Unit 5 – Cell Cycle (Short Questions)
Q.1. Define following.
Q.2. Differentiate necrosis & apparatus?
Q.3. What are the functions of mitotic apparatus?
Q.4. How can you identify the Cancer Cells?
Q.5. Define Chromosomal Non-disjunction.
Q.6. In Interphase a resting phase. Why?
Q.7. What respect mitosis in plant cells differs from that of in animal cells?
Q.8. What are specific durations of all stages of cell cycle in human?
Q.9. What is Diakinesis?
Q.10. What is crossing over?
Q.1. Define following.
i. Cell cycle
ii. Mitosis
iii. Meiosis
iv. Cytokinesis
v. Karyokinesis
Answer:
i. Cell cycle
The cycle in which growth, replication of DNA & cell division take place is called cell cycle.
ii. Mitosis
The process by which a cell nucleus divides to produce 2 daughter nuclei containing identical sets of chromosomes to the parent cells.
iii. Meiosis
The type of nuclear division that reduces two sets of chromosomes to one set in the daughter cells is called Meiosis.
iv. Karyokinesis
The division of nucleus is called Karyokinesis.
v. Cytokinesis
The division of cytoplasm is called Cytokinesis
Q.2. Differentiate necrosis & Apoptosis.
Answer:
Internal programme of event and sequence of morphological changes by which cell commits suicide is collectively called as Apoptosis.
Necrosis can be defined as the sudden or accidental death of cells and living tissue.
Q.3. What are the functions of mitotic apparatus?
Answer:
Its functions are to attach and capture chromosomes, align them and finally separating them so that equal distribution of chromosomes is ensured.
Q.4. How can you identify the Cancer Cells?
Answer:
Cancer Cells can be differentiated from normal cells because they are less specialized / differentiated than normal cells.
Q.5. Define Chromosomal Non-disjunction.
Answer:
In it chromosomes fail to segregate during anaphase & Telophase and do not finish with equal distribution of chromosomes among all other daughter nuclei. This result in either decreases or increases in number of chromosomes.
Q.6. In Interphase a resting phase. Why?
Answer:
Yes because it is the period between two divisions, during this phase, no apparent division occurs.
Q.7. What respect mitosis in plant cells differs from that of in animal cells?
Answer:
| Plant Mitosis | Animal Mitosis |
| (1) Centriole absent | (1) Centriole present |
| (2) No aster formation | (2) Aster formation takes place. |
| (3) Cell plate involved in cell division | (3) Cell division involves furrowing & cleavage of cytoplasm |
| (4) Occurs mainly in Meristem | (4) Occurs in all tissues and body. |
Q.8. What are specific durations of all stages of cell cycle in human?
Answer:
Mitosis →30 min
G1 →9 hours
S-phase →10 hours
G2 → 405 hours (90min in yeast cells)
Average cell cycle is about 24 hours.
Q.9. What is Diakinesis?
Answer:
It is the phase of maximum condensation of Chromosomes.
Q.10. What is crossing over?
Answer:
During meiosis the segments of chromosomes are exchanged resulting in Recombinant DNA, this is called Crossing Over.