2nd year Chapter 21: Cell Cycle Short and Simple Question & Answer
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Q 1. What is the cell cycle?
Ans. The cell cycle is a sequence of changes in a cell, including growth, DNA replication, and cell division.
Q 2. How long is the human cell cycle?
Ans. The average human cell cycle takes about 24 hours.
Q 3. What is chromatin?
Ans. Chromatin is a network of fine threads made visible with histologic stains of DNA.
Q 4. What do higher plants have instead of visible centrioles?
Ans. Higher plants have an analogous region from which spindle microtubules radiate.
Q 5. What is metastasis?
Ans. Metastasis is the spread of cancer cells to other parts of the body from their original site.
Q 6. When does meiosis occur in plants and animals?
Ans. Meiosis occurs in diploid cells during gamete formation in animals and when spores are produced in plants.
Q 7. Define crossing over?
Ans. Crossing over is the exchange of segments between non-sister chromatids of homologous chromosomes due to chiasmata formation.
Q 8. Name two significant events of meiosis?
Ans. Two significant events of meiosis are crossing over and random assortment of chromosomes.
Q 9. How many chromosomes are present in males affected by Klinefelter’s syndrome?
Ans. Males with Klinefelter’s syndrome can have 48 chromosomes (XXXY), 49 chromosomes (XXXY), or 47 chromosomes (XYY).
Q 10. What are the symptoms of Turner’s syndrome?
Ans. Symptoms of Turner’s syndrome include short stature, webbed neck, absence of ovaries, and a complete absence of germ cells in individuals with one missing X chromosome (45 chromosomes).
Q 11. What is apoptosis?
Ans. Apoptosis is the programmed sequence of events leading to cell self-destruction.
Q 12. Name the stages of interphase?
Ans. Interphase consists of G1-phase, S-phase, and G2-phase.
Q 13. What is G1-phase?
Ans. G1-phase is a period of metabolic activity, growth, and accumulation of DNA base units.
Q 14. What is G0?
Ans. G0 is a phase where post-mitotic cells exit the cell cycle and may remain without further proliferation.
Q 15. What happens in the S-phase of the cell cycle?
Ans. In the S-phase, DNA is synthesized, and the chromosome number doubles.
Q 16. What occurs in the G2-phase (pre-mitotic phase)?
Ans. In the G2-phase, the cell prepares for division by synthesizing energy, proteins, RNA, and microtubule subunits. Q 17. Define mitosis?
Ans. Mitosis is a type of cell division that ensures the same number of chromosomes in daughter cells as in the parent cells.
Q 18. What are the two conventional phases of Mitosis?
Ans. The two conventional phases of Mitosis are Karyokinesis (nucleus division) and Cytokinesis (whole cell division).
Q 19. What is the Mitotic apparatus?
Ans. The specialized microtubule structure, including asters and spindles, is called the Mitotic apparatus. Q 20. Name the microtubules originating from centrioles?
Ans. The microtubules originating from centrioles are astral microtubules, kinetochore microtubules, and polar microtubules.
Q 21. What happens in Prophase of mitosis?
Ans. Chromosomes become visible and nuclear changes occur.
Q 22. What is kinetochore?
Ans. A specialized region on the centromere.
Q 23. What occurs in Telophase of mitosis?
Ans. Chromosomes decondense, nuclear changes happen.
Q 24. What is Phragmoplast?
Ans. A membrane structure in plant cytokinesis.
Q 25. Define cancer?
Ans. Malignant growth from uncontrolled cell division.
Q 26. What is Tumour?
Ans. Uncontrolled cell proliferation forming a mass.
Q 27. What are two basic types of tumour?
Ans. Benign and Malignant.
Q 28. What is benign tumours?
Ans. Small, localized, behave like normal cells.
Q 29. What is malignant tumour?
Ans. Rapidly dividing, invasive, can spread.
Q 30. How to distinguish cancer cells from normal cells?
Ans. Less differentiated, rapid growth characteristics.
Q 31. What are the main causes of cancer?
Ans. Somatic cell mutations in cell division genes.
Q 32. Define meiosis?
Ans. Cell division reducing chromosome number.
Q 33. How does prophase of meiosis differ from mitosis?
Ans. Chromosomes behave as homologous pairs.
Q 34. What are homologous chromosomes?
Ans. Similar but not necessarily identical chromosomes.
Q 35. Name sub-stages of prophase I of meiosis?
Ans. Leptotene, zygotene, diplotene, diakinesis.
Q 36. What is synapsis?
Ans. Pairing of homologous chromosomes.
Q 37. What is bivalent or tetrad?
Ans. Paired homologous chromosomes.
Q 38. Duration of Pachytene, leptotene, zygotene?
Ans. Pachytene can last long, leptotene and zygotene are short.
Q 39. What is chiasmata?
Ans. Points of interchange in homologous chromosomes.
Q 40. What happens in Diakinesis?
Ans. Maximum chromosome condensation, separation.
Q 41. Events in metaphase I of meiosis?
Ans. Nuclear changes, spindle fibers, bivalent alignment.
Q 42. How does anaphase I of meiosis differ from mitosis?
Ans. Only homologous chromosomes separate.
Q 43. How does meiosis maintain constant chromosome number?
Ans. Halves chromosome number in gametes, restores after fertilization.
Q 44. Define non-disjunction?
Ans. Failure to segregate chromosomes in cell division.
Q 45. What is autosomal non-disjunction?
Ans. Failure of autosomal chromosomes to segregate.
Q 46. What is Downs Syndrome (Mongolism)?
Ans. Extra 21st chromosome, resulting in 47 chromosomes.
Q 47. Is Downs syndrome related to the mother’s age?
Ans. Yes, risk increases with mother’s age.
Q 48. What are symptoms of Downs syndrome?
Ans. Flat face, squint eyes, mental retardation.
Q 49. What is sex chromosomal non-disjunction?
Ans. Failure of sex chromosomes to segregate.
Q 50. What is Necrosis?
Ans. Cell death due to tissue damage.
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