Question

Cells of quiescent centre are characterized by
A. Dense cytoplasm and prominent nuclei
B. Light cytoplasm and small nuclei
C. Dividing regularly to add to the corpus
D. Dividing regularly to add to tunica

Answer 1

Hint: Cell division: It is a very important process in living organisms.
During cell division: DNA replication and cell growth take place.
All these processes that are cell division, DNA replication and cell growth have to take place in a coordinated way to make sure the division is correct and formation of progeny cells.

Complete answer:
Cell cycle: It is an order of events by which a cell duplicates its genome and synthesizes the other constituents of the cell and further divides into two daughter cells.

> The cell cycle is divided into two phases:
- Interphase (95%)
- M Phase (5%)

> The interphase is further divided into three more phases:
- Gap 1
- S phase
- Gap 2

Quiescent centre:
- It is a region in the apical meristem of a root where cell division begins very slowly or not at all.
- These cells divide casually as they are inactive and are present at the pole of cortex and stele.
- The cells with a Quiescent centre have small dictyosomes, nuclei and nucleoli with little cytoplasm.
- These cells contain endoplasmic reticulum, mitochondria and contain low concentrations of RNA, DNA and protein.

Hence, The correct answer is option (B).

Additional information:
Meiosis: It is a special type of cell division that reduces the chromosome number by half and results in the production of haploid daughter cells.
- Meiosis involves two sequential cycles of nuclear and cell division called meiosis 1 and meiosis 2. It can be best seen in microspore mother cells.

Note: Prokaryotes which included bacteria and archaebacteria usually undergo a vegetative cell division known as binary fission. In this their genetic material is segregated equally into two daughter cells. There are alternative manners of division such as budding.
All cell division, regardless of organisms, is preceded by a single round of DNA replication.