks, which enables the plant to flower.