Linkage mapping

Linkage is a phenomenon seen during.....

• Mitosis

• Meiosis

• DNA replication

• During a mutation

Crossingover occurs between

• Homologous Non sisters

• Homologous Sisters

• Between both homologous sisters and non sisters

• Occurs between different crhomosomes

What is the difference between Chromatin and Chromosomes? (1 mark)

How many genes can be mapped with the help of a double crossover?

• 3

• 2

• 4

• either 2 or 3

If Crossing over is a tool for generating variation in the population, then what is the purpose of the S phase in the cell cycle

• S phase is the phase in which mutations mostly occur in the DNA of the cell

• S phase is the phase during which DNA is getting condensed to form a chromosome

• S phase is the phase during which DNA is replicated in the cell

• S phase is the phase during which the proteins needed for mitosis are prepared

The corssing over happens in which stage of Meiosis

• Prophase I: Zygotene

• Prophase II: Zygotene

• Prophase II: Pachytene

• Anaphase

• Prophase I: Pachytene

The progeny of a test cross is not in a 1:1 ratio, this means

• Independent assortment failed to occur

• Segregation failed to occur

• There was some error in data analysis, the progeny of a test cross are always 1:1

• This is because of a lethal gene influence

Why is a test cross always performed when we need to map the gene distance? (2 marks)

How many progeny will be have if we have 3 genes that are being mapped?

• 9

• 8

• 4

• 6

During Meiosis at the tetrad stage the paternal chromosome and the maternal chromosome are accurately described as

• Homologue sister

• homologues

• Non Homologue sister

• Homologue non sister

• sister homologues