A Level Biology Practice Exam

What is a common trait of homologous chromosomes?

1. They contain different types of genes

2. They pair together during cell division

3. They originate from the same gamete

4. They are identical in size and shape

The correct answer is: They pair together during cell division

Homologous chromosomes are a pair of chromosomes, one inherited from each parent, that contain the same types of genes but may have different alleles. A key characteristic of homologous chromosomes is that they undergo pairing during cell division, specifically during meiosis. This pairing allows for the exchange of genetic material through a process known as crossing over, which contributes to genetic diversity in gametes. The pairing of homologous chromosomes is crucial for proper segregation during the formation of gametes. It ensures that each gamete receives one chromosome from each pair, maintaining the chromosome number across generations. This process also allows for the recombination of genetic information, which is important for evolution and variation within a population. While the other options contain truths about chromosomes, they do not accurately describe a common trait of homologous chromosomes as effectively. For example, homologous chromosomes contain the same types of genes but can differ in alleles, so they do not contain different types of genes. They originate from different gametes (one from each parent), and while they are often similar in size and shape, they can also exhibit slight variations due to genetic diversity. Therefore, the pairing during cell division stands out as the defining trait of homologous chromosomes.