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Meiosis worksheet: crossing over, independent assortment and meiosis vs mitosis

A free, printable worksheet for high school and AP Biology. Students track chromosome numbers through both divisions, explain crossing over and independent assortment, compare meiosis with mitosis, and work out what nondisjunction does.

Download the PDF (free)Answer key (Teacher plan)

What's inside

  1. Vocabulary (10 terms)
  2. Why meiosis (3 questions)
  3. Meiosis I (6 questions)
  4. Meiosis II and the gametes (3 questions)
  5. Comparing, errors and variation (4 questions)

Teach it with the 3D lesson

Every question matches a step in CytoTour's 3D chapter on meiosis, which follows a human cell and all 46 of its chromosomes through both divisions. Read the steps with pictures on meiosis, step by step, or project the lesson in class — Chapter 1 is free, Chapters 5 and 7 are free with an account, and the Teacher plan opens every chapter.

The worksheet

This is the printable sheet (17 questions). Printing this page prints only the worksheet.

CytoTour · cytotour.com · free to print and copy for your classes

Meiosis

NameDatePeriod

Part 1 · Vocabulary

1. Write the letter of the matching description next to each term.

  1. Haploid
  2. Diploid
  3. Homologous chromosomes
  4. Sister chromatids
  5. Synapsis
  6. Tetrad
  7. Crossing over
  8. Chiasma
  9. Independent assortment
  10. Nondisjunction
  1. AThe pairing of homologous chromosomes in prophase I
  2. BExchange of matching segments between nonsister chromatids
  3. CA point where crossing over can be seen
  4. DChromosomes or chromatids failing to separate in meiosis
  5. EA homologous pair held together, made of four chromatids
  6. FA pair with the same genes at the same locations, one from each parent
  7. GHaving one set of chromosomes
  8. HEach homologous pair lines up either way, independently of the other pairs
  9. IHaving two sets of chromosomes
  10. JTwo identical copies of a chromosome, made in S phase and joined at the centromere

Part 2 · Why meiosis

2. Why must gametes be haploid?

3. Complete the table for a human cell going through meiosis.

CellsChromosomes per cellChromatids per chromosome
Start (after S phase)
After meiosis I
After meiosis II

4. What makes two chromosomes a homologous pair?

  1. AThey are identical copies made in S phase
  2. BThey carry the same genes at the same locations, one from each parent
  3. CThey are the two sex chromosomes
  4. DThey are joined at a centromere

Part 3 · Meiosis I

5. Put the stages of meiosis in order. Number them 1–8.

  1. Telophase I
  2. Anaphase I
  3. Prophase II
  4. Anaphase II
  5. Metaphase I
  6. Telophase II
  7. Metaphase II
  8. Prophase I

6. Crossing over exchanges segments between which chromatids?

  1. ASister chromatids of one chromosome
  2. BNonsister chromatids of a homologous pair
  3. CChromatids of different, non-homologous chromosomes
  4. DAny two chromatids in the nucleus

7. What holds the homologs of a pair together at the end of prophase I, and why must every pair have at least one?

8. Ignoring crossing over, how many different arrangements of the 23 pairs at the metaphase I plate are possible?

  1. A23
  2. B46
  3. C2²³ — over eight million
  4. D23²

9. What separates in anaphase I?

  1. ASister chromatids
  2. BHomologous chromosomes
  3. CThe two centrioles of each centrosome
  4. DNothing — the chromosomes only line up

10. A human cell starts meiosis with 46 chromosomes. How many chromosomes does each cell have after meiosis I?

Part 4 · Meiosis II and the gametes

11. How is meiosis II like mitosis, and how is it different?

12. Give two reasons the four cells made by meiosis are genetically different.

13. How many gametes does one meiosis make in a male? In a female?

Part 5 · Comparing, errors and variation

14. Compare mitosis and meiosis.

MitosisMeiosis
Number of divisions
Cells made
Chromosome number
Genetically
Homologs pair, crossing over
Used for

15. The homologs of chromosome 21 fail to separate in meiosis I. What do the four gametes get?

  1. AAll four are normal
  2. BTwo have two copies of chromosome 21, two have none
  3. COne has two copies, one has none, two are normal
  4. DAll four have two copies

16. A sperm with 24 chromosomes — two copies of chromosome 21 — fertilizes a normal egg. How many chromosomes does the zygote have, and what condition results?

17. List three sources of genetic variation in sexual reproduction.