Meiosis 10.1 HL

This topic is all about the higher level details of meiosis. That includes the formation of a chiasmata in crossing over and the movement of chromosomes during the two division of meiosis. Remember some of the details of meiosis have also been covered in the standard level topic Meiosis 3.3.

Key concepts

Learn and test your biological vocabulary using these 10.1 Meiosis flashcards

Essentials

These slides summarise the essential understanding and skills in this topic. 
They contain short explanations in text and images - great revision.

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Summary

Summary list for 10.1 Meiosis

Crossing over

  • DNA replication makes a second chromatid in each chromosome in interphase before meiosis.
  • Crossing over exchanges pieces of DNA between non-sister homologous chromatids and forms new combinations of alleles on the chromosomes formed in meiosis.
  • Chiasmata are the crossing over points.

Chromosomes movements

  • Details of chromosome movements in meiosis.
    • Homologous chromosomes separate in meiosis I.
    • Sister chromatids separate in meiosis II.
  • Random orientation of homologous chromosomes in meiosis I leads to independent assortment of alleles.

Student skills and applications

  • Drawing diagrams to show chiasmata formed by crossing over.
  • show sister chromatids still closely aligned, except at the point where crossing over occurred and a chiasma was formed.

Mindmaps

This diagram summaries the main sections of topic 10.1.
Test if you can draw something like these concept maps from memory.

Exam style questions

Exam style question about meiosis

Explaining the movement of chromosomes is an important skill from this topic.

Answer the question below, on a piece of paper, then check your answer against the model answer below.

Describe crossing over and the formation of a chiasma. Credit will be given to labelled diagrams. [4]

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Extra exam question on variation due to meiosis.   Click to open.

Genetic variation caused by meiosis is an important aspect of this topic.

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Question: Outline the ways in which genetic variation is achieved in gamete production by meiosis. (5 marks).







Outline – important points with an explanation. .
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Extra exam question on the process of mitosis and meiosis.    Click to open.

An understanding of the similarities and differences between mitosis and meiosis is conceptually important.

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Compare the events of the process of meiosis with mitosis. (3 marks).





Hint:

Compare is asking for similarities (not differences).

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Test yourself

Multiple choice questions

This is a self marking quiz containing questions covering the topic outlined above.
Try the questions to check your understanding.


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Drag and drop activities

Test your ability to construct biological explanations using the drag and drop questions below.

Independent assortment during meiosis creates genetic variation.

Drag an drop the correct word or phrase into the gap to outline how independent assortment occurs.

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Prophase 1 equator second centromere randomly Prophase II sister centre separated gamete homologous

In of meiosis, chromosomes pair and become attached by their . The pairs of homologous chromosomes then associate into a bivalent of chromosomes.

In Metaphase 1 of meiosis, the bivalents line up on the spindle at the . Each tertrad orientates and independently of any other set of bivalents.

In Anaphase 1, the bivalents are , any pair can be drawn to either pole independently. The pairs of chromatids later separate during the division of meiosis giving different combinations of chromatids in the .

Homologous chromosomes have identical alleles, inherited from on of the parents. Sister chromosomes have identical genes but may have different alleles and are inherited from the other parent.


Just for fun

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