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Asthma can be a serious medical condition that affects over 2.2 million Australians - VCE - SSCE Biology - Question 6 - 2004 - Paper 1
Question 6
Asthma can be a serious medical condition that affects over 2.2 million Australians. People with asthma may experience shortness of breath and wheezing due to narrow... show full transcript
Worked Solution & Example Answer:Asthma can be a serious medical condition that affects over 2.2 million Australians - VCE - SSCE Biology - Question 6 - 2004 - Paper 1
Step 1
In terms of genetic variation, how are identical twins different from nonidentical twins?
Answer
Identical twins (monozygotic) are genetically identical, as they come from a single fertilized egg that splits into two, sharing the same genetic material. Nonidentical twins (dizygotic), on the other hand, develop from two separate eggs fertilized by two separate sperm cells, resulting in siblings that share around 50% of their DNA, similar to regular siblings.
Step 2
Fill in the missing percentages of twin pairs that both develop asthma in column D of the table above.
Answer
The missing percentage for monozygotic twins is calculated as follows: In monozygotic twins, 25 pairs developed asthma out of 50 total pairs, resulting in a percentage of:
rac{25}{50} imes 100 = 50\\%
Thus, the entry for monozygotic twins in column D is 50%.
Step 3
From these results, are identical twins more or less likely to share a tendency to develop asthma than nonidentical twins?
Answer
Identical twins are more likely to share a tendency to develop asthma. The data shows that 50% of monozygotic twins developed asthma compared to 25% of dizygotic twins, indicating a stronger genetic influence in monozygotic twins.
Step 4
What evidence from the data suggests that the environment has a role in the development of asthma?
Answer
The evidence indicating environmental influence stems from the fact that 50% of identical twins do not develop asthma. Since they are genetically identical, the differences in asthma occurrence suggest that other factors, likely environmental, must contribute to the development of asthma.