Mitochondrial DNA (mtDNA) is a small circular DNA molecule located in mitochondria - AQA - A-Level Biology - Question 4 - 2019 - Paper 3

The student's conclusion states that training positively affects VO₂max and CS activity. However, while both measurements did increase, it's critical to note that there is no statistical test to confirm the significance of these differences. Thus, the observed changes might be due to the 8-week training duration rather than a direct effect of the training itself. The conclusion lacks sufficient evidence and is thus not entirely justified.

1. The mutation could lead to reduced mitochondrial replication or production, affecting the amount of mitochondrial proteins synthesized necessary for energy production.
2. There may be less transcription of genes involved in mitochondrial function, leading to decreased levels of CS activity.

The assertion that having thymine at nucleotide position 16 519 causes an increase in exercise ability is not conclusively supported by the data. Although Group T showed higher VO₂max and CS activity, correlation does not imply causation. Additionally, factors like individual training response and genetic diversity must be considered. Furthermore, more comprehensive experiments are needed to establish a direct relationship between the mutation and exercise performance.