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

If a researcher examines primordial germ cells in a prepubertal human male under the microscope, in what stage of the cell cycle will he find them?

  1. Interphase

  2. Prophase

  3. Anaphase

  4. Telophase

  5. Metaphase
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Interphase occurs just prior to cell division. Prepubertal male primordial germ cells are reactivated from interphase at puberty and enter rounds of mitoses followed by meiosis 1 and 2 to produce a unique haploid sperm.

Multiple choice

Which among the following statements regarding the cytokinesis in animal cells is false?

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

  2. A contractile ring, made of muscle myosin II and actin filaments, assembles parallelly at the cell cortex.

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

  4. Abscission depends on septin filaments.

  5. The position at which the contractile ring assembles is dictated by the mitotic spindle.
Reveal answer Fill a bubble to check yourself
B 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

The kinetochores are the protein structures found on chromatids. These are prominent in _____________.

  1. prophase

  2. prometaphase

  3. metaphase

  4. anaphase

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

Prometaphase is the phase of mitosis following prophase and preceding metaphase, in eukaryotic somatic cells. In prometaphase, the nuclear membrane breaks apart into numerous membrane vesicles and the chromosomes inside form protein structures called kinetochores.

Multiple choice

Which among the following chromosomes is not present in humans?

  1. Metacentric chromosome

  2. Subtelocentric chromosome

  3. Telocentric chromosome

  4. Submetacentric chromosome

  5. Acrocentric chromosome
Reveal answer Fill a bubble to check yourself
C 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

In which of the following stages, the number of chromosomes per cell is 46 i.e. 2N and identical to the somatic cells of the human body?

  1. Growth 1 phase

  2. Anaphase II

  3. Prophase II

  4. Metaphase II

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

Growth 1 phase is a very active period. In this period, the cell synthesizes vast range of proteins which includes the enzymes and structural proteins necessary for growth of the cell. In the G1 phase, the chromosome are made of single molecule of DNA, at this point in humans, the number of chromosomes per cell is 46 which is 2N and identical to the somatic cells.

Multiple choice

Cyclin-dependent kinases (CDKs) are the protein kinases which play a vital role in regulating the cell cycle. The CDK involved in the processes of neuronal maturation is _______________.

  1. CDK1

  2. CDK2

  3. CDK3

  4. CDK5

  5. CDK6
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

CDK5 is required for proper development of the brain. Cdk5 is involved in the processes of neuronal maturation and migration, phosphorylating the key intracellular adaptor of the reelin signaling chain.

Multiple choice

The chromosomes formed due to the effects of certain chromosome-breaking process like irradiation is ______________.

  1. dicentric chromosomes

  2. polycentric chromosomes

  3. monocentric chromosomes

  4. acentric chromosomes

  5. holocentric chromosome
Reveal answer Fill a bubble to check yourself
D 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

How many chromosomes are present in a normal human cell?

  1. 43 pairs

  2. 42 pairs

  3. 23 pairs

  4. 22 pairs

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Normal human somatic cells contain 46 chromosomes arranged in 23 pairs - one set of 23 from each parent. This diploid number is characteristic of most human cells except gametes which are haploid.

Multiple choice

Chromatin diminution can be seen in

  1. Oocytes of amphibians

  2. Depteran flies

  3. Parascaris

  4. Down syndrome

  5. Salivary gland of Drosophila
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In nematode, parascaris at 32 celled stage of cleavage,  only two cells have the full gene component (Primordial germ cell),  where as others will undergo chromatin diminution.