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Independent Assortment & Crossing Over

I don’t know which one to choose to write about or what each of the two actually is, can I please have some help?

Welcome to StudyIt munrotheboat :blush:
This is a great question, these terms frequently crop up in 90948 exam papers.
Indepdent assortment and crossing over are processes related to how sexual reproduction leads to variation in species.
I’ll go through what each term means and then have a look at how to answer an exam question.

Both independent assortment and crossing over occur during meiosis. They cause variation/differences to occur between the gametes (sperm and egg cells) formed during meiosis.

When cells divide during meiosis homologous chromosomes (chromosomes which contain the same genes) randomly line up. The random order of the chromosomes results in gametes which have unique combinations of chromosomes.
images (1)
In the diagram you can see the random and unique gametes. This is variation!

When homologous chromosomes line up during meiosis chromosomes may exchange genetic info. This causes new combinations of genes on each chromosome. Therefore the gametes can get unique combinations.
images (2)

In the 2019 exam paper question 3 part b it asks you to explain how sexual reproduction of kauri trees causes genetic variation. Here you would talk about either independent assortment OR crossing over. If you read the mark schedule you will see you that
They aren’t explained in a lot of depth. But you need to link the description to how they create variation in the offspring.

I hope this makes sense, sing out if you need more info.

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