Prepare for NEET Biology Anatomy of Flowering Plants with MCQs & PYQs on NEET.GUIDE. Enjoy free practice, previous year questions, and expert insights on plant tissues and structures.
The specific arrangement of sieve elements and companion cells in phloem tissue, where a single companion cell is associated with multiple sieve elements, is MOST characteristic of which plant group?
Angiosperms
Gymnosperms
Bryophytes
Pteridophytes
Which specific plasmodesmatal characteristic is crucial for the symplastic loading of sucrose into the phloem's sieve element-companion cell complex?
Absence of plasmodesmata between companion cells and sieve elements
Uniformly distributed plasmodesmata with a low density throughout the phloem
Branched plasmodesmata with a high density between companion cells and bundle sheath cells
Numerous plasmodesmata between companion cells and surrounding parenchyma cells, but few between companion cells and sieve elements
The 'polymer trapping' model explains phloem loading by suggesting that sucrose is converted into larger molecules in which specific cell type?
Sieve elements
Companion cells
Phloem parenchyma cells
Bundle sheath cells
Which P-protein configuration within a damaged sieve element is MOST directly responsible for preventing excessive sap loss?
P-protein dispersing throughout the sieve element lumen
P-protein degrading into amino acids
P-protein lining the sieve element cell wall
P-protein forming a 'plug' at the sieve plate pores
Besides sucrose, which other carbohydrate is commonly transported in the phloem, particularly in some tree species during early spring?
Starch
Cellulose
Glycogen
Sugar alcohols (e.g., sorbitol, mannitol)
In which specific cellular location are the informational molecules, such as RNA and proteins, that are transported via the phloem, synthesized?
Sieve elements
Companion cells
Phloem parenchyma cells
Xylem parenchyma cells
A unique feature observed in the dicot root vascular cylinder is the presence of:
Endarch xylem with four protoxylem poles
Exarch xylem with more than six protoxylem poles
Mesarch xylem with two protoxylem poles
Centrarch xylem with a single protoxylem pole
During secondary growth in dicot roots, which tissue initiates the formation of the vascular cambium?
The innermost layer of the cortex
The pericycle cells opposite to the protoxylem poles
The pith parenchyma cells
Partly from the pericycle and partly from the conjunctive parenchyma cells lying just below the phloem bundles
The passage cells in the endodermis of a dicot root are characterized by the absence of which Casparian strip component?
Lignin
Suberin lamellae
Cellulose
Pectin
Which tissue layer in the dicot root is primarily responsible for the initiation of lateral roots?
Endodermis
Pericycle
Cortex
Epiblema
