Bay scallops (Argopecten irradians) have three shell colours: orange, yellow and black - VCE - SSCE Biology - Question 2 - 2005 - Paper 1
Question 2
Bay scallops (Argopecten irradians) have three shell colours: orange, yellow and black. It is known that the colour is under the control of one gene locus with three... show full transcript
Worked Solution & Example Answer:Bay scallops (Argopecten irradians) have three shell colours: orange, yellow and black - VCE - SSCE Biology - Question 2 - 2005 - Paper 1
Step 1
What is a gene locus?
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Answer
A gene locus is the position of a gene on a chromosome. It describes where a particular gene is located within the genomic organization.
Step 2
If you compared the alleles of this locus at the molecular level, what would be different?
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Answer
At the molecular level, the sequence of bases or nucleotides in the DNA would be different among the alleles. Each allele represents a variation of the gene that results in different physical traits.
Step 3
What is the name given to the process which gives rise to new alleles?
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The process that gives rise to new alleles is called mutation. Mutations can lead to changes in the DNA sequence that may result in different traits.
Step 4
Using the allelic symbols p^Y for yellow, p^O for orange and p^B for black, show the genotypes of the parents and offspring in cross 1.
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Answer
Parent's phenotype
yellow
yellow
Parent's genotype(s)
p^Y p^Y
p^Y p^Y
Offspring phenotype
yellow
Offspring genotype(s)
p^Y p^Y
Step 5
What term is used to describe the genotype of the black parents and offspring in cross 2?
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Answer
The term used to describe the genotype of the black parents and offspring in cross 2 is homozygous recessive, as both parents would have the genotype p^B p^B, resulting in all offspring also being black.
