Question

Cause of chromosome laggards in meiosis
(a) Inversion
(b) Dicentric chromosome
(c) Acentric chromosome
(d) Duplicate of a gene

Answer 1

Hint: Meiosis is the specialised kind of cell division that results in reducing the chromosome number into half, to produce haploid daughter cells.

Complete answer:
Dicentric chromosome is the cause of chromosome laggards in meiosis as it is an abnormal chromosome with two centromeres. When two chromosome segments fuse, each having a centromere, resulting in the loss of acentric fragments, and forming dicentric fragments, a dicentric chromosome is formed. "A laggard was defined as a chromosome that did not overlap along the long axis of the spindle with any of the properly segregating chromosomes".

Additional Information:
Key features of meiosis are as follows -
1. Meiosis involves two sequential cycles of nuclear and cellular division called meiosis 1 and meiosis 2 but only one cycle of DNA replication.
2. Meiosis 1 is initiated after the parental chromosomes have replicated to produce identical sister chromatids at S phase.
3. During the process of meiosis, pairing of homologous chromosomes and recombination between them occurs.
4. Four haploid cells are formed at the end of meiosis 1.

So the correct answer is, ‘Dicentric Chromosome’

Notes:
1. Homologous chromosomes pair together during Zygotene of prophase-I of meiosis. This pairing is called synapsis.
2. Crossing over is a mechanism of physical exchange of segments of chromosomes taking place between non-sister chromatids of homologous chromosomes at a point known as chiasmata.
3. Anaphase lag occurs due to an occasion during cellular division where sister chromatids don't properly break away one another due to improper spindle formation.