Biology

Cell Cycle and Chromosomes

1,219 Questions

Explore a curated list of questions covering the cell cycle, mitosis, and meiosis. Topics include DNA replication, chromosomal structures, and genetic disorders. This material is essential for students preparing for biology and general science competitive exams.

Cell cycle eventsDNA replicationMeiosis processChromosomal structuresGenetic disorders

Cell Cycle and Chromosomes Questions

Multiple choice

Which among the following genotypes represents Klinefelter syndrome in an individual?

  1. XO

  2. XX

  3. XXY

  4. XYY
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

XXY is Klinefelter's syndome. It is described as an inequality in X chromosomes where a male (dubbed by inheriting a X chromosome) also inherits an extra X chromosome, giving them female qualities. This can include a more slender shape, more refined hips, breast development, absence of facial hair, etc.

Multiple choice

Polytene chromosomes are formed because of

  1. DNA replication and cell division

  2. RNA transcription and cell division

  3. DNA replication without cell division

  4. RNA transcription without cell division
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

DNA replication occurs several times without cell division, thereby increasing cell volume in case of polytene chromosomes.

Multiple choice

During meiosis, the 'rough pairing' of chromosomes takes place at ______________.

  1. diakinesis

  2. leptonema

  3. diplonema

  4. zygonema

  5. pachynema
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The chromosomes continue to become denser. The homologous pairs have also found each other and begin to initially align with one another, referred to as 'rough pairing'. Lateral elements also form between the two homologous pairs, forming a synaptonemal complex.

Multiple choice

In which of the following stages, the equatorial plate formed is rotated by 90 degrees?

  1. Growth 1 phase

  2. Anaphase II

  3. Prophase II

  4. Metaphase II

  5. Telophase II
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

During this stage, the centromeres that contain two kinetochores attach to the spindle fibers at each pole from the centrioles. The equatorial plate formed here is rotated by 90 degrees, compared to meiosis I and is perpendicular to the previous metaphase plate.

Multiple choice

Chromosomes are thread-like structures being found in the nucleus of every living cell. Which among the following chromosomes is not present in humans?

  1. Metacentric chromosome

  2. Telocentric chromosome

  3. Subtelocentric chromosome

  4. Submetacentric chromosome

  5. Acrocentric chromosome
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Also known as the monarchial type of chromosomes, they have a centromere that is located towards the end of the chromosome. Thus, telocentric chromosomes have a 'rod' shaped appearance. In some cases, the telomeres extend from both the chromosome ends. The telocentric chromosome is not present in humans.

Multiple choice

Certain chromosome-breaking processes like irradiation leads to the formation of ________________.

  1. dicentric chromosomes

  2. monocentric chromosomes

  3. acentric chromosomes

  4. holocentric chromosome

  5. polycentric chromosome
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Acentric chromosomes are those that lack centromeres, i.e. the centromere is totally absent on the chromosome. These chromosomes are observed due to effects of chromosome-breaking process like irradiation.

Multiple choice

Cytokinesis is the physical process of cell division that divides the cytoplasm of a parent cell into two daughter cells. Which among the following statements regarding the cytokinesis in the animal cells is incorrect?

  1. The position at which the contractile ring assembles is dictated by the mitotic spindle.

  2. Abscission depends on septin filaments.

  3. The process of abscission physically cleaves this midbody into two.

  4. It begins shortly after the onset of sister chromatid separation.

  5. A contractile ring made of muscle myosin II and actin filaments assembles parallelly at the cell cortex.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

A contractile ring made of non-muscle myosin II and actin filaments assembles equatorially (in the middle of the cell) at the cell cortex (adjacent to the cell membrane). Myosin II uses the free energy released when ATP is hydrolysed to move along these actin filaments, constricting the cell membrane to form a cleavage furrow.

Multiple choice

Which among the following statements does not characterise meiosis in cell division?

  1. Meiosis occurs in eukaryotic life cycles involving sexual reproduction.

  2. Meiosis uses many of the same mechanisms as mitosis.

  3. Meiosis does not occur in archaea or bacteria.

  4. Before meiosis begins, during S phase of the cell cycle, the DNA of each chromosome is replicated.

  5. Meiosis begins with one haploid cell.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Meiosis begins with one diploid cell containing two copies of each chromosome- one from the organism's mother and one from its father. The cell divides twice, potentially producing up to four haploid cells containing one copy of each chromosome.

Multiple choice

Husband & wife present for counseling following three first trimester miscarriages. As part of their evaluation, both partners have chromosomal analysis. Husband is found to have the karyotype 46,XY,inv8(p13q23). What would you counsel them?

  1. This is a normal progeny likely of no significance.

  2. This is an abnormal chromosomal composition that would cause congenital anomalies if transmitted to a child.

  3. This rearrangement may lead to chromosomal imbalance in the offsprings and could explain multiple miscarriages in the female.

  4. This rearrangement may cause to dicentric or acentric chromosomes in the offsprings, which would probably not be appropriate with survival.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This is a pericentric inversion. Crossing over within the inversion loop would lead to duplication and deficiency of parts of chromosome 8, which might cause congenital anomalies.

Multiple choice

Which of the following statements is true about polytene chromosome?

  1. They are inert cellular objects seen in drosophilla.

  2. Banding pattern of polytene chromosome is constant in individuals of one species.

  3. Puffs seen in polytene chromosomes are the sites of gene expression.

  4. Giant chromosomes are not useful in studies of gene expression system.

  5. Formation of giant chromosomes happen in adult fly.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Puffs seen in polytene chromosomes are the sites of gene expression, where DNA strands are unwinded and actively take part in transcription.

Multiple choice

In which of the following stages does recombination of genes take place?

  1. Zygotene stage

  2. Pachytene stage

  3. Leptotene stage

  4. Diakinesis
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Recombination of genes takes place at pachytene stage. During pachytene stage of meiosis I, non-sister adjacent chromatids in a tetrad, coil around each other at one or more points called Chiasmata. Chromatids break down at Chiasmata and then rejoin with the exchange of segments resulting in recombinants.