Biology

Cell Cycle and Chromosomes

1,348 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

Molecular analysis is performed on the three copies of chromosome 21 in a child with Down syndrome using DNA polymorphisms for which both parents are heterozygous for different alleles. Two of the chromosomes contain same alleles as one of the mother's alleles. Based on this, when did the nondisjunction event most likely occur?

  1. Maternal meiosis I

  2. Maternal meiosis II

  3. Paternal meiosis I

  4. Paternal meiosis II
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

If two copies of chromosome 21 have the same maternal alleles, the nondisjunction must have occurred in maternal meiosis II, when the two identical chromatids normally separate.

Multiple choice

Which of the following syndromes is associated with Uniparental disomy for chromosome 15 in which both chromosomes are maternally derived?

  1. Prader-Willi syndrome

  2. Angelman syndrome

  3. Rett syndrome

  4. Beckwith-Wiedemann syndrome
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Having maternal uniparental disomy for chromosome 15 results in Prader-Willi syndrome. It is caused by the loss of function of genes in a particular region of chromosome 15 & affects many parts of the body.

Multiple choice

The phase of mitosis during which chromosomes condense is

  1. prophase

  2. telophase

  3. metaphase

  4. anaphase
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

It is the first stage of mitosis, during which the chromosomes condense and become visible. The nuclear membrane breaks down & the chromosomes condense during prophase.

Multiple choice

Pick out the true statement regarding the karyotype analysis.

  1. It is frequently done on the cells of foetus because it cannot detect the most genetic disorders.

  2. It is now an important medical tool used in forecasting the likelihood that the foetus will be normal.

  3. It is not used, now a days, because human pregnancy has only a small risk of birth defects.

  4. It is the number and appearance of chromosomes in the nucleus of a prokaryotic cell.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When the family history or age of the mother indicates a high risk of gross chromosomal abnormalities, embryonic or fetal tissue samples are often collected and cultured so that a karyotype of the chromosomes can be analyzed.

Multiple choice

Karyotyping can be done from

  1. any cell in the body

  2. only sex cells

  3. only foetal cells

  4. only zygotic cells
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cells in blood, hair, finger nails, and any other tissues in our body can be cultured to create a karyotype of the chromosomes. Since all of your somatic cells will have the same chromosomes, it generally doesn't matter which ones are used.

Multiple choice

A female is suffering from unusually short height (average 4'7), webbed neck, & lacks all feminine secondary sexual characteristics. This chromosomal abnormality is caused by

  1. Triple-X syndrome

  2. Turner's syndrome

  3. XYY syndrome

  4. Klinefelter's syndrome
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Women with Turner syndrome are essentially postmenopausal from early childhood and are sterile because their ovaries do not develop normally and they do not ovulate.

Multiple choice

Pick out the true statements regarding the sex chromosome abnormalities in humans.

  1. These generally have mild effects, which are rarely fatal.

  2. These are not gender specific.

  3. These cannot be diagnosed before birth.

  4. These are more common than autosomal abnormalities.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Because sex chromosome abnormalities rarely result in an early death and their symptoms are not often severe, comparatively large number of people with these abnormalities survive to old age.

Multiple choice

Why each generation of offspring bears impregnation of maternal and paternal traits ?

  1. Because each cell carries same number of chromosomes.

  2. Because of the frequent grabbing of chromosomes by the microtubules during metaphase I

  3. Because of the biological composition of the chromosomes

  4. Because of the high frequency of viral invasion
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Each generation of offspring bears so many possible impregnation of maternal and paternal traits as a consequence of the frequent grabbing of chromosomes by the microtubules during metaphase I.

Multiple choice

The shrinking and disorganizing of cytoskeleton are seen in the cell, which is generally

  1. cancerous

  2. ready to start mitosis

  3. getting engulfed by a phagocyte

  4. shutting down one of its X chromosomes as dosage compensation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Phagocytes literally means eating of the cells. To do this, and be able to get the nutrients from inside the cell, it has to break down the outer defenses (cell walls, cell membranes, plasma membranes). The cytoskeleton provides the structural integrity for the cell, so it should be disassembled.