In the following pedigree the shaded individual has the trait under investigation - VCE - SSCE Biology - Question 1 - 2007 - Paper 1

To determine the mode of inheritance of the trait represented in the pedigree, we must analyze the pattern of inheritance displayed.

1. Identify the Individuals: In the pedigree, the shaded individual represents the affected individual. It is essential to observe the relationships and shading of other individuals in the pedigree to establish inheritance patterns.

2. Pattern Analysis:

   • If the trait is autosomal dominant, at least one affected parent must have the trait, with a 50% chance of passing it on to each child.
   • If the trait is autosomal recessive, an affected individual can be born to unaffected parents (carriers).
   • X-linked traits can appear more frequently in one sex than the other. For instance, X-linked recessive traits are often more common in males.

3. Conclusion: After analyzing the pedigree, if the affected individual has non-affected parents but can be passed to their offspring, it indicates an autosomal recessive inheritance. Therefore, the correct answer is B. autosomal recessive.