Genetics HL - dihybrid crosses

Presence of recombinants in dihybrid crosses with gene linkage depends on:

• frequency of crossing-over

• independent assortment of chromosomes in meiosis I

• frequency of mutations

• fusion of gametes

Alleles of linked genes:

• have their loci on the same chromosome

• have their loci on non-homologous chromosomes

• are inherited together

• separate in crossing-over

The Law of Independent Assortment is visible in:

• metaphase I of meiosis

• metaphase II of mitosis

• metaphase of mitosis

• prophase I of meiosis

Which gametes can result from the following crossover?

• A

• B

• C

• D

The frequency of crossing over between two linked genes depends on:

• the distance between their loci

• the length of both genes

• the number of chromosomes in the karyotype

• the distance betwen chromosomes

The first step of prophase I of meiosis is called:

• pachytene

• leptotene

• diakinesis

• zygotene

In which phase of prophase I does crossing-over occur?

• leptotene

• zygotene

• pachytene

• diakinesis

Proteins that link bivalents allowing for crossing-over are called:

• cohesins

• microtubules

• kinetochores

• histones

Chiasmata are visible during what stage of meoisis?

• diplotene

• diakinesis

• cytokinesis

• metaphase I

How many chiasmata are visible in this electron micrograph?