Courses
Courses for Kids
Free study material
Offline Centres
More
Store Icon
Store

Perforations are not found in cell wall of the following cell 

a) Tracheid

b) Companion cell 

c) Sieve Tube 

d) Vessels

seo-qna
Last updated date: 13th Jun 2024
Total views: 413.1k
Views today: 6.13k
Answer
VerifiedVerified
413.1k+ views

Hint: Perforated cell walls mean it is a cell with holes in it. In a biological cell, the holes are in the cell membrane/cell wall. In some angiosperm plants, end walls of some cells of xylem and phloem are modified into perforation plates, an area or areas in which there is no shared wall material or membrane.


Complete answer:

Xylem elements contain the tracheid and vessels. These help in the conduction of water. They are long tube-like structures with partially or completely dissolved walls to form water pipes (in vessels) and pits in the cell wall (in tracheid) for conducting water. Pits are relatively thinner portions of the cell wall that adjacent cells can communicate or exchange fluid through. Sieve tube and companion cells are part of phloem. Sieve tube members do not have ribosomes or a nucleus and thus need companion cells to help them function as transport molecules. Companion cells provide sieve tube members with proteins necessary for signaling and ATP in order to help them transfer molecules. They are associated with the cells of the sieve tube with the help of plasmodesmatal connections. Plasmodesmatal connections are the connections of cytoplasms of neighboring cells established through the plasmodesmata. The plant cells exchange small molecules with their neighboring cells through these plasmodesmatal connections. So, plasmodesmata connection itself means pores in the cell wall.

So, our first option is tracheid. Tracheid have pits in their cell wall but do not have pores. People confuse these pits with pores but it is just a thinned out cell wall not pores. So, tracheids do not have perforated cell walls. 

Our next option is companion cells. As we already mentioned, companion cells have plasmodesmatal connection with sieve tubes and plasmodesmatal connection itself means they have pores in the cell wall. So, companion cells have perforated cell walls. So, this option is wrong. 

Next option is sieve tube, which is a part of phloem as the name suggests sieve tube has perforated cell wall.

Vessels are part of xylem and they have perforated cell walls. So, the correct option is a) Tracheids. 


The correct option is (a) Tracheids.


Note: Do not confuse between companion cell and tracheid. Tracheid have pits in their cell that doesn't mean they have pores in their cell wall .Companion cells have plasmodesmata connection with sieve tubes and have perforated cell walls.