Transcription of eukaryotic genes can be repressed in various ways. These include the four mechanisms

1. Competition	a-Repression is caused by recruiting histone modifiers that alter nucleosomes in ways that inhibit transcript
2. Inhibition	b-A repressor binds to a site on DNA beside an activator and interacts with that activator, occluding its activating region
3. Direct repression	c-By binding to a site on DNA that overlaps the binding site of an activator, a repressor can inhibit binding of the activator to a gene and thus block activation of that gene.
4. Indirect repression	d-A repressor binds to a site upstream of a gene and, by interacting with the transcriptional machinery at the promoter in some specific way, inhibits transcription initiation.

#Question id: 7288

#Unit 5. Developmental Biology

Following statements are regarding to the expression of genes in floral quartate model in Arabidopsis thaliana.

A. Sepals- AP1(heterodimer) + SEP(homodimer)

B. Petals-AP1(monomer)+PI(monomer)+AP3(monomer)+SEP(monomer)

C. Stamens- AP3(monomer)+PI(monomer)+AG(monomer)+SEP(monomer)

D. Carpels- AG(homodimer)+SEP(homodimer)

Which of the following genetic combinations are incorrect?

#Question id: 7289

#Unit 5. Developmental Biology

The following scheme shows the flowering status of a plant species and the photoperiodism. Which of the following conclusions is most appropriate?

#Question id: 7289

#Unit 1. Molecules and their Interaction Relevant to Biology

The following scheme shows the flowering status of a plant species and the photoperiodism. Which of the following conclusions is most appropriate?

#Question id: 7290

#Unit 5. Developmental Biology

Following figure regarding to regulatory network in the Arabidopsis shoot meristem stem-cell niche.

A. The transcription factor WUS is synthesized in the cell A and moves via plasmodesmata into cell B, where one of its functions is to induce expression of the CLV3.

B. The transcription factor CLV3 is synthesized in the cell A and moves via plasmodesmata into cell B, where one of its functions is to induce expression of the WUS.

C. Secreted CLV3 protein from cell B binds to the receptor protein kinase on the surface of cell A; there, it activates a signal that represses WUS transcription.

D. Secreted WUS protein from cell B binds to the receptor protein kinase on the surface of cell A; there, it activates a signal that represses CLV3 transcription.

Which of the following combination is correct?

#Question id: 7291

#Unit 5. Developmental Biology

Five different genes are known to specify floral organ identity in Arabidopsis: APETALA1 (AP1), APETALA2 (AP2), APETALA3 (AP3), PISTILLATA (PI), and AGAMOUS (AG).

Which one of the following statement is incorrect?

#Question id: 7292

#Unit 5. Developmental Biology

How is plant cell cytokinesis different from animal cell cytokinesis?