Original editorial cover illustration for cell division
Original editorial cover illustration for cell division. It is not a scale model — use the labelled teaching diagrams below for revision.

Cell Division: Mitosis, Meiosis and the Cell Cycle

Parent hub: Cell Biology, Genetics & Evolution | Prerequisites: Cell Organelles, Microscopy and Cell Size, Cell Membrane Structure, Membrane Transport | Next logical topic (separate): Inheritance and Genetic Variation

Quick Definition

Cell division is the process by which one cell produces two or more new cells. In most eukaryotes (organisms whose cells have a nucleus, such as animals, plants and fungi) it has two linked parts: nuclear division, in which the copied genetic material is shared out, and cytokinesis (the division of the cytoplasm), which produces separate cells. Without accurate division, growth, repair and sexual reproduction would all fail, because new cells would not receive a complete, working set of instructions.

Why It Matters

Every cell in your body came from one fertilised egg cell by repeated division, yet a skin cell is not a nerve cell, and a root cell is not a leaf cell. Division supplies the new cells; differentiation (specialisation) decides what they become. When division goes wrong, the consequences are concrete: a cell that receives the wrong number of chromosomes may not develop normally, and a cell that divides when it should stop can start a tumour. That is why this topic is not just a list of stages to memorise — it is the mechanism behind growth, healing, fertility and cancer.

Learning Objectives

  • Describe the phases of the cell cycle and explain why most of a cell's life is spent in interphase.
  • Explain the checkpoints that stop a damaged or unready cell from dividing.
  • Describe each stage of mitosis and explain how sister chromatids are separated accurately.
  • Compare cytokinesis in animal and plant cells.
  • Outline meiosis and explain how it halves the chromosome number while creating variation.
  • Use chromosome and chromatid counts to predict the outcome of mitosis and meiosis.
  • Explain errors in division, including nondisjunction and uncontrolled division.

Key Terms

Chromosome — a single, packaged length of DNA with its proteins, visible as a compact structure during division. Chromatid — one of the two identical copies of a chromosome after DNA replication, joined to its sister at the centromere. Centromere — the constricted region where sister chromatids are held together and where spindle fibres attach. Homologous chromosomes — a pair of chromosomes, one from each parent, carrying genes for the same traits in the same order, but not necessarily the same versions of those genes. Haploid (n) — having one set of chromosomes. Diploid (2n) — having two sets of chromosomes, one from each parent. Spindle — the structure of microtubules (protein fibres) that moves chromosomes during division. Kinetochore — the protein structure on a centromere where spindle microtubules attach.

The cell cycle as a circle: G1 growth, S DNA copying, G2 preparation and M division, with checkpoints marked.
Figure 1. The cell cycle: interphase (G1, S, G2) prepares the cell and takes about 90% of the cycle; the M phase divides it. Checkpoints at G1, G2 and the spindle stop the cycle if the cell is not ready.

The Cell Cycle: Life Between Divisions

A cell does not spend most of its life dividing. The cell cycle is the ordered series of events from one division to the next, and it has two main parts: interphase, the long period of growth and preparation, and the M phase, the much shorter period of division itself.

Interphase has three phases. In G1 (first gap), the cell grows, makes proteins and new organelles, and checks that conditions are suitable. In S (synthesis), the DNA is copied, so each chromosome becomes two identical sister chromatids. In G2 (second gap), the cell grows further, makes the proteins needed for division, and checks the copied DNA. A cell that is not preparing to divide may leave the cycle into G0, a resting state; nerve cells and many mature muscle cells stay in G0, while skin and gut-lining cells re-enter the cycle frequently.

The M phase then has two parts: mitosis, the division of the nucleus, and cytokinesis, the division of the cytoplasm. In a typical fast-dividing animal cell, interphase takes roughly 90% of the cycle and the M phase roughly 10%. That proportion matters for exams: a cell seen under a microscope is far more likely to be in interphase, with its DNA spread out as chromatin (unpacked DNA and protein), than in any one stage of mitosis.

Cell Cycle Control: Checkpoints

Division is controlled, not automatic. At checkpoints, the cell pauses and asks whether it is safe to continue. The three main checkpoints are the G1 checkpoint, which checks cell size, nutrients and DNA damage before DNA is copied; the G2 checkpoint, which checks that DNA replication is complete and undamaged before mitosis begins; and the spindle assembly checkpoint during mitosis, which checks that every chromosome is properly attached to the spindle before separation begins.

The control signals are proteins called cyclins and cyclin-dependent kinases (CDKs). A cyclin rises and falls during the cycle, and when it binds its CDK partner, the complex switches on the next step — for example, the complex commonly called MPF (maturation-promoting factor, cyclin B with CDK1) drives the cell into mitosis. Tumour suppressor proteins such as p53 can halt the cycle or trigger cell death when DNA damage cannot be repaired. In short, cyclins and CDKs are the accelerators, checkpoints are the brakes, and tumour suppressors are the emergency stop. When the brakes fail, division can continue unchecked.

Six panels showing interphase, prophase, metaphase, anaphase, telophase and cytokinesis in mitosis, with two chromosome pairs.
Figure 2. Mitosis stages for a cell with 2n = 4. Chromosomes condense in prophase, line up in metaphase, separate in anaphase, and form two nuclei in telophase, before cytokinesis splits the cell.

Mitosis in Full: One Division, Two Identical Cells

Mitosis is nuclear division that produces two daughter nuclei, each genetically identical to the parent nucleus and with the same chromosome number. It is used for growth, repair, replacement and asexual reproduction. It is not itself the whole of cell division: without cytokinesis afterwards, one cell would end up with two nuclei.

Before mitosis begins, DNA replication in the S phase has already duplicated every chromosome. A human cell therefore enters mitosis with 46 chromosomes, each made of two sister chromatids, so 92 chromatids in total — but still 46 chromosomes, because chromosome number is counted by centromeres, not by chromatids. That distinction is the single most common source of errors in this topic, and it is worth fixing now: copying DNA doubles the chromatids, not the chromosome number.

Prophase

In prophase, chromatin condenses into visible chromosomes, each clearly made of two sister chromatids joined at the centromere. The nucleolus (the dense region inside the nucleus where ribosomal RNA is made) disappears, the nuclear envelope breaks down, and the spindle begins to form from microtubule-organising centres — centrosomes in animal cells, equivalent organising regions in plant cells, which generally lack centrioles. By the end of prophase, spindle microtubules are reaching towards the chromosomes.

Metaphase

In metaphase, spindle microtubules attach to the kinetochore of each chromosome, and the chromosomes line up along the metaphase plate, the imaginary plane across the middle of the cell. Chromosomes are at their most condensed here, which is why metaphase spreads are used to count chromosomes and to examine karyotypes (ordered displays of a cell's chromosomes). The spindle assembly checkpoint holds the cell here until every kinetochore is attached; a chromosome pulled from one side only would be a recipe for an unequal share-out.

Anaphase

In anaphase, the sister chromatids separate. The protein holding them together is cut, the centromeres split, and each chromatid — now called a daughter chromosome in its own right — is pulled towards opposite poles of the cell as spindle microtubules shorten. Anaphase is usually the shortest stage of mitosis. If you can see two groups of chromosomes moving apart, you are looking at anaphase; if they are still lined up in the middle, you are not.

Telophase

In telophase, the separated chromosomes arrive at the poles, the spindle disassembles, the nuclear envelope reforms around each set, the nucleolus reappears, and the chromosomes decondense back into chromatin. At this point the cell has two nuclei, but it is still one cell. Cytokinesis must follow to finish the job.

An animal cell pinching in two by a cleavage furrow, and a plant cell building a cell plate from Golgi vesicles.
Figure 3. Cytokinesis differs by cell type: animal cells pinch in by a contractile ring, while plant cells build a cell plate because their rigid wall blocks pinching.

Cytokinesis: Dividing the Cytoplasm

Cytokinesis is not the same in animal and plant cells, and the reason is structural. Animal cells have no rigid wall, so a contractile ring of actin and myosin filaments (the same proteins that contract muscle) forms just under the membrane at the equator and tightens like a drawstring, pinching the cell in two. The groove it creates is called the cleavage furrow, and it deepens until the cell is split.

Plant cells cannot be pinched in, because their rigid cell wall is in the way. Instead, vesicles from the Golgi apparatus gather at the equator, guided by a microtubule structure called the phragmoplast, and fuse to form the cell plate. The cell plate grows outwards until it meets the existing wall, and its membranes become the new plasma membranes of the two daughter cells, with new wall material laid down between them. The new membrane between daughter cells follows the bilayer structure taught in Cell Membrane Structure, and the vesicle traffic that builds the plant cell plate is a bulk-transport process taught in Membrane Transport.

Sometimes nuclear division happens without cytokinesis. The result is a multinucleate cell, which is normal in some tissues — for example, early endosperm in flowering plants and skeletal muscle fibres, which are formed by fusion rather than by failed division. Do not assume that every mitosis automatically ends with two separate cells.

Worked Example: Counting Chromosomes and Chromatids

Take a cell with 2n = 6 (three pairs of chromosomes). Before the S phase, it has 6 chromosomes and 6 chromatids. After the S phase, it still has 6 chromosomes, but each now has two sister chromatids, so 12 chromatids and twice the DNA. After mitosis and cytokinesis, each daughter cell has 6 chromosomes and 6 chromatids, exactly like the parent before replication. Mitosis has therefore conserved the chromosome number: 2n stays 2n.

Try the same counting on a human cell, 2n = 46. After the S phase: 46 chromosomes, 92 chromatids. After mitosis: each daughter has 46 chromosomes and 46 chromatids. If your answer for the daughter cells ever gives 92 chromosomes, you have counted chromatids as chromosomes — the classic trap.

Meiosis in Outline: Two Divisions, Four Different Cells

Meiosis is the specialised division that produces gametes (sex cells) in animals, and spores in plants. It halves the chromosome number, so that fertilisation can restore it without doubling it every generation. It consists of two divisions, meiosis I and meiosis II, with no DNA replication between them.

Meiosis I is the reduction division. In prophase I, homologous chromosomes pair up (synapsis) and exchange segments by crossing over, which swaps alleles (versions of genes) between non-sister chromatids and creates new combinations on each chromatid. In metaphase I, homologous pairs line up at the equator, and their random orientation — independent assortment — means each pair can face either pole. In anaphase I, homologous chromosomes separate, while sister chromatids stay together. In telophase I, two haploid cells form, each with one chromosome from each pair, still made of two chromatids.

Meiosis II is like a mitotic division, but of haploid cells: in its anaphase, sister chromatids finally separate. The result is four haploid cells, each genetically different from the parent and from each other. The variation comes from three sources: crossing over, independent assortment, and random fertilisation.

How much variation does independent assortment alone give? For n pairs of chromosomes, there are 2 to the power n possible combinations of parental chromosomes in a gamete. For the worked cell with n = 3, that is 2 cubed = 8 combinations. For humans, with n = 23, it is 2 to the power 23 = 8,388,608 combinations — before crossing over adds even more. That is why siblings, apart from identical twins, are never genetically identical.

Meiosis stages for 2n = 4: prophase I pairing and crossing over, metaphase I pairs lining up, anaphase I homologues separating, telophase I two haploid cells, meiosis II sister chromatids separating into four haploid cells
Figure 4. Meiosis I and II for 2n = 4. In prophase I homologues pair and cross over; in metaphase I pairs line up; in anaphase I homologues separate while sister chromatids stay together; after telophase I, meiosis II separates sister chromatids, giving four genetically different haploid cells.
Variation in meiosis: crossing over creating recombinant chromatids, independent assortment giving four gamete combinations for two chromosome pairs
Figure 5. Two sources of variation in meiosis. Crossing over in prophase I swaps segments between non-sister chromatids, creating recombinant chromatids; independent assortment in metaphase I orients each pair independently, giving 2 to the power n gamete combinations — 4 for n = 2 pairs. Pair 1 carries A/a and Pair 2 carries B/b.
Mitosis producing two identical diploid cells from a 2n = 4 parent, and meiosis producing four different haploid cells, with chromosome bars.
Figure 6. Mitosis vs meiosis with 2n = 4. A double bar is a chromosome with two sister chromatids; a single bar is one chromatid. Mitosis conserves 2n; meiosis halves it to n.

Mitosis and Meiosis Compared

The key differences follow from one question: do homologous chromosomes pair and separate, or do sister chromatids separate in a single division? Mitosis has one division, no pairing of homologues, no crossing over, and produces two genetically identical diploid cells. Meiosis has two divisions, pairing and crossing over in prophase I, separation of homologues in anaphase I, and produces four genetically different haploid cells. Meiosis II resembles mitosis, but it starts from haploid cells and there is no DNA replication before it, so it cannot restore the diploid number.

A related route, for the plant case in detail, is Mitosis vs Meiosis in Plants, and a meiosis-only introduction is Introduction to Meiosis. This article is the general canonical lesson: it covers the cell cycle, its control, both kinds of cytokinesis, and the counting rules that those narrower pages do not teach as a system.

Why Division Matters: Growth, Repair, Reproduction, Stability

Growth in a multicellular organism is mostly more cells, not bigger cells: a child grows because mitosis adds cells, and cell size is limited, as taught in Microscopy and Cell Size. Repair replaces damaged or dead cells — skin, gut lining and blood cells are replaced continuously by mitosis in stem-cell populations. Asexual reproduction in many single-celled eukaryotes and in vegetatively propagated plants is mitosis alone. Sexual reproduction depends on meiosis: it keeps the chromosome number stable across generations, because a haploid gamete plus a haploid gamete restores the diploid number, and it generates the variation on which natural selection acts.

Prokaryotes (bacteria and archaea) do not use mitosis at all. They divide by binary fission: the single circular chromosome is copied and the cell splits in two. The result is similar — two cells from one — but the machinery is different, and binary fission is not mitosis. Do not label a bacterial division as mitosis in an exam.

When Division Goes Wrong

Nondisjunction is the failure of chromosomes or chromatids to separate properly. If homologous chromosomes fail to separate in meiosis I, or sister chromatids fail to separate in meiosis II, a gamete receives an extra chromosome or loses one. After fertilisation, the zygote has an abnormal number — aneuploidy. The best-known human example is Down syndrome, usually trisomy 21: three copies of chromosome 21 instead of two, most often from nondisjunction in meiosis.

Nondisjunction in meiosis I leading to a gamete with an extra chromosome and, after fertilisation, trisomy 21
Figure 7. Nondisjunction in meiosis I: homologous chromosomes fail to separate, giving one gamete with an extra chromosome and one missing it; fertilisation of the extra-chromosome gamete gives trisomy (aneuploidy), for example Down syndrome, trisomy 21.

Uncontrolled division is the other failure. Mutations in proto-oncogenes (genes that normally promote division) can turn them into oncogenes that drive division too hard, while loss of tumour suppressor genes removes the brakes. The result is a cell lineage that divides without respecting checkpoints or signals from its neighbours — a tumour. Cancer is therefore not one disease of one mechanism, but a family of diseases in which cell-cycle control has broken down in different ways. Understanding checkpoints is what makes that statement meaningful rather than a slogan.

Common Misconceptions

  • DNA replication does not double the chromosome number; it doubles the chromatids and the DNA content.
  • Mitosis and cell division are not synonyms: mitosis is nuclear division, and cytokinesis is needed to make two cells.
  • Meiosis does not produce four identical cells, and it does not produce diploid gametes; it produces four different haploid cells.
  • Interphase is not a resting phase and it is not part of mitosis; it is the working, growing, copying part of the cycle.
  • Crossing over happens in prophase I of meiosis, not in mitosis, and not in metaphase.
  • A cell in G0 has not necessarily stopped for good; many cells can re-enter the cycle when signalled to do so.

Exam Focus

GCSE / IGCSE: stages of mitosis in order, the purpose of mitosis (growth, repair, asexual reproduction), and the purpose of meiosis (gametes, halving chromosome number, variation). A-Level: the cell cycle phases and checkpoints, chromosome versus chromatid counting, cytokinesis in animal versus plant cells, crossing over and independent assortment, and nondisjunction. FSc Class 11 and MDCAT: mitosis stages with diagrams, meiosis I versus meiosis II, significance of mitosis and meiosis, and numerical questions on chromosome number. BS Botany and introductory university: cyclin-CDK control, the spindle checkpoint, plant cell-plate formation, and the distinction between this general lesson and the plant-specific comparison linked above.

Advanced Understanding

Control is now understood as a network, not a single switch. Different cyclin-CDK complexes act at different transitions, checkpoints can arrest the cycle at several points, and p53 — often called the guardian of the genome — can pause the cycle for repair or trigger apoptosis (programmed cell death) if repair fails. Research into CDK inhibitors as cancer drugs follows directly from this model: if a tumour's accelerator is stuck on, blocking the relevant CDK may slow it. Conversely, the existence of G0 shows that exit from the cycle is a regulated decision, not a failure: stem cells balance self-renewal (staying in the cycle) against differentiation (leaving it), and that balance is central to both development and regenerative medicine.

Quick Summary

  • The cell cycle is interphase (G1, S, G2) plus the M phase (mitosis and cytokinesis); interphase dominates.
  • Checkpoints at G1, G2 and the spindle control whether division proceeds; cyclins and CDKs drive it, tumour suppressors restrain it.
  • Mitosis: prophase, metaphase, anaphase, telophase — one division, two identical diploid cells, chromosome number conserved.
  • Cytokinesis: cleavage furrow in animal cells, cell plate in plant cells.
  • Meiosis: two divisions, no replication between them — four different haploid cells, variation from crossing over, independent assortment and random fertilisation.
  • Errors: nondisjunction gives aneuploidy; loss of control gives uncontrolled division.

FAQ

Why does a cell copy its DNA before mitosis? So that each daughter cell receives a complete copy. Without replication, dividing the chromosomes would halve the genetic material each generation.

If chromosomes double in the S phase, why is the cell still 2n? Because chromosome number is counted by centromeres. After replication, each chromosome has two chromatids but one centromere, so the count stays 2n.

What is the difference between meiosis I and meiosis II? Meiosis I separates homologous chromosomes and halves the number; meiosis II separates sister chromatids, like mitosis, but in haploid cells.

Can a cell divide without cytokinesis? Yes, giving a multinucleate cell. It happens normally in some tissues, but in most contexts the two processes follow each other.

Why is variation from meiosis useful? Variation gives a population different combinations of alleles, so some individuals are more likely to survive a changed environment. Without it, selection would have nothing to act on.

Related Topics

Sources (synthesised, not copied): OpenStax Biology 2e, Chapters 10 and 11; NCBI Bookshelf, The Cell Cycle and Mitosis; Campbell Biology, Chapters 12 and 13. Historical wording: Walther Flemming is commonly credited with describing chromosome behaviour during division and coining the term mitosis in the 1880s; the term meiosis is commonly credited to J. B. Farmer and J. E. S. Moore in 1905.

Next logical topic, to be written separately: Inheritance and Genetic Variation.

20 Explained MCQs — answers hidden until opened

Open each question to reveal its answer and explanation.

1. During which phase of the cell cycle is DNA copied?

A. G2 phase   B. G1 phase   C. S phase   D. Cytokinesis
Answer: C. DNA synthesis happens in the S phase, between G1 and G2.

2. A cell in G1 has 2n = 8. After the S phase, how many chromosomes and chromatids does it have?

A. 8 chromosomes, 8 chromatids   B. 16 chromosomes, 16 chromatids   C. 16 chromosomes, 8 chromatids   D. 8 chromosomes, 16 chromatids
Answer: D. Replication doubles chromatids, not chromosome number: 8 chromosomes, each with two chromatids.

3. Which checkpoint checks that every chromosome is attached to the spindle before separation?

A. G1 checkpoint   B. Spindle assembly checkpoint   C. G2 checkpoint   D. Cytokinesis checkpoint
Answer: B. The spindle assembly checkpoint holds the cell in metaphase until all kinetochores are attached.

4. In which stage of mitosis do sister chromatids separate?

A. Metaphase   B. Prophase   C. Telophase   D. Anaphase
Answer: D. Anaphase is defined by sister chromatid separation and movement to opposite poles.

5. Chromosomes are most condensed and easiest to count in which stage?

A. Metaphase   B. Interphase   C. Cytokinesis   D. Prophase
Answer: A. Chromosomes reach maximum condensation at metaphase, when they line up at the equator.

6. What is the main role of the G2 checkpoint?

A. To pair homologous chromosomes   B. To separate sister chromatids   C. To form the cleavage furrow   D. To check that DNA replication is complete and undamaged before mitosis
Answer: D. G2 checks replication and damage before the cell is allowed into mitosis.

7. A human cell has 46 chromosomes. After mitosis and cytokinesis, each daughter cell has:

A. 92 chromosomes   B. 23 chromosomes   C. 46 chromatids and no chromosomes   D. 46 chromosomes
Answer: D. Mitosis conserves chromosome number: each daughter is diploid, 2n = 46.

8. Cytokinesis in an animal cell is carried out by:

A. The nuclear envelope splitting in two   B. A contractile ring of actin and myosin forming a cleavage furrow   C. Spindle fibres pushing the nucleus apart   D. A cell plate built from Golgi vesicles
Answer: B. Animal cells pinch in two by a contractile ring; the cell plate is the plant mechanism.

9. Why do plant cells form a cell plate instead of a cleavage furrow?

A. The rigid cell wall prevents pinching in, so a new wall must be built across the cell   B. Plant cells have no cytoplasm   C. Plant cells have no Golgi apparatus   D. Plant cells divide only by binary fission
Answer: A. A rigid wall cannot be pinched, so vesicles build a plate that becomes new membrane and wall.

10. Which event happens ONLY in meiosis, not in mitosis?

A. Sister chromatids separating   B. Nuclear envelope breakdown   C. Spindle formation   D. Crossing over between homologous chromosomes in prophase I
Answer: D. Crossing over requires pairing of homologues, which happens in prophase I of meiosis.

11. Meiosis I is called the reduction division because:

A. It reduces the cell's size   B. It reduces the number of chromatids to zero   C. It removes the nuclear envelope permanently   D. It separates homologous chromosomes and halves the chromosome number
Answer: D. Homologues separate in anaphase I, so each daughter cell is haploid.

12. An organism has n = 4. How many chromosome combinations can independent assortment alone produce in its gametes?

A. 4   B. 8   C. 16   D. 32
Answer: C. Combinations = 2 to the power n = 2^4 = 16.

13. There is no DNA replication between meiosis I and meiosis II. What follows from this?

A. Meiosis II produces diploid cells   B. Meiosis II cannot happen   C. The four final cells stay haploid, because chromatids are separated without another round of copying   D. Meiosis II restores the diploid number
Answer: C. Without replication, separating chromatids in meiosis II keeps the cells haploid.

14. Nondisjunction in meiosis can produce:

A. Only plant cells   B. A gamete with an extra chromosome or one missing, leading to aneuploidy after fertilisation   C. A cell with no DNA at all   D. Four identical diploid gametes
Answer: B. Failure to separate gives gametes with abnormal chromosome numbers.

15. Down syndrome is usually caused by:

A. Failure of cytokinesis in skin cells   B. Trisomy 21, three copies of chromosome 21, usually from nondisjunction   C. A missing cell membrane   D. Loss of a whole chromosome set
Answer: B. Trisomy 21 is the classic aneuploidy example: an extra copy of one chromosome.

16. Which statement about G0 is correct?

A. G0 is when DNA is copied   B. G0 is a resting state outside the cycle; some cells can re-enter the cycle later   C. G0 is a stage of mitosis   D. All cells in G0 are dead
Answer: B. G0 cells are quiescent, not dead, and many can be signalled back into G1.

17. Bacteria divide by:

A. Meiosis   B. Binary fission   C. Budding of the nucleus   D. Mitosis
Answer: B. Prokaryotes have no nucleus or spindle, so they copy their circular chromosome and split by binary fission.

18. Cyclins and CDKs control the cell cycle by:

A. Building the cell wall   B. Copying DNA directly   C. Physically pulling chromosomes apart   D. Forming complexes that switch on the next phase at the right time
Answer: D. A cyclin-CDK complex acts as a switch for a cell-cycle transition.

19. Which pair correctly matches a phase with its key event?

A. Telophase — nuclear envelope reforms and chromosomes decondense   B. Anaphase — chromosomes line up at the equator   C. Prophase — cleavage furrow forms   D. Metaphase — sister chromatids separate
Answer: A. Telophase reverses prophase: envelopes reform, spindles disassemble, chromosomes unwind.

20. A cell with 2n = 10 completes meiosis. Each resulting gamete has:

A. 20 chromosomes   B. 5 chromosomes, each with one chromatid   C. 10 chromosomes, each with two chromatids   D. 10 chromosomes, each with one chromatid
Answer: B. Meiosis halves the number to n = 5, and after meiosis II each chromosome has a single chromatid.

Separate Interactive Quiz — 20 different questions

These quiz questions are different from the MCQs above. Select an answer for each question. You will not see whether an answer is correct until you submit all 20 questions. Use Reset to try again.