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Consider the following pedigree - VCE - SSCE Biology - Question 1 - 2010 - Paper 1
Question 1
Consider the following pedigree. I II Molly (a) What is the mode of inheritance of the trait? (b) What is the chance that Molly is heterozygous for the trait? Sh... show full transcript
Worked Solution & Example Answer:Consider the following pedigree - VCE - SSCE Biology - Question 1 - 2010 - Paper 1
Step 1
Step 2
What is the chance that Molly is heterozygous for the trait? Show your working out including the genotype of Molly’s parents.
Answer
Molly's parents are heterozygous for the trait, indicated by both appearing in the pedigree without expressing the trait, implying that they each carry one recessive allele.
Assuming the following genotypes:
- Parent 1 (P1): Aa (heterozygous)
- Parent 2 (P2): Aa (heterozygous)
Using a Punnett square, the probabilities of the offspring are:
- AA: 25%
- Aa: 50%
- aa: 25%
Thus, the chance that Molly is heterozygous (Aa) is 50%.
Step 3
What is one other key difference between a eukaryotic and a prokaryotic chromosome?
Answer
One key difference is that eukaryotic chromosomes are linear and organized into chromatin, whereas prokaryotic chromosomes are circular and typically consist of a single chromosome that is not associated with histone proteins.
Step 4
What is one other key difference between a prokaryotic chromosome and a plasmid?
Answer
A prokaryotic chromosome is the main genetic material of the cell and contains essential genes for survival, while a plasmid is a small, circular piece of DNA that can replicate independently of the main chromosome and often carries genes that confer advantageous traits, such as antibiotic resistance.