One Kind of Cell Division Copies Cells, the Other Halves Their Chromosomes
Follow the chromosomes, spindle and nuclear membrane through prophase, metaphase, anaphase and telophase, see how plant and animal cells differ in centrioles and cytokinesis, understand meiosis as reduction division, and compare mitosis and meiosis in growth, repair and reproduction.
Why does the body need two different kinds of cell division?
A newborn baby grows from a single cell into trillions. A scraped knee grows new skin within a week. Both happen by one kind of division — mitosis — in which a cell makes two exact copies of itself, each with the full set of chromosomes.
But the cells that make the next generation cannot divide that way. If a sperm and an egg each carried chromosomes, **the child would have , the grandchild , and the number would double every generation. A second kind of division — meiosis — halves the chromosome number when gametes are made, so that fertilisation restores it exactly.
So the two divisions have opposite jobs.
- Mitosis keeps the chromosome number the same — for growth, repair and replacing worn-out cells
- Meiosis halves the chromosome number — for making gametes and keeping the number constant from parents to offspring
This part covers:
- The four stages of mitosis — prophase, metaphase, anaphase and telophase — and what the chromosomes, spindle and nuclear membrane do in each
- How plant and animal cells divide differently — centrioles, asters, and a cell plate versus a cleavage furrow
- Meiosis as reduction division, and its role across generations
- A comparison of mitosis and meiosis, and the significance of each
An everyday way to see mitosis. In many school laboratories, students squash the tip of an onion root on a slide, stain it and look through a microscope. Because root tips grow fast, many cells are caught in the middle of mitosis, with their chromosomes visible as dark threads in different stages.
The link to Part 1. Every stage described here depends on what happened in interphase. The chromosomes that separate in anaphase are the sister chromatids copied in the S phase**, and the homologous pairs that separate in meiosis are the maternal and paternal chromosomes defined in Part 1.
This page covers the second part of the ICSE Class 10 Biology chapter on the structure of chromosomes, cell cycle and cell division: the stages of mitosis, mitosis in plant and animal cells, meiosis, and their comparison.
But the cells that make the next generation cannot divide that way. If a sperm and an egg each carried chromosomes, **the child would have , the grandchild , and the number would double every generation. A second kind of division — meiosis — halves the chromosome number when gametes are made, so that fertilisation restores it exactly.
So the two divisions have opposite jobs.
- Mitosis keeps the chromosome number the same — for growth, repair and replacing worn-out cells
- Meiosis halves the chromosome number — for making gametes and keeping the number constant from parents to offspring
This part covers:
- The four stages of mitosis — prophase, metaphase, anaphase and telophase — and what the chromosomes, spindle and nuclear membrane do in each
- How plant and animal cells divide differently — centrioles, asters, and a cell plate versus a cleavage furrow
- Meiosis as reduction division, and its role across generations
- A comparison of mitosis and meiosis, and the significance of each
An everyday way to see mitosis. In many school laboratories, students squash the tip of an onion root on a slide, stain it and look through a microscope. Because root tips grow fast, many cells are caught in the middle of mitosis, with their chromosomes visible as dark threads in different stages.
The link to Part 1. Every stage described here depends on what happened in interphase. The chromosomes that separate in anaphase are the sister chromatids copied in the S phase**, and the homologous pairs that separate in meiosis are the maternal and paternal chromosomes defined in Part 1.
This page covers the second part of the ICSE Class 10 Biology chapter on the structure of chromosomes, cell cycle and cell division: the stages of mitosis, mitosis in plant and animal cells, meiosis, and their comparison.
What happens to the chromosomes, spindle and nuclear membrane in each stage of mitosis?
In prophase the chromosomes become visible and the nuclear membrane breaks down; in metaphase they line up at the equator attached to spindle fibres; in anaphase the sister chromatids separate to opposite poles; and in telophase new nuclear membranes form around the two groups.
1. Prophase.
- Chromosomes: chromatin coils and condenses into visible chromosomes, each made of two sister chromatids joined at the centromere
- Spindle: spindle fibres begin to form; in animal cells the centrioles move to opposite poles
- Nuclear membrane and nucleolus: begin to disappear
2. Metaphase.
- Chromosomes: line up in a single row at the equator of the cell, forming the metaphase plate
- Spindle: fibres from each pole attach to the centromere of every chromosome
- Nuclear membrane: absent
- Chromosomes are most condensed, so this is the best stage to count and study them
3. Anaphase.
- Chromosomes: each centromere splits, and the two sister chromatids separate; each is now called a daughter chromosome
- Spindle: the fibres shorten, pulling the daughter chromosomes towards opposite poles
- The chromosomes often look V-shaped or J-shaped as they are dragged by the centromere
4. Telophase.
- Chromosomes: reach the poles and uncoil back into chromatin
- Spindle: disappears
- Nuclear membrane and nucleolus: reappear around each group, forming two nuclei
Cytokinesis then divides the cytoplasm, producing two daughter cells.
Worked example — counting through mitosis in a human cell.
- Prophase: chromosomes, chromatids
- Metaphase: chromosomes, chromatids, all at the equator
- Anaphase: centromeres split, so separate daughter chromosomes, moving to each pole
- Each daughter cell: chromosomes, each a single chromatid
Worked example — a smaller number. A cell with divides by mitosis. How many chromosomes are at each pole in anaphase, and in each daughter cell?
The chromosome number of each daughter cell equals that of the parent — the defining result of mitosis.
An everyday example. In an onion root tip squash, cells in metaphase are easy to spot because their chromosomes form a neat line across the middle, while cells in anaphase show two clusters moving apart. Recognising those two pictures is a standard practical skill.
The boundary case. The chromosome number doubles only briefly, during anaphase, when sister chromatids become separate chromosomes. By the end of telophase each nucleus again has the original number — so saying mitosis doubles the chromosome number, without mentioning that it is then halved between two cells, is incorrect.
1. Prophase.
- Chromosomes: chromatin coils and condenses into visible chromosomes, each made of two sister chromatids joined at the centromere
- Spindle: spindle fibres begin to form; in animal cells the centrioles move to opposite poles
- Nuclear membrane and nucleolus: begin to disappear
2. Metaphase.
- Chromosomes: line up in a single row at the equator of the cell, forming the metaphase plate
- Spindle: fibres from each pole attach to the centromere of every chromosome
- Nuclear membrane: absent
- Chromosomes are most condensed, so this is the best stage to count and study them
3. Anaphase.
- Chromosomes: each centromere splits, and the two sister chromatids separate; each is now called a daughter chromosome
- Spindle: the fibres shorten, pulling the daughter chromosomes towards opposite poles
- The chromosomes often look V-shaped or J-shaped as they are dragged by the centromere
4. Telophase.
- Chromosomes: reach the poles and uncoil back into chromatin
- Spindle: disappears
- Nuclear membrane and nucleolus: reappear around each group, forming two nuclei
Cytokinesis then divides the cytoplasm, producing two daughter cells.
Worked example — counting through mitosis in a human cell.
- Prophase: chromosomes, chromatids
- Metaphase: chromosomes, chromatids, all at the equator
- Anaphase: centromeres split, so separate daughter chromosomes, moving to each pole
- Each daughter cell: chromosomes, each a single chromatid
Worked example — a smaller number. A cell with divides by mitosis. How many chromosomes are at each pole in anaphase, and in each daughter cell?
The chromosome number of each daughter cell equals that of the parent — the defining result of mitosis.
An everyday example. In an onion root tip squash, cells in metaphase are easy to spot because their chromosomes form a neat line across the middle, while cells in anaphase show two clusters moving apart. Recognising those two pictures is a standard practical skill.
The boundary case. The chromosome number doubles only briefly, during anaphase, when sister chromatids become separate chromosomes. By the end of telophase each nucleus again has the original number — so saying mitosis doubles the chromosome number, without mentioning that it is then halved between two cells, is incorrect.
How does mitosis differ in plant cells and animal cells?
Animal cells use centrioles with asters to form the spindle and divide their cytoplasm by a cleavage furrow pinching inwards, while most plant cells form the spindle without centrioles and divide their cytoplasm by a cell plate growing outwards from the centre.
1. Centrioles and asters.
- Animal cells: centrioles are present. During prophase they move to opposite poles, and short fibres radiate from them like rays — these are the asters. The spindle forms between the two centrioles
- Plant cells (flowering plants): centrioles and asters are absent. The spindle still forms, organised from regions near the poles without centrioles
2. Cytokinesis — dividing the cytoplasm.
- Animal cells — cleavage furrow. The cell membrane is pulled inwards around the middle of the cell, forming a furrow that deepens from the outside inwards until the cell pinches into two
- Plant cells — cell plate. Small vesicles gather at the centre of the cell and fuse to form a cell plate, which grows outwards until it meets the side walls, becoming the new wall between the two cells
Why plant cells cannot use a furrow. A plant cell is enclosed by a rigid cell wall, which cannot be pinched inwards like a flexible membrane. So the new wall has to be built from the inside out.
3. Where mitosis happens.
- Animals: in tissues throughout the body — skin, the lining of the gut, bone marrow and many others
- Plants: mainly in meristems — the growing regions at root tips and shoot tips
The comparison in one list:
- Centrioles: present in animal cells; absent in most plant cells
- Asters: formed in animal cells; not formed in plant cells
- Cytokinesis: cleavage furrow, from outside inwards, in animal cells; cell plate, from centre outwards, in plant cells
- Location: many body tissues in animals; meristems in plants
Worked example — identify the cell. A dividing cell shows no asters, and a line of material is forming across the middle of the cell, starting at the centre. Is it a plant or an animal cell?
A plant cell — the absence of asters and the cell plate growing from the centre both point the same way.
An everyday example. The tips of the roots of a sprouting moong or chana seed grow quickly because cells in their meristems divide by mitosis again and again. Each division ends with a cell plate, so the root lengthens by adding walled cells one after another.
The boundary case. The behaviour of the chromosomes is the same in plant and animal cells — the same four stages, the same separation of chromatids. Only the spindle's origin and the way the cytoplasm divides differ, so an answer describing different chromosome movements in plants would be wrong.
1. Centrioles and asters.
- Animal cells: centrioles are present. During prophase they move to opposite poles, and short fibres radiate from them like rays — these are the asters. The spindle forms between the two centrioles
- Plant cells (flowering plants): centrioles and asters are absent. The spindle still forms, organised from regions near the poles without centrioles
2. Cytokinesis — dividing the cytoplasm.
- Animal cells — cleavage furrow. The cell membrane is pulled inwards around the middle of the cell, forming a furrow that deepens from the outside inwards until the cell pinches into two
- Plant cells — cell plate. Small vesicles gather at the centre of the cell and fuse to form a cell plate, which grows outwards until it meets the side walls, becoming the new wall between the two cells
Why plant cells cannot use a furrow. A plant cell is enclosed by a rigid cell wall, which cannot be pinched inwards like a flexible membrane. So the new wall has to be built from the inside out.
3. Where mitosis happens.
- Animals: in tissues throughout the body — skin, the lining of the gut, bone marrow and many others
- Plants: mainly in meristems — the growing regions at root tips and shoot tips
The comparison in one list:
- Centrioles: present in animal cells; absent in most plant cells
- Asters: formed in animal cells; not formed in plant cells
- Cytokinesis: cleavage furrow, from outside inwards, in animal cells; cell plate, from centre outwards, in plant cells
- Location: many body tissues in animals; meristems in plants
Worked example — identify the cell. A dividing cell shows no asters, and a line of material is forming across the middle of the cell, starting at the centre. Is it a plant or an animal cell?
A plant cell — the absence of asters and the cell plate growing from the centre both point the same way.
An everyday example. The tips of the roots of a sprouting moong or chana seed grow quickly because cells in their meristems divide by mitosis again and again. Each division ends with a cell plate, so the root lengthens by adding walled cells one after another.
The boundary case. The behaviour of the chromosomes is the same in plant and animal cells — the same four stages, the same separation of chromatids. Only the spindle's origin and the way the cytoplasm divides differ, so an answer describing different chromosome movements in plants would be wrong.
Why is meiosis called reduction division, and how does it keep chromosome numbers constant?
Meiosis is called reduction division because one diploid cell divides twice to form four haploid cells with half the chromosome number; when two haploid gametes fuse at fertilisation, the diploid number is restored, so it stays constant from generation to generation.
What meiosis is. A type of cell division in which one diploid cell (2n) undergoes two successive divisions to produce four haploid cells (n).
- Meiosis I — homologous chromosomes pair up and then separate to different cells. This is the division that halves the chromosome number
- Meiosis II — sister chromatids separate, much as in mitosis, so that each of the four cells receives one chromatid of every chromosome
Where meiosis happens:
- Animals: in the reproductive organs — testes and ovaries — forming sperm and eggs
- Plants: in the reproductive parts of flowers, forming spores that give rise to gametes
Crossing over — a source of variation. During meiosis I, the paired homologous chromosomes exchange segments with each other. This mixes the genes inherited from the two parents, so each gamete carries a new combination.
How meiosis keeps the chromosome number constant:
Worked example — what would happen without meiosis. Suppose gametes were made by mitosis and each carried chromosomes. Find the chromosome number of the zygote in each of three generations.
The number would double every generation. Meiosis prevents this by halving it before fertilisation.
Worked example — cells produced. In an animal with , cells in the testes complete meiosis. How many sperm are formed, and how many chromosomes does each carry?
An everyday example. Children of the same parents inherit a different mixture of their parents' characteristics. Crossing over and the random way homologous chromosomes are shared out in meiosis mean that no two gametes, and so no two siblings apart from identical twins, receive exactly the same set of genes.
The boundary case. Meiosis halves the number of chromosomes, not the amount of each chromosome. Every haploid gamete still contains one complete member of each homologous pair — a full set of instructions, with no chromosome missing.
What meiosis is. A type of cell division in which one diploid cell (2n) undergoes two successive divisions to produce four haploid cells (n).
- Meiosis I — homologous chromosomes pair up and then separate to different cells. This is the division that halves the chromosome number
- Meiosis II — sister chromatids separate, much as in mitosis, so that each of the four cells receives one chromatid of every chromosome
Where meiosis happens:
- Animals: in the reproductive organs — testes and ovaries — forming sperm and eggs
- Plants: in the reproductive parts of flowers, forming spores that give rise to gametes
Crossing over — a source of variation. During meiosis I, the paired homologous chromosomes exchange segments with each other. This mixes the genes inherited from the two parents, so each gamete carries a new combination.
How meiosis keeps the chromosome number constant:
Worked example — what would happen without meiosis. Suppose gametes were made by mitosis and each carried chromosomes. Find the chromosome number of the zygote in each of three generations.
The number would double every generation. Meiosis prevents this by halving it before fertilisation.
Worked example — cells produced. In an animal with , cells in the testes complete meiosis. How many sperm are formed, and how many chromosomes does each carry?
An everyday example. Children of the same parents inherit a different mixture of their parents' characteristics. Crossing over and the random way homologous chromosomes are shared out in meiosis mean that no two gametes, and so no two siblings apart from identical twins, receive exactly the same set of genes.
The boundary case. Meiosis halves the number of chromosomes, not the amount of each chromosome. Every haploid gamete still contains one complete member of each homologous pair — a full set of instructions, with no chromosome missing.
How do mitosis and meiosis compare, and why is each important?
Mitosis produces two genetically identical diploid cells for growth, repair and asexual reproduction, while meiosis produces four genetically varied haploid cells for sexual reproduction and keeping the chromosome number constant.
Point-by-point comparison:
- Where it occurs: mitosis — body cells; meiosis — reproductive cells
- Number of divisions: mitosis — one; meiosis — two
- Number of daughter cells: mitosis — two; meiosis — four
- Chromosome number: mitosis — same as parent, 2n to 2n; meiosis — halved, 2n to n
- Pairing of homologous chromosomes: mitosis — does not occur; meiosis — occurs
- Crossing over: mitosis — absent; meiosis — present
- Genetic make-up of daughter cells: mitosis — identical to the parent and each other; meiosis — different from the parent and each other
Significance of mitosis:
- Growth — a single-celled zygote becomes a many-celled body
- Repair — healing wounds and mending broken bones
- Replacement — renewing skin, blood and gut lining cells
- Asexual reproduction — in single-celled organisms, and vegetative propagation in plants
- Keeping the chromosome number the same in every body cell
Significance of meiosis:
- Forming gametes for sexual reproduction
- Halving the chromosome number, so fertilisation restores the diploid number
- Producing variation through crossing over and the random sharing of chromosomes, which helps species adapt over time
Worked example 1 — cells from repeated mitosis. One cell divides by mitosis, and every new cell divides again, for rounds. How many cells are formed?
Worked example 2 — comparing outputs. diploid cells with divide, some by mitosis and some by meiosis. Compare the results of cells dividing each way.
- Mitosis: cells, each with chromosomes
- Meiosis: cells, each with chromosomes
An everyday example. Farmers grow sugarcane from pieces of stem and potatoes from pieces of tuber. Every new plant grows by mitosis from cells of the parent, so the crop is genetically uniform and keeps the qualities the farmer chose.
The boundary case. Mitosis is normally controlled tightly. When cells lose that control and divide by mitosis without stopping, they can form a tumour — which is why cancer is described as uncontrolled cell division, and why understanding the cell cycle matters in medicine.
Point-by-point comparison:
- Where it occurs: mitosis — body cells; meiosis — reproductive cells
- Number of divisions: mitosis — one; meiosis — two
- Number of daughter cells: mitosis — two; meiosis — four
- Chromosome number: mitosis — same as parent, 2n to 2n; meiosis — halved, 2n to n
- Pairing of homologous chromosomes: mitosis — does not occur; meiosis — occurs
- Crossing over: mitosis — absent; meiosis — present
- Genetic make-up of daughter cells: mitosis — identical to the parent and each other; meiosis — different from the parent and each other
Significance of mitosis:
- Growth — a single-celled zygote becomes a many-celled body
- Repair — healing wounds and mending broken bones
- Replacement — renewing skin, blood and gut lining cells
- Asexual reproduction — in single-celled organisms, and vegetative propagation in plants
- Keeping the chromosome number the same in every body cell
Significance of meiosis:
- Forming gametes for sexual reproduction
- Halving the chromosome number, so fertilisation restores the diploid number
- Producing variation through crossing over and the random sharing of chromosomes, which helps species adapt over time
Worked example 1 — cells from repeated mitosis. One cell divides by mitosis, and every new cell divides again, for rounds. How many cells are formed?
Worked example 2 — comparing outputs. diploid cells with divide, some by mitosis and some by meiosis. Compare the results of cells dividing each way.
- Mitosis: cells, each with chromosomes
- Meiosis: cells, each with chromosomes
An everyday example. Farmers grow sugarcane from pieces of stem and potatoes from pieces of tuber. Every new plant grows by mitosis from cells of the parent, so the crop is genetically uniform and keeps the qualities the farmer chose.
The boundary case. Mitosis is normally controlled tightly. When cells lose that control and divide by mitosis without stopping, they can form a tumour — which is why cancer is described as uncontrolled cell division, and why understanding the cell cycle matters in medicine.
Exam tip
What earns full marks on mitosis and meiosis?
For each stage of mitosis, state what happens to the chromosomes, the spindle and the nuclear membrane; for comparisons, give matched points side by side.
- Name the stages in order: prophase, metaphase, anaphase, telophase
- Give three observations per stage — chromosomes, spindle, nuclear membrane or nucleolus
- Say metaphase is best for counting chromosomes, because they are most condensed and lined up
- Describe anaphase precisely: centromeres split and sister chromatids move to opposite poles
- For plant versus animal cells, mention centrioles, asters and cell plate versus cleavage furrow, with the reason — the rigid cell wall
- Define meiosis as reduction division, with one diploid cell giving four haploid cells
- Explain how the chromosome number stays constant using
- Mention crossing over as the source of variation in meiosis
- Compare mitosis and meiosis in pairs — site, divisions, daughter cells, chromosome number, variation
- Give significance — growth, repair and asexual reproduction for mitosis; gametes, constant number and variation for meiosis
The misconception to name. Homologous chromosomes do not separate in mitosis. In mitosis only sister chromatids separate; homologous chromosomes separate in meiosis I. Writing that homologues move apart in mitotic anaphase confuses the two divisions entirely.
A second trap. Drawing a cell plate in an animal cell. Animal cells divide by a cleavage furrow, and a diagram with a cell plate is marked wrong however well the chromosomes are drawn.
- Name the stages in order: prophase, metaphase, anaphase, telophase
- Give three observations per stage — chromosomes, spindle, nuclear membrane or nucleolus
- Say metaphase is best for counting chromosomes, because they are most condensed and lined up
- Describe anaphase precisely: centromeres split and sister chromatids move to opposite poles
- For plant versus animal cells, mention centrioles, asters and cell plate versus cleavage furrow, with the reason — the rigid cell wall
- Define meiosis as reduction division, with one diploid cell giving four haploid cells
- Explain how the chromosome number stays constant using
- Mention crossing over as the source of variation in meiosis
- Compare mitosis and meiosis in pairs — site, divisions, daughter cells, chromosome number, variation
- Give significance — growth, repair and asexual reproduction for mitosis; gametes, constant number and variation for meiosis
The misconception to name. Homologous chromosomes do not separate in mitosis. In mitosis only sister chromatids separate; homologous chromosomes separate in meiosis I. Writing that homologues move apart in mitotic anaphase confuses the two divisions entirely.
A second trap. Drawing a cell plate in an animal cell. Animal cells divide by a cleavage furrow, and a diagram with a cell plate is marked wrong however well the chromosomes are drawn.
Did you know
Why do farmers grow bananas and sugarcane from cuttings instead of seeds?
Walk past a banana plantation or a sugarcane field and nearly every plant is the same height, the same colour and gives the same kind of fruit or cane. That uniformity is no accident. Most banana and sugarcane crops are grown not from seeds but from pieces of the parent plant — suckers for bananas and stem cuttings for sugarcane — and mitosis is the reason this works so well.
A cutting grows into a new plant entirely by mitosis.
- The cells at the buds of a sugarcane stem piece divide by mitosis to form roots and shoots
- Every new cell receives an exact copy of the parent's chromosomes
- So the whole new plant is genetically identical to the plant it came from — a clone
This matters to farmers. A variety chosen for sweet cane or large, tasty bananas keeps exactly those qualities in every plant grown from its cuttings, season after season.
Seeds would behave very differently. Seeds form through sexual reproduction, which depends on meiosis. Crossing over and the mixing of chromosomes from two parents produce offspring that differ from each other and from the parents — and many of them would lose the qualities the farmer wanted. The cultivated bananas sold in markets usually do not even form proper seeds, so vegetative propagation is the only practical way to grow them.
But the uniformity carries a risk. Because every plant in a field grown from cuttings is genetically identical, a disease that attacks one can attack them all. A crop raised from seeds would contain more variation, and some plants might resist the disease.
So the two divisions of this lesson present a real trade-off in farming. Mitosis gives reliable, identical plants; meiosis gives variety and the chance of resistance. Plant breeders use sexual reproduction to create new varieties, and then use cuttings to multiply the best ones — putting both kinds of cell division to work.
A cutting grows into a new plant entirely by mitosis.
- The cells at the buds of a sugarcane stem piece divide by mitosis to form roots and shoots
- Every new cell receives an exact copy of the parent's chromosomes
- So the whole new plant is genetically identical to the plant it came from — a clone
This matters to farmers. A variety chosen for sweet cane or large, tasty bananas keeps exactly those qualities in every plant grown from its cuttings, season after season.
Seeds would behave very differently. Seeds form through sexual reproduction, which depends on meiosis. Crossing over and the mixing of chromosomes from two parents produce offspring that differ from each other and from the parents — and many of them would lose the qualities the farmer wanted. The cultivated bananas sold in markets usually do not even form proper seeds, so vegetative propagation is the only practical way to grow them.
But the uniformity carries a risk. Because every plant in a field grown from cuttings is genetically identical, a disease that attacks one can attack them all. A crop raised from seeds would contain more variation, and some plants might resist the disease.
So the two divisions of this lesson present a real trade-off in farming. Mitosis gives reliable, identical plants; meiosis gives variety and the chance of resistance. Plant breeders use sexual reproduction to create new varieties, and then use cuttings to multiply the best ones — putting both kinds of cell division to work.
Exam relevance
How do mitosis and meiosis appear in NEET Biology?
This is foundation work for Class 11 Cell Cycle and Cell Division, and for Class 12 Human Reproduction, Sexual Reproduction in Flowering Plants and Principles of Inheritance and Variation — chapters central to NEET Biology.
Where the stages of mitosis lead. Class 11 Cell Cycle and Cell Division describes each stage of mitosis in greater detail, including the role of kinetochores at the centromere. Identifying a stage from a description or diagram, and stating the event of each stage, are recurring NEET question types.
Where meiosis leads. The same chapter divides prophase I into sub-stages — leptotene, zygotene, pachytene, diplotene and diakinesis — with pairing of homologues, crossing over and the formation of chiasmata assigned to particular sub-stages. Matching each event to its sub-stage is a standard match-the-column item.
Where chromosome counting leads. NEET asks for the number of chromosomes and the amount of DNA at different stages of mitosis and meiosis, and in cells such as the zygote, gametes and endosperm. The counting method in this lesson — tracking chromosomes and chromatids separately — is exactly what those questions require.
Where the significance of meiosis leads. Class 12 Human Reproduction covers the formation of sperm and eggs, where the number of gametes produced from each parent cell differs between males and females, and Class 12 Sexual Reproduction in Flowering Plants covers spore and gamete formation. Principles of Inheritance and Variation links crossing over to recombination and linkage.
Where plant versus animal division leads. Differences in cytokinesis — cell plate formation versus cleavage furrow — appear as statement-based questions.
Question types to expect. At this level: stages with diagrams, plant and animal differences, and comparisons. In NEET: sub-stages of prophase I, chromosome and DNA counts, events matched to stages, gametogenesis outputs and crossing-over consequences.
The single trap that costs marks. Mixing up what separates in each division. Sister chromatids separate in mitotic anaphase and in anaphase II; homologous chromosomes separate in anaphase I. NEET statements are frequently written to test exactly this.
A second trap. Stating that meiosis II reduces the chromosome number. The reduction happens in meiosis I; meiosis II separates chromatids without changing the number of chromosomes.
Board versus competitive emphasis. The ICSE paper marks the four stages, labelled diagrams and clear comparisons; NEET marks sub-stages, counts and precise statements. The transferable habit is asking, for every stage, whether homologues or sister chromatids are moving — the question that separates correct answers from near-misses.
Where the stages of mitosis lead. Class 11 Cell Cycle and Cell Division describes each stage of mitosis in greater detail, including the role of kinetochores at the centromere. Identifying a stage from a description or diagram, and stating the event of each stage, are recurring NEET question types.
Where meiosis leads. The same chapter divides prophase I into sub-stages — leptotene, zygotene, pachytene, diplotene and diakinesis — with pairing of homologues, crossing over and the formation of chiasmata assigned to particular sub-stages. Matching each event to its sub-stage is a standard match-the-column item.
Where chromosome counting leads. NEET asks for the number of chromosomes and the amount of DNA at different stages of mitosis and meiosis, and in cells such as the zygote, gametes and endosperm. The counting method in this lesson — tracking chromosomes and chromatids separately — is exactly what those questions require.
Where the significance of meiosis leads. Class 12 Human Reproduction covers the formation of sperm and eggs, where the number of gametes produced from each parent cell differs between males and females, and Class 12 Sexual Reproduction in Flowering Plants covers spore and gamete formation. Principles of Inheritance and Variation links crossing over to recombination and linkage.
Where plant versus animal division leads. Differences in cytokinesis — cell plate formation versus cleavage furrow — appear as statement-based questions.
Question types to expect. At this level: stages with diagrams, plant and animal differences, and comparisons. In NEET: sub-stages of prophase I, chromosome and DNA counts, events matched to stages, gametogenesis outputs and crossing-over consequences.
The single trap that costs marks. Mixing up what separates in each division. Sister chromatids separate in mitotic anaphase and in anaphase II; homologous chromosomes separate in anaphase I. NEET statements are frequently written to test exactly this.
A second trap. Stating that meiosis II reduces the chromosome number. The reduction happens in meiosis I; meiosis II separates chromatids without changing the number of chromosomes.
Board versus competitive emphasis. The ICSE paper marks the four stages, labelled diagrams and clear comparisons; NEET marks sub-stages, counts and precise statements. The transferable habit is asking, for every stage, whether homologues or sister chromatids are moving — the question that separates correct answers from near-misses.
Key takeaways
What must you be able to do from this part?
Four stages, two kinds of cell, one reduction division and a full comparison.
- Prophase: chromosomes condense with two chromatids; spindle forms; nuclear membrane and nucleolus disappear
- Metaphase: chromosomes line up at the equator; spindle fibres attach to centromeres; best stage for counting
- Anaphase: centromeres split; sister chromatids move to opposite poles as daughter chromosomes
- Telophase: chromosomes uncoil at the poles; spindle disappears; two nuclear membranes and nucleoli reappear
- Cytokinesis then forms two cells, each with the parent's chromosome number
- Human mitosis: chromosomes and chromatids at metaphase; daughter chromosomes in anaphase; in each new cell
- Animal cells: centrioles and asters present; cleavage furrow from outside inwards
- Plant cells: no centrioles or asters; cell plate from centre outwards, because of the rigid cell wall
- Meiosis: one diploid cell, two divisions, four haploid cells — reduction division
- Meiosis I separates homologous chromosomes and halves the number; meiosis II separates sister chromatids
- Crossing over in meiosis I produces variation
- Constant chromosome number: ; without meiosis, would become , then
- Mitosis: body cells, one division, two identical diploid cells — growth, repair, replacement, asexual reproduction
- Meiosis: reproductive cells, two divisions, four varied haploid cells — gametes, constant number, variation
- Three rounds of mitosis from one cell give cells
- Uncontrolled mitosis can lead to cancer
The sharpest self-test is two blank circles. In one, sketch a cell with going through mitosis; in the other, the same cell going through meiosis — and label the chromosome number at every step until the final cells are formed.
- Prophase: chromosomes condense with two chromatids; spindle forms; nuclear membrane and nucleolus disappear
- Metaphase: chromosomes line up at the equator; spindle fibres attach to centromeres; best stage for counting
- Anaphase: centromeres split; sister chromatids move to opposite poles as daughter chromosomes
- Telophase: chromosomes uncoil at the poles; spindle disappears; two nuclear membranes and nucleoli reappear
- Cytokinesis then forms two cells, each with the parent's chromosome number
- Human mitosis: chromosomes and chromatids at metaphase; daughter chromosomes in anaphase; in each new cell
- Animal cells: centrioles and asters present; cleavage furrow from outside inwards
- Plant cells: no centrioles or asters; cell plate from centre outwards, because of the rigid cell wall
- Meiosis: one diploid cell, two divisions, four haploid cells — reduction division
- Meiosis I separates homologous chromosomes and halves the number; meiosis II separates sister chromatids
- Crossing over in meiosis I produces variation
- Constant chromosome number: ; without meiosis, would become , then
- Mitosis: body cells, one division, two identical diploid cells — growth, repair, replacement, asexual reproduction
- Meiosis: reproductive cells, two divisions, four varied haploid cells — gametes, constant number, variation
- Three rounds of mitosis from one cell give cells
- Uncontrolled mitosis can lead to cancer
The sharpest self-test is two blank circles. In one, sketch a cell with going through mitosis; in the other, the same cell going through meiosis — and label the chromosome number at every step until the final cells are formed.