---
title: "Crossing Over — AP Biology Definition & Exam Guide"
description: "Crossing over is the exchange of genetic material between homologous chromosomes during meiosis I, a major source of genetic diversity tested in AP Bio Unit 5."
canonical: "https://fiveable.me/ap-bio/key-terms/crossing-over"
type: "key-term"
subject: "AP Biology"
---

# Crossing Over — AP Biology Definition & Exam Guide

## Definition

Crossing over is a process that occurs during meiosis where two chromosomes pair up and exchange segments of their genetic material. This leads to a mix of parental traits in offspring, contributing to genetic diversity.

## Related Study Guides

- [Chromosomal Inheritance Review](/ap-bio/unit-5/chromosomal-inheritance/study-guide/PzK71wcPD3xAmEId5SWv)
- [5.2 Meiosis and Genetic Diversity](/ap-bio/unit-5/meiosis-genetic-diversity/study-guide/YZOFYsQw4twZNkp5WM3l)

## Review

### Related Terms

- [Recombination](/ap-bio/key-terms/recombination): The rearrangement of genetic material, especially by crossing over in chromosomes.
- [Meiosis](/ap-bio/key-terms/meiosis): A type of cell division that results in four daughter cells each with half the number of chromosomes as the parent cell; it's how sex cells are produced.
- [Genetic Diversity](/ap-bio/key-terms/genetic-diversity): The total number of genetic characteristics in the genetic makeup of a species, enhanced by crossing over.