The diagram below represents connections between parts of the male reproductive system - Scottish Highers Human Biology - Question 10 - 2016

To determine which arrow does not represent a male reproductive hormone, we need to analyze each connection. The Prostate Gland, Pituitary Gland, and Testes are linked by various hormones.

1. Prostate Gland and Pituitary Gland (Arrow A): This arrow likely represents the influence of hormones from the Pituitary Gland, such as Luteinizing Hormone (LH) or Follicle-Stimulating Hormone (FSH). These hormones directly impact male reproductive functions.

2. Testes and Pituitary Gland (Arrow C): This arrow represents hormones produced by the Testes, such as testosterone, which affects the secretion of LH and FSH from the Pituitary Gland.

3. Testes and Prostate Gland (Arrow B): This can represent the role of testosterone, which is produced by the Testes and influences the Prostate Gland.

4. Arrow D: Since this option wasn't analyzed in depth previously, we now recognize it might reference interactions that are not hormonal.

Based on the associations, it is clear that Arrow A is the one that does not directly represent a male reproductive hormone, as it is an effect of the hormones produced by the Pituitary Gland but does not convey a direct hormonal influence.