Prepare for NEET Biology Anatomy of Flowering Plants (Phloem) with MCQs & PYQs on NEET.GUIDE. Access free practice, previous year questions, and expert guidance to study sieve tubes, companion cells, and translocation of food.
NEET Questions / Botany / Anatomy of Flowering Plants / Phloem
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
Which of the following is NOT a characteristic of phloem sieve tubes?
Presence of a nucleus at maturity
Living cells
Presence of sieve plates
Transport of organic substances
The primary driving force for the movement of substances in the phloem is:
Transpiration pull
Capillary action
Root pressure
A pressure gradient created by active loading and unloading of sugars
Which cells are closely associated with sieve tube elements and provide metabolic support?
Parenchyma cells
Sclerenchyma cells
Companion cells
Tracheids
The direction of phloem transport is:
Unidirectional, always upwards
Unidirectional, always downwards
Source to sink
Sink to source
