Question

In sieve elements, the pores in the sieve plate are blocked by a substance called-
A. Cutin
B. Callose
C. Suberin
D. Lignin

Answer 1

Hint: The phloem comprises sieve components, companion cells, phloem parenchyma cells, and phloem fibers. We know that the sieve tubes are the enlarged living cells found in the phloem of the flowering plants, which are concerned with the conduction of food transport, mostly glucose inside the plant body.

Complete Answer:
- Sieve tubes consist of sifter components which are lengthened cells, associated with one another utilizing sifter plates to frame a continuous tube framework that spreads out through the whole plant.
- Sieve plates are end dividers containing enormous pores to give an association between adjoining sifter components. To create a tube of low obstruction, sieve components free the vast majority of their cell parts, for example, nucleus, cytoskeleton, ribosomes, tonoplast, and so on during ontogeny. Develop sifter components contain basic phloem explicit proteins (P-proteins), mitochondria, ER and strainer components plastids.
- We should know that in gymnosperms vascular plants, the composition of the sieve tubes have primitive features. The members of the sieve tube are tubular in structure. These members are placed continuously and have specialized sieve areas that are known as sieve plates that are located in the posterior region.
- We can also say that there are severe perforations in the sieve areas meant for interconnection, using protoplasmic strands. When they are matured, they are blocked by callose. It plays a critical function in the regenerative science of angiosperms, especially. The callose wall encompasses the sporophytes while meiosis happens. Due to its structure, it might give a segregation obstruction fixing off one meiotic cell (pollen mother cell or megaspore mother cell) from another.

Thus, we can say that option B is correct because callose blocks the sieve pores to keep the phloem translocation active.

Note: We get to know that callose plays significant functions in numerous cycles during plant growth and development. It will regulate the transportation in plants which is very necessary for the growth and development of the plant.