Cell Cycle and Cell Division Class 11 Biology: Interphase, Mitosis and Meiosis

What Cell Cycle and Cell Division is about

Weightage: This chapter is part of Unit III, Cell: Structure and Function, which carries 15 of the 70 theory marks in the school annual exam together with Cell: The Unit of Life and Biomolecules.Source: CBSE Biology (044) syllabus 2026-27, Class XI course structure, Unit III Cell: Structure and Function

Key concepts

The cell cycle: interphase and M phase

NCERT section 10.1 Cell Cycle (10.1.1 Phases of Cell Cycle)

Duration: human cells in culture divide roughly once every 24 hours; yeast completes a cycle in about 90 minutes. The length varies between organisms and between cell types.

Two basic phases:

• Interphase: the period between two M phases. Though called the 'resting phase', the cell is busy growing and replicating DNA in an orderly way. It lasts more than 95% of the cycle.
• M phase (mitosis phase): the actual division. In a 24-hour human cycle, division proper lasts only about an hour. It begins with karyokinesis (nuclear division, separating daughter chromosomes) and usually ends with cytokinesis (division of cytoplasm).

Three sub-phases of interphase:
1. G1 (Gap 1): between mitosis and the start of DNA replication. The cell is metabolically active and grows, but does not copy its DNA.
2. S (Synthesis): DNA replication. DNA per cell doubles from 2C to 4C, but the chromosome number stays the same (2n), because each chromosome now has two sister chromatids joined at one centromere. In animal cells, the centriole duplicates in the cytoplasm during S phase while DNA replicates in the nucleus.
3. G2 (Gap 2): proteins are made in preparation for mitosis and growth continues.

G0 (quiescent stage): cells that stop dividing exit G1 into G0. They stay metabolically active but do not multiply unless the body needs them to. Example: heart cells in adults do not seem to divide; many other cells divide only occasionally to replace cells lost by injury or death.

Who divides by mitosis? In animals, mitosis is seen only in diploid somatic cells, with a few exceptions such as male honey bees (haploid cells divide by mitosis). Plants show mitosis in both haploid and diploid cells (e.g. the haploid gametophyte of mosses and ferns).

Worked example

A diploid cell in G1 has 2C DNA and 16 chromosomes. State its DNA content and chromosome number in G2, and explain why only one of the two values changes. (3 marks)

Try it first, then show the solutionSolution

1. G2: DNA = 4C; chromosomes = 16. (1)
2. During S phase each DNA molecule is copied, so DNA doubles. (1)
3. The two copies stay as sister chromatids attached at one centromere; chromosomes are counted by centromeres, so the number does not change. (1)

Answer: 4C and 16 chromosomes; DNA doubles but chromatids share a centromere.

Mitosis: prophase and metaphase

NCERT section 10.2 M Phase (10.2.1 Prophase; 10.2.2 Metaphase)

Mitosis is called equational division because the parent and daughter cells have the same number of chromosomes. It is divided into four stages for convenience, but it is a continuous process with no sharp boundaries.

Prophase (follows S and G2, whose new DNA molecules are intertwined):

• Chromosomal material condenses into compact mitotic chromosomes; each chromosome is seen to have two chromatids attached at the centromere.
• The centrosome, which duplicated during interphase, begins to move towards opposite poles. Each centrosome radiates microtubules called asters; the two asters with spindle fibres form the mitotic apparatus.
• At the end of prophase, the Golgi complex, ER, nucleolus and nuclear envelope are no longer seen under the microscope.

Metaphase:

• Begins with the complete disintegration of the nuclear envelope, so chromosomes spread through the cytoplasm.
• Chromosome condensation is complete; this is the best stage to study chromosome morphology. Each chromosome shows two sister chromatids held by the centromere.
• Small disc-shaped kinetochores on the surface of the centromere are the sites where spindle fibres attach.
• Chromosomes move to the spindle equator; one chromatid of each is attached by its kinetochore to fibres from one pole and its sister to fibres from the opposite pole.
• The plane where chromosomes line up is the metaphase plate.

Key features: spindle fibres attach to kinetochores; chromosomes align at the equator.

Worked example

Why is metaphase the best stage to count and study chromosomes? Name the structure through which spindle fibres attach to a chromosome. (2 marks)

Try it first, then show the solutionSolution

1. Chromosomes are fully condensed and lie spread in one plane (metaphase plate), so their shape and number are clearest. (1)
2. Kinetochores, disc-shaped structures on the centromere. (1)

Answer: Maximum condensation and alignment; kinetochores.

Mitosis: anaphase, telophase and cytokinesis

NCERT section 10.2.3 Anaphase; 10.2.4 Telophase; 10.2.5 Cytokinesis; 10.3 Significance of Mitosis

Anaphase:

• Each chromosome at the metaphase plate splits at the centromere; the two sister chromatids, now daughter chromosomes, begin moving to opposite poles.
• As they move, the centromere leads and the arms trail behind.

Telophase (final stage of karyokinesis):

• Chromosomes reach the poles and decondense, losing their individuality; chromatin collects at each pole.
• The nuclear envelope reassembles around each cluster, forming two daughter nuclei.
• Nucleolus, Golgi complex and ER reform.

Cytokinesis (division of the cytoplasm), completing cell division:

• Animal cells: a furrow appears in the plasma membrane and deepens until it meets in the centre, splitting the cytoplasm in two (outside → inside).
• Plant cells: the wall is relatively inextensible, so a furrow cannot form. Wall formation starts in the centre and grows outward to meet the side walls (inside → outside). It begins with a simple precursor, the cell plate, which becomes the middle lamella between the two new cells.
• Organelles such as mitochondria and plastids are shared between the daughter cells.
• Syncytium: in some organisms karyokinesis is not followed by cytokinesis, producing a multinucleate cell, e.g. the liquid endosperm of coconut.

Significance of mitosis:
1. Produces diploid daughter cells with identical genetic material (usually restricted to diploid cells; haploid cells in some lower plants and social insects also divide by mitosis).
2. Growth of multicellular organisms.
3. Restores the nucleo-cytoplasmic ratio, which is disturbed as a cell grows.
4. Cell repair and replacement: upper epidermis, gut lining and blood cells are constantly replaced.
5. Mitosis in meristems (apical meristem and lateral cambium) lets plants grow throughout life.

Worked example

(a) A nucleus goes through three successive rounds of karyokinesis, but no cytokinesis follows any of them. How many nuclei does the cell now hold, what is such a cell called, and where is one found naturally? (b) Why must a dividing plant cell build a cell plate instead of forming a furrow? (3 marks)

Try it first, then show the solutionSolution

1. (a) Each karyokinesis doubles the number of nuclei: 1 → 2 → 4 → 8 nuclei (2³ = 8). (1)
2. A multinucleate cell formed this way is a syncytium; the liquid endosperm of coconut is an example. (1)
3. (b) The plant cell wall is relatively inextensible and cannot be pinched in, so a new wall is laid down from the centre outwards, starting as the cell plate that becomes the middle lamella. (1)

Answer: 8 nuclei, a syncytium (liquid endosperm of coconut); the rigid wall rules out a furrow, so a cell plate grows outwards from the centre.

Meiosis: key features and prophase I

NCERT section 10.4 Meiosis (10.4.1 Meiosis I, prophase I)

Meiosis is the special division that halves the chromosome number, producing haploid cells. It occurs during gametogenesis in plants and animals. Meiosis creates the haploid phase of the life cycle; fertilisation restores the diploid phase.

Key features:

• Two sequential divisions (meiosis I and meiosis II) but only one round of DNA replication.
• Meiosis I starts after the chromosomes have replicated in S phase to form identical sister chromatids.
• Pairing of homologous chromosomes and recombination between non-sister chromatids of homologues.
• Four haploid cells form at the end of meiosis II.

Prophase I is longer and more complex than mitotic prophase, with five substages:
1. Leptotene: chromosomes gradually become visible under the light microscope; compaction continues.
2. Zygotene: homologous chromosomes start pairing: synapsis. A complex structure, the synaptonemal complex, forms between them. A synapsed pair of homologues is a bivalent or tetrad (four chromatids).
3. Pachytene: the four chromatids of each bivalent become distinct and clear. Recombination nodules appear: sites of crossing over between non-sister chromatids. Crossing over is the exchange of genetic material between two homologues, catalysed by the enzyme recombinase. It leads to recombination of genetic material. Crossing over is completed by the end of pachytene, leaving homologues linked at the crossing-over sites.
4. Diplotene: the synaptonemal complex dissolves and the recombined homologues tend to separate, except at the sites of crossover. These X-shaped points are chiasmata. In the oocytes of some vertebrates, diplotene can last for months or years.
5. Diakinesis: terminalisation of chiasmata (they move towards the chromosome ends). Chromosomes are fully condensed and the meiotic spindle assembles. By the end, the nucleolus disappears and the nuclear envelope breaks down. Diakinesis is the transition to metaphase I.

Memory flow: Leptotene (threads appear) → Zygotene (pairing) → Pachytene (crossing over) → Diplotene (chiasmata seen) → Diakinesis (chiasmata slide to ends).

Worked example

Name the substage of prophase I in which (a) the synaptonemal complex forms, (b) crossing over occurs, (c) chiasmata first become visible, (d) chiasmata terminalise. Name the enzyme involved in crossing over. (3 marks)

Try it first, then show the solutionSolution

1. (a) Zygotene (½) (b) pachytene (½)
2. (c) Diplotene (½) (d) diakinesis (½)
3. Recombinase. (1)

Answer: Zygotene, pachytene, diplotene, diakinesis; recombinase.

Meiosis I (metaphase I to telophase I), interkinesis and meiosis II

NCERT section 10.4.1 Meiosis I; 10.4.2 Meiosis II; 10.5 Significance of Meiosis

Metaphase I: the bivalents line up on the equatorial plate. Microtubules from opposite poles attach to the kinetochores of the two homologous chromosomes (not of sister chromatids).

Anaphase I: homologous chromosomes separate and move to opposite poles, but sister chromatids stay together at their centromeres. Each pole therefore receives half the chromosome number. *This is the reduction step.*

Telophase I: nuclear membrane and nucleolus reappear; cytokinesis follows. The two cells formed are a dyad of cells. Chromosomes may not decondense fully.

Interkinesis: the stage between the two divisions; usually short-lived, with no DNA replication.

Meiosis II (resembles a normal mitosis):

• Prophase II: begins immediately after cytokinesis, usually before chromosomes have fully elongated; simpler than prophase I. Nuclear membrane disappears and chromosomes become compact again.
• Metaphase II: chromosomes align at the equator; microtubules from opposite poles attach to the kinetochores of sister chromatids.
• Anaphase II: the centromere of each chromosome splits (it had held sister chromatids together), and chromatids move to opposite poles as microtubules attached to kinetochores shorten.
• Telophase II: two groups of chromosomes get enclosed by a nuclear envelope; cytokinesis follows, forming a tetrad of cells: four haploid daughter cells.

Significance of meiosis:
1. Conserves the species' chromosome number across generations in sexually reproducing organisms, even though the division itself halves the number (fertilisation restores it).
2. Increases genetic variability in the population from one generation to the next, through crossing over and the random separation of homologues. Variations are important for evolution.

Worked example

In anaphase I, what separates, and in anaphase II, what separates? Why is meiosis II described as similar to mitosis? (3 marks)

Try it first, then show the solutionSolution

1. Anaphase I: homologous chromosomes separate; sister chromatids remain joined at the centromere. (1)
2. Anaphase II: centromeres split and sister chromatids separate. (1)
3. Meiosis II does not change the chromosome number (n → n) and separates sister chromatids, just as mitosis does. (1)

Answer: Homologues in anaphase I; sister chromatids in anaphase II; meiosis II is equational like mitosis.

Tracking chromosome number and DNA content (numericals)

NCERT section 10.1.1 Phases of Cell Cycle; 10.2 M Phase; 10.4 Meiosis

Two quantities change differently through division. Learn to tabulate them.

Rules:

• Chromosome number = number of centromeres. It changes only when centromeres split (anaphase of mitosis or anaphase II) or when homologues go to different cells (meiosis I).
• DNA content (C): a haploid set of unreplicated chromosomes = 1C. Doubles in S phase, halves whenever a cell divides.

Mitosis of a diploid cell (2n):

• G1: 2n, 2C
• S → G2: 2n, 4C
• Prophase and metaphase: 2n, 4C (each chromosome has two chromatids)
• Anaphase (one cell, both sets of daughter chromosomes): 4n, 4C
• After cytokinesis, each daughter cell: 2n, 2C

Meiosis of a diploid cell (2n):

• After S: 2n, 4C
• After meiosis I (each cell): n, 2C (each chromosome still has two chromatids)
• After meiosis II (each cell): n, 1C

Counting cells:

• After *k* rounds of mitosis from one cell: 2^k cells.
• One meiosis: 4 haploid cells from one meiocyte; so *N* gametes need N ÷ 4 meiotic divisions (in males, where all four products are functional).

Tip: always write the starting values (n and C) given in the question before working, and say whether you are counting per cell or per nucleus at that stage.

Worked example

An onion root-tip cell has 16 chromosomes in G1. How many chromatids are present at metaphase, and how many chromosomes are present in the cell at anaphase? (2 marks)

Try it first, then show the solutionSolution

1. Metaphase: 16 chromosomes, each with 2 chromatids = 32 chromatids. (1)
2. Anaphase: centromeres split, so each chromatid becomes a chromosome: 32 chromosomes in the cell (16 moving to each pole). (1)

Answer: 32 chromatids at metaphase; 32 chromosomes at anaphase.

Cell Cycle and Cell Division in real life

Each concept, met in an everyday situation. Read the situation, answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Topics in this chapter

• Meiosis: Phases and Chromosome Numbers
• Mitosis: Phases and Significance

Cell Cycle and Cell Division: key facts

Cell cycle

${\text{G}}_1\to \text{S}\to {\text{G}}_2\to \text{M}\to {\text{G}}_1;{\text{G}}_1\to {\text{G}}_0\text{ (quiescent)}$

Interphase = G1 + S + G2 (more than 95% of the cycle).

DNA change in S phase

$\text{DNA: }2C\text{ becomes }4C;\text{chromosomes: }2n\text{ stays }2n$

DNA doubles; chromosome number unchanged.

Mitosis stages

$\text{prophase}\to \text{metaphase}\to \text{anaphase}\to \text{telophase}\to \text{cytokinesis}$

2n parent → two 2n daughters (equational).

Prophase I substages

$\text{leptotene}\to \text{zygotene}\to \text{pachytene}\to \text{diplotene}\to \text{diakinesis}$

Synapsis in zygotene; crossing over in pachytene; chiasmata in diplotene.

Meiosis counts

$2n,4C\stackrel{\text{meiosis I}}{\to }n,2C\stackrel{\text{meiosis II}}{\to }n,1C$

One meiocyte gives four haploid cells.

Cells after repeated mitosis

$\text{cells}=2^k$

k = number of successive mitotic divisions starting from one cell.

Cell Cycle and Cell Division: diagrams to practise

Practise each one on paper: draw it from the checklist, then tick off every label.

How the school exam asks Cell Cycle and Cell Division

The question patterns to expect, and the method that works for each.

Tricks to remember Cell Cycle and Cell Division

Short memory aids. Say each one aloud once, then use it on a question the same day.

• PMAT

  Prophase, Metaphase, Anaphase, Telophase: 'Please Make A Tea'.

  Use it when: Order of mitotic stages.

• Lazy Zebras Prefer Dry Dates

  Leptotene, Zygotene, Pachytene, Diplotene, Diakinesis.

  Use it when: Order of prophase I substages.

• Z for Zip, P for Pass

  Zygotene zips homologues together (synapsis); Pachytene passes genes across (crossing over).

  Use it when: Linking substages to events.

• A-I splits pairs, A-II splits twins

  Anaphase I separates homologous pairs; anaphase II (and mitotic anaphase) separates sister chromatids (twins).

  Use it when: What separates in each anaphase.

• Animals pinch in, plants build out

  Animal cytokinesis: furrow from outside inwards. Plant cytokinesis: cell plate from centre outwards.

  Use it when: Comparing cytokinesis.

Cell Cycle and Cell Division: exam-level solved questions

Ordered from exam level to HOTS. Cover the solution, write your own, then compare step by step.

Case-study practice (Section E style)

Read the situation, then answer every part. In a school exam set on the board pattern this is a 4-mark question split into 1 + 1 + 2 marks.

Where the marks are

How a typical answer is split into step marks. Show every step: a right final answer alone rarely earns full marks.

Where students lose marks in Cell Cycle and Cell Division

The slips examiners see most often, and what to write instead.

• ✗Mistake: Saying chromosome number doubles in S phase

  DNA doubling is confused with chromosome doubling.

  ✓Do this: S phase: DNA 2C → 4C; chromosome number remains 2n (chromatids share one centromere).

  Usually costs: 1 mark.

• ✗Mistake: Writing that crossing over happens in zygotene or diplotene

  Synapsis and chiasmata are mixed up with crossing over.

  ✓Do this: Synapsis: zygotene. Crossing over: pachytene. Chiasmata visible: diplotene. Terminalisation: diakinesis.

  Usually costs: 1 mark.

• ✗Mistake: Saying centromeres split in anaphase I

  Anaphase I is treated like mitotic anaphase.

  ✓Do this: In anaphase I, homologues separate and sister chromatids stay together; centromeres split in anaphase II.

  Usually costs: 1-2 marks.

• ✗Mistake: Calling interphase a resting phase where nothing happens

  The old name is taken literally.

  ✓Do this: Interphase is the busiest time: growth (G1, G2) and DNA replication (S).

  Usually costs: ½-1 mark.

• ✗Mistake: Claiming DNA is replicated during interkinesis

  Assuming every division needs a fresh S phase.

  ✓Do this: There is no DNA replication in interkinesis; meiosis has only one S phase.

  Usually costs: 1 mark.

NCERT exercise guide: Cell Cycle and Cell Division

What each exercise in the NCERT chapter tests, how to approach it, and a question of the same kind solved step by step. Questions here are written in our own words.

Practice questions on Cell Cycle and Cell Division

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

1. Q1 · 1 mark · MCQExam level

   Crossing over takes place between:
   (a) sister chromatids of a chromosome (b) non-sister chromatids of homologous chromosomes (c) non-homologous chromosomes (d) two daughter cells

   Hint

   Pachytene.

   Answer

   (b) non-sister chromatids of homologous chromosomes

2. Q2 · 1 mark · MCQExam level

   Terminalisation of chiasmata occurs in:
   (a) zygotene (b) pachytene (c) diplotene (d) diakinesis

   Hint

   Last substage.

   Answer

   (d) diakinesis

3. Q3 · 2 marks · Very short answerExam level

   State what happens to the Golgi complex, ER, nucleolus and nuclear envelope by the end of prophase, and when they reappear. (2 marks)

   Hint

   Telophase rebuilds.

   Answer

   They are no longer seen at the end of prophase (1); they reform in telophase (1).

4. Q4 · 2 marks · Very short answerHarder exam level

   Why is the restoration of the nucleo-cytoplasmic ratio a reason for cells to divide? (2 marks)

   Hint

   Growth disturbs balance.

   Answer

   As a cell grows, its cytoplasm increases while the nucleus does not, so one nucleus must control a larger volume (1). Division into two smaller cells restores a balanced nucleus-to-cytoplasm ratio (1).

5. Q5 · 2 marks · Very short answerHarder exam level

   Explain what is meant by synapsis and the synaptonemal complex. (2 marks)

   Hint

   Zygotene.

   Answer

   Synapsis is the pairing of homologous chromosomes during zygotene (1); the synaptonemal complex is the structure formed between the paired homologues that holds them together (1).

6. Q6 · 2 marks · Very short answerHarder exam level

   A plant cell has 2n = 18. Give the chromosome number in (a) a leaf cell, (b) the egg cell, (c) each cell after telophase I, (d) the cell at mitotic anaphase. (2 marks)

   Hint

   Count centromeres.

   Answer

   (a) 18 (b) 9 (c) 9 (d) 36 in the cell (18 moving to each pole) (½ each).

7. Q7 · 3 marks · Short answerHarder exam level

   Explain how mitosis allows plants to grow throughout their lives, and name two kinds of animal cells continuously replaced by mitosis. (3 marks)

   Hint

   Meristems; skin, gut, blood.

   Answer

   Meristematic tissues (apical meristem and lateral cambium) keep dividing by mitosis, adding cells for growth in length and girth (2). In animals, cells of the upper epidermis, gut lining or blood cells are constantly replaced (any two) (1).

8. Q8 · 3 marks · Short answerHarder exam level

   A cell completes one cycle in 20 hours, and M phase takes 4% of this time. G1 lasts 9 hours and S phase 6 hours. (a) Find the duration of M phase and of interphase. (b) How long is G2? (c) State the main event in each of G1, S and G2. (3 marks)

   Hint

   Interphase = G1 + S + G2 = whole cycle minus M.

   Answer

   (a) M phase = 4% of 20 h = 0.8 h (48 minutes); interphase = 20 − 0.8 = 19.2 h (1). (b) G2 = 19.2 − 9 − 6 = 4.2 h (1). (c) G1: cell grows and is metabolically active without copying DNA; S: DNA replicates (2C → 4C) with chromosome number unchanged; G2: proteins for mitosis are made while growth continues (1).

9. Q9 · 5 marks · Long answerHarder exam level

   (a) Describe the events of meiosis II. (b) State two ways in which meiosis contributes to variation. (c) Why is there no S phase before meiosis II? (5 marks)

   Hint

   Like mitosis; crossing over.

   Answer

   (a) Prophase II: nuclear membrane disappears, chromosomes compact; metaphase II: chromosomes at equator, fibres attach to kinetochores of sister chromatids; anaphase II: centromeres split, chromatids move to poles; telophase II: nuclear envelopes form, cytokinesis gives four haploid cells (2½). (b) Crossing over in pachytene creates new combinations; random separation of homologues at anaphase I gives different maternal-paternal mixes (1½). (c) Each chromosome already has two chromatids after meiosis I, so another replication is not needed; meiosis II only separates them (1).

10. Q10 · 3 marks · Short answerHOTS / competency

    Suppose spindle fibres fail to form in a dividing plant cell after its chromosomes have replicated. Predict the chromosome number of the resulting cell and explain how such failure might be useful to plant breeders. (3 marks)

    Hint

    Chromatids separate but cannot move.

    Answer

    Without a spindle, chromatids cannot be pulled to two poles, and no division follows, so the nucleus ends up with doubled chromosomes: 2n becomes 4n (1½). Such cells give polyploid plants, which are often larger, with bigger fruits or flowers, useful to breeders (1½).

11. Q11 · 3 marks · Short answerHOTS / competency

    Two cells from the same animal are observed: cell X has 23 chromosomes, each made of two chromatids; cell Y has 46 chromosomes, each made of one chromatid, arranged in two groups at opposite ends. Identify the likely stage of each and give reasons. (3 marks)

    Hint

    Human 2n = 46.

    Answer

    X: after meiosis I (telophase I or prophase II/metaphase II), since the cell is haploid (n = 23) but chromatids are still joined (1½). Y: anaphase II of meiosis, since the centromeres have split and 23 single-chromatid chromosomes are moving to each pole; a human cell at mitotic anaphase would instead show 92 chromosomes, 46 at each pole (1½).

12. Q12 · 1 mark · Assertion-reasonHOTS / competency

    Assertion (A): Meiosis II is called an equational division.
    Reason (R): In meiosis II, sister chromatids separate and the chromosome number of the cells does not change.
    (a) Both A and R are true and R is the correct explanation of A.
    (b) Both A and R are true but R is not the correct explanation of A.
    (c) A is true but R is false.
    (d) A is false but R is true.

    Hint

    n stays n.

    Answer

    (a)

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1. 1.How long is the cell cycle of human cells in culture?Show answer

   About 24 hours.

2. 2.How long does yeast take to complete a cell cycle?Show answer

   About 90 minutes.

3. 3.In which phase does the centriole duplicate in animal cells?Show answer

   S phase.

4. 4.Give an example of cells in G0.Show answer

   Adult heart cells.

5. 5.Name an animal in which haploid cells divide by mitosis.Show answer

   Male honey bee.

6. 6.What is the metaphase plate?Show answer

   The plane at the cell's equator where chromosomes line up during metaphase.

7. 7.What is a syncytium? Give an example.Show answer

   A multinucleate cell formed when karyokinesis is not followed by cytokinesis; liquid endosperm of coconut.

8. 8.What does the cell plate become?Show answer

   The middle lamella between the two new cells.

9. 9.What is a bivalent?Show answer

   A pair of synapsed homologous chromosomes (also called a tetrad).

10. 10.Which substage of prophase I can last months or years in some vertebrate oocytes?Show answer

    Diplotene.

11. 11.Is DNA replicated during interkinesis?Show answer

    No.

12. 12.How many cells form at the end of meiosis II from one meiocyte?Show answer

    Four haploid cells.

Quick revision checklist

The night before the exam: can you do each of these without looking?

• ☐Can you name the four sub-phases of interphase and G0 and say what happens in each?
• ☐Can you say why interphase is not truly a resting phase?
• ☐Can you describe each mitotic stage in three points?
• ☐Can you compare cytokinesis in plant and animal cells?
• ☐Can you give five points on the significance of mitosis?
• ☐Can you list the five substages of prophase I and their key events?
• ☐Can you say what separates in anaphase I and anaphase II?
• ☐Can you give n and C values at G1, G2, after meiosis I and after meiosis II?

Cell Cycle and Cell Division: frequently asked questions