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Edexcel IAL Biology 3.9 Loci and gene linkage

Locate both genes on the same chromosome, use their distance to explain crossing-over frequency and identify parental or recombinant combinations in the data.

Syllabus
First assessment 2019
Course
Biology YBI11
Level
AS

Exam points

  • Define a locus precisely as the position of a gene or allele on a chromosome.
  • Explain linkage through genes on the same chromosome and limited recombination.
  • Interpret gamete or phenotype frequencies to identify linked and recombinant alleles.

3.9—Loci and gene linkage question 1

[Maximum number: 1]

The photograph shows some pollen grains, as seen using an electron microscope.

Figure for Question 3.9—Loci and gene linkage question 1 — Edexcel A-Level Biology AS
Figure for Question 3.9—Loci and gene linkage question 1 — Edexcel A-Level Biology AS

Flower colour and pollen grain size are genetically determined in foxglove plants. The linkage of the genes for flower colour and pollen grain size has been investigated.

State what is meant by the term linkage with reference to these two genes.

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