Photosynthetic sugar molecules are transported via phloem to other parts of the plants. The following aspects are associated with sucrose unloading in phloem and its transport;

a) The presence of plasmodesmata is assumed to provide apoplastic transport. An absence of plasmodesmata between cells indicates an nonfunctional symplastic continuity

b) Phloem unloading and short-distance transport can occur via symplastic as well as apoplastic pathways

c) Both unloading and the short-distance pathway appear to be completely symplastic in some young eudicot leaves, such as sugar beet and tobacco

d) An apoplastic step is required in developing seeds because there are no symplastic connections between the maternal tissues and the tissues of the embryo

Which of the following combination is INCORRECT?

#Question id: 2863

#Unit 2. Cellular Organization

The promoter of the araBAD operon from E. coli is activated in the presence of arabinose and the absence of glucose and directs expression of genes encoding enzymes required for arabinose metabolism. Unlike the cases of lac and gal genes, where a repressor and an activator work together, here two activators work together: AraC and CAP

#Question id: 2864

#Unit 2. Cellular Organization

In E. coli, the five contiguoustrp genes encode enzymes that sythesize the amino acid tryptophan. These genes are expressed efficiently only when tryptophan is limiting. The genes are controlled by a repressor, just as the lac genes are, although in this case, it is the absence of its ligand (tryptophan) that relieves repression, match trp genes to their gene product,

#Question id: 2865

#Unit 2. Cellular Organization

The trp operon is controlled by repression and attenuation, providing a two-stage response to progressively more stringent tryptophan starvation. But attenuation alone can provide robust regulation: other amino acid operons such as leu and his rely entirely on attenuation for their control. Correct number of codons in leader peptide of leu & his operon  in a row;

#Question id: 2867

#Unit 2. Cellular Organization

Deletion in region 3 enhances operon or rate of transcription (in trp operon); Choose an incorrect statement.

#Question id: 2868

#Unit 2. Cellular Organization

Given the following mutants and conditions, predict the expression of the of the lacZ gene (no expression, basal level of expression, or activated level of expression). A mutant of E. coli that has a mutation in the operator of the lac operon that prevents the repressor from binding

#Question id: 2869

#Unit 2. Cellular Organization

Galactose imported into the yeast cell is converted to galactose 6-phosphate by a pathway involving six enzymes, whose genes are scattered over three chromosomes. Transcription of these genes is regulated by the combined actions of the proteins Gal4p, Gal80p, and Gal3p,