Biology 9700 · AS & A Level · Passage of information from parents to offspring
Passage of information from parents to offspring — practice question
A collection of plants called Rapid Cycling Brassicas (RCBs) has been bred for use in schools and colleges in genetics experiments.
As RCB seedlings grow, they may develop either purple stems or non-purple stems. Their seed leaves may be green or yellow-green.
Purple stems and green seed leaves are controlled by dominant alleles.
The genes for stem colour and seed-leaf colour are found on separate chromosomes.
(a)[2]
Explain what the term dominant allele means.
(b)[6]
Draw a genetic diagram to show the probable result of crossing two RCB plants that are heterozygous for both stem colour and seed-leaf colour. Use the symbols $A / a$ for stem colour and $B / b$ for seed leaf colour.
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “An allele is a different / alternative version of a gene” …